Low-temperature air separation system

Abstract

The invention relates to the technical field of air separation, in particular to a low-temperature air separation system. The separation efficiency and the separation purity of oxygen, nitrogen and argon components in low-temperature air are improved, and the production energy consumption is reduced. The air filtering and compressing system is used for filtering mechanical impurities and dust in the air and then compressing the air to the required pressure; the air pre-cooling system is used for receiving the compressed air source from the air filtering and compressing system and cooling the compressed air source; the air purification system is used for removing H2O, CO2 and part of C and H in the air; the air pressurization expansion system provides a cold source guarantee for low-temperature rectification; the first rectification system is used for cooling the pressurized and expanded air to a liquefaction critical temperature and rectifying and separating a pure oxygen product and a pure nitrogen product from the air cooled to the liquefaction critical temperature; and the second rectification system is used for rectifying and separating a pure argon product from the rectified air, so that efficient and safe separation and extraction operation is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of air separation, in particular to a low-temperature air separation system. Background Art

[0002] Due to the implementation of the green transformation project of electric furnaces, it is necessary to supply them with oxygen, nitrogen and argon for production. The implementation of this project has broken the material balance of the original energy medium pipeline network, and it is necessary to re-establish a new material balance point. Through the overall planning of the energy medium demand of the green transformation project of electric furnaces and the ever-expanding demand for oxygen, nitrogen and argon in steelmaking and ironmaking processes, a low-temperature air separation system has been developed independently to meet the supply of energy media. Summary of the invention

[0003] The object of the present invention is to provide a cryogenic air separation system, which improves the separation efficiency and separation purity of oxygen, nitrogen and argon components in cryogenic air in the prior art.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a cryogenic air separation system, comprising: An air filtration and compression system, the air filtration and compression system comprising an air filter and an air compressor; An air precooling system, the air precooling system comprising an air cooling tower and a water cooling tower, the air cooling tower and the water cooling tower are connected in parallel, and the air compressor is connected to the air filter and the air cooling tower; An air purification system, the air purification system comprising a molecular sieve adsorber, an electric heater and a steam heater; the molecular sieve adsorber is connected to the air cooling tower; An air boosting and expansion system, the air boosting and expansion system comprising an air booster, a booster turbine expander and a booster aftercooler; the air booster connects the molecular sieve adsorber and the booster turbine expander; a first distillation system, wherein the first distillation system comprises a main heat exchanger, a lower tower, an upper tower, a main condenser evaporator, a subcooler, a process liquid oxygen pump and a process liquid nitrogen pump; the first distillation system is connected to the air booster and the booster turbine expander; The second distillation system includes a crude argon column I, a crude argon column II, a crude argon condenser, a circulating liquid argon pump, a pure argon column, a pure argon condenser, a pure argon evaporator and a process liquid argon pump; the second distillation system is connected to the first distillation system.

[0005] Furthermore, the air precooling system also includes a cooling water pump, a chiller and a refrigerated water pump; the air cooling tower is connected to the cooling water pump and the chiller respectively, the chiller is connected to the water cooling tower through a pipeline, and the refrigerated water pump is arranged between the chiller and the water cooling tower.

[0006] Furthermore, three groups of the electric heaters are arranged in parallel, and the electric heaters are connected in series and parallel with the steam heaters.

[0007] Furthermore, the booster turbine expander includes a booster end and an expansion end, and the booster end and the expansion end are respectively connected to the air booster, the main heat exchanger and the lower tower through pipelines; the booster aftercooler is arranged between the booster end of the booster turbine expander and the main heat exchanger.

[0008] Furthermore, the main condenser evaporator is arranged between the lower tower and the upper tower, one end of the process liquid oxygen pump is connected to the main condenser evaporator, and the other end of the process liquid oxygen pump is connected to the main heat exchanger; the lower tower is connected to the upper tower through the subcooler; one end of the process liquid nitrogen pump is connected to the main heat exchanger, and the other end of the process liquid nitrogen pump is connected to the lower tower.

[0009] Furthermore, the crude argon condenser is arranged above the crude argon tower II, and the crude argon condenser is connected to the pure argon tower; the circulating liquid argon pump connects the crude argon tower I and the crude argon tower II; the pure argon tower is arranged between the pure argon condenser and the pure argon evaporator.

