Device for separating air, oxygen and nitrogen based on krypton-xenon refined liquid

Abstract

The utility model discloses a device for separating oxygen and nitrogen based on krypton-xenon refined liquid air. The device comprises a liquid air storage tank, a liquid pump, a rectifying tower, a subcooler, a main heat exchanger, an oxygen heat exchanger, a liquid nitrogen storage tank, a liquid oxygen storage tank and a nitrogen circulating compressor. The liquid air storage tank is communicated with a liquid air inlet of a rectifying tower through a liquid pump, the rectifying tower separates oxygen, nitrogen and liquid oxygen, the nitrogen is partially circulated to a condensation evaporator after passing through a cooler and a main heat exchanger, and the other part is stored or sent to a krypton-xenon refining device as a liquid nitrogen product; the oxygen is partially emptied or connected into a pipe network after heat exchange, and the liquid oxygen is collected into a liquid oxygen storage tank. The liquid nitrogen supercooling channel is additionally arranged to reduce the vaporization rate, liquid air serves as raw materials, thermodynamic characteristics are fully utilized, the process is simplified, and energy consumption is reduced; the separated nitrogen is recycled, so that waste is avoided; and a cold source is provided by linkage with krypton-xenon refining, and gasified nitrogen is recycled. The device needs less equipment, is high in reliability, reduces the production and maintenance cost, and has remarkable economic and environment-friendly benefits.

Description

Technical Field

[0001] This utility model belongs to the field of liquid air energy storage technology, and relates to a device for oxygen and nitrogen separation based on krypton-xenon refined liquid air. Background Technology

[0002] Liquid air energy storage (LIFS) technology, as an emerging energy storage technology, operates on the principle of cooling air to extremely low temperatures through an air liquefaction device, transforming it into a liquid form for storage and use. This technology has attracted considerable attention due to its potential in energy storage and conversion. However, current applications of LIFS mainly focus on power generation and cold energy storage, such as using liquid air vaporization to drive turbines for power generation or recovering cold energy for refrigeration needs. While these applications demonstrate the value of LIFS to some extent, the development of its potential remains significantly insufficient, particularly in the direct use of liquid air for oxygen-nitrogen separation to obtain cryogenic liquid oxygen and nitrogen products. Currently, there are no mature precedents or technical solutions in this area, leaving research and practice in this field largely unexplored.

[0003] In existing technologies, liquid air energy storage systems typically utilize liquid air for a single purpose after power generation or cooling storage, resulting in low reuse efficiency and failing to fully exploit the potential inherent in the thermodynamic properties of liquid air. For example, in existing systems, after liquid air vaporization, large amounts of nitrogen are directly emitted or not effectively utilized, leading to resource waste and additional energy consumption. Furthermore, existing technologies lack targeted subcooling channels in the liquid air separation process, resulting in high vaporization rates of liquid nitrogen products during storage or transportation to downstream processes (such as krypton-xenon refining), insufficient liquid nitrogen extraction capacity, and consequently increased unit costs of liquid nitrogen products. This inefficient resource utilization limits the economic benefits of liquid air energy storage technology, making it difficult to meet diverse industrial needs.

[0004] Meanwhile, traditional all-liquid air separation (ALLS) technology uses ambient temperature air as feedstock, producing liquid oxygen and nitrogen products through complex processes such as compression, cooling, liquefaction, and distillation. While this technology is widely used in industrial gas production, its lengthy process requires pre-cooling and purification systems, resulting in a large number of devices, high investment costs, increased potential failure points, and poor operational reliability and maintenance economy. More importantly, traditional ALLS requires substantial external cooling, leading to high energy consumption, and fails to fully utilize the low-temperature characteristics of the feedstock during separation, resulting in high production and operating costs. In contrast, directly using liquid air as feedstock for oxygen and nitrogen separation not only eliminates the initial air liquefaction step but also leverages the low-temperature advantage of liquid air to reduce energy consumption. However, existing technologies lack corresponding device designs to achieve this goal, resulting in the untapped thermodynamic potential of liquid air.

