Air separation device

Abstract

The utility model discloses an air separation device which comprises an air cooling tower, a low-pressure heat exchanger, a rectifying tower and a pump set, the air cooling tower is provided with an air outlet; the low-pressure heat exchanger has a first low-pressure channel; the rectifying tower comprises an upper tower and a lower tower, the upper tower is provided with a liquid oxygen outlet, the lower tower is provided with a first air inlet and a liquid nitrogen outlet, and the air outlet is connected with the first air inlet through a first low-pressure channel; the pump set comprises at least one liquid oxygen pump and at least two liquid nitrogen pumps, inlets of the liquid oxygen pumps are connected with the liquid oxygen outlet, outlets of the liquid oxygen pumps are connected with a first oxygen supply pipe, the at least two liquid nitrogen pumps are the first liquid nitrogen pump and the second liquid nitrogen pump, and inlets of the first liquid nitrogen pump and the second liquid nitrogen pump are both connected with the liquid nitrogen outlet. An outlet of the first liquid nitrogen pump is connected with a first nitrogen supply pipe, and an outlet of the second liquid nitrogen pump is connected with a second nitrogen supply pipe. The air separation device provided by the embodiment of the utility model can be used for producing various liquid nitrogen and liquid oxygen with different pressure grades, so that the requirements of different users on different gas pressure grades are met.

Description

Technical Field

[0001] This utility model relates to the technical field of air separation equipment, and specifically to an air separation device. Background Technology

[0002] A dual-pump air separation unit is disclosed in the related technology, including an air-cooled tower and a distillation tower. Air is cooled by the air-cooled tower and then enters the distillation tower for distillation. Oxygen is obtained in the upper column of the distillation tower, which has an oxygen outlet. Nitrogen is obtained in the lower column of the distillation tower, which has a nitrogen outlet. The oxygen outlet is connected to a liquid oxygen pump, and the nitrogen outlet is connected to a liquid nitrogen pump. The obtained oxygen and nitrogen can be compressed separately to obtain oxygen and nitrogen at different pressures.

[0003] In practical applications, different users have different requirements for gas pressure levels. For example, the synthetic ammonia process uses a new coal gasification process of coal-water slurry, liquid nitrogen washing, and methanol washing, which requires an air separation unit to supply 8.5MPa oxygen, 6.5MPa nitrogen, and 0.4MPa nitrogen. Welding, packaging, and other fields require 2.2MPa nitrogen, requiring a variety of gas pressure levels. However, the air separation units of the above-mentioned technologies can only produce two pressure levels of gas, which is difficult to meet the user's needs for multiple pressure levels of gas. Utility Model Content

[0004] This utility model aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of this utility model propose an air separation device that can produce liquid nitrogen and liquid oxygen at various pressure levels to meet the needs of different users for different gas pressure levels.

[0006] The air separation unit of this utility model includes an air-cooled tower, a low-pressure heat exchanger, a distillation tower, and a pump group; the air-cooled tower has an air outlet; the low-pressure heat exchanger has a first low-pressure channel; the distillation tower includes an upper tower and a lower tower, the upper tower has a liquid oxygen outlet, the lower tower has a first air inlet and a liquid nitrogen outlet, and the air outlet is connected to the first air inlet through the first low-pressure channel;

[0007] The pump set includes at least one liquid oxygen pump and at least two liquid nitrogen pumps. The inlet of the liquid oxygen pump is connected to the liquid oxygen outlet, and the outlet of the liquid oxygen pump is connected to a first oxygen supply pipe. At least one liquid nitrogen pump is a first liquid nitrogen pump, and at least one liquid nitrogen pump is a second liquid nitrogen pump. The inlets of both the first liquid nitrogen pump and the second liquid nitrogen pump are connected to the liquid nitrogen outlet. The outlet of the first liquid nitrogen pump is connected to a first nitrogen supply pipe, and the outlet of the second liquid nitrogen pump is connected to a second nitrogen supply pipe.