[0010] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: The present invention provides a low-temperature air separation system, which compresses the air to a required pressure after filtering out mechanical impurities and dust in the air through an air filtration and compression system; receives a compressed air source from the air filtration and compression system through an air precooling system to cool the compressed air source; removes H2O, CO2 and part of C and H in the air through an air purification system to keep the air clean; and provides a cold source guarantee for low-temperature distillation through an air boosting and expansion system. The pressurized and expanded air is cooled to the critical temperature of liquefaction through a first distillation system, and pure oxygen products and pure nitrogen products are distilled and separated from the air cooled to the critical temperature of liquefaction; the second distillation system is used to distill and separate pure argon products from the distilled air; thereby achieving efficient and safe extraction operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings: Figure 1 A plan view of a cryogenic air separation system provided in the present invention; The reference numerals are as follows: 1. Air filter; 2. Air compressor; 3. Air cooling tower; 4. Water cooling tower; 5. Cooling water pump; 6. Chiller; 7. Chilled water pump; 8. Molecular sieve adsorber; 9. Electric heater; 10. Steam heater; 11. Air booster; 12. Booster turbine expander; 120. Boosting end; 121. Expansion end; 13. Aftercooler; 14. Main heat exchanger; 15. Lower tower; 16. Upper tower Tower; 17. Main condenser evaporator; 18. Subcooler; 19. Process liquid oxygen pump; 20. Process liquid nitrogen pump; 21. Crude argon tower I; 22. Crude argon tower II; 23. Crude argon condenser; 24. Circulating liquid argon pump; 25. Pure argon tower; 26. Pure argon condenser; 27. Pure argon evaporator; 28. Process liquid argon pump; 29. ​​Medium-pressure argon heat exchanger; 30. Low-pressure nitrogen compressor; 31. Medium-pressure nitrogen compressor; 32. Medium-pressure oxygen compressor. DETAILED DESCRIPTION

[0012] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] See also Figure 1 A low-temperature air separation system of the present invention includes an air filtration and compression system, an air precooling system, an air purification system, an air boosting and expansion system, a first distillation system and a second distillation system which are connected in sequence.

[0014] Specifically, the air filtering and compressing system is provided with an air filter 1 and an air compressor 2. The air filter 1 and the air compressor 2 are connected in series, and the raw air is filtered by the air filter 1 to remove dust and mechanical impurities in the raw air, and then enters the air compressor 2 for multi-stage compression until the raw air is compressed to the required pressure.

[0015] The air precooling system includes an air cooling tower 3, a water cooling tower 4, a cooling water pump 5, a chiller 6 and a refrigeration water pump 7. The air cooling tower 3 in the precooling system is connected to the air compressor 2 and is used to receive the compressed air source from the air compressor 2 and cool the compressed air source. The compressed air source enters the air cooling tower 3 from the bottom, passes through the packing layer in the tower from bottom to top, and is cooled by the cooling water passed from top to bottom and then discharged from the top, so as to reduce the temperature of the compressed air source as much as possible, reduce the water content in the air, and reduce the load for subsequent operations. At the same time, it can also wash away some harmful impurities such as NOx, SO2, Cl- in the air source.

[0016] The cooling water in the air cooling tower 3 is provided by circulating cooling water and low-temperature refrigerated water cooled by the water cooling tower 4 and the chiller 6. The water source of the water cooling tower 4 is also provided by circulating cooling water.

[0017] Specifically, one circulating cooling water is directly pumped into the air cooling tower 3 via the cooling water pump 5; another circulating cooling water is transported to the water cooling tower 4 to exchange heat and mass with the excess dirty nitrogen from the first distillation system (the dirty nitrogen from the first distillation system enters the bottom of the packing of the water cooling tower 4, and the circulating cooling water flows through the packing layer from top to bottom to exchange heat and mass with the rising dirty nitrogen). The dirty nitrogen is dry when it enters the water cooling tower 4, and is discharged from the top of the tower to the atmosphere after taking away the heat, and the humidity is close to saturation. Subsequently, it is pressurized by the chilled water pump 5, pumped into the chiller 6 for cooling, and finally sent to the top of the air cooling tower 3.

[0018] In addition, in the present embodiment, emergency fire water is synchronously provided downstream of the above-mentioned chilled water pump 5 and chiller 6. When the chilled water pump 5 and / or chiller 6 fails and shuts down and runs out of water, emergency fire water can be used to maintain production temporarily, thereby buying time for equipment repair and maintenance.