[0005] Furthermore, existing liquid air energy storage technologies suffer from insufficient cold source supply and resource recycling when integrated with high-value-added processes such as krypton-xenon refining. For example, krypton-xenon refining requires cryogenic liquid nitrogen as a cold source, but in existing systems, the production and utilization efficiency of liquid nitrogen after vaporization is low, failing to meet the requirements of the refining process. Simultaneously, the nitrogen generated during the separation process is not recycled, further exacerbating energy waste. These problems limit the application of existing liquid air energy storage technologies in the field of oxygen and nitrogen separation, making it difficult to achieve the production goals of high efficiency, low cost, and environmental protection.

[0006] In summary, existing technologies for separating oxygen and nitrogen from liquid air suffer from the following main problems: First, they fail to fully utilize the thermodynamic properties of liquid air, resulting in low separation efficiency and high energy consumption; second, they lack subcooling designs for liquid nitrogen products, leading to high vaporization rates and insufficient extraction capacity, thus increasing product costs; third, the separated nitrogen is not recycled, resulting in significant resource waste; fourth, the efficiency of cold source supply and resource reuse is low when linked with krypton-xenon refining; and fifth, the process is complex, involves numerous pieces of equipment, and incurs high investment and maintenance costs, resulting in poor operational reliability. Therefore, a novel device is urgently needed to address these issues, achieving efficient separation and comprehensive resource utilization of liquid air, and promoting the further development of liquid air energy storage technology. Utility Model Content

[0007] In view of this, the purpose of this utility model is to solve the above problems and provide a device for separating oxygen and nitrogen from liquid air based on krypton-xenon refining.

[0008] To achieve the above objectives, this utility model provides the following technical solution:

[0009] An apparatus for separating liquid air oxygen and nitrogen based on krypton-xenon refining includes a liquid air storage tank, a liquid pump, a distillation column, a subcooler, a main heat exchanger, an oxygen heat exchanger, a liquid nitrogen storage tank, a liquid oxygen storage tank, and a nitrogen circulation compressor.

[0010] The distillation column includes a column body, structured packing material disposed within the column body, and a condenser-evaporator integrated at the bottom of the column body. The column body has six inlets / outlets: liquid nitrogen inlet, liquid air inlet, liquid oxygen outlet, oxygen outlet, nitrogen outlet, and waste nitrogen outlet. The subcooler has four sets of inlets / outlets: subcooler first inlet and subcooler first outlet, subcooler second inlet and subcooler second outlet, subcooler third inlet and subcooler third outlet, and subcooler fourth inlet and subcooler fourth outlet. The main heat exchanger has four sets of inlets / outlets: main heat exchanger first inlet and main heat exchanger first outlet, main heat exchanger second inlet and main heat exchanger second outlet, main heat exchanger third inlet and main heat exchanger third outlet, and main heat exchanger fourth inlet and main heat exchanger fourth outlet. The oxygen heat exchanger has two sets of inlets / outlets: oxygen heat exchanger first inlet and oxygen heat exchanger first outlet, and oxygen heat exchanger second inlet and oxygen heat exchanger second outlet.

[0011] The liquid air storage tank is connected to the liquid air inlet via a liquid pump. The nitrogen outlet is connected to the first inlet of the subcooler, and the first outlet of the subcooler is connected to the first inlet of the main heat exchanger. The first outlet of the main heat exchanger is connected to the inlet of the nitrogen circulation compressor. The outlet of the nitrogen circulation compressor is divided into two paths: one goes to the instrument gas, heating gas, and purge gas main pipe, and the other connects to the third inlet of the main heat exchanger. The third outlet of the main heat exchanger is connected to the inlet of the condenser-evaporator, and the outlet of the condenser-evaporator is divided into two paths: one connects to the second inlet of the subcooler, and the other connects to the third inlet of the subcooler. The second outlet of the subcooler is further divided into two paths: one connects to the liquid nitrogen inlet via a first throttle valve, and the other connects to the second inlet of the oxygen heat exchanger via a third throttle valve. The second outlet of the oxygen heat exchanger is connected to the inlet of the nitrogen circulation compressor. The third outlet of the subcooler is also divided into two paths: one goes to the krypton-xenon refining unit as a cold source, and the other connects to the liquid nitrogen storage tank via a second throttle valve.

[0012] The oxygen outlet is connected to the second inlet of the main heat exchanger, and the second outlet of the main heat exchanger is connected to the low-pressure oxygen pipeline or to the atmosphere for venting; the waste nitrogen outlet is connected to the fourth inlet of the subcooler, the fourth outlet of the subcooler is connected to the fourth inlet of the main heat exchanger, and the fourth outlet of the main heat exchanger is connected to the atmosphere for venting.