[0008] In some embodiments, the air separation unit further includes a high-pressure heat exchanger having a first high-pressure channel, a second high-pressure channel, and a third high-pressure channel. The first oxygen supply pipe is connected to the liquid oxygen pump through the first high-pressure channel, the first nitrogen supply pipe is connected to the first liquid nitrogen pump through the second high-pressure channel, and the second nitrogen supply pipe is connected to the second liquid nitrogen pump through the third high-pressure channel.

[0009] In some embodiments, the air separation unit further includes a second oxygen supply pipe and a third nitrogen supply pipe, the upper column has an oxygen outlet, the lower column has a nitrogen outlet, the low-pressure heat exchanger has a second low-pressure channel and a third low-pressure channel, the second oxygen supply pipe is connected to the oxygen outlet through the second low-pressure channel, and the third nitrogen supply pipe is connected to the nitrogen outlet through the third low-pressure channel.

[0010] In some embodiments, the air separation unit further includes a subcooler, a liquid oxygen storage tank, and a liquid nitrogen storage tank. The subcooler has a first subcooling channel and a second subcooling channel. The liquid oxygen storage tank is connected to the liquid oxygen outlet through the first subcooling channel, and the liquid nitrogen storage tank is connected to the liquid nitrogen outlet through the second subcooling channel.

[0011] In some embodiments, the air separation unit further includes a purification component, and the air outlet is connected to the first air inlet via the purification component.

[0012] In some embodiments, the high-pressure heat exchanger has a fourth high-pressure channel and a fifth high-pressure channel, the lower tower has a second air inlet and a third air inlet, and the air separation unit further includes a second air compressor, an expander, and a cooler. The second air compressor has a first outlet and a second outlet, and the first outlet is connected to the second air inlet through the fourth high-pressure channel. The expander includes a booster end and an expansion end, and the second outlet of the second air compressor, the booster end, the cooler, the fifth high-pressure channel, the expansion end, and the third air inlet are connected in sequence.

[0013] In some embodiments, the air separation unit further includes a crude argon column and a refined argon column. The crude argon column has an argon fraction gas inlet and a crude argon outlet. The refined argon column has a crude argon inlet and a liquid argon outlet. The upper column has an argon fraction gas outlet, which is connected to the argon fraction gas inlet. The crude argon outlet is connected to the crude argon inlet.

[0014] In some embodiments, the air separation unit further includes a water-cooled tower, the outlet of which is connected to the inlet of the air-cooled tower to cool the air inside the air-cooled tower using water from the water-cooled tower; the water-cooled tower has a waste nitrogen inlet, and the upper tower has a first waste nitrogen outlet connected to the waste nitrogen inlet.

[0015] In some embodiments, the argon column has a second waste nitrogen outlet connected to the waste nitrogen inlet.

[0016] In some embodiments, the high-pressure heat exchanger has a sixth high-pressure channel, and the low-pressure heat exchanger has a fourth low-pressure channel; the first waste nitrogen outlet is connected to a first waste nitrogen pipe and a second waste nitrogen pipe, the first waste nitrogen pipe is connected to the waste nitrogen inlet through the sixth high-pressure channel, and the second waste nitrogen pipe is connected to the waste nitrogen inlet through the fourth low-pressure channel.

[0017] The air separation unit of this utility model uses a liquid oxygen pump and multiple liquid nitrogen pumps in a pump group to pressurize the liquid oxygen and liquid nitrogen products from the distillation column to obtain gases of different pressure levels, thereby meeting the pressure requirements of different users for different gases. Specifically, the liquid oxygen produced in the upper column of the distillation column is pressurized by the liquid oxygen pump and supplied to users through the first oxygen supply pipe, enabling the supply of high-pressure liquid oxygen, such as 8.5 MPa. The liquid nitrogen produced in the lower column of the distillation column is divided into two paths: one path is compressed by the first liquid nitrogen pump and supplied to users through the first nitrogen supply pipe, and the other path is compressed by the second liquid nitrogen pump and supplied to users through the second nitrogen supply pipe. The first and second liquid nitrogen pumps can pressurize the liquid nitrogen separately to obtain liquid nitrogen of different pressure levels, such as high-pressure liquid nitrogen of 6.5 MPa and medium-pressure liquid nitrogen of 2.2 MPa; thus, the needs of different users for different gas pressure levels can be met. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of an air separation device according to an embodiment of the present invention.

