Nitrogen storage tank liquid nitrogen recycling system

Abstract

The utility model relates to a nitrogen supply system, in particular to a system for recycling the cooling capacity and high-purity nitrogen of low-temperature high-purity nitrogen (conventionally directly discharged into the atmosphere) with liquid nitrogen naturally evaporated in a liquid nitrogen storage tank, which comprises the liquid nitrogen storage tank, a nitrogen supply system, a nitrogen supply system and a nitrogen supply system, and is characterized in that the liquid nitrogen storage tank is used for storing and supplying low-temperature liquid nitrogen; the air separation nitrogen generation system is used for extracting high-purity nitrogen through fractionation; and the liquid nitrogen reverse assisting pipeline is used for connecting the liquid nitrogen storage tank and the air separation nitrogen making system, and evaporated liquid nitrogen in the liquid nitrogen storage tank is conveyed into the air separation nitrogen making system through the liquid nitrogen reverse assisting pipeline. Gas-liquid high-purity nitrogen entrained in low-temperature liquid gas discharged from a liquid nitrogen storage tank is recovered and then is fed to a tower C1 and a tower C2 through a liquid nitrogen return assisting pipeline system, so that cold energy is provided for a high-purity rectifying tower, the nitrogen extraction rate is increased, the energy consumption is reduced, and nitrogen is recovered.

Description

Technical Field

[0001] The utility model relates to a nitrogen supply system, in particular to a system for recycling the cold and high-purity nitrogen produced by the natural evaporation of liquid nitrogen in a liquid nitrogen storage tank (conventionally, the nitrogen is directly discharged into the atmosphere). Background Art

[0002] In order to achieve uninterrupted gas supply, photovoltaic cells, lithium batteries and other industries are often equipped with a 24-hour backup system for liquid nitrogen storage. However, liquid nitrogen evaporation occurs in liquid nitrogen storage tanks, and conventional methods are to directly vent them, which wastes both nitrogen and cooling capacity. Therefore, finding a more efficient solution to achieve the rational use of cryogenic nitrogen will be an urgent problem to be solved in the industry.

[0003] The above information disclosed in the above background technology section is only used to enhance the understanding of the background technology of the technology described in this article. Therefore, the background technology may contain certain information that does not form the prior art known in this country to those skilled in the art. Utility Model Content

[0004] In order to solve the defects of the above-mentioned prior art, the utility model proposes a nitrogen storage tank liquid nitrogen recycling system, which recovers the gas-liquid high-purity nitrogen entrained in the low-temperature liquid gas discharged from the liquid nitrogen storage tank, and then returns it to the C1 tower and the C2 tower through the liquid nitrogen return auxiliary pipeline system, thereby providing cooling capacity for the high-purity distillation tower, improving the nitrogen extraction rate, reducing energy consumption, reducing energy consumption and recovering nitrogen.

[0005] The technical solution adopted by the utility model is as follows:

[0006] A nitrogen storage tank liquid nitrogen recycling system, characterized by comprising:

[0007] Liquid nitrogen storage tank: used to store and supply low-temperature liquid nitrogen;

[0008] Air separation nitrogen production system: extract high-purity nitrogen through fractional distillation;

[0009] Liquid nitrogen reverse assist pipeline: used to connect the liquid nitrogen storage tank and the air separation nitrogen production system. The evaporated liquid nitrogen in the liquid nitrogen storage tank is transported to the air separation nitrogen production system through the liquid nitrogen reverse assist pipeline.

[0010] There are two liquid nitrogen storage tanks, which are connected in parallel with the air separation nitrogen production system through a liquid nitrogen reverse auxiliary pipeline.

[0011] The liquid nitrogen reverse assist pipeline comprises an upper reverse assist pipe, a lower reverse assist pipe and a reverse assist main pipe. The upper reverse assist pipe and the lower reverse assist pipe are connected in parallel to one end of the reverse assist main pipe, and the other end of the reverse assist main pipe is connected to an air separation nitrogen making system.