[0019] In this embodiment, the chiller 6 used is one for use and one for backup. In case of a sudden failure, the backup chiller 6 can be automatically interlocked to prevent the temperature in the air cooling tower 3 from being too high and affecting production. In addition, during some periods of high temperature, two chillers 6 can be used in combination to increase the cooling rate and reduce the energy consumption of other related equipment.

[0020] The top of the air cooling tower 3 in this embodiment is also provided with a free water separation device and a wire mesh demister. The free water separation device can effectively remove the free water in the cooling tower and prevent the free water in the process air from being brought out, so as to ensure that the cooling process is more efficient and improve the heat exchange efficiency, so that it can still maintain good working performance under high load or high temperature conditions.

[0021] In addition, the hot water at the bottom of the air cooling tower 3 is discharged from the tower body through a liquid level control valve and connected to the circulating cooling water pipeline for circulating cooling utilization.

[0022] The air purification system comprises a molecular sieve adsorber 8, an electric heater 9 and a steam heater 10. One end of the molecular sieve adsorber 8 is connected to the air cooling tower 3 to receive the air source from the air cooling tower 3. The other end of the molecular sieve adsorber 8 is connected to the electric heater 9 and the steam heater 10 in sequence.

[0023] In this embodiment, two molecular sieve adsorbers 8 are arranged in parallel to remove H2O, CO2 and part of C and H in the air, so that the air entering the first distillation system remains clean.

[0024] The molecular sieve in the molecular sieve adsorber 8 has a specific pore size and structure, and can selectively adsorb molecules of a specific size. In addition, the molecular sieve has a large specific surface area and pore volume, and has a strong adsorption capacity for gas. In addition, the molecular sieve can be regenerated by heating or decompression, thereby restoring its adsorption capacity and being recycled multiple times. After the air is adsorbed by the molecular sieve adsorber 8, a portion of it is used as instrument gas and heating gas, and the rest is sent to the air boost expansion system, the first distillation system, and the second distillation system.

[0025] In this embodiment, the adsorbent in the molecular sieve adsorber 8 is divided into two layers, the lower layer is alumina, and the upper layer is molecular sieve. Due to the adsorption characteristics of alumina and molecular sieve, when the air passes through the alumina and molecular sieve beds from bottom to top, some hydrocarbons such as H2O, CO2, C2H2 in the air are adsorbed by the adsorbent, and the purified air is discharged from the top. The adsorbent has an upper limit on its adsorption capacity for the above components, and it must be regenerated after working for a certain period of time. During the regeneration cycle, after the adsorber is depressurized, the dry gas is first heated by a heater, and the high-temperature gas passes through the adsorbent bed from top to bottom to desorb and regenerate the adsorbent, and then it is cooled to room temperature with room temperature dry gas. Two adsorbers are configured and used alternately. When one is working, the other is regenerated.

[0026] Regarding how to achieve regeneration of the above-mentioned molecular sieve adsorber 8, in this embodiment, the molecular sieve adsorber 8 is connected to an electric heater 9. Specifically, when one adsorber is working, the other adsorber can be regenerated and cold-blown for standby through the regeneration dirty nitrogen bypass. The dirty nitrogen gas refluxed from the first distillation system is heated to a certain temperature by the electric heater 9, and then enters the molecular sieve adsorber 8 for heating and regeneration, so as to desorb H2O, CO2 and CnH2 therein and then be discharged into the atmosphere. Then, the dirty nitrogen gas is used to cold-blown the molecular sieve adsorber 8, and the adsorber can restore its adsorption capacity after being fully cooled.

[0027] In this embodiment, the air purified by the molecular sieve adsorber 8 goes to the regeneration waste nitrogen bypass for adsorption regeneration of the molecular sieve adsorber 8 (see Figure 1 All the way to the medium pressure argon heat exchanger 29 for heat exchange with the reflux liquid argon (see Figure 1 all the way to sealing gas, pneumatic valve supply gas and heating gas (see Figure 1 35 in the figure), all the way to the air booster 11 for boosting (see Figure 1 36 in the figure), and one way to the main heat exchanger 14 in the first distillation system for reheating with the reflux liquid (see Figure 1 37 in the figure).

