Device for liquefying pipe network oxygen and nitrogen gas by using liquid air cold energy

Abstract

The utility model relates to a device for liquefying oxygen and nitrogen gas in a pipe network by using liquid air cold energy. The device comprises a main heat exchanger, a liquid oxygen storage tank, a liquid nitrogen storage tank, a liquid air normal pressure storage tank, a liquid air pump and a liquid air pressure storage tank. And the main heat exchanger is provided with four groups of inlets and outlets which are respectively connected with a high-pressure oxygen pipe network, a medium-pressure oxygen pipe network, a high-pressure nitrogen pipe network and a liquid air pressure storage tank. Oxygen and nitrogen exchange heat with liquid air in the main heat exchanger, and enter corresponding storage tanks after being cooled and liquefied; and the liquid air is led out after being gasified and is connected with an air separation device. According to the method, liquid oxygen, liquid nitrogen and compressed air products are obtained by liquefying oxygen and nitrogen in a pipe network through cold energy of liquid air, meanwhile, investment of cyclic compression refrigeration equipment is reduced, energy consumption is reduced, and the utilization rate of cold energy is increased. Compared with the prior art, the device has the advantages of low energy consumption, high efficiency, less equipment investment and environmental friendliness.

Description

Technical Field

[0001] The utility model belongs to the technical field of oxygen-nitrogen liquefaction production, and relates to a device for liquefying oxygen-nitrogen gas in a pipeline by using the cold energy of liquid air. Background Technique

[0002] With the acceleration of the industrialization process, as important industrial gases, the demand for oxygen and nitrogen is continuously increasing in many fields such as steel, chemical industry, electronic manufacturing, and aerospace. Oxygen is usually used as a combustion-supporting agent in steel smelting, an oxidation reaction agent in chemical production, and oxygen therapy in the medical field, etc.; nitrogen is widely used as a production protection gas for electronic components, a raw material gas for chemical synthesis, and food preservation, etc. In order to meet the demand for oxygen and nitrogen in these industries, the production and storage technologies of oxygen-nitrogen gas have gradually become the key links in the industrial gas supply chain.

[0003] Traditional oxygen-nitrogen gas liquefaction devices mainly rely on cyclic compression refrigeration liquefaction technology. This technology liquefies oxygen-nitrogen gas by circulating and compressing nitrogen gas and then cooling it through an expansion throttling process. However, this technical solution has the following main disadvantages:

[0004] 1. High energy consumption: The cyclic compression refrigeration equipment requires a large amount of electrical energy to drive the compressor, resulting in large energy consumption and high production costs of liquid oxygen and liquid nitrogen products.

[0005] 2. Large equipment investment: The structure of the cyclic compression refrigeration device is complex and includes multiple moving devices such as compressors, expanders, and heat exchangers. These devices not only have high manufacturing and maintenance costs but also require a large amount of space, increasing the overall equipment investment cost.

[0006] 3. Low efficiency: During the liquefaction process, due to the high pressure, the high-pressure liquid throttles and reduces pressure, resulting in large energy losses and restricting the operating efficiency of the entire system.

[0007] To solve the above problems, in recent years, some researchers have begun to explore using the cold energy of liquid air (liquid oxygen) as a new liquefaction method. As a cold energy carrier, liquid air releases a large amount of cold energy during the gasification process. If this cold energy can be fully utilized to liquefy oxygen-nitrogen gas, the production costs of liquid oxygen and liquid nitrogen will be significantly reduced, and the energy utilization efficiency of the system will be improved.

[0008] However, there are still deficiencies in the utilization of liquid air cold energy in the existing technology. First, the utilization rate of liquid air cold energy is low, and the full recovery of low-temperature energy cannot be achieved. Second, the compressed air generated during the gasification of liquid air is usually not effectively utilized, resulting in energy waste. Content of the Utility Model

[0009] In view of this, the purpose of the present utility model is to solve the above problems and provide a device for liquefying oxygen and nitrogen gases in a pipeline network by using the cold energy of liquid air.

