Peak regulation type device for preparing high-purity nitrogen through low-temperature rectification

Abstract

The utility model provides a peak regulation type device for preparing high-purity nitrogen through low-temperature rectification, which can provide a 30-120% load regulation working condition under the conditions of not reducing the nitrogen extraction rate and not increasing nitrogen emptying, is simple in load regulation working condition transformation, quick in response, stable in operation after working condition transformation, and capable of quickly responding to the change of nitrogen demand, and has a wide application prospect. The investment cost and the operation energy consumption are reduced. The main heat exchanger is connected with the first rectifying tower, the first rectifying tower is connected with the subcooler, and the subcooler is connected with the main condensation evaporator. The rectifying tower I is connected with the main condensing evaporator and the main heat exchanger; the main condensing evaporator is connected with the rectifying tower I, the rectifying tower II and the auxiliary condensing evaporator; the rectifying tower II is connected with the auxiliary condensation evaporator; the rectifying tower II is connected with the rectifying tower I; the auxiliary condensation evaporator is connected with the subcooler, and the subcooler is connected with the main heat exchanger; the rectifying tower II is connected with the liquid nitrogen subcooler; the liquid nitrogen subcooler is connected with the vacuum storage tank, and the vacuum storage tank is connected with the first rectifying tower.

Description

Technical Field

[0001] The utility model relates to a peak-shaving low-temperature distillation device for preparing high-purity nitrogen. Background Art

[0002] With the development of the hydrogen energy industry, we have been using wind and solar power generation, combined with water electrolysis to provide hydrogen, and air separation nitrogen production equipment to extract nitrogen. Hydrogen and nitrogen are used as synthetic ammonia raw materials to synthesize ammonia to meet the development needs of the green chemical industry.

[0003] Due to the instability of wind or solar power generation, the output of hydrogen produced by water electrolysis also fluctuates, and the demand for nitrogen, another raw gas required for synthetic ammonia, also fluctuates. It is usually required that the nitrogen production device can provide a load adjustment capacity of 30%-120% to meet the uninterrupted production of synthetic ammonia.

[0004] At present, the common process flow of low-temperature nitrogen production equipment on the market is mainly divided into single-tower nitrogen production and double-tower nitrogen production. Although the single-tower nitrogen production has a simple structure, it has a low product extraction rate and high product unit consumption, which is not suitable for large-scale nitrogen demand. The double-tower nitrogen production process has a high nitrogen extraction rate and lower unit energy consumption than the single-tower nitrogen production, but the liquid nitrogen output is small, and the backup system has a weak peak-shaving nitrogen supply capacity. Generally, it is necessary to increase the scale of nitrogen production to meet the peak demand for gas, but the excess nitrogen must be vented when the gas demand is low. The load adjustment capacity of the above two air separation nitrogen production devices is 75%-105%, which is quite different from the market demand. When the demand for nitrogen is low, the low load condition can only be solved by venting the product nitrogen. The nitrogen emission rate is high, which is not conducive to economical and efficient operation. In order to meet the demand for nitrogen during peak hours, it is necessary to set up a buffer tank with a larger capacity or adopt a backup system liquid nitrogen vaporization to meet the demand, which increases investment costs and operating energy consumption. Utility Model Content

[0005] The purpose of the utility model is to overcome the above-mentioned deficiencies in the prior art and to provide a peak-shaving type low-temperature distillation device for preparing high-purity nitrogen with a reasonable structural design, which can provide a load adjustment condition of 30%-120% without reducing the nitrogen extraction rate or increasing the nitrogen venting. The load adjustment condition is simple to change, the response is rapid, and the operation is stable after the condition is changed. It can quickly respond to changes in nitrogen demand and reduce investment costs and operating energy consumption.