[0012] The upper reverse auxiliary pipe is connected to the top of the liquid nitrogen storage tank for conveying the exhaust gas-liquid entrainment evaporated from the top of the liquid nitrogen storage tank, and the lower reverse auxiliary pipe is connected to the bottom of the liquid nitrogen storage tank for conveying the liquid nitrogen in the liquid nitrogen storage tank.

[0013] The upper reverse auxiliary pipe includes a main pipe and two groups of branch pipes arranged in parallel, the main pipe is connected to the reverse auxiliary main pipe, and the two groups of branch pipes arranged in parallel are respectively connected to each liquid nitrogen storage tank.

[0014] A check valve I is arranged on the lower reverse auxiliary pipe, and a check valve II is arranged on the main pipe.

[0015] A liquid nitrogen storage tank safety valve is provided on each set of branch pipes.

[0016] The air separation nitrogen production system consists of a C1 high-pressure tower primary distillation tower and a C2 low-pressure tower secondary distillation tower. The counter-assist main pipe is connected to the C1 high-pressure tower primary distillation tower. The C1 high-pressure tower primary distillation tower and the C2 low-pressure tower secondary distillation tower are also connected through pipelines I and II.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0018] In general, compared with the prior art, the nitrogen storage tank liquid nitrogen recycling system provided by the utility model recovers the gas-liquid high-purity nitrogen entrained in the cryogenic liquid gas discharged from the liquid nitrogen storage tank, and then returns the high-purity nitrogen to the C1 tower and the C2 tower through the liquid nitrogen return pipeline system, thereby providing cold capacity for the high-purity distillation tower, improving the nitrogen extraction rate, and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described by way of examples with reference to the accompanying drawings, in which:

[0020] Figure 1 This is a schematic diagram of the structure of the nitrogen storage tank liquid nitrogen recycling system in the utility model;

[0021] Figure 2 It is a structural schematic diagram of a nitrogen supply system in the prior art. DETAILED DESCRIPTION

[0022] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0023] Photovoltaic cells, lithium batteries and other industries need to be equipped with a 24-hour backup system to ensure uninterrupted gas supply. However, liquid nitrogen evaporation occurs in liquid nitrogen storage tanks. Figure 2 Conventionally, direct venting is adopted, which wastes both nitrogen and refrigeration capacity. Therefore, finding a more efficient solution to achieve the rational use of cryogenic nitrogen will be an urgent problem to be solved in the industry.

[0024] In view of the above technical problems, this embodiment provides a nitrogen storage tank liquid nitrogen recycling system, see Figure 1 ,include:

[0025] Liquid nitrogen storage tank 1: used to store and supply low-temperature liquid nitrogen.

[0026] Air separation nitrogen production system: extract high-purity nitrogen through distillation to meet production needs.

[0027] Liquid nitrogen return pipeline: used to connect the liquid nitrogen storage tank 1 and the air separation nitrogen production system. The liquid nitrogen at -194°C evaporated in the liquid nitrogen storage tank 1 is transported to the air separation nitrogen production system through the liquid nitrogen return pipeline system. The liquid nitrogen provides cooling capacity for the air separation nitrogen production system, thereby improving the nitrogen extraction rate and reducing energy consumption.

[0028] In a specific embodiment, two liquid nitrogen storage tanks 1 are provided, which are connected in parallel with the air separation nitrogen production system through a liquid nitrogen reverse auxiliary pipeline.

[0029] This design has the following advantages:

[0030] Redundancy and reliability: By setting up two liquid nitrogen storage tanks 1, when one storage tank fails or undergoes maintenance, it can ensure that the system can still operate stably, thereby improving the reliability of gas supply.

[0031] Load balancing: When two liquid nitrogen storage tanks 1 work in parallel, the supply of liquid nitrogen can be flexibly adjusted according to actual needs to avoid a reduction in efficiency due to overload of a single storage tank.

[0032] Increased cooling capacity: Two liquid nitrogen storage tanks 1 supply cryogenic nitrogen at the same time, which can increase the total flow of cryogenic nitrogen and improve the cooling capacity of the cryogenic nitrogen buffer tank.

