A liquid air separation rectification apparatus

Abstract

The utility model relates to a kind of rectification equipment of liquid air separation, including rectification tower, rectification tower includes upper tower, main condensing evaporator and lower tower, main condensing evaporator and lower tower are connected by first nitrogen gas conveying pipe, first liquid nitrogen conveying main pipe is equipped on main condensing evaporator, first liquid nitrogen conveying main pipe is equipped with first liquid nitrogen conveying branch pipe, second liquid nitrogen conveying branch pipe, first regulating valve and liquid nitrogen graduated cylinder, second regulating valve is respectively equipped on first liquid nitrogen conveying branch pipe and second liquid nitrogen conveying branch pipe, the top of liquid nitrogen graduated cylinder is equipped with second nitrogen gas conveying pipe, self-standing type regulating valve is equipped on second nitrogen gas conveying pipe, second nitrogen gas conveying pipe and first nitrogen gas conveying pipe are connected, second liquid nitrogen conveying main pipe is equipped on the bottom end of liquid nitrogen graduated cylinder, liquid nitrogen pump and third regulating valve are equipped on second liquid nitrogen conveying main pipe.In the process of a large number of liquid nitrogen production, still can maintain normal supply to upper tower and lower tower sufficient liquid nitrogen.The utility model is convenient to use, with wide market prospect.

Description

Technical Field

[0001] This utility model relates to the field of distillation equipment for liquid air separation, and specifically to a distillation equipment for liquid air separation. Background Technology

[0002] With increasing energy scarcity, the gas production industry is comparing various production methods to achieve higher economic efficiency. Liquid air products are gaining popularity among gas producers due to their good quality, low transportation costs, favorable price-performance ratio, ease of use, and safety. Currently, industrial gas production and supply in my country are mainly handled by small and medium-sized gas stations, and are highly dispersed. Large-scale air separation units in domestic metallurgical and chemical enterprises primarily produce industrial gases for internal use, while the liquid byproducts from these units can be sold separately, effectively mitigating the imbalance between supply and demand in different regions.

[0003] Cryogenic air separation systems that supply nitrogen as a standalone product can achieve nitrogen supply through both single-tower and dual-tower nitrogen production processes. Relatively speaking, single-tower nitrogen production is simpler in structure and requires less initial infrastructure investment, but the energy cost of the nitrogen produced by single-tower processes is relatively higher. The advantage of dual-tower nitrogen production lies in its relatively lower energy consumption and the ability to produce oxygen as a byproduct. However, for cryogenic air separation systems that only require nitrogen as a gaseous product, producing oxygen as a byproduct is generally done in liquid oxygen form. This requires introducing more cooling energy into the distillation system to produce liquid oxygen. To ensure that the compressed air used as feedstock carries sufficient cooling energy into the distillation column, high- and low-pressure expanders are typically used to pressurize and expand the compressed air. Furthermore, even when nitrogen is the primary gaseous product and liquid oxygen is the primary liquid product, a small amount of liquid nitrogen will generally be produced as a secondary liquid product. Because liquid nitrogen is produced in the heat source channel of the main condenser-evaporator, the liquid nitrogen produced in this channel is divided into three parts: the first part serves as the first reflux condensate in the lower column, the second part as the second reflux condensate in the upper column, and the third part is collected at the end of the liquid nitrogen delivery main and transported to the liquid nitrogen storage tank, which is the final liquid nitrogen product. According to production requirements, when the liquid nitrogen level in the storage tank falls below the normal range, a large amount of finished liquid nitrogen needs to be withdrawn to maintain the minimum liquid nitrogen level in the tank and prevent the temperature inside the storage tank from rising due to insufficient cooling. However, withdrawing a large amount of liquid nitrogen will reduce the flow rate of the first reflux condensate supplied to the lower column and the second reflux condensate supplied to the upper column, which may lead to changes in the distillation state of the upper column due to insufficient cooling, resulting in the production of substandard products. Therefore, there is room for improvement in the existing technology, which aims to ensure a normal supply of liquid nitrogen to the upper and lower columns when there is a large demand for liquid nitrogen extraction, thereby reducing the non-conforming products caused by fluctuations in the distillation conditions of the distillation column. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a liquid air separation distillation apparatus that can maintain a normal supply of sufficient liquid nitrogen to both the upper and lower columns during the process of large-scale liquid nitrogen extraction, thereby overcoming the deficiencies in existing technologies.