[0010] To achieve the above purpose, the present utility model provides the following technical solutions:

[0011] A device for liquefying oxygen and nitrogen gases in a pipeline network by using the cold energy of liquid air, comprising a main heat exchanger, a liquid oxygen storage tank, a liquid nitrogen storage tank, a liquid air atmospheric storage tank, a liquid air pump and a liquid air pressure storage tank;

[0012] The main heat exchanger is provided with four groups of inlets and outlets, namely a first heat exchange inlet and a first heat exchange outlet, a second heat exchange inlet and a second heat exchange outlet, a third heat exchange inlet and a third heat exchange outlet, and a fourth heat exchange inlet and a fourth heat exchange outlet;

[0013] The first heat exchange inlet is connected to a high-pressure oxygen pipeline network, and the first heat exchange outlet is communicated with the liquid oxygen storage tank through a throttle valve V1; the second heat exchange inlet is connected to a medium-pressure oxygen pipeline network, and the second heat exchange outlet is communicated with the liquid oxygen storage tank through a throttle valve V2; the third heat exchange inlet is connected to a high-pressure nitrogen pipeline network, and the third heat exchange outlet is communicated with the liquid nitrogen storage tank through a throttle valve V3; the fourth heat exchange inlet is connected to the liquid air pressure storage tank, and the fourth heat exchange outlet is communicated with an external air separation device through a pipeline; the liquid air pressure storage tank is communicated with the liquid air atmospheric storage tank through a liquid air pump;

[0014] The high-pressure oxygen from the high-pressure oxygen pipeline network, the medium-pressure oxygen from the medium-pressure oxygen pipeline network and the high-pressure nitrogen from the high-pressure nitrogen pipeline network all exchange heat with the liquid air from the liquid air pressure storage tank in the main heat exchanger. After being cooled, liquefied and subcooled, the high-pressure oxygen, medium-pressure oxygen and high-pressure nitrogen are led out from the main heat exchanger and respectively enter the liquid oxygen storage tank and the liquid nitrogen storage tank, and the liquid air is led out from the main heat exchanger after being vaporized and reheated.

[0015] Further, the liquid oxygen storage tank is provided with four inlets and outlets, namely a first liquid oxygen inlet, a second liquid oxygen inlet, a liquid oxygen outlet and an oxygen outlet; the first heat exchange outlet is communicated with the first liquid oxygen inlet, and the second heat exchange outlet is communicated with the second liquid oxygen inlet.

[0016] Further, the liquid nitrogen storage tank is provided with three inlets and outlets, namely a liquid nitrogen inlet, a liquid nitrogen outlet and a nitrogen outlet; the third heat exchange outlet is communicated with the liquid nitrogen inlet.

[0017] Further, both the liquid air atmospheric storage tank and the liquid air pressure storage tank are provided with three inlets and outlets, namely a liquid air inlet, a liquid air outlet and an air outlet.

[0018] The beneficial effects of the present utility model are as follows:

[0019] 1. The utility model liquefies high-pressure oxygen, medium-pressure oxygen, and high-pressure nitrogen in the pipe network through the cold energy of liquid air to obtain liquid products, reducing the dynamic equipment for circulating compression refrigeration in the liquefaction device and reducing equipment investment.

[0020] 2. The utility model recovers the cold energy of liquid air with high-pressure oxygen, medium-pressure oxygen, and high-pressure nitrogen, and the low-temperature energy is fully utilized.

[0021] 3. In the utility model, the compressed air after the liquid air is vaporized enters the air separation device to replace part of the raw air compressed by the air compressor, reducing the energy consumption of the air compressor.

[0022] 4. The utility model can use the liquid air pressure storage tank to temporarily store liquid air, vaporize it only when the pipe network pressure is on the high side, realize the timely adjustment of the pipe network pressure, and reduce the emission of oxygen and nitrogen gases.

[0023] 5. The utility model uses the cold energy of liquid air to produce liquid oxygen and liquid nitrogen products, and at the same time obtains compressed air, which has a higher efficiency than using liquid air vaporization to generate electricity in the field of liquid air energy storage.

[0024] 6. The utility model uses the liquid products obtained by liquefying the oxygen and nitrogen gases that are about to be emitted in the pipe network with liquid air. It has no additional energy consumption itself, and the cost of the liquid is lower.

[0025] 7. The utility model connects high-pressure oxygen, medium-pressure oxygen, and high-pressure nitrogen to the device at the same time, which is conducive to arbitrarily matching the proportions of products with different pressure grades and different media, and stepless adjustment within the full load range.

[0026] Other advantages, objectives, and features of the utility model will be described to some extent in the subsequent description, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the utility model. The objectives and other advantages of the utility model can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the objectives, technical solutions, and advantages of the utility model clearer, the utility model will be described in detail preferably with reference to the accompanying drawings, where:

[0028] Figure 1 It is the schematic diagram of the device in Embodiment 1 of the utility model.