[0033] Flexible configuration: The parallel design can flexibly adjust the amount of liquid nitrogen used according to production needs, adapt to different production situations, and improve the overall adaptability of the system.

[0034] In this embodiment, each liquid nitrogen storage tank 1 is also equipped with a liquid nitrogen level monitoring system and a temperature sensor to monitor the inventory and temperature of the liquid nitrogen in real time, and to intelligently adjust the supply of liquid nitrogen through the control system.

[0035] In a specific embodiment, the liquid nitrogen reverse auxiliary pipeline includes an upper reverse auxiliary pipe 5, a lower reverse auxiliary pipe 6 and a reverse auxiliary main pipe 7. The upper reverse auxiliary pipe 5 and the lower reverse auxiliary pipe 6 are connected in parallel to one end of the reverse auxiliary main pipe 7, and the other end of the reverse auxiliary main pipe 7 is connected to the air separation nitrogen production system.

[0036] Among them, the upper reverse auxiliary pipe 5 is connected to the top of the liquid nitrogen storage tank 1, and is used to transport the exhaust gas-liquid entrainment evaporated from the top of the liquid nitrogen storage tank 1. The lower reverse auxiliary pipe 6 is connected to the bottom of the liquid nitrogen storage tank 1, and is used to transport the liquid nitrogen in the liquid nitrogen storage tank 1. The exhaust gas-liquid entrainment and liquid nitrogen are mixed in the reverse auxiliary main pipe 7 and transported to the air separation nitrogen production system as a reflux liquid to participate in distillation.

[0037] A check valve Ⅰ8 is provided on the lower reverse auxiliary pipe 6, which can reverse flow when the main function fails to ensure the safety and stable operation of the system. The check valve can effectively prevent the liquid nitrogen in the liquid nitrogen storage tank 1 from flowing back due to pressure changes and maintain the pressure balance of the system.

[0038] In addition, the design of the liquid nitrogen reverse auxiliary pipeline should ensure the low temperature characteristics of the fluid and use high insulation materials to reduce cold loss.

[0039] In a further embodiment, the upward auxiliary pipe 5 includes a main pipe and two sets of branch pipes arranged in parallel. This structural design can effectively improve the safety and stability of the system, and is specifically described as follows:

[0040] Main pipe: The main pipe connecting the liquid nitrogen storage tank 1 and the anti-auxiliary main pipe 7 is responsible for the overall gas flow to ensure the effective transmission of low-temperature nitrogen.

[0041] Branch pipes: Two sets of branch pipes arranged in parallel are respectively connected to each liquid nitrogen storage tank 1 to ensure that when the system is running, low-temperature nitrogen can be evenly supplied from the two storage tanks to the reverse auxiliary main pipe 7.

[0042] In this embodiment, a check valve II 9 is provided on the main pipe, the main function of which is to prevent the cryogenic nitrogen from flowing back when the gas supply stops or a failure occurs, thereby ensuring the safe and stable operation of the system. The check valve can effectively prevent the liquid nitrogen in the liquid nitrogen storage tank 1 from flowing back due to pressure changes, thereby maintaining the pressure balance of the system.

[0043] A liquid nitrogen storage tank safety valve 4 is provided on each group of branch pipes, which is used to automatically open when the internal pressure of the liquid nitrogen storage tank 1 is too high to release excess pressure and prevent the liquid nitrogen storage tank 1 from being dangerous due to overpressure. The provision of the safety valve 4 enhances the safety of the system and ensures the safety of operators and equipment.

[0044] In the above implementation, not only the safety and reliability of the liquid nitrogen supply system are improved, but also the system can respond quickly to pressure changes during operation to avoid system failures or accidents caused by pressure problems. Through the cooperation of the check valve II9 and the safety valve 4, the entire system has good self-protection capabilities, which helps to achieve long-term stable low-temperature nitrogen supply, effectively improves the safety, stability and operational flexibility of the system, and provides a more reliable guarantee for the use of liquid nitrogen, which meets the requirements of modern industry for safety, efficiency and environmental protection.