[0019] Figure label:

[0020] 100. Air separation unit;

[0021] 1. Air-cooled tower; 11. Air outlet; 12. First water inlet; 121. First water pump; 13. Second water inlet; 131. Second water pump; 14. Water-cooled tower; 141. Sludge nitrogen inlet;

[0022] 21. Low-pressure heat exchanger; 211. First low-pressure channel; 212. Second low-pressure channel; 213. Third low-pressure channel; 214. Fourth low-pressure channel; 22. High-pressure heat exchanger; 221. First high-pressure channel; 222. Second high-pressure channel; 223. Third high-pressure channel; 224. Fourth high-pressure channel; 225. Fifth high-pressure channel; 226. Sixth high-pressure channel; 23. Subcooler;

[0023] 31. Upper tower; 311. Liquid oxygen outlet; 3111. First oxygen supply pipe; 3112. Oxygen storage pipe; 312. Oxygen outlet; 3121. Second oxygen supply pipe; 313. Argon fraction outlet; 314. First waste nitrogen outlet; 3141. First waste nitrogen pipe; 3142. Second waste nitrogen pipe; 32. Lower tower; 321. First air inlet; 322. Liquid nitrogen outlet; 3221. First nitrogen supply pipe; 3222. Second nitrogen supply pipe; 3223. Nitrogen storage pipe; 323. Nitrogen outlet; 3231. Third nitrogen supply pipe; 324. First reflux port; 325. Second reflux port; 326. Second air inlet; 327. Third air inlet; 328. Third reflux port; 33. Condenser / evaporator;

[0024] 4. Pump set; 41. Liquid oxygen pump; 42. First liquid nitrogen pump; 43. Second liquid nitrogen pump;

[0025] 51. Filter; 52. First air compressor;

[0026] 6. Purification components;

[0027] 71. Second air compressor; 711. First outlet; 712. Second outlet; 72. Expander; 721. Pressure boosting end; 722. Expansion end; 73. Cooler;

[0028] 8. Crude argon column; 81. Argon fraction gas inlet; 82. Crude argon outlet; 83. Crude argon condenser;

[0029] 9. Refined argon tower; 91. Crude argon inlet; 92. Liquid argon outlet; 93. Refined argon condenser; 94. Refined argon evaporator; 95. Second waste nitrogen outlet. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] like Figure 1As shown, the air separation unit 100 of this embodiment includes an air-cooled tower 1, a low-pressure heat exchanger 21, a distillation column, and a pump group 4; the air-cooled tower 1 has an air outlet 11; the low-pressure heat exchanger 21 has a first low-pressure channel 211; the distillation column includes an upper column 31 and a lower column 32, the upper column 31 has a liquid oxygen outlet 311, and the lower column 32 has a first air inlet 321 and a liquid nitrogen outlet 322, the air outlet 11 being connected to the first air inlet 321 through the first low-pressure channel 211; the pump group 4 includes at least The system includes one liquid oxygen pump 41 and at least two liquid nitrogen pumps. The inlet of the liquid oxygen pump 41 is connected to the liquid oxygen outlet 311, and the outlet of the liquid oxygen pump 41 is connected to a first oxygen supply pipe 3111. At least one liquid nitrogen pump is a first liquid nitrogen pump 42, and at least one liquid nitrogen pump is a second liquid nitrogen pump 43. The inlets of both the first liquid nitrogen pump 42 and the second liquid nitrogen pump 43 are connected to the liquid nitrogen outlet 322. The outlet of the first liquid nitrogen pump 42 is connected to a first nitrogen supply pipe 3221, and the outlet of the second liquid nitrogen pump 43 is connected to a second nitrogen supply pipe 3222.