[0029] Figure 2 It is the schematic diagram of the device in Embodiment 2 of the utility model.

[0030] Figure 3 It is the schematic diagram of the device in Embodiment 3 of the utility model.

[0031] Figure 4This is the schematic diagram of the device in the fourth embodiment of the present utility model.

[0032] Reference numerals: 1 - main heat exchanger; 11 - first heat exchange inlet; 12 - first heat exchange outlet; 13 - second heat exchange inlet; 14 - second heat exchange outlet; 15 - third heat exchange inlet; 16 - third heat exchange outlet; 17 - fourth heat exchange inlet; 18 - fourth heat exchange outlet; 2 - liquid oxygen storage tank; 21 - first liquid oxygen inlet; 22 - second liquid oxygen inlet; 23 - oxygen outlet; 24 - liquid oxygen outlet; 3 - liquid nitrogen storage tank; 31 - liquid nitrogen inlet; 32 - liquid nitrogen outlet; 33 - nitrogen outlet; 4 - liquid air atmospheric storage tank; 41 - liquid air inlet; 42 - liquid air outlet; 43 - air outlet; 5 - liquid air pump; 6 - liquid air pressure storage tank; 61 - liquid air inlet; 62 - liquid air outlet; 63 - air outlet. Detailed implementation manners

[0033] The following uses specific specific examples to illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0034] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as limitations on the present utility model; in order to better illustrate the embodiments of the present utility model, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual products; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0035] In the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as limitations on the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] Embodiment 1

[0037] Please refer toFigure 1 , which is a device for liquefying oxygen and nitrogen gases in a pipeline network by using the cold energy of liquid air, including a main heat exchanger 1, a liquid oxygen storage tank 2, a liquid nitrogen storage tank 3, a liquid air atmospheric storage tank 4, a liquid air pump 5 and a liquid air pressure storage tank 6;

[0038] The main heat exchanger 1 is provided with four groups of inlets and outlets, namely a first heat exchange inlet 11 and a first heat exchange outlet 12, a second heat exchange inlet 13 and a second heat exchange outlet 14, a third heat exchange inlet 15 and a third heat exchange outlet 16, and a fourth heat exchange inlet 17 and a fourth heat exchange outlet 18;

[0039] The first heat exchange inlet 11 is connected to a high-pressure oxygen pipeline network, and the first heat exchange outlet 12 is communicated with the liquid oxygen storage tank 2 through a throttle valve V1; the second heat exchange inlet 13 is connected to a medium-pressure oxygen pipeline network, and the second heat exchange outlet 14 is communicated with the liquid oxygen storage tank 2 through a throttle valve V2; the third heat exchange inlet 15 is connected to a high-pressure nitrogen pipeline network, and the third heat exchange outlet 16 is communicated with the liquid nitrogen storage tank 3 through a throttle valve V3; the fourth heat exchange inlet 17 is connected to the liquid air pressure storage tank 6, and the fourth heat exchange outlet 18 is communicated with an external air separation device through a pipeline; the liquid air pressure storage tank 6 is communicated with the liquid air atmospheric storage tank 4 through the liquid air pump 5;

[0040] The high-pressure oxygen from the high-pressure oxygen pipeline network, the medium-pressure oxygen from the medium-pressure oxygen pipeline network and the high-pressure nitrogen from the high-pressure nitrogen pipeline network all exchange heat with the liquid air from the liquid air pressure storage tank 6 in the main heat exchanger 1. The high-pressure oxygen, medium-pressure oxygen and high-pressure nitrogen are led out from the main heat exchanger 1 after being cooled, liquefied and subcooled, and the liquid air is led out from the main heat exchanger 1 after being vaporized and reheated.

[0041] The liquid oxygen storage tank 2 is provided with four inlets and outlets, namely a first liquid oxygen inlet 21, a second liquid oxygen inlet 22, a liquid oxygen outlet 24 and an oxygen outlet 23; the first heat exchange outlet 12 is communicated with the first liquid oxygen inlet 21, and the second heat exchange outlet 14 is communicated with the second liquid oxygen inlet 22.

[0042] The liquid nitrogen storage tank 3 is provided with three inlets and outlets, namely a liquid nitrogen inlet 31, a liquid nitrogen outlet 32 and a nitrogen outlet 33; the third heat exchange outlet 16 is communicated with the liquid nitrogen inlet 31.