[0005] The technical solution adopted in this utility model is as follows: a liquid air separation distillation device, including a distillation column, which comprises, from top to bottom, an upper column, a main condenser-evaporator, and a lower column. The inlet end of the heat source channel of the main condenser-evaporator and the lower column are connected by a first nitrogen delivery pipe. A first liquid nitrogen delivery main pipe is provided at the outlet end of the heat source channel of the main condenser-evaporator. The first liquid nitrogen delivery main pipe is provided with, along the direction from near the main condenser-evaporator to away from the main condenser-evaporator, the inlet end of a first liquid nitrogen delivery branch pipe, the inlet end of a second liquid nitrogen delivery branch pipe, and a first regulating valve. The liquid nitrogen graduated cylinder, the first liquid nitrogen delivery branch pipe and the second liquid nitrogen delivery branch pipe are each equipped with a second regulating valve. The outlet end of the first liquid nitrogen delivery branch pipe is connected to the top of the upper tower, and the outlet end of the second liquid nitrogen delivery branch pipe is connected to the top of the lower tower. The top of the liquid nitrogen graduated cylinder is equipped with the inlet end of the second nitrogen delivery pipe. The second nitrogen delivery pipe is equipped with a self-standing regulating valve. The outlet end of the second nitrogen delivery pipe is connected to the first nitrogen delivery pipe. The bottom end of the liquid nitrogen graduated cylinder is equipped with the inlet end of the second liquid nitrogen delivery main pipe. The second liquid nitrogen delivery main pipe is equipped with a liquid nitrogen pump and a third regulating valve.

[0006] Preferably, the upper tower is provided with a finished nitrogen gas delivery pipe, and the lower tower and the upper tower are provided with oxygen-enriched liquid air delivery pipes. The oxygen-enriched liquid air delivery pipes are provided with a liquid air delivery pump and a fourth regulating valve. The cold source channel of the main condenser-evaporator is provided with a liquid oxygen delivery pipe. The first liquid nitrogen delivery branch pipe, the second liquid nitrogen delivery main pipe, the oxygen-enriched liquid air delivery pipe and the finished nitrogen gas delivery pipe are provided with a first subcooler, and the finished nitrogen gas delivery pipe and the liquid oxygen delivery pipe are provided with a second subcooler.

[0007] Preferably, the lower tower is provided with a compressed air delivery main pipe. The compressed air delivery main pipe is provided with the following components in sequence along the direction from near to far from the lower tower: the outlet end of the liquefied air delivery pipe, the inlet end of the first expansion air return pipe, a fifth regulating valve, the expansion end of the first turbine expander, the inlet end of the liquefied air delivery pipe, the boosting end of the first turbine expander, the circulating air compressor unit, and the outlet end of the first expansion air return pipe. A sixth regulating valve is provided on both the liquefied air delivery pipe and the first expansion air return pipe. A main heat exchanger is provided on the compressed air delivery main pipe between the expansion end and the boosting end of the first turbine expander, the first expansion air return pipe, and the liquefied air delivery pipe.

[0008] Preferably, the main compressed air supply pipe and the main heat exchanger are provided with compressed air supply branch pipes. The inlet end of the compressed air supply main pipe and the compressed air supply branch pipe between the pressurization end of the first turbo expander and the circulating air compressor unit are connected. The pressurization end of the second turbo expander is provided on the main compressed air supply pipe between the pressurization end of the first turbo expander and the main heat exchanger. The outlet end of the compressed air supply branch pipe is connected to the inlet of the expansion end of the second turbo expander. The outlet end of the first expansion air return pipe and the first expansion air return pipe between the main heat exchanger, the main heat exchanger, and the expansion end outlet of the second turbo expander are provided with second expansion air return pipes. The main compressed air supply pipe between the compressed air supply branch pipe and the pressurization end of the first turbo expander, as well as the compressed air supply branch pipe, are each provided with a seventh regulating valve.