[0032] The air separation unit 100 of this embodiment pressurizes the liquid oxygen and liquid nitrogen products from the distillation column using a liquid oxygen pump 41 and multiple liquid nitrogen pumps in the pump group 4 to obtain gases of different pressure levels, thereby meeting the pressure requirements of different users for different gases. Specifically, the liquid oxygen produced in the upper column 31 of the distillation column is pressurized by the liquid oxygen pump 41 and supplied to users through the first oxygen supply pipe 3111, enabling the supply of high-pressure liquid oxygen, such as 8.5 MPa. The liquid nitrogen produced in the lower column 32 of the distillation column is divided into two paths: one path is compressed by the first liquid nitrogen pump 42 and supplied to users through the first nitrogen supply pipe 3221, and the other path is compressed by the second liquid nitrogen pump 43 and supplied to users through the second nitrogen supply pipe 3222. The first liquid nitrogen pump 42 and the second liquid nitrogen pump 43 can pressurize the liquid nitrogen separately to obtain liquid nitrogen of different pressure levels, such as high-pressure liquid nitrogen of 6.5 MPa and medium-pressure liquid nitrogen of 2.2 MPa; thus, the needs of different users for different gas pressure levels can be met.

[0033] Understandably, the number and pressurization capacity of the liquid oxygen pump 41 and the liquid nitrogen pump can be adjusted according to user needs.

[0034] Optionally, the low-pressure heat exchanger 21 is a low-pressure plate heat exchanger.

[0035] Specifically, such as Figure 1 As shown, the air separation unit 100 is an internal compression air separation unit. The air separation unit 100 also includes a filter 51 and a first air compressor 52 connected in sequence. The first air compressor 52 is connected to the air inlet of the air-cooled tower 1, and the air inlet of the air-cooled tower 1 is located at its lower part. The raw material air is first filtered by the filter 51, then compressed by the first air compressor 52 and sent to the air-cooled tower 1 for water washing and cooling.

[0036] The air-cooled tower 1 has two water inlets, namely a first water inlet 12 and a second water inlet 13. The first water inlet 12 is located at the top of the air-cooled tower 1, and the second water inlet 13 is located at the middle of the air-cooled tower 1. The first water inlet 12 is connected to a first water pump 121 through a pipe. One stream of circulating water enters the middle of the air-cooled tower 1 through the first water pump 121 to wash and cool the air being transported upward inside the air-cooled tower 1. The second water inlet 13 is connected to a second water pump 131 through a pipe. The air separation unit 100 also includes a water-cooled tower 14, which is used to cool another stream of circulating water. The outlet of the water-cooled tower 14 is connected to the second water pump 131 through a pipe. The cooled circulating water enters the top of the air-cooled tower 1 through the second water pump 131 to wash and cool the air.

[0037] The air cooled by the air-cooled tower 1 is output from the top of the air-cooled tower 1, and is heated to -173°C through the first low-pressure channel 211 of the low-pressure heat exchanger 21. Then it enters the distillation column through the first air inlet 321 of the lower column 32. High-purity nitrogen is then generated at the top of the lower column 32. The distillation column also includes a condenser-evaporator 33 located between the upper column 31 and the lower column 32. The nitrogen is condensed into liquid nitrogen by the condenser-evaporator 33 to obtain liquid nitrogen product. At the same time, the liquid nitrogen can be used as the reflux liquid of the upper column 31 to promote the liquefaction of the high-purity oxygen generated at the bottom of the upper column 31 to obtain liquid oxygen product.

[0038] After being discharged from the liquid nitrogen outlet 322, the liquid nitrogen is divided into two paths. One path is pressurized to 6.5 MPa by the first liquid nitrogen pump 42 and enters the first nitrogen supply pipe 3221, which supplies the user (e.g., the liquid nitrogen scrubbing tower of the ammonia synthesis system) through the first nitrogen supply pipe 3221. The other path is pressurized to 2.2 MPa by the second liquid nitrogen pump 43 and enters the second nitrogen supply pipe 3222, which supplies the user through the second nitrogen supply pipe 3222.

[0039] After being output from the liquid oxygen outlet 311, the liquid oxygen is pressurized to 8.5 MPa by the liquid oxygen pump 41 and enters the first oxygen supply pipe 3111, which supplies oxygen to users (such as the gasifier of the ammonia synthesis system).