[0006] The technical solution adopted by the utility model to solve the above-mentioned problems is: a peak-shaving low-temperature distillation device for preparing high-purity nitrogen, including a low-temperature distillation unit; the low-temperature distillation unit includes a main heat exchanger, a distillation tower, a main condenser evaporator, a subcooler, a distillation tower, an auxiliary condenser evaporator and a liquid nitrogen subcooler; the hot runner outlet of the main heat exchanger is connected to the inlet of the distillation tower, the liquid air outlet of the distillation tower is connected to the hot runner inlet of the subcooler, and the hot runner outlet of the subcooler is connected to the liquid inlet of the main condenser evaporator; the gas outlet of the distillation tower is respectively connected to the inlet of the main condenser evaporator and the cold runner inlet of the main heat exchanger, and the outlet of the main condenser evaporator is connected to the upper part of the distillation tower; the gas outlet of the main condenser evaporator is connected to the gas inlet of the distillation tower, and the liquid outlet of the main condenser evaporator is connected to the auxiliary condenser evaporator. The liquid inlet of the distillation tower is connected; the liquid air outlet of the distillation tower two is connected to the liquid inlet of the auxiliary condensation evaporator, the gas outlet of the distillation tower two is connected to the gas inlet of the auxiliary condensation evaporator, and the outlet of the main condensation evaporator is connected to the upper part of the distillation tower two; the liquid nitrogen outlet of the distillation tower two is connected to the liquid inlet of the distillation tower one; the gas outlet of the auxiliary condensation evaporator is connected to the cold runner inlet of the supercooler, and the cold runner outlet of the supercooler is connected to the cold runner inlet of the main heat exchanger; the liquid nitrogen product extraction port of the distillation tower two is connected to the hot runner inlet of the liquid nitrogen supercooler; it is characterized in that: it also includes a liquid nitrogen load adjustment unit, the liquid nitrogen load adjustment unit includes a vacuum storage tank and a liquid nitrogen re-injection valve; the hot runner outlet of the liquid nitrogen supercooler is connected to the inlet of the vacuum storage tank, and the outlet of the vacuum storage tank is connected to the liquid inlet of the distillation tower one through the liquid nitrogen re-injection valve.

[0007] The utility model also comprises a compression unit, a precooling unit and a purification unit. The compression unit is connected with the precooling unit, the precooling unit is connected with the purification unit, and the purification unit is connected with the low-temperature distillation unit.

[0008] The compression unit of the utility model comprises an air filter and an air compressor. The air filter is connected with the compressor, and the compressor is connected with the precooling unit.

[0009] The precooling unit described in the utility model comprises an air cooling tower, a water cooling tower and a chiller; the compression unit is connected to the air cooling tower, the air cooling tower is connected to the purification unit; the main heat exchanger is connected to the water cooling tower, the water cooling tower is connected to the chiller, and the chiller is connected to the air cooling tower.

[0010] The purification unit of the utility model comprises an adsorber and an electric heater; the adsorber is connected to a main heat exchanger, the main heat exchanger is connected to the electric heater, and the electric heater is connected to the adsorber.

[0011] The utility model

[0012] The liquid nitrogen outlet of the second distillation tower is connected to the liquid inlet at the top of the first distillation tower through a liquid nitrogen pump.

[0013] The utility model also comprises an expander, and the main heat exchanger is connected with the expander.

[0014] The main heat exchanger, the subcooler and the liquid nitrogen subcooler described in the utility model are all plate-fin heat exchangers.

[0015] The utility model is provided with two vacuum storage tanks, one of which is at low pressure and the other is at working pressure.

[0016] Compared with the prior art, the utility model has the following advantages and effects:

[0017] (1) The variable load capacity of the nitrogen production device can reach 30%-120%, which can quickly adjust the nitrogen production of the cold box according to the nitrogen demand of the pipeline network and reduce the nitrogen emission rate.

[0018] (2) Liquid nitrogen re-injection can be achieved through the utility model:

[0019] Without changing the amount of air entering the cold box, liquid nitrogen can be injected through reflux to increase the reflux ratio of the distillation tower, which can improve the nitrogen extraction rate and increase the nitrogen production. The ratio of the amount of injected liquid nitrogen to the nitrogen production can increase the nitrogen extraction rate of the nitrogen generator by 2%-8%, and the increased nitrogen production is generally 1.5-2.5 times the amount of injected liquid nitrogen;

[0020] Liquid nitrogen can be reinjected to recover the cold energy from vaporization of liquid nitrogen, thereby reducing the energy consumption of the device. Air can also be fully involved in cryogenic distillation without changing the amount of expanded gas, thereby improving separation efficiency and further increasing nitrogen production.