[0043] The liquid air atmospheric storage tank 4 is provided with three inlets and outlets, namely a liquid air inlet 41, a liquid air outlet 42 and an air outlet 43. The liquid air pressure storage tank 6 is provided with three inlets and outlets, namely a liquid air inlet 61, a liquid air outlet 62 and an air outlet 63.

[0044] Adopt the device for liquefying oxygen and nitrogen gases in the pipe network by utilizing the cold energy of liquid air as above, and utilize the cold energy of liquid air to liquefy high-pressure oxygen, medium-pressure oxygen and high-pressure nitrogen in the pipe network to obtain liquid oxygen and liquid nitrogen products, and at the same time obtain compressed air products. The obtained compressed air products are connected to the air separation unit to replace part of the dry and clean raw air in the air separation unit; the pressure of the obtained compressed air products is 0.6 - 0.7 MPa.

[0045] The working process in this embodiment is as follows:

[0046] High-pressure oxygen GO11 is introduced into the main heat exchanger 1 through the high-pressure oxygen pipe network. The high-pressure liquid oxygen LO12 after being cooled, liquefied and subcooled is throttled by the throttle valve V1 to obtain liquid oxygen product LO13 and enter the liquid oxygen storage tank 2; medium-pressure oxygen GO21 is introduced into the main heat exchanger 1 through the medium-pressure oxygen pipe network. The medium-pressure liquid oxygen LO22 after being cooled, liquefied and subcooled is throttled by the throttle valve V2 to obtain liquid oxygen product LO23 and enter the liquid oxygen storage tank 2; high-pressure nitrogen GN11 is introduced into the main heat exchanger 1 through the high-pressure nitrogen pipe network. The high-pressure liquid nitrogen LN12 after being cooled, liquefied and subcooled is throttled by the throttle valve V3 to obtain liquid nitrogen product LN13 and enter the liquid nitrogen storage tank 3.

[0047] LAir22 pressurized by the liquid air pump 5 from the liquid air atmospheric storage tank 4 enters the liquid air pressure storage tank 6 for temporary storage. When the oxygen and nitrogen pressure in the pipe network is on the high side, the pressurized liquid air LAir23 enters the main heat exchanger 1, and the medium-pressure air GAir12 after gasification and reheating is sent through the pipeline to the air pipeline after the molecular sieve purifier of the air separation unit to replace part of the dry and clean air.

[0048] Embodiment 2

[0049] Please refer to Figure 2 , which is a device for liquefying nitrogen in the pipe network by utilizing the cold energy of liquid air, and is a simplified version of the liquid air cold energy liquefaction device, including a main heat exchanger 1 and a liquid air pump 5;

[0050] Two groups of inlets and outlets are arranged on the main heat exchanger 1, namely the first heat exchange inlet 11 and the first heat exchange outlet 12, the second heat exchange inlet 13 and the second heat exchange outlet 14;

[0051] The first heat exchange inlet 11 is connected to the high-pressure nitrogen pipe network, and the first heat exchange outlet 12 is connected to the liquid nitrogen storage tank through the throttle valve V1; the second heat exchange inlet 13 is connected to the outlet of the liquid air pump 5, and the second heat exchange outlet 14 is connected to the external air separation unit through the pipeline; the inlet of the liquid air pump is connected to the liquid air atmospheric storage tank;

[0052] The high-pressure nitrogen from the high-pressure nitrogen pipe network exchanges heat with the liquid air from the liquid air pump in the main heat exchanger 1. The high-pressure nitrogen is led out from the main heat exchanger 1 after being cooled, liquefied and subcooled, and the liquid air is led out from the main heat exchanger 1 after gasification and reheating.

[0053] Using the device for liquefying nitrogen in the pipe network by utilizing the cold energy of liquid air as described above, the cold energy of liquid air is used to liquefy the high-pressure nitrogen in the pipe network to obtain liquid nitrogen products, and at the same time, compressed air products are obtained. The obtained compressed air products are connected to the air separation unit to replace part of the dry and clean raw air in the air separation unit; the pressure of the obtained compressed air products is 0.6 - 0.7 MPa.

[0054] The working process in this embodiment is as follows:

[0055] The high-pressure nitrogen is introduced into the main heat exchanger 1 through the high-pressure nitrogen pipe network. After being cooled, liquefied, and subcooled, the high-pressure liquid nitrogen passes through the throttle valve V1 and then enters the liquid nitrogen storage tank to obtain liquid nitrogen products.