[0028] In this embodiment, three groups of electric heaters 9 are arranged in parallel. To save energy, steam heaters 10 are arranged in series and parallel on the electric heaters 9. The above-mentioned polluted nitrogen gas for desorption is first heated by the byproduct steam in the plant area, and then the number of groups of electric heaters 9 to be put into use is selected according to the heating temperature to save electricity. In addition, the condensed water in the steam heater 10 is also reused, which truly achieves energy saving and consumption reduction, cost reduction and expenditure saving.

[0029] For the above-mentioned air boosting and expansion system, the system includes an air booster 11, a booster turbine expander 12 and a booster aftercooler 13. The air booster 11 is used to further compress the purified air after being treated by the molecular sieve adsorber 8, one end of which is connected to the aforementioned molecular sieve adsorber 8, and the other end is connected to the booster turbine expander 12, the booster aftercooler 13 and the first distillation system. The first distillation system includes a main heat exchanger 14, a lower tower 15, an upper tower 16, a main condenser evaporator 17, a subcooler 18, a process liquid oxygen pump 19 and a process liquid nitrogen pump 20.

[0030] In this embodiment, the booster turbine expander 12 is used to provide cooling capacity and provide a cooling source for low-temperature distillation. Specifically, the booster turbine expander 12 includes a boosting end 120 and an expansion end 121. The air treated by the air booster 11 is divided into two paths. One path goes to the boosting end 120 of the booster turbine expander 12 for further pressurization, and then directly enters the main heat exchanger 14, and after throttling and depressurization, enters the lower tower 15 to participate in distillation (see Figure 1 The other path goes to the main heat exchanger 14 and then splits into two paths, one of which goes to the expansion end 121 of the booster turbine expander 12 and expands before entering the lower tower 15 in the first distillation system to participate in distillation (see Figure 1 The other path directly passes through the main heat exchanger 14 for throttling and pressure reduction, and then enters the lower tower 15 for distillation (see Figure 1 number 40 in the figure).

[0031] In this embodiment, a reflux automatic regulating valve is also provided at the boosting end 120 of the booster turbine expander 12 to control the rotation speed of the boosting end 120. During production, the booster turbine expander 12 also adopts one in use and one in standby mode, and can be interlocked and started when one expander fails suddenly, and can also start two expanders at the same time to increase the refrigeration capacity, save startup time, and improve production efficiency.

[0032] For the aforementioned first distillation system, specifically, the main condenser evaporator 17 is arranged between the lower tower 15 and the upper tower 16, and is used to liquefy the nitrogen at the top of the lower tower 15 and vaporize the liquid oxygen at the bottom of the upper tower 16 to maintain the distillation working conditions of the upper and lower towers. The main condenser 17 in this embodiment is a multi-layer plate-fin type, and the channels of each layer are separated by partitions, and fins are laid between the partitions. Low-boiling point components in nitrogen, such as neon and helium, will gradually accumulate on the plate surface, thereby affecting the heat exchange effect. Therefore, a non-condensable gas discharge pipeline is provided in this embodiment, which can be directly discharged to the atmosphere.

[0033] In the lower tower 15, most of the dirty liquid nitrogen in the upper part is liquefied by the main condenser evaporator 17 and used as the reflux liquid of the upper and lower towers; a part of it is treated by the subcooler 18 as the product liquid nitrogen and sent to the liquid nitrogen storage tank (see Figure 1 The rest is pressurized by the process liquid nitrogen pump 20, enters the main heat exchanger 14 for reheating, and is then delivered to the user (see Figure 1 number 42 in the figure).

[0034] In the lower tower 15, the lean liquid in the lower part is sent back to the upper part of the upper tower 16 after being supercooled by the supercooler 18 to be used as the reflux liquid of the upper tower (see Figure 1 The oxygen-rich liquid air at the bottom of the lower tower 15 is sent back to the upper tower 16 after being supercooled by the cooler 18 to serve as the cooling source for the reflux liquid of the upper tower and the condenser of the efficiency tower (see Figure 1 44 and 45 in FIG.