[0009] Preferably, the main compressed air supply pipe between the pressurization end of the first turbine expander and the pressurization end of the second turbine expander, as well as the branch compressed air supply pipe between the pressurization end of the second turbine expander and the main heat exchanger, are each provided with a heat source channel for the organic post-heat exchanger.

[0010] Preferably, the liquid nitrogen graduated cylinder is equipped with a liquid level sensor.

[0011] The beneficial effects of this invention are as follows: First, when no liquid nitrogen extraction target is received, a portion of the liquid nitrogen produced by the condenser / evaporator is continuously supplied to a liquid nitrogen measuring cylinder for temporary storage. When a production order requiring a large extraction of liquid nitrogen is received, the liquid nitrogen temporarily stored in the measuring cylinder can be transferred to the first subcooler for subcooling before extraction. This avoids the production of substandard products caused by insufficient liquid nitrogen supplied to the upper and lower columns due to insufficient liquid nitrogen extraction based on production orders, which could alter the distillation conditions of the upper and lower columns.

[0012] Secondly, the liquid nitrogen graduated cylinder described in this invention is equipped with a liquid level sensor, which facilitates the feedback of liquid level parameters.

[0013] This utility model has a simple structure, is easy to operate, and has a clever design, which greatly improves work efficiency and has good social and economic benefits. It is a product that is easy to promote and use. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0015] like Figure 1As shown, a liquid air separation distillation apparatus includes a distillation column, which, from top to bottom, comprises an upper column 1, a main condenser-evaporator 2, and a lower column 3. The inlet end of the heat source channel of the main condenser-evaporator 2 and the lower column 3 are connected by a first nitrogen delivery pipe 4. A first liquid nitrogen delivery main pipe 5 is provided at the outlet end of the heat source channel of the main condenser-evaporator 2. The first liquid nitrogen delivery main pipe 5, along the direction from near to far from the main condenser-evaporator 2, is provided with the inlet end of a first liquid nitrogen delivery branch pipe 6, the inlet end of a second liquid nitrogen delivery branch pipe 7, a first regulating valve 8, and a liquid nitrogen measuring cylinder 9. A second regulating valve 10 is provided on both the first liquid nitrogen delivery branch pipe 6 and the second liquid nitrogen delivery branch pipe 7. The outlet end of the first liquid nitrogen delivery branch pipe 6 is connected to the top of the upper tower 1, and the outlet end of the second liquid nitrogen delivery branch pipe 7 is connected to the top of the lower tower 3. The top of the liquid nitrogen measuring cylinder 9 is provided with the inlet end of the second nitrogen delivery pipe 11. The second nitrogen delivery pipe 11 is provided with a self-standing regulating valve 12. The self-standing regulating valve 12 includes a regulating valve body and a pressure tapping pipe. The pressure tapping pipe and the regulating valve body are connected to the second nitrogen delivery pipe 11 between the liquid nitrogen measuring cylinder 9 and the liquid nitrogen measuring cylinder 9. The outlet end of the second nitrogen delivery pipe 11 is connected to the first nitrogen delivery pipe 4. The bottom end of the liquid nitrogen measuring cylinder 9 is provided with the inlet end of the second liquid nitrogen delivery main pipe 13. The second liquid nitrogen delivery main pipe 13 is provided with a liquid nitrogen pump 14 and a third regulating valve 15. The upper tower 1 is equipped with a finished nitrogen gas delivery pipe 16, and the lower tower 3 and the upper tower 1 are equipped with oxygen-enriched liquid air delivery pipes 17. The oxygen-enriched liquid air delivery pipe 17 is equipped with a liquid air delivery pump 18 and a fourth regulating valve 19. The cold source channel of the main condenser evaporator 2 is equipped with a liquid oxygen delivery pipe 20. The first liquid nitrogen delivery branch pipe 6, the second liquid nitrogen delivery main pipe 13, the oxygen-enriched liquid air delivery pipe 17 and the finished nitrogen gas delivery pipe 16 are equipped with a first subcooler 21, and the finished nitrogen gas delivery pipe 16 and the liquid oxygen delivery pipe 20 are equipped with a second subcooler 22.