[0021] (3) Compared with the method of using a liquid nitrogen backup system to vaporize and provide nitrogen during the peak period of nitrogen use, the method of the utility model eliminates the backup system vaporizer equipment and can use liquid nitrogen to directly adjust the reflux ratio of the distillation tower. The process operation is simpler and more reliable, the response is faster, and it is more economical and energy-saving. According to calculations, when 500Nm³ / h of liquid nitrogen passes through the distillation tower, the nitrogen production of the cold box can be increased by 1000Nm³ / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an embodiment of the utility model. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0024] The embodiment of the utility model comprises a compression unit, a precooling unit, a purification unit, a cryogenic distillation unit and a liquid nitrogen load adjustment unit.

[0025] The compression unit includes an air filter 1 and an air compressor 2. The compression unit can be connected in parallel with multiple compressors and coolers to meet the air demand under different working conditions. The precooling unit includes an air cooling tower 3, a water cooling tower 4, a chiller 5, a cooling water pump 6 and a refrigeration water pump 7. The purification unit includes an adsorber 8 and an electric heater 9. The low-temperature distillation unit is arranged in a cold box 29, which includes an expander 10, a bypass valve 11, a main heat exchanger 12, a distillation tower 13, a main condenser evaporator 14, a subcooler 15, a distillation tower 2 16, an auxiliary condenser evaporator 17, a liquid nitrogen pump 18, a liquid nitrogen subcooler 19, a liquid nitrogen throttle valve 20, and a liquid nitrogen delivery valve 21. The liquid nitrogen load adjustment unit includes a vacuum storage tank 22 and a liquid nitrogen return valve 23.

[0026] The main heat exchanger 12 has a first cold runner, a second cold runner, a third cold runner and a hot runner. The subcooler 15 has a cold runner and a hot runner. The liquid nitrogen subcooler 19 has a cold runner and a hot runner. The main heat exchanger 12, the subcooler 15 and the liquid nitrogen subcooler 19 are all vacuum brazed plate-fin heat exchangers.

[0027] The inlet of the air filter 1 sucks air from the atmosphere, the outlet of the air filter 1 is connected to the inlet of the compressor 2, the outlet of the compressor 2 is connected to the inlet of the air cooling tower 3, the outlet of the air cooling tower 3 is connected to the inlet of the adsorber 8, and the outlet of the adsorber 8 is connected to the hot runner inlet of the main heat exchanger 12. The outlet of the water cooling tower 4 is connected to the inlet of the chiller 5 through the chilled water pump 7, and the outlet of the chiller 5 is connected to the inlet of the air cooling tower 3.

[0028] There are two adsorbers 8, which are arranged in parallel. The adsorbers 8 are used alternately in pairs, and when one is working, the other is regenerated. The adsorber 8 can select a vertical axial flow, horizontal or vertical radial flow bed according to the air working pressure and flow rate.

[0029] The distillation tower can be a plate-type distillation tower or a packed distillation tower, and the condenser evaporator is a vacuum brazed plate-fin heat exchanger. The condenser evaporator can be integrated with the distillation tower, and the condenser evaporator is integrated and arranged at the top of the distillation tower; the condenser evaporator can also be selected as a shell and tube heat exchanger, which is separately arranged outside the distillation tower and connected to the distillation tower through a pipeline.

[0030] The hot runner outlet of the main heat exchanger 12 is connected to the inlet of the distillation tower 13, the liquid air outlet at the bottom of the distillation tower 13 is connected to the hot runner inlet of the subcooler 15, and the hot runner outlet of the subcooler 15 is connected to the liquid inlet of the main condenser evaporator 14 through the throttle valve 24. The gas outlet at the top of the distillation tower 13 is divided into two paths, one of which is connected to the inlet of the main condenser evaporator 14 to feed nitrogen, and the outlet of the main condenser evaporator 14 is connected to the upper part of the distillation tower 13 through the liquid nitrogen reflux valve 25, and the other is connected to the first cold runner inlet of the main heat exchanger 12 to feed nitrogen, and the first cold runner outlet of the main heat exchanger 12 is connected to the nitrogen product pipeline network.