[0040] In some embodiments, such as Figure 1 As shown, the air separation unit 100 also includes a high-pressure heat exchanger 22, which has a first high-pressure channel 221, a second high-pressure channel 222 and a third high-pressure channel 223. The first oxygen supply pipe 3111 is connected to the liquid oxygen pump 41 through the first high-pressure channel 221, the first nitrogen supply pipe 3221 is connected to the first liquid nitrogen pump 42 through the second high-pressure channel 222, and the second nitrogen supply pipe 3222 is connected to the second liquid nitrogen pump 43 through the third high-pressure channel 223.

[0041] Liquid oxygen, pressurized by liquid oxygen pump 41, flows through the first high-pressure channel 221 to exchange heat to room temperature, and is then supplied to users through the first oxygen supply pipe 3111; liquid nitrogen, pressurized by the first liquid nitrogen pump 42, flows through the second high-pressure channel 222 to exchange heat to room temperature, and is then supplied to users through the first nitrogen supply pipe 3221; liquid nitrogen, pressurized by the second liquid nitrogen pump 43, flows through the third high-pressure channel 223 to exchange heat to room temperature, and is then supplied to users through the second nitrogen supply pipe 3222.

[0042] Optionally, the high-pressure heat exchanger 22 is a high-pressure plate heat exchanger.

[0043] In some embodiments, such as Figure 1 As shown, the air separation unit 100 also includes a second oxygen supply pipe 3121 and a third nitrogen supply pipe 3231. The upper column 31 has an oxygen outlet 312, and the lower column 32 has a nitrogen outlet 323. The low-pressure heat exchanger 21 has a second low-pressure channel 212 and a third low-pressure channel 213. The second oxygen supply pipe 3121 is connected to the oxygen outlet 312 through the second low-pressure channel 212, and the third nitrogen supply pipe 3231 is connected to the nitrogen outlet 323 through the third low-pressure channel 213.

[0044] Low-pressure nitrogen and oxygen can be supplied to users through the second oxygen supply pipe 3121 and the third nitrogen supply pipe 3231. For example, 0.4 MPa nitrogen can be supplied to the methanol washing tower of the ammonia synthesis system, thereby meeting the user's demand for low-pressure gas.

[0045] In some embodiments, such as Figure 1 As shown, the air separation unit 100 also includes a subcooler 23, a liquid oxygen storage tank and a liquid nitrogen storage tank (the liquid oxygen storage tank and liquid nitrogen storage tank are not shown in the figure). The subcooler 23 has a first subcooling channel and a second subcooling channel. The liquid oxygen storage tank is connected to the liquid oxygen outlet 311 through the first subcooling channel, and the liquid nitrogen storage tank is connected to the liquid nitrogen outlet 322 through the second subcooling channel.

[0046] With the above setup, excess liquid oxygen can be stored in a liquid oxygen storage tank, and excess liquid nitrogen can be stored in a liquid nitrogen storage tank to prevent waste. At the same time, when liquid oxygen or liquid nitrogen is in short supply, it can be replenished through the liquid oxygen storage tank or liquid nitrogen storage tank to maintain continuous production.

[0047] In addition, the subcooler 23 can cool liquid oxygen and liquid nitrogen to below their boiling points, reducing evaporation losses during storage, extending storage time, ensuring a continuous and stable supply of liquid oxygen and liquid nitrogen, and thus improving the reliability of the air separation unit 100.

[0048] like Figure 1As shown, the air separation unit 100 includes an oxygen storage pipe 3112 and a nitrogen storage pipe 3223. The first subcooling channel is connected to the liquid oxygen storage tank through the oxygen storage pipe 3112, and the second subcooling channel is connected to the liquid nitrogen storage tank through the nitrogen storage pipe 3223. The liquid oxygen output from the liquid oxygen outlet 311 is divided into two paths: one path is pressurized by the aforementioned liquid oxygen pump 41 and supplied, and the other path enters the liquid oxygen storage tank after passing through the cooler 23. The liquid nitrogen output from the liquid nitrogen outlet 322 is divided into three paths: two paths are pressurized by the first liquid nitrogen pump 42 and the second liquid nitrogen pump 43 respectively and supplied, and the other path enters the liquid nitrogen storage tank after passing through the cooler 23.