[0035] Most of the liquid oxygen at the bottom of the upper tower 16 is vaporized by the nitrogen in the lower tower 15 to become the rising gas of the upper tower 16. The remaining liquid oxygen is extracted from the bottom of the main condenser evaporator 17. A part of it is pressurized by the process liquid oxygen pump 19 and then enters the main heat exchanger 14 for reheating, and then transported to the user (see Figure 1 The other part is directly sent to the liquid oxygen storage tank as liquid oxygen product (see Figure 1 number 47 in the figure).

[0036] The part of liquid oxygen that is reheated by the main heat exchanger 14 can also be reduced in pressure by setting a throttle valve before entering the main heat exchanger 14, thereby forming low-pressure oxygen for delivery to the user (see Figure 1After being processed by the throttle valve and the main heat exchanger 14, the oxygen can be pressurized from the low-pressure oxygen to the medium-pressure oxygen by the medium-pressure oxygen compressor 32, and then can be allocated according to the actual demand for medium and low oxygen (see Figure 1 number 49 in the figure).

[0037] The dirty nitrogen gas at the upper part of the upper tower 16 is extracted from the top of the upper tower, and is processed by the subcooler 18 to recover part of the cold capacity. After being reheated to the required temperature by the main heat exchanger 14, part of it goes to the molecular sieve adsorber 8 for molecular sieve regeneration (see Figure 1 The other part is directly sent to the water cooling tower 4 to recover the cold (see Figure 1 51 in the figure).

[0038] A portion of the nitrogen at the top of the upper tower 16 is transported to the water cooling tower 4 to recover the cooling capacity (see Figure 1 The other part is used as the sealing gas for the first distillation system. Figure 1 66 in the figure).

[0039] The aforementioned second distillation system includes a crude argon tower I 21, a crude argon tower II 22, a crude argon condenser 23, a circulating liquid argon pump 24, a pure argon tower 25, a pure argon condenser 26, a pure argon evaporator 27 and a process liquid argon pump 28; the pure argon tower 25 is arranged between the pure argon condenser 26 and the pure argon evaporator 27, the crude argon condenser 23 is arranged above the crude argon tower II 22, and the circulating liquid argon pump 24 connects the crude argon tower I 21 and the crude argon tower II 22.

[0040] Specifically, an argon fraction is extracted from the middle of the upper tower 16 and enters the crude argon tower I 21 for rectification to reduce the oxygen content (see Figure 1 The reflux liquid of crude argon column I 21 is the liquid crude argon drawn from the bottom of crude argon column II 22 and transported by circulating liquid argon pump 24 (see Figure 1 The liquid at the bottom of the crude argon column I 21 is returned to the upper column 16 for distillation (see Figure 1 54 in the figure).

[0041] The gas drawn from the top of crude argon column I 21 enters the bottom of crude argon column II 22 and undergoes further separation of argon and oxygen therein (see Figure 1 As a result, crude argon gas with O2 ≤ 1.5 ppm is obtained at the top of crude argon column II 22, which is condensed into liquid by crude argon condenser 23 and returned to crude argon column II 22 as reflux liquid (see Figure 1 The cold source of the crude argon condenser 23 is the oxygen-rich liquid air drawn out after the subcooler 18 (see Figure 1 45 in the figure), after being evaporated by heat exchange with the crude argon gas, returns to the appropriate part of the upper tower 16 to participate in the distillation (see Figure 1 57 in the figure).

[0042] The crude argon gas with O2≤1.5ppm drawn from the plate unit of the crude argon condenser 23 enters the middle of the pure argon tower 25 (see Figure 1 After distillation, liquid argon with O2≤1.5ppm and N2≤4ppm is obtained at the bottom of the pure argon tower 25, and a part of it is sent out of the second distillation system as a product and enters the liquid argon storage tank (see Figure 1 A portion is pressurized by the process liquid argon pump 28 and then reheated by the medium pressure argon heat exchanger 29 and sent out of the second distillation system (see Figure 1 The rest is heat exchanged with the medium-pressure nitrogen from the lower tower 15 to evaporate and participate in the distillation as the rising gas (see Figure 1 61 in the figure), while the nitrogen is liquefied and returned to the top of the upper tower 16 to participate in the distillation (see Figure 1 62 in the figure).

[0043] A pure argon condenser 26 is provided at the top of the pure argon tower 25 to condense the rising argon gas into liquid and return it to the pure argon tower 25 as reflux liquid (see Figure 1 The cooling source of the condenser comes from the liquid nitrogen after the subcooler 18. The evaporated nitrogen returns to the waste nitrogen outlet pipeline 16 of the upper tower and is sent out of the second distillation system (see Figure 1 number 64 in the figure).