[0031] The gas outlet of the main condenser evaporator 14 is connected to the gas inlet of the second distillation tower 16 through a valve 26 , and the liquid outlet of the main condenser evaporator 14 is connected to the liquid inlet of the auxiliary condenser evaporator 17 through a valve 27 .

[0032] The liquid air outlet at the bottom of the second distillation tower 16 is connected to the liquid inlet of the auxiliary condenser evaporator 17 through a throttle valve 27. The gas outlet at the top of the second distillation tower 16 is connected to the gas inlet of the auxiliary condenser evaporator 17, and the outlet of the main condenser evaporator 14 is connected to the upper part of the second distillation tower 16 through a liquid nitrogen reflux valve 28. The liquid nitrogen outlet at the top of the second distillation tower 16 is pressurized by a liquid nitrogen pump 18 and connected to the liquid inlet at the top of the first distillation tower 13.

[0033] The gas outlet of the auxiliary condenser evaporator 17 is connected to the cold channel inlet of the subcooler 15, and the cold channel outlet of the subcooler 15 is connected to the third cold channel inlet of the main heat exchanger 12; the third cold channel outlet of the main heat exchanger 12 is connected to the inlet of the expander 10, and the outlet of the expander 10 is connected to the second cold channel inlet of the main heat exchanger 12, and the second cold channel outlet of the main heat exchanger 12 is connected to the electric heater 9 and the inlet of the water cooling tower 4.

[0034] The liquid nitrogen product extraction port at the top of the second distillation tower 16 is connected to the hot runner inlet of the liquid nitrogen subcooler 19. The hot runner outlet of the liquid nitrogen subcooler 19 is connected to the cold runner inlet of the liquid nitrogen subcooler 19 through the throttle valve 20, and the cold runner outlet of the liquid nitrogen subcooler 19 is connected to the second cold runner inlet of the main heat exchanger 12. The hot runner outlet of the liquid nitrogen subcooler 19 is connected to the inlet of the vacuum storage tank 22 through the liquid nitrogen delivery valve 21.

[0035] The outlet of the vacuum storage tank 22 is connected to the liquid inlet at the top of the distillation tower 13 through a liquid nitrogen return valve 23.

[0036] The working method of the utility model comprises the following steps:

[0037] 1) After the air is dusted by the air filter 1, it enters the air compressor 2. Three air compressors are selected. Compressed air can be provided by starting and stopping the compressor and adjusting the load to meet the air demand under different load conditions. The outlet pressure of the compressor is 0.8-1.0Mpa.A. The 110-130℃ hot and humid air from the compressor 2 enters the lower part of the air cooling tower 3, and directly contacts with the circulating water (≤32℃) from the water pump 6 in the lower section of the air cooling tower 3 through countercurrent to exchange heat and mass, so that the air is initially cooled; when the air rises to the upper section of the air cooling tower 3, it further exchanges heat and mass with the chilled water (8-10℃) from the bottom of the water cooling tower 4 that is pressurized by the chilled water pump 7 and cooled by the chiller 5, and finally the air is cooled to 8-13℃ and leaves the air cooling tower to go to the molecular sieve purification system. The oxygen-rich air from the cold box 29 enters the lower part of the water cooling tower 4, contacts with the circulating water in the water cooling tower 4 in countercurrent to exchange heat and mass, and finally is directly discharged from the top of the water cooling tower 4.

[0038] 2) When the air at the outlet of the air cooling tower 3 passes through the adsorber 8 from bottom to top, the impurities such as H2O, C2H2, CO2 contained in the air are successively adsorbed and removed, and the purified air enters the cold box 29. The adsorbers 8 are used alternately in pairs, and when one is working, the other is regenerated. The regeneration of the adsorber 8 is generally carried out in four steps, the first step: pressure reduction; the second step: heating; the third step: cooling; the fourth step: pressure increase. After the four steps of regeneration are completed, the adsorber can be put into operation, and after about 3 minutes of parallel operation, the switching process is completed.

[0039] The raw air is dried in the adsorber; after adsorbing water, carbon dioxide and some hydrocarbons in the purification unit, it is sent to the cryogenic distillation unit; the moisture dew point of the air leaving the purification unit is ≤-60℃ and the carbon dioxide is less than 1PPm.