[0013] The first oxygen heat exchange inlet is connected to oxygen refined from krypton and xenon, and the first oxygen heat exchange outlet is connected to the liquid oxygen outlet after being combined with the liquid oxygen outlet through the fourth throttle valve.

[0014] Preferably, the distillation column is a structured packed reboiler absorption column.

[0015] Preferably, the liquid oxygen storage tank and the liquid nitrogen storage tank are both atmospheric pressure cryogenic liquid storage tanks.

[0016] Preferably, the liquid air storage tank is an atmospheric pressure cryogenic liquid storage tank.

[0017] Preferably, the liquid pump is a centrifugal cryogenic liquid pump.

[0018] Preferably, the condenser-evaporator is a fully immersed liquid oxygen plate-fin condenser-evaporator.

[0019] Preferably, the nitrogen recirculation compressor is a centrifugal nitrogen recirculation compressor.

[0020] Preferably, the main heat exchanger, subcooler, and oxygen heat exchanger are all plate-fin heat exchangers.

[0021] The beneficial effects of this utility model are as follows:

[0022] 1. The feature of this utility model is that a separate subcooling channel is added for liquid nitrogen products in the design of the subcooler, which reduces the vaporization rate of liquid nitrogen entering the storage tank and the krypton-xenon refining device, improves the liquid nitrogen product acquisition capacity of the device, and reduces the unit cost of liquid nitrogen products.

[0023] 2. This invention uses liquid air as raw material to directly separate oxygen and nitrogen, obtaining liquid oxygen and liquid nitrogen products, which is different from the traditional all-liquid air separation that uses air as raw material. When separating oxygen and nitrogen through liquid air, the thermodynamic properties of liquid air itself are fully utilized, and the entire process does not require the supplementation of external cooling, reducing the energy consumption of oxygen and nitrogen separation and improving the economic efficiency of oxygen and nitrogen separation.

[0024] 3. In the process of linkage with krypton-xenon refining, this utility model not only solves the problem of the need for cold source liquid nitrogen and the reuse of liquid nitrogen after vaporization in krypton-xenon refining, but also directly separates the liquid air obtained from liquid air energy storage into the required liquid oxygen and nitrogen products, while avoiding the waste of a large amount of nitrogen and the consumption of energy.

[0025] 4. This utility model utilizes liquid air for oxygen and nitrogen separation, and there is no emission of waste gas, wastewater, or dust during the production process.

[0026] 5. This utility model uses liquid air as raw material, and the oxygen-nitrogen separation process is simplified, eliminating the need for a pre-cooling system and a purification system. This reduces the number of equipment failure points, increases the reliability of equipment operation, and saves on overall investment and equipment maintenance costs.

[0027] 6. This utility model utilizes nitrogen gas after liquid-air separation as a heat source for recycling, eliminating the need for external replenishment and reducing production costs.

[0028] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is a schematic diagram of the device based on the separation of oxygen and nitrogen in a krypton-xenon purified liquid air.

[0031] Figure labels: 1-Distillation column; 2-Subcooler; 3-Main heat exchanger; 4-Liquid air storage tank; 5-Liquid pump; 6-Nitrogen circulating compressor; 7-Liquid oxygen storage tank; 8-Liquid nitrogen storage tank; 9-Oxygen heat exchanger; 11-Liquid nitrogen inlet; 12-Liquid air inlet; 13-Condenser / evaporator inlet; 14-Liquid oxygen outlet; 15-Condenser / evaporator outlet; 16-Oxygen outlet; 17-Sludge nitrogen outlet; 18-Nitrogen outlet; 25-First subcooler inlet; 22-Second subcooler inlet; 23-Third subcooler inlet; 24-Fourth subcooler outlet 21-First outlet of subcooler; 26-Second outlet of subcooler; 27-Third outlet of subcooler; 28-Fourth inlet of subcooler; 31-First inlet of main heat exchanger; 32-Second inlet of main heat exchanger; 33-Third outlet of main heat exchanger; 34-Fourth inlet of main heat exchanger; 35-First outlet of main heat exchanger; 36-Second outlet of main heat exchanger; 37-Third inlet of main heat exchanger; 38-Fourth outlet of main heat exchanger; 91-First outlet of oxygen heat exchanger; 92-Second inlet of oxygen heat exchanger; 93-First inlet of oxygen heat exchanger; 94-Second outlet of oxygen heat exchanger. Detailed Implementation