[0045] In a specific embodiment, the air separation nitrogen production system is composed of a C1 high-pressure tower primary distillation tower 2 and a C2 low-pressure tower secondary distillation tower 3, the counter-assist main pipe 7 is connected to the C1 high-pressure tower primary distillation tower 2, and the C1 high-pressure tower primary distillation tower 2 and the C2 low-pressure tower secondary distillation tower 3 are also connected through pipeline Ⅰ11 and pipeline Ⅱ10. The pipeline Ⅰ11 is used to extract low-purity liquid nitrogen from the C1 high-pressure tower primary distillation tower 2 and transport it to the C2 low-pressure tower secondary distillation tower 3 for purification. The pipeline Ⅱ10 is used to transport the high-purity liquid nitrogen in the C2 low-pressure tower secondary distillation tower 3 to the C1 high-pressure tower primary distillation tower 2 as a reflux liquid to participate in distillation, thereby improving the nitrogen extraction rate.

[0046] As described above, the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A nitrogen storage tank liquid nitrogen recycling system, characterized in that: include: Liquid nitrogen storage tank (1): used to store and supply low-temperature liquid nitrogen; Air separation nitrogen production system: extract high-purity nitrogen through fractional distillation; Liquid nitrogen reverse assist pipeline: used to connect the liquid nitrogen storage tank (1) and the air separation nitrogen production system. The evaporated liquid nitrogen in the liquid nitrogen storage tank (1) is transported to the air separation nitrogen production system through the liquid nitrogen reverse assist pipeline.

2. A nitrogen storage tank liquid nitrogen recycling system according to claim 1, characterized in that: The liquid nitrogen storage tanks (1) are provided in two numbers, which are connected in parallel with each other and are connected to the air separation nitrogen production system via a liquid nitrogen reverse auxiliary pipeline.

3. The nitrogen storage tank liquid nitrogen recycling system according to claim 1, characterized in that: The liquid nitrogen reaction auxiliary pipeline comprises an upper reaction auxiliary pipe (5), a lower reaction auxiliary pipe (6) and a reaction auxiliary main pipe (7); the upper reaction auxiliary pipe (5) and the lower reaction auxiliary pipe (6) are connected to one end of the reaction auxiliary main pipe (7) in parallel, and the other end of the reaction auxiliary main pipe (7) is connected to an air separation nitrogen production system.

4. A nitrogen storage tank liquid nitrogen recycling system according to claim 3, characterized in that: The upper reverse auxiliary pipe (5) is connected to the top of the liquid nitrogen storage tank (1) and is used to transport the exhaust gas-liquid entrainment evaporated from the top of the liquid nitrogen storage tank (1). The lower reverse auxiliary pipe (6) is connected to the bottom of the liquid nitrogen storage tank (1) and is used to transport the liquid nitrogen in the liquid nitrogen storage tank (1).

5. The nitrogen storage tank liquid nitrogen recycling system according to claim 3, characterized in that: The upper reverse auxiliary pipe (5) comprises a main pipe and two groups of branch pipes arranged in parallel, the main pipe is connected to the reverse auxiliary main pipe (7), and the two groups of branch pipes arranged in parallel are respectively connected to each liquid nitrogen storage tank (1).

6. A nitrogen storage tank liquid nitrogen recycling system according to claim 5, characterized in that: A check valve I (8) is arranged on the lower auxiliary pipe (6), and a check valve II (9) is arranged on the main pipe.

7. The nitrogen storage tank liquid nitrogen recycling system according to claim 5, characterized in that: A liquid nitrogen storage tank safety valve (4) is provided on each group of branch pipes.

8. The nitrogen storage tank liquid nitrogen recycling system according to claim 3, characterized in that: The air separation nitrogen production system is composed of a C1 high-pressure tower primary distillation tower (2) and a C2 low-pressure tower secondary distillation tower (3). The counter-assist main pipe (7) is connected to the C1 high-pressure tower primary distillation tower (2). The C1 high-pressure tower primary distillation tower (2) and the C2 low-pressure tower secondary distillation tower (3) are also connected via pipeline I (11) and pipeline II (10).

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