[0040] 3) The purified processed air enters the cold box 29, and after being cooled to the dew point temperature in the main heat exchanger 12, enters the bottom of the distillation tower 13. A portion of the nitrogen gas at the top of the distillation tower 13 after distillation enters the main heat exchanger 12, and while cooling the raw air, it is reheated and sent out of the cold box 29 as product nitrogen gas. Another portion of the nitrogen gas at the top of the tower is condensed into liquid nitrogen in the main condenser evaporator 14, and the flow rate is controlled by the liquid nitrogen reflux valve 25, and enters the top of the distillation tower 13 as the tower reflux liquid.

[0041] 4) The oxygen-rich liquid air at the bottom of the distillation tower 13 is supercooled and throttled by the cooler 15 and then enters the main condenser evaporator 14 as its cold source; the evaporated oxygen-rich air is sent to the bottom of the distillation tower 2 16 as the raw gas for secondary distillation to participate in distillation. The liquid nitrogen obtained after distillation in the distillation tower 2 16 is pressurized by the liquid nitrogen pump 18 and sent to the top of the distillation tower 13 as reflux liquid. The oxygen-rich liquid air is extracted from the bottom of the distillation tower 2 16 and throttled by the throttle valve 27 and then enters the auxiliary condenser evaporator 17 to provide a cold source for nitrogen liquefaction and is evaporated and vaporized. The vaporized oxygen-rich air is reheated to the pre-expansion temperature (-140--150℃) by the cooler 15 and the main heat exchanger 12, and then enters the expander 10 for expansion and refrigeration, providing cold capacity for the device. After the expanded oxygen-rich air is reheated to room temperature by the main heat exchanger 12, part of it is sent to the electric heater 9 for molecular sieve regeneration, and the other part is sent to the water cooling tower 4 to recover cold capacity.

[0042] 5) After the liquid nitrogen product is obtained from the top of the second distillation tower 16, it is supercooled by the liquid nitrogen supercooler 19 and then sent to the vacuum storage tank 22. There are two vacuum storage tanks, one vacuum storage tank 22 is at low pressure and is used to receive liquid nitrogen, and the other vacuum storage tank 22 is at working pressure, and the liquid nitrogen can be returned to the distillation tower through the liquid nitrogen return valve 23 at any time.

[0043] 6) When the nitrogen variable load is in the range of 75%-105% of the design working condition, the nitrogen product variable load requirement can be met by adjusting the air volume entering the cold box 29, the opening of the liquid reflux valve 25, the opening of the liquid nitrogen reflux valve 28 and the nozzle opening of the expander.

[0044] 7) When the nitrogen demand is 105%-120% of the design condition and more nitrogen products are needed, the liquid nitrogen product valve 21 for external delivery is closed and the liquid nitrogen return valve 23 is opened to return the liquid nitrogen in the vacuum storage tank to the top of the distillation tower 13. By increasing the liquid nitrogen reflux ratio of the distillation tower 13, the nitrogen extraction rate of the nitrogen generator is increased from 70%-74% of the design condition to 74%-80%. Without increasing the amount of air, the nitrogen product output is increased to 105%-120% of the design value to meet the demand for extracting more nitrogen from the distillation tower.

[0045] 8) When the nitrogen demand is lower than 60% of the design condition, the reflux gas volume of the expander is insufficient and the expander cannot operate normally and efficiently. The expander can be stopped and the reflux oxygen-rich gas can enter the main heat exchanger 2 through the bypass valve 11 for reheating. By re-injecting liquid nitrogen, not only can the nitrogen extraction rate be kept from decreasing, but liquid nitrogen can also provide the cooling capacity required for the normal operation of the nitrogen generator. At the same time, when the expander fails, the nitrogen generator can still operate normally for a period of time under low load by re-injecting liquid nitrogen, leaving enough time for maintenance of the device.