[0016] The liquid products of this product are liquid oxygen and liquid nitrogen, with liquid oxygen being the primary liquid product extracted. Producing sufficient liquid products requires introducing more cooling energy into the distillation system. Therefore, the lower column 3 of this product is equipped with a compressed air delivery main pipe 23. Along the direction from near to far from the lower column 3, the compressed air delivery main pipe 23 is sequentially equipped with the outlet end of a liquefied air delivery pipe 24, the inlet end of a first expansion air return pipe 25, a fifth regulating valve 26, and a first turbine expander 27. The expansion end, the inlet end of the liquefied air delivery pipe 24, the boosting end of the first turbine expander 27, the outlet end of the circulating air compressor unit 28 and the first expansion air return pipe 25 are all equipped with a sixth regulating valve 29. A main heat exchanger 30 is installed on the compressed air delivery main pipe 23 between the expansion end and the boosting end of the first turbine expander 27, the first expansion air return pipe 25, and the liquefied air delivery pipe 24. A waste nitrogen delivery pipe 37 is installed on the main heat exchanger 30 and the upper tower 1. The finished nitrogen delivery pipe 16 is connected to the first cold source channel of the main heat exchanger 30, and a second subcooler 22 is located on the finished nitrogen delivery pipe 16 between the main heat exchanger 30 and the first subcooler 21. This product uses compressed air that has passed through the booster end of the circulating air compressor unit 28 and the first turbine expander 27 in sequence as the heat source and cold source continuously supplied to the main heat exchanger 30 for heat exchange. After cooling, the compressed air expands and cools down at the expansion end of the first turbine expander 27 and is divided into two parts. One part is sent to the main heat exchanger 30 as the cold source and heat source continuously supplied to the main heat exchanger 30 for heat exchange, and then sent back to the circulating air compressor unit 28 to form the first refrigeration cycle. The remaining part of the compressed air is supplied to the lower column 3 as one of the distillation raw materials of the lower column 3.

[0017] Furthermore, the main compressed air supply pipe 23 and the main heat exchanger 30 are provided with compressed air supply branch pipes 31. The inlet end of the compressed air supply pipe 23 and the compressed air supply branch pipe 31 between the pressurization end of the first turbo expander 27 and the circulating air compressor unit 28 are connected. The pressurization end of the second turbo expander 32 is provided on the compressed air supply pipe 23 between the pressurization end of the first turbo expander 27 and the main heat exchanger 30. The outlet end of the compressed air supply branch pipe 31 is connected to the expansion end inlet of the second turbo expander 32. The outlet end of the first expansion air return pipe 25 and the expansion end outlet of the main heat exchanger 30, the main heat exchanger 30, and the second turbo expander 32 are provided with a second expansion air return pipe 33. The compressed air supply pipe 23 between the compressed air supply branch pipe 31 and the pressurization end of the first turbo expander 27, as well as the compressed air supply branch pipe 31, are each provided with a seventh regulating valve 34. A portion of the gas, after being pressurized by the circulating air compressor unit 28, is diverted to serve as one of the heat sources for the main heat exchanger 30. This gas is then fed into the main heat exchanger 30 and continuously supplied with cold air for heat exchange. The cooled portion of compressed air is then fed into the expansion end of the second turbine expander 32 for expansion and cooling to form a cooling airflow. This cooling airflow is first fed into the main heat exchanger 30 as one of the cold sources for heat exchange and continuously supplied with heat to the main heat exchanger 30, and then returned to the circulating air compressor unit 28 to form a second refrigeration cycle. This enhances the cooling effect on the distillation feedstock supplied to the lower column 3.

[0018] The main compressed air supply pipe 23 between the pressurization end of the first turboexpander 27 and the pressurization end of the second turboexpander 32, and the compressed air supply branch pipe 31 between the pressurization end of the second turboexpander 32 and the main heat exchanger 30, are each provided with a heat source channel for the post-heat exchanger 35. Installing the post-heat exchanger 35 facilitates the absorption of the heat energy carried by the compressed air after it has been pressurized by the pressurization end of the first turboexpander 27 or the second turboexpander 32.