[0032] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] Please see Figure 1 The device is a liquid air oxygen-nitrogen separation device based on krypton-xenon refining, which includes a liquid air storage tank 4, a liquid pump 5, a distillation column 1, a subcooler 2, a main heat exchanger 3, an oxygen heat exchanger 9, a liquid nitrogen storage tank 8, a liquid oxygen storage tank 7, and a nitrogen circulation compressor 6.

[0036] The distillation column 1 includes a column body, structured packing material disposed within the column body, and a condenser / evaporator integrated at the bottom of the column body. The column body has six inlets / outlets: liquid nitrogen inlet 11, liquid air inlet 12, liquid oxygen outlet 14, oxygen outlet 16, nitrogen outlet 18, and waste nitrogen outlet 17. The subcooler 2 has three sets of inlets / outlets: subcooler first inlet 25, subcooler first outlet 21, subcooler second inlet 22, subcooler second outlet 26, subcooler third inlet 23, subcooler third outlet 27, and subcooler fourth outlet. Inlet 28, subcooler fourth outlet 24; the main heat exchanger 3 is provided with four sets of inlets and outlets, namely the main heat exchange first inlet 31, the main heat exchange first outlet 35, the main heat exchange second inlet 32, the main heat exchange second outlet 36, the main heat exchange third inlet 37, the main heat exchange third outlet 33, the main heat exchange fourth inlet 34, and the main heat exchange fourth outlet 38; the oxygen heat exchanger 9 is provided with two sets of inlets and outlets, namely the oxygen heat exchange first inlet 93, the oxygen heat exchange first outlet 91, the oxygen heat exchange second inlet 92, and the oxygen heat exchange second outlet 94.

[0037] The liquid air storage tank 4 is connected to the liquid air inlet 12 via the liquid pump 5. The nitrogen outlet 18 is connected to the first inlet 25 of the subcooler, and the first outlet 21 of the subcooler is connected to the first inlet 31 of the main heat exchanger. The first outlet 35 of the main heat exchanger is connected to the inlet 61 of the nitrogen circulation compressor. The outlet 62 of the nitrogen circulation compressor is divided into two paths: one path goes to the instrument gas, heating gas, and purge gas main pipe, and the other path is connected to the third inlet 37 of the main heat exchanger. The third outlet 33 of the main heat exchanger is connected to the inlet 13 of the condenser-evaporator, and the outlet 18 of the condenser-evaporator is connected to the inlet 12 of the main heat exchanger. 5 is divided into two paths: one path connects to the second inlet 22 of the subcooler, and the other path connects to the third inlet 23 of the subcooler. The second outlet 26 of the subcooler is also divided into two paths: one path connects to the liquid nitrogen inlet 11 via the first throttle valve V1, and the other path connects to the second inlet 92 of the oxygen heat exchanger via the third throttle valve V3. The second outlet 94 of the oxygen heat exchanger connects to the inlet 61 of the nitrogen circulation compressor. The third outlet 27 of the subcooler is also divided into two paths: one path goes to the krypton-xenon refining device as a cold source, and the other path connects to the liquid nitrogen storage tank 8 via the second throttle valve V2.

[0038] Oxygen outlet 16 is connected to the second inlet 32 ​​of the main heat exchanger, and the second outlet 36 of the main heat exchanger is connected to the low-pressure oxygen pipeline or to the atmosphere for venting; waste nitrogen outlet 17 is connected to the fourth inlet 28 of the subcooler, the fourth outlet 24 of the subcooler is connected to the fourth inlet 34 of the main heat exchanger, and the fourth outlet 38 of the main heat exchanger is connected to the atmosphere for venting.

[0039] The first oxygen heat exchange inlet 93 receives oxygen refined from krypton and xenon, and the first oxygen heat exchange outlet 91 is connected to the liquid oxygen outlet 14 via the fourth throttle valve V4 and then connected to the liquid oxygen storage tank 7.