[0049] The lower column 32 has a first reflux port 324 and a second reflux port 325 in the middle. The second reflux port 325 is located below the first reflux port 324. One stream of liquid nitrogen in the middle of the lower column 32 is output from the first reflux port 324, and after being subcooled by the cooler 23, it enters the upper column 31 as the reflux liquid for the rectification of the upper column 31. The lean liquid air in the middle of the lower column 32 is output from the second reflux port 325, and after being subcooled by the cooler 23, it enters the upper column 31 as the reflux liquid for the rectification of the upper column 31.

[0050] In some embodiments, such as Figure 1 As shown, the air separation unit 100 also includes a purification component 6, and the air outlet 11 is connected to the first air inlet 321 through the purification component 6.

[0051] Purification component 6 can remove impurities such as carbon dioxide, hydrocarbons, and moisture from the air, thereby purifying the raw material air and preventing the oxygen and nitrogen products in the distillation tower from being contaminated by carbon dioxide, moisture, etc., ensuring the purity of the oxygen and nitrogen products.

[0052] Optionally, purification component 6 is a molecular sieve purification system.

[0053] In some embodiments, the high-pressure heat exchanger 22 has a fourth high-pressure channel 224 and a fifth high-pressure channel 225, the lower tower 32 has a second air inlet 326 and a third air inlet 327, and the air separation unit 100 further includes a second air compressor 71, an expander 72 and a cooler 73. The second air compressor 71 has a first outlet 711 and a second outlet 712. The first outlet 711 is connected to the second air inlet 326 through the fourth high-pressure channel 224. The expander 72 includes a boosting end 721 and an expansion end 722. The second outlet 712, the boosting end 721, the cooler 73, the fifth high-pressure channel 225, the expansion end 722 and the third air inlet 327 of the second air compressor 71 are connected in sequence.

[0054] With the above configuration, the lower column 32 of the distillation column receives three streams of air. The first stream is low-pressure air entering through the first air inlet 321, which provides most of the air required by the distillation column and participates in nitrogen and oxygen separation. The second stream is high-pressure air entering through the second air inlet 326, which mixes with the low-pressure air after entering the lower column 32 to maintain the pressure stability of the lower column 32. The third stream is expanded air entering through the third air inlet 327. After being expanded by the expander 72, the air temperature drops sharply. This part of the air entering the lower column 32 can provide cooling capacity, reducing the external refrigeration demand and energy consumption. Thus, through the synergistic effect of the three streams of air, the stable operation of the air separation unit 100 can be guaranteed.

[0055] Optionally, the inlet of the second air compressor 71 is connected to the outlet of the purification component 6.

[0056] Therefore, the air entering the second air compressor 71 is purified by the purification component 6, which can prevent carbon dioxide, moisture and other substances in the air from affecting the purity of oxygen and nitrogen products.

[0057] In some embodiments, such as Figure 1 As shown, the air separation unit 100 also includes a crude argon column 8 and a refined argon column 9. The crude argon column 8 has an argon fraction gas inlet 81 and a crude argon outlet 82. The refined argon column 9 has a crude argon inlet 91 and a liquid argon outlet 92. The upper column 31 has an argon fraction gas outlet 313, which is connected to the argon fraction gas inlet 81. The crude argon outlet 82 is connected to the crude argon inlet 91.

[0058] Argon distillate gas in the upper column 31 passes through the crude argon column 8 to obtain crude argon gas. The crude argon gas passes through the fine argon column 9 to remove nitrogen gas, thereby obtaining high-purity liquid argon. High-purity liquid argon can be used in semiconductor manufacturing, special welding and other scenarios.

[0059] Specifically, such as Figure 1 As shown, the argon gas outlet 313 is located in the middle of the upper column 31, and the argon gas inlet 81 is located in the lower part of the argon refining column 9. The argon gas outlet 313 and the argon gas inlet 81 are connected by a pipeline, which can transport the argon gas in the middle of the upper column 31 to the crude argon column 8. Then, crude argon gas with an oxygen content of less than 1 ppm is obtained in the upper part of the crude argon column 8. The crude argon gas enters the argon refining column 9 to remove nitrogen gas, thereby obtaining high-purity liquid argon. The high-purity liquid argon is discharged from the liquid argon outlet 92 at the bottom of the argon refining column 9 to the liquid argon storage tank for storage.