[0019] A liquid level sensor 36 is installed on the liquid nitrogen measuring cylinder 9. Installing the liquid level sensor 36 facilitates the feedback of liquid level parameters.

[0020] The usage instructions for this product are as follows: Figure 1 As shown, it includes the following steps: S1. The purified compressed air is supplied to the compressed air supply main pipe 23, where it is pressurized by the circulating air compressor unit 28 and divided into two parts: a first part of compressed air and a second part of compressed air. The first part of compressed air is pressurized sequentially through the pressurization end of the first turbine expander 27 and the pressurization end of the second turbine expander 32, and then supplied to the first heat source channel of the main heat exchanger 30 for heat exchange with the cold source continuously supplied to the main heat exchanger 30. After that, it is divided into two parts: a third part of compressed air and a fourth part of compressed air. The third part of compressed air is discharged from the medium temperature zone of the main heat exchanger 30 and then supplied to the expansion end of the first turbine expander 27 for expansion and cooling. The fourth part of compressed air... The compressed air, after being completely liquefied and discharged from the low-temperature end of the main heat exchanger 30 via the liquefied air delivery pipe 24, continues to travel along the liquefied air delivery pipe 24. After being expanded and cooled at the expansion end of the first turbine expander 27, the third portion of compressed air is further divided into two parts: the fifth portion and the sixth portion. The fifth portion of compressed air is delivered to the first expansion air return pipe 25, and then, after exchanging heat with the heat source continuously supplied to the main heat exchanger 30 via the second cold source channel of the main heat exchanger 30, it is discharged from the high-temperature zone of the main heat exchanger 30 and returned to the inlet of the circulating air compressor unit 28 via the outlet end of the first expansion air return pipe 25, forming the first refrigeration cycle. The sixth portion of compressed air continues along the compressed air delivery main pipe 23 and then merges with the liquefied air delivered via the liquefied air delivery pipe 24 to form a gas-liquid mixture, which is then delivered to the lower column 3 as the distillation feedstock for the lower column 3.

[0021] The second portion of compressed air is delivered to the compressed air delivery branch pipe 31 and then to the second heat source channel of the main heat exchanger 30. After heat exchange with the cold source continuously supplied to the main heat exchanger 30, it is discharged from the medium temperature zone of the main heat exchanger 30 and then delivered to the expansion end of the second turbine expander 32 for expansion and cooling. After expansion and cooling, the second portion of compressed air is delivered to the third cold source channel of the main heat exchanger 30 through the second expansion air return pipe 33 and to the heat source continuously supplied to the main heat exchanger 30 for heat exchange. Then, it is sent back to the inlet of the circulating air compressor unit 28 through the outlet end of the first expansion air return pipe 25 to form the second refrigeration cycle.

[0022] S2. After the gas-liquid mixture enters the lower tower 3, the gas phase component in the gas-liquid mixture forms a first upward gas flow, and the liquid phase component in the gas-liquid mixture forms a first downward liquid flow. During the continuous upward movement of the first upward gas flow along the lower tower 3, it exchanges heat countercurrently with the first reflux condensate continuously supplied to the lower tower 3. During this period, the oxygen component in the first upward gas flow is liquefied and merged into the first reflux condensate as it continues to descend. The nitrogen component in the first reflux condensate is continuously vaporized and merged into the first upward gas flow as it continues to rise. As the first reflux condensate continues to descend, it eventually merges into the first downward liquid flow, ultimately forming a first nitrogen enrichment zone at the top of the lower tower 3 and an oxygen-rich liquid air enrichment zone at the bottom of the lower tower 3.