[0040] As a preferred embodiment, in this case, the distillation column 1 is a structured packed reboiler absorption column. The liquid oxygen storage tank 7 and liquid nitrogen storage tank 8 are both atmospheric pressure cryogenic liquid storage tanks. The liquid air storage tank 4 is an atmospheric pressure cryogenic liquid storage tank. The liquid pump 5 is a centrifugal cryogenic liquid pump. The condenser-evaporator is a fully immersed liquid oxygen plate-fin condenser-evaporator. The nitrogen recirculation compressor 6 is a centrifugal nitrogen recirculation compressor. The main heat exchanger 3, subcooler 2, and oxygen heat exchanger 9 are all plate-fin heat exchangers.

[0041] Liquid air, obtained from liquefied air storage, is used as a raw material. After being pressurized by liquid pump 5, it is sent into distillation column 1 as reflux liquid to participate in distillation. Nitrogen gas obtained at the top of distillation column 1 is reheated to room temperature through main heat exchanger 3 and subcooler 2, then sent to nitrogen circulation compressor 6 for pressurization. Afterward, it enters main heat exchanger 3 for heat exchange and cooling, and then returns to the bottom condenser / evaporator of distillation column 1 to exchange heat with liquid oxygen. While partially evaporating the liquid oxygen, the nitrogen gas itself is condensed into liquid nitrogen. The liquid nitrogen exiting the bottom condenser / evaporator of distillation column is first divided into two paths, entering the second and third channels of subcooler 2 for subcooling. The cooled liquid nitrogen is then divided into two streams. One portion of the liquid nitrogen from the second channel of the subcooler is throttled and sent to distillation column 1 as reflux to continue distillation. The other portion is throttled and enters oxygen heat exchanger 9 to exchange heat with oxygen from krypton-xenon refining, converting gaseous oxygen into liquid oxygen, which is then sent to liquid oxygen storage tank 7. The liquid nitrogen itself is vaporized and merges with the ambient temperature nitrogen exiting the top of distillation column 1 and reheated by the main heat exchanger 3, entering nitrogen circulation compressor 6. Another portion of the liquid nitrogen from the third channel of the subcooler is throttled and sent to liquid nitrogen storage tank 8, while the other portion is sent to the krypton-xenon refining unit as a cold source. A small amount of oxygen product is also obtained at the bottom of distillation column 1 during the entire distillation process.

[0042] The nitrogen obtained from the distillation process is recycled, so that the entire unit does not consume additional nitrogen except during the start-up process. Only the nitrogen produced by the unit is recycled for its own use.

[0043] The device for separating oxygen and nitrogen from liquid air in krypton-xenon refining, when linked with krypton-xenon refining, not only solves the problem of needing cold source liquid nitrogen for krypton-xenon refining, but also directly separates the liquid air obtained from liquid air energy storage into the required liquid oxygen and nitrogen products, while avoiding the waste of a large amount of nitrogen and the consumption of energy.

[0044] The design of the unit includes a separate subcooling channel for liquid nitrogen products, which can significantly reduce the vaporization rate of liquid nitrogen entering the storage tank and the krypton-xenon refining unit, improve the unit's ability to obtain liquid nitrogen products, and reduce the unit cost of liquid nitrogen products.

[0045] In practice:

[0046] Liquid air is pressurized by a liquid pump and fed into the distillation column at a connection pressure of approximately 0.4 MPa (A), with a DN50 connection pipe. Nitrogen is pressurized by a nitrogen compressor and fed into the main heat exchanger at a connection pressure of approximately 0.55 MPa (A), with a DN200 connection pipe. Oxygen is drawn from the main heat exchanger and sent to the low-pressure oxygen network or vented, at a connection pressure of approximately 135 kPa (A), with a DN40 connection pipe. Liquid oxygen is sent to the liquid oxygen storage tank at a connection pressure of approximately 145 kPa (A), with a DN40 connection pipe. Liquid nitrogen is drawn from the subcooler and sent to the liquid nitrogen storage tank at a connection pressure of approximately 0.2 MPa (A), with a DN50 connection pipe.