[0056] The pressurized liquid air from the liquid air pump enters the main heat exchanger 1. The medium-pressure air after gasification and reheating is sent through the pipeline to the air pipeline after the molecular sieve purifier of the air separation unit to replace part of the dry and clean air.

[0057] Embodiment III

[0058] Please refer to Figure 3 , which is a device for liquefying oxygen in the pipe network by utilizing the cold energy of liquid air and is another simplified version of the liquid air cold energy liquefaction device. It also includes a main heat exchanger 1 and a liquid air pump 5;

[0059] There are two groups of inlets and outlets on the main heat exchanger 1, namely the first heat exchange inlet 11 and the first heat exchange outlet 12, and the second heat exchange inlet 13 and the second heat exchange outlet 14;

[0060] The first heat exchange inlet 11 is connected to the high-pressure or medium-pressure oxygen pipe network. The first heat exchange outlet 12 is connected to the liquid oxygen storage tank through the throttle valve V1; the second heat exchange inlet 13 is connected to the outlet of the liquid air pump 5, and the second heat exchange outlet 14 is connected to the external air separation unit through the pipeline; the inlet of the liquid air pump is connected to the liquid air atmospheric storage tank;

[0061] The oxygen from the high-pressure or medium-pressure oxygen pipe network exchanges heat with the liquid air from the liquid air pump in the main heat exchanger 1. The high-pressure or medium-pressure oxygen is led out from the main heat exchanger 1 after being cooled, liquefied, and subcooled, and the liquid air is led out from the main heat exchanger 1 after gasification and reheating.

[0062] Using the device for liquefying oxygen in the pipe network by utilizing the cold energy of liquid air as described above, the cold energy of liquid air is used to liquefy the high-pressure or medium-pressure oxygen in the pipe network to obtain liquid oxygen products, and at the same time, compressed air products are obtained. The obtained compressed air products are connected to the air separation unit to replace part of the dry and clean raw air in the air separation unit; the pressure of the obtained compressed air products is 0.6 - 0.7 MPa.

[0063] The working process in this embodiment is as follows:

[0064] High-pressure or medium-pressure oxygen is introduced into the main heat exchanger 1 through the oxygen pipeline network. The high-pressure or medium-pressure liquid oxygen after being cooled, liquefied and subcooled is throttled by the throttle valve V1 to obtain liquid oxygen products and enter the liquid oxygen storage tank.

[0065] The pressurized liquid air from the liquid air pump enters the main heat exchanger 1. The medium-pressure air after gasification and reheating is sent through the pipeline to the air pipeline after the molecular sieve purifier of the air separation unit to replace part of the dry and clean air.

[0066] Example 4

[0067] Please refer to Figure 4 , which is a device for liquefying the oxygen in the pipeline network by using the cold energy of liquid air, including the main heat exchanger 1, the liquid air pump 5, and the liquid air pressure storage tank 6;

[0068] There are two groups of inlets and outlets on the main heat exchanger 1, namely the first heat exchange inlet 11 and the first heat exchange outlet 12, the second heat exchange inlet 13 and the second heat exchange outlet 14;

[0069] The first heat exchange inlet 11 is connected to the high-pressure or medium-pressure oxygen pipeline network, and the first heat exchange outlet 12 is connected to the liquid oxygen storage tank through the throttle valve V1; the second heat exchange inlet 13 is connected to the liquid air outlet 62, the liquid air inlet 61 is connected to the outlet of the liquid air pump 5, the air outlet 63 is connected to the atmosphere, and the second heat exchange outlet 14 is connected to the external air separation unit through the pipeline; the inlet of the liquid air pump is connected to the normal-pressure liquid air storage tank;

[0070] When the pipeline network pressure is on the high side, the oxygen from the high-pressure or medium-pressure oxygen pipeline network exchanges heat with the liquid air from the liquid air pressure storage tank 6 in the main heat exchanger 1. The high-pressure or medium-pressure oxygen is led out from the main heat exchanger 1 after being cooled, liquefied and subcooled, and the liquid air is led out from the main heat exchanger 1 after being gasified and reheated; the liquid air pump 5 starts when the liquid level in the liquid air pressure storage tank 6 is on the low side to supplement the liquid level of the liquid air pressure storage tank 6.