[0046] 9) Set temperature measuring points at appropriate positions at the top, middle and bottom of distillation tower 13 and distillation tower 2 16. Whether the distillation tower is normal can be accurately identified based on the temperature change trend in the distillation tower. Before the purity of nitrogen is damaged, take measures to inject liquid nitrogen to ensure the normal operation of the distillation condition. When abnormal conditions are found, inject liquid nitrogen in time to make the reflux ratio of the distillation tower greater than the minimum reflux ratio, and ensure the purity of the nitrogen sent out in time.

[0047] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the utility model. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the utility model are included in the protection scope of the utility model patent. Technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.

Claims

1. A peak-shaving type low-temperature distillation device for producing high-purity nitrogen, comprising a low-temperature distillation unit; the low-temperature distillation unit comprises a main heat exchanger, a distillation tower 1, a main condenser evaporator, a subcooler, a distillation tower 2, an auxiliary condenser evaporator and a liquid nitrogen subcooler; the hot runner outlet of the main heat exchanger is connected to the inlet of the distillation tower 1, the liquid air outlet of the distillation tower 1 is connected to the hot runner inlet of the subcooler, and the hot runner outlet of the subcooler is connected to the liquid inlet of the main condenser evaporator; the gas outlet of the distillation tower 1 is respectively connected to the inlet of the main condenser evaporator and the cold runner inlet of the main heat exchanger, and the outlet of the main condenser evaporator is connected to the upper part of the distillation tower 1; the gas outlet of the main condenser evaporator is .... The gas inlet of the second distillation tower is connected, and the liquid outlet of the main condenser evaporator is connected to the liquid inlet of the auxiliary condenser evaporator; the liquid air outlet of the second distillation tower is connected to the liquid inlet of the auxiliary condenser evaporator, the gas outlet of the second distillation tower is connected to the gas inlet of the auxiliary condenser evaporator, and the outlet of the main condenser evaporator is connected to the upper part of the second distillation tower; the liquid nitrogen outlet of the second distillation tower is connected to the liquid inlet of the first distillation tower; the gas outlet of the auxiliary condenser evaporator is connected to the cold runner inlet of the subcooler, and the cold runner outlet of the subcooler is connected to the cold runner inlet of the main heat exchanger; the liquid nitrogen product extraction port of the second distillation tower is connected to the hot runner inlet of the liquid nitrogen subcooler; it is characterized in that: It also includes a liquid nitrogen load adjustment unit, which includes a vacuum storage tank and a liquid nitrogen return valve; the hot runner outlet of the liquid nitrogen supercooler is connected to the inlet of the vacuum storage tank, and the outlet of the vacuum storage tank is connected to the liquid inlet of the distillation tower one through the liquid nitrogen return valve.

2. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 1, characterized in that: It also includes a compression unit, a precooling unit and a purification unit. The compression unit is connected to the precooling unit, the precooling unit is connected to the purification unit, and the purification unit is connected to the low-temperature distillation unit.

3. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 2, characterized in that: The compression unit comprises an air filter and an air compressor, the air filter is connected to the compressor, and the compressor is connected to the precooling unit.

4. The peak-shaving type low-temperature distillation device for producing high-purity nitrogen according to claim 2, characterized in that: The precooling unit includes an air cooling tower, a water cooling tower and a chiller; the compression unit is connected to the air cooling tower, the air cooling tower is connected to the purification unit; the main heat exchanger is connected to the water cooling tower, the water cooling tower is connected to the chiller, and the chiller is connected to the air cooling tower.

5. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 2, characterized in that: The purification unit comprises an adsorber and an electric heater; the adsorber is connected to a main heat exchanger, the main heat exchanger is connected to the electric heater, and the electric heater is connected to the adsorber.

6. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 1, characterized in that: The liquid nitrogen outlet of the second distillation tower is connected to the liquid inlet at the top of the first distillation tower through a liquid nitrogen pump.

7. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 1, characterized in that: It also includes an expander, and the main heat exchanger is connected to the expander.

8. The peak-shaving type low-temperature distillation device for producing high-purity nitrogen according to claim 1, characterized in that: The main heat exchanger, subcooler and liquid nitrogen subcooler are all plate-fin heat exchangers.

9. The peak-shaving low-temperature distillation device for producing high-purity nitrogen according to claim 1, characterized in that: There are two vacuum storage tanks, one of which is at low pressure and the other is at working pressure.

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