[0060] The crude argon column 8 includes a crude argon condenser 83. The bottom of the lower column 32 has a third reflux port 328. The oxygen-enriched liquid air at the bottom of the lower column 32 is output from the third reflux port 328. After being subcooled by the cooler 23, it is divided into two paths. One path enters the upper column 31 as reflux liquid, and the other path enters the condenser of the crude argon column 8 to cool the crude argon gas. After that, the oxygen-enriched liquid air after the crude argon gas is condensed returns to the upper column 31.

[0061] The argon refining column 9 includes an argon refining condenser 93 located at the top and an argon refining evaporator 94 located at the bottom. After being subcooled by the cooler 23, the liquid nitrogen in the lower column 32 is divided into two paths. One path is sent to the liquid nitrogen storage tank for storage, and the other path is used as the cold source for the argon refining condenser 93. A branch of the nitrogen outlet 323 of the lower column 32 is used as the heat source for the argon refining evaporator 94 to help separate nitrogen and oxygen impurities in the crude argon. This part of the nitrogen is then sent to the upper part of the upper column 31, where it merges with the liquid nitrogen output from the first reflux port 324 and enters the upper column 31 to be used as the reflux liquid for the distillation of the upper column 31.

[0062] In addition, the liquid air vapor at the top of the crude argon column 8 returns to the upper column 31, and the oxygen-enriched liquid at the bottom of the crude argon column 8 returns to the upper column 31.

[0063] In some embodiments, such as Figure 1 As shown, the water-cooled tower 14 has a waste nitrogen inlet 141, and the upper tower 31 has a first waste nitrogen outlet 314, which is connected to the waste nitrogen inlet 141.

[0064] With the above settings, the waste nitrogen gas produced by the upper tower 31 can be used to cool the circulating water in the water cooling tower 14, thereby realizing the recovery of cooling capacity and reducing energy consumption.

[0065] In some embodiments, such as Figure 1 As shown, the argon column 9 has a second waste nitrogen outlet 95, which is connected to the waste nitrogen inlet 141.

[0066] Specifically, the waste nitrogen gas produced at the top of the argon tower 9 is output through the second waste nitrogen outlet 95 and merges with the waste nitrogen gas output from the first waste nitrogen outlet 314. After passing through the high-pressure heat exchanger 22 and the low-pressure heat exchanger 21 respectively, the circulating water in the water-cooled tower 14 is cooled.

[0067] In some embodiments, the high-pressure heat exchanger 22 has a sixth high-pressure channel 226, and the low-pressure heat exchanger 21 has a fourth low-pressure channel 214; the first waste nitrogen outlet 314 is connected to a first waste nitrogen pipe 3141 and a second waste nitrogen pipe 3142, the first waste nitrogen pipe 3141 is connected to the waste nitrogen inlet 141 through the sixth high-pressure channel 226, and the second waste nitrogen pipe 3142 is connected to the waste nitrogen inlet 141 through the fourth low-pressure channel 214.

[0068] Specifically, such as Figure 1As shown, the first waste nitrogen outlet 314 is located at the top of the upper tower 31. The waste nitrogen gas produced at the top of the upper tower 31 and the top of the refined argon tower 9 merges and then splits into two paths. One path enters the water-cooled tower 14 after heat exchange through the sixth high-pressure channel 226 of the high-pressure heat exchanger 22, and the other path enters the water-cooled tower 14 after heat exchange through the fourth low-pressure channel 214 of the low-pressure heat exchanger 21. Among them, the waste nitrogen gas passing through the sixth high-pressure channel 226 can exchange heat with the high-pressure air passing through the fourth high-pressure channel 224 to achieve cooling of the high-pressure air. The waste nitrogen gas passing through the fourth low-pressure channel 214 can exchange heat with the low-pressure air passing through the first low-pressure channel 211 to achieve cooling of the low-pressure air.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An air separation unit, characterized in that, include: An air-cooled tower, wherein the air-cooled tower has an air outlet; A low-pressure heat exchanger having a first low-pressure passage; A distillation column, comprising an upper column and a lower column, the upper column having a liquid oxygen outlet, and the lower column having a first air inlet and a liquid nitrogen outlet, the air outlet being connected to the first air inlet via a first low-pressure channel; The pump set includes at least one liquid oxygen pump and at least two liquid nitrogen pumps. The inlet of the liquid oxygen pump is connected to the liquid oxygen outlet, and the outlet of the liquid oxygen pump is connected to a first oxygen supply pipe. At least one liquid nitrogen pump is a first liquid nitrogen pump, and at least one liquid nitrogen pump is a second liquid nitrogen pump. The inlets of both the first liquid nitrogen pump and the second liquid nitrogen pump are connected to the liquid nitrogen outlet. The outlet of the first liquid nitrogen pump is connected to a first nitrogen supply pipe, and the outlet of the second liquid nitrogen pump is connected to a second nitrogen supply pipe.