[0071] Using the device for liquefying the oxygen in the pipeline network as above, the cold energy of the liquid air is used to liquefy the high-pressure or medium-pressure oxygen in the pipeline network to obtain liquid oxygen products, and at the same time, compressed air products are obtained. The obtained compressed air products are connected to the air separation unit to replace part of the dry and clean raw material air in the air separation unit; the pressure of the obtained compressed air products is 0.6 - 0.7 MPa. Since it is connected to the liquid air pressure storage tank, the start-up time of the liquefaction device is greatly shortened, and the timeliness of adjusting the pipeline network pressure is improved.

[0072] The working process in this embodiment is as follows:

[0073] High-pressure or medium-pressure oxygen is introduced into the main heat exchanger 1 through the oxygen pipeline network. The high-pressure or medium-pressure liquid oxygen after being cooled, liquefied and subcooled is throttled by the throttle valve V1 to obtain liquid oxygen products and enter the liquid oxygen storage tank.

[0074] The pressurized liquid air from the liquid air pump 5 enters the liquid air pressure storage tank 6 for storage and standby. When the pipeline network pressure is on the high side, the liquid air in the liquid air pressure storage tank 6 enters the main heat exchanger 1, and the medium-pressure air after gasification and reheating is sent through the pipeline to the air pipeline after the molecular sieve purifier of the air separation unit to replace part of the dry and clean air.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An apparatus for liquefying oxygen and nitrogen gases in a pipe network by utilizing the cold energy of liquid air, characterized in that: It includes a main heat exchanger, a liquid oxygen storage tank, a liquid nitrogen storage tank, a liquid air atmospheric storage tank, a liquid air pump and a liquid air pressure storage tank; The main heat exchanger is provided with four groups of inlets and outlets, namely a first heat exchange inlet and a first heat exchange outlet, a second heat exchange inlet and a second heat exchange outlet, a third heat exchange inlet and a third heat exchange outlet, and a fourth heat exchange inlet and a fourth heat exchange outlet; The first heat exchange inlet is connected to a high-pressure oxygen pipeline network, and the first heat exchange outlet is communicated with the liquid oxygen storage tank through a throttle valve V1; the second heat exchange inlet is connected to a medium-pressure oxygen pipeline network, and the second heat exchange outlet is communicated with the liquid oxygen storage tank through a throttle valve V2; the third heat exchange inlet is connected to a high-pressure nitrogen pipeline network, and the third heat exchange outlet is communicated with the liquid nitrogen storage tank through a throttle valve V3; the fourth heat exchange inlet is connected to the liquid air pressure storage tank, and the fourth heat exchange outlet is communicated with an external air separation device through a pipeline; the liquid air pressure storage tank is communicated with the liquid air atmospheric storage tank through a liquid air pump; High-pressure oxygen from the high-pressure oxygen pipeline network, medium-pressure oxygen from the medium-pressure oxygen pipeline network and high-pressure nitrogen from the high-pressure nitrogen pipeline network all perform heat exchange with liquid air from the liquid air pressure storage tank in the main heat exchanger. The high-pressure oxygen, medium-pressure oxygen and high-pressure nitrogen are led out from the main heat exchanger after being cooled, liquefied and subcooled, and enter the liquid oxygen storage tank and the liquid nitrogen storage tank respectively. The liquid air is led out from the main heat exchanger after being vaporized and reheated.

2. The device for liquefying oxygen and nitrogen gases in a pipeline network using the cold energy of liquid air according to claim 1, characterized in that: The liquid oxygen storage tank is provided with four inlets and outlets, namely a first liquid oxygen inlet, a second liquid oxygen inlet, a liquid oxygen outlet and an oxygen outlet; the first heat exchange outlet is communicated with the first liquid oxygen inlet, and the second heat exchange outlet is communicated with the second liquid oxygen inlet.

3. The device for liquefying oxygen and nitrogen gases in a pipe network by utilizing the liquid air cooling energy according to claim 1, wherein: The liquid nitrogen storage tank is provided with three inlets and outlets, namely a liquid nitrogen inlet, a liquid nitrogen outlet and a nitrogen outlet; the third heat exchange outlet is communicated with the liquid nitrogen inlet.

4. The device for liquefying oxygen and nitrogen gases in a pipe network by utilizing the liquid air cooling energy according to claim 1, wherein: Both the liquid air atmospheric storage tank and the liquid air pressure storage tank are provided with three inlets and outlets, namely a liquid air inlet, a liquid air outlet and an air outlet.

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