[0047] The raw material used in this embodiment is: liquid air: 3000 Nm³ 3 / h (converted to gaseous state), 0.40MPa. Product obtained: Liquid nitrogen: 1700Nm³ 3 / h (converted to gaseous state); Liquid oxygen: 1000Nm 3 / h (converted to gaseous state); Oxygen: 29Nm 3 / h, 135kPa.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A device for separating oxygen and nitrogen in liquid air based on krypton-xenon refining, characterized in that: Includes liquid air storage tank, liquid pump, distillation column, subcooler, main heat exchanger, oxygen heat exchanger, liquid nitrogen storage tank, liquid oxygen storage tank, and nitrogen circulation compressor; The distillation column includes a column body, structured packing material disposed within the column body, and a condenser-evaporator integrated at the bottom of the column body. The column body has six inlets / outlets: liquid nitrogen inlet, liquid air inlet, liquid oxygen outlet, oxygen outlet, nitrogen outlet, and waste nitrogen outlet. The subcooler has four sets of inlets / outlets: subcooler first inlet and subcooler first outlet, subcooler second inlet and subcooler second outlet, subcooler third inlet and subcooler third outlet, and subcooler fourth inlet and subcooler fourth outlet. The main heat exchanger has four sets of inlets / outlets: main heat exchanger first inlet and main heat exchanger first outlet, main heat exchanger second inlet and main heat exchanger second outlet, main heat exchanger third inlet and main heat exchanger third outlet, and main heat exchanger fourth inlet and main heat exchanger fourth outlet. The oxygen heat exchanger has two sets of inlets / outlets: oxygen heat exchanger first inlet and oxygen heat exchanger first outlet, and oxygen heat exchanger second inlet and oxygen heat exchanger second outlet. The liquid air storage tank is connected to the liquid air inlet via a liquid pump. The nitrogen outlet is connected to the first inlet of the subcooler, and the first outlet of the subcooler is connected to the first inlet of the main heat exchanger. The first outlet of the main heat exchanger is connected to the inlet of the nitrogen circulation compressor. The outlet of the nitrogen circulation compressor is divided into two paths: one goes to the instrument gas, heating gas, and purge gas main pipe, and the other connects to the third inlet of the main heat exchanger. The third outlet of the main heat exchanger is connected to the inlet of the condenser-evaporator, and the outlet of the condenser-evaporator is divided into two paths: one connects to the second inlet of the subcooler, and the other connects to the third inlet of the subcooler. The second outlet of the subcooler is further divided into two paths: one connects to the liquid nitrogen inlet via a first throttle valve, and the other connects to the second inlet of the oxygen heat exchanger via a third throttle valve. The second outlet of the oxygen heat exchanger is connected to the inlet of the nitrogen circulation compressor. The third outlet of the subcooler is also divided into two paths: one goes to the krypton-xenon refining unit as a cold source, and the other connects to the liquid nitrogen storage tank via a second throttle valve. The oxygen outlet is connected to the second inlet of the main heat exchanger, and the second outlet of the main heat exchanger is connected to the low-pressure oxygen pipeline or to the atmosphere for venting; the waste nitrogen outlet is connected to the fourth inlet of the subcooler, the fourth outlet of the subcooler is connected to the fourth inlet of the main heat exchanger, and the fourth outlet of the main heat exchanger is connected to the atmosphere for venting. The first oxygen heat exchange inlet is connected to oxygen refined from krypton and xenon, and the first oxygen heat exchange outlet is connected to the liquid oxygen outlet via the fourth throttle valve.

2. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining as described in claim 1, characterized in that: The distillation column is a structured packed reboiler absorption column.

3. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining as described in claim 1, characterized in that: Both the liquid oxygen storage tank and the liquid nitrogen storage tank are atmospheric pressure cryogenic liquid storage tanks.

4. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining according to claim 1, characterized in that: The liquid air storage tank is an atmospheric pressure cryogenic liquid storage tank.

5. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining according to claim 1, characterized in that: The liquid pump is a centrifugal cryogenic liquid pump.

6. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining according to claim 1, characterized in that: The condenser-evaporator is a fully immersed liquid oxygen plate-fin condenser-evaporator.

7. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining according to claim 1, characterized in that: The nitrogen recirculation compressor is a centrifugal nitrogen recirculation compressor.

8. The apparatus for separating oxygen and nitrogen in liquid air based on krypton-xenon refining according to claim 1, characterized in that: The main heat exchanger, subcooler, and oxygen heat exchanger are all plate-fin heat exchangers.

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