2. The air separation unit according to claim 1, characterized in that, It also includes a high-pressure heat exchanger, which has a first high-pressure channel, a second high-pressure channel and a third high-pressure channel. The first oxygen supply pipe is connected to the liquid oxygen pump through the first high-pressure channel, the first nitrogen supply pipe is connected to the first liquid nitrogen pump through the second high-pressure channel, and the second nitrogen supply pipe is connected to the second liquid nitrogen pump through the third high-pressure channel.

3. The air separation unit according to claim 1, characterized in that, It also includes a second oxygen supply pipe and a third nitrogen supply pipe. The upper tower has an oxygen outlet, the lower tower has a nitrogen outlet, and the low-pressure heat exchanger has a second low-pressure channel and a third low-pressure channel. The second oxygen supply pipe is connected to the oxygen outlet through the second low-pressure channel, and the third nitrogen supply pipe is connected to the nitrogen outlet through the third low-pressure channel.

4. The air separation unit according to claim 1, characterized in that, It also includes a subcooler, a liquid oxygen storage tank, and a liquid nitrogen storage tank. The subcooler has a first subcooling channel and a second subcooling channel. The liquid oxygen storage tank is connected to the liquid oxygen outlet through the first subcooling channel, and the liquid nitrogen storage tank is connected to the liquid nitrogen outlet through the second subcooling channel.

5. The air separation unit according to claim 1, characterized in that, It also includes a purification component, through which the air outlet is connected to the first air inlet.

6. The air separation unit according to claim 2, characterized in that, The high-pressure heat exchanger has a fourth high-pressure channel and a fifth high-pressure channel, the lower tower has a second air inlet and a third air inlet, and the air separation unit further includes a second air compressor, an expander and a cooler. The second air compressor has a first outlet and a second outlet, and the first outlet is connected to the second air inlet through the fourth high-pressure channel. The expander includes a booster end and an expansion end, and the second outlet of the second air compressor, the booster end, the cooler, the fifth high-pressure channel, the expansion end, and the third air inlet are connected in sequence.

7. The air separation unit according to claim 6, characterized in that, It also includes a crude argon column and a refined argon column. The crude argon column has an argon fraction gas inlet and a crude argon outlet. The refined argon column has a crude argon inlet and a liquid argon outlet. The upper column has an argon fraction gas outlet, which is connected to the argon fraction gas inlet. The crude argon outlet is connected to the crude argon inlet.

8. The air separation unit according to claim 7, characterized in that, It also includes a water-cooled tower, the outlet of which is connected to the inlet of the air-cooled tower, so as to cool the air in the air-cooled tower by using water in the water-cooled tower. The water-cooled tower has a waste nitrogen inlet, and the upper tower has a first waste nitrogen outlet, which is connected to the waste nitrogen inlet.

9. The air separation unit according to claim 8, characterized in that, The argon column has a second waste nitrogen outlet, which is connected to the waste nitrogen inlet.

10. The air separation unit according to claim 8, characterized in that, The high-pressure heat exchanger has a sixth high-pressure channel, and the low-pressure heat exchanger has a fourth low-pressure channel; the first waste nitrogen outlet is connected to a first waste nitrogen pipe and a second waste nitrogen pipe, the first waste nitrogen pipe is connected to the waste nitrogen inlet through the sixth high-pressure channel, and the second waste nitrogen pipe is connected to the waste nitrogen inlet through the fourth low-pressure channel.

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