[0023] S3. The first nitrogen enrichment zone continuously supplies pressurized nitrogen through the first nitrogen delivery pipe 4 to the heat source channel of the main condenser evaporator 2 as a heat source and exchanges heat with the medium in the cold source channel of the main condenser evaporator 2. Then the pressurized nitrogen is liquefied to form liquid nitrogen and is delivered to the first liquid nitrogen delivery branch pipe 6. Then it is divided into three parts, namely the first part of liquid nitrogen, the second part of liquid nitrogen and the third part of liquid nitrogen. The first part of liquid nitrogen is delivered to the lower tower 3 through the second liquid nitrogen delivery branch pipe 7 as the first reflux condensate of the lower tower 3. The second part of liquid nitrogen continues to move along the first liquid nitrogen delivery branch pipe 6 and is delivered to the liquid nitrogen measuring cylinder 9 for temporary storage. The third part of liquid nitrogen exchanges heat with the first heat source channel of the first subcooler 21 and the cold source continuously supplied to the first subcooler 21 and is delivered to the upper tower 1 as the second reflux condensate of the upper tower 1. The oxygen-enriched liquid air enrichment zone is fed to the second heat source channel of the first subcooler 21 via the oxygen-enriched liquid air conveying pipe 17. After heat exchange with the first subcooler 21, the oxygen-enriched liquid air continues to be conveyed along the oxygen-enriched liquid air conveying pipe 17 to the upper column 1 as the distillation feedstock of the upper column 1.

[0024] S4. The oxygen-enriched liquid air entering the upper column 1 continues to descend into the cold source channel of the main condenser-evaporator 2 and is continuously supplied to the heat source of the main condenser-evaporator 2 for heat exchange. The nitrogen component in the oxygen-enriched liquid air in the cold source channel of the main condenser-evaporator 2 is continuously evaporated to form a second rising airflow, which continues to rise along the upper column 1. During the upward movement of the second rising airflow, it first exchanges heat with the oxygen-enriched liquid air that continues to descend along the inner cavity of the upper column 1 in a countercurrent manner. During this period, the nitrogen component in the oxygen-enriched liquid air is continuously liquefied and merged into the second rising airflow. The oxygen component in the second rising airflow is continuously liquefied and merged into the oxygen-enriched liquid air to form a second descending liquid flow. The second rising airflow continues to rise and then exchanges heat with the second reflux condensate that continues to descend along the inner cavity of the upper column 1 in a countercurrent manner. During this period, the nitrogen component in the second reflux condensate is continuously vaporized and merged into the second rising airflow. The oxygen component in the second rising airflow is continuously liquefied and merged into the second reflux condensate. The second reflux condensate continues to descend and merges into the second descending liquid flow. Finally, a second nitrogen enrichment zone is formed at the top of the upper column 1, a waste nitrogen enrichment zone is formed in the upper column 1 between the outlet end of the first liquid nitrogen delivery branch pipe 6 and the outlet end of the oxygen-enriched liquid air delivery pipe 17, and a liquid oxygen enrichment zone is formed in the cold source channel of the main condenser evaporator 2.

[0025] S5. The second nitrogen enrichment zone continuously supplies finished nitrogen to the finished nitrogen delivery pipe 16. The finished nitrogen travels along the finished nitrogen delivery pipe 16, first serving as a cold source for the first subcooler 21 and a heat source continuously supplied to the first subcooler 21 for heat exchange, then serving as a cold source for the second subcooler 22 and a heat source continuously supplied to the second subcooler 22 for heat exchange, and finally being supplied to the first cold source channel of the main heat exchanger 30 and a heat source continuously supplied to the main heat exchanger 30 for heat exchange, before being delivered to the user through the outlet end of the finished nitrogen delivery pipe 16. The waste nitrogen enrichment zone continuously supplies waste nitrogen to the waste nitrogen delivery pipe 37. The waste nitrogen passes through the fourth cold source channel of the main heat exchanger 30 and a heat source continuously supplied to the main heat exchanger 30 for heat exchange, before being delivered to the user through the outlet end of the waste nitrogen delivery pipe 37. The liquid oxygen enrichment zone continuously supplies liquid oxygen to the liquid oxygen delivery pipe 20. The liquid oxygen exchanges heat with the heat source channel of the second subcooler 22 and the cold source continuously supplied to the second subcooler 22, and then is delivered to the user through the outlet end of the liquid oxygen delivery pipe 20.