[0044] In summary, the cryogenic air separation system disclosed in the present invention compresses the air to the required pressure after filtering out mechanical impurities and dust in the air through an air filtration and compression system; receives a compressed air source from the air filtration and compression system through an air precooling system to cool the compressed air source; removes H2O, CO2 and part of C and H in the air through an air purification system to keep the air clean; provides a cold source guarantee for cryogenic distillation through an air boosting and expansion system. Through the first distillation system, the pressurized and expanded air is cooled to the critical temperature of liquefaction, and pure oxygen products and pure nitrogen products are distilled and separated from the air cooled to the critical temperature of liquefaction; through the second distillation system, it is used to distill and separate pure argon products from the distilled air; thereby achieving efficient and safe separation and extraction operations.

[0045] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A cryogenic air separation system, characterized in that: include: An air filtering and compressing system, the air filtering and compressing system comprising an air filter (1) and an air compressor (2); An air precooling system, the air precooling system comprising an air cooling tower (3) and a water cooling tower (4), the air cooling tower (3) and the water cooling tower (4) being connected in parallel, and the air compressor (2) being connected to the air filter (1) and the air cooling tower (3); An air purification system, the air purification system comprising a molecular sieve adsorber (8), an electric heater (9) and a steam heater (10); the molecular sieve adsorber (8) is connected to the air cooling tower (3); An air boosting and expansion system, the air boosting and expansion system comprising an air booster (11), a booster turbine expander (12) and a booster aftercooler (13); the air booster (11) is connected to the molecular sieve adsorber (8) and the booster turbine expander (12); a first distillation system, the first distillation system comprising a main heat exchanger (14), a lower tower (15), an upper tower (16), a main condenser evaporator (17), a subcooler (18), a process liquid oxygen pump (19), and a process liquid nitrogen pump (20); the first distillation system is connected to the air booster (11) and the booster turbine expander (12); A second distillation system, the second distillation system comprising a crude argon column I (21), a crude argon column II (22), a crude argon condenser (23), a circulating liquid argon pump (24), a pure argon column (25), a pure argon condenser (26), a pure argon evaporator (27) and a process liquid argon pump (28); the second distillation system is connected to the first distillation system.

2. A cryogenic air separation system according to claim 1, characterized in that: The air precooling system further comprises a cooling water pump (5), a chiller (6) and a refrigerated water pump (7); the air cooling tower (3) is connected to the cooling water pump (5) and the chiller (6) respectively, the chiller (6) is connected to the water cooling tower (4) via a pipeline, and the refrigerated water pump (7) is arranged between the chiller (6) and the water cooling tower (4).

3. A cryogenic air separation system according to claim 1, characterized in that: The electric heaters (9) are arranged in three groups in parallel, and the electric heaters (9) are connected in series and in parallel with the steam heaters (10).

4. A cryogenic air separation system according to claim 1, characterized in that: The booster turbine expander (12) comprises a booster end (120) and an expansion end (121), wherein the booster end (120) and the expansion end (121) are respectively connected to the air booster (11), the main heat exchanger (14) and the lower tower (15) via pipelines; the booster aftercooler (13) is arranged between the booster end (120) of the booster turbine expander (12) and the main heat exchanger (14).

5. A cryogenic air separation system according to claim 1, characterized in that: The main condenser evaporator (17) is arranged between the lower tower (15) and the upper tower (16); one end of the process liquid oxygen pump (19) is connected to the main condenser evaporator (17), and the other end of the process liquid oxygen pump (19) is connected to the main heat exchanger (14); the lower tower (15) is connected to the upper tower (16) via the subcooler (18); one end of the process liquid nitrogen pump (20) is connected to the main heat exchanger (14), and the other end of the process liquid nitrogen pump (20) is connected to the lower tower (15).

6. A cryogenic air separation system according to claim 1, characterized in that: The crude argon condenser (23) is arranged above the crude argon tower II (22), and the crude argon condenser (23) is connected to the pure argon tower (25); the circulating liquid argon pump (24) is connected to the crude argon tower I (21) and the crude argon tower II (22); the pure argon tower (25) is arranged between the pure argon condenser (26) and the pure argon evaporator (27).

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