[0026] In steps S3 to S5, the second portion of liquid nitrogen supplied to the liquid nitrogen measuring cylinder 9 is supplied according to the liquid level height fed back by the liquid level sensor 36 installed on the liquid nitrogen measuring cylinder 9. When the liquid level sensor 36 reaches the maximum liquid level, the supply of the second portion of liquid nitrogen to the liquid nitrogen measuring cylinder 9 needs to be stopped. The liquid nitrogen temporarily stored in the liquid nitrogen measuring cylinder 9 vaporizes to form nitrogen gas, which is then transported through the second nitrogen gas supply pipe 11 to the first nitrogen gas supply pipe 4 and merged into the pressurized nitrogen gas supplied through the first nitrogen gas supply pipe 4.

[0027] When liquid nitrogen is discharged as needed, the liquid nitrogen pump 14 needs to be turned on and the opening of the third regulating valve 15 needs to be adjusted. At this time, the liquid nitrogen in the liquid nitrogen measuring cylinder 9 is transported through the second liquid nitrogen delivery main pipe 13 to the third heat source channel of the first subcooler 21 and exchanged with the cold source continuously supplied to the first subcooler 21 to form subcooled liquid nitrogen. The subcooled liquid nitrogen is then delivered to the user through the outlet end of the second liquid nitrogen delivery main pipe 13.

[0028] In this embodiment, when no liquid nitrogen extraction requirement is received, a portion of the liquid nitrogen produced by the condenser evaporator 2 is continuously supplied to the liquid nitrogen measuring cylinder 9 for temporary storage. When a production order requiring a large extraction of liquid nitrogen is received, the liquid nitrogen temporarily stored in the measuring cylinder 9 can be transferred to the first subcooler 21 for subcooling before extraction. This avoids the production of substandard products caused by insufficient liquid nitrogen supplied to the upper column 1 and lower column 3 due to a large extraction requirement based on the production order, which would alter the distillation conditions of the upper column 1 and lower column 3.

[0029] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. A liquid air separation distillation apparatus, comprising a distillation column, wherein the distillation column comprises, from top to bottom, an upper column (1), a main condenser-evaporator (2), and a lower column (3), characterized in that: The inlet end of the heat source channel of the main condenser evaporator (2) and the lower tower (3) are connected by a first nitrogen delivery pipe (4). A first liquid nitrogen delivery main pipe (5) is provided at the outlet end of the heat source channel of the main condenser evaporator (2). The first liquid nitrogen delivery main pipe (5) is provided with the inlet end of a first liquid nitrogen delivery branch pipe (6), the inlet end of a second liquid nitrogen delivery branch pipe (7), a first regulating valve (8), and a liquid nitrogen measuring cylinder (9) in sequence along the direction from near the main condenser evaporator (2) to away from the main condenser evaporator (2). A second regulating valve (1) is provided on both the first liquid nitrogen delivery branch pipe (6) and the second liquid nitrogen delivery branch pipe (7). 0), the outlet end of the first liquid nitrogen delivery branch pipe (6) is connected to the top of the upper tower (1), the outlet end of the second liquid nitrogen delivery branch pipe (7) is connected to the top of the lower tower (3), the top of the liquid nitrogen measuring cylinder (9) is provided with the inlet end of the second nitrogen delivery pipe (11), the second nitrogen delivery pipe (11) is provided with a self-standing regulating valve (12), the outlet end of the second nitrogen delivery pipe (11) is connected to the first nitrogen delivery pipe (4), the bottom end of the liquid nitrogen measuring cylinder (9) is provided with the inlet end of the second liquid nitrogen delivery main pipe (13), the second liquid nitrogen delivery main pipe (13) is provided with a liquid nitrogen pump (14) and a third regulating valve (15).

2. The liquid air separation distillation apparatus according to claim 1, characterized in that: The upper tower (1) is provided with a finished nitrogen gas delivery pipe (16), the lower tower (3) and the upper tower (1) are provided with an oxygen-enriched liquid air delivery pipe (17), the oxygen-enriched liquid air delivery pipe (17) is provided with a liquid air delivery pump (18) and a fourth regulating valve (19), the cold source channel of the main condenser evaporator (2) is provided with a liquid oxygen delivery pipe (20), the first liquid nitrogen delivery branch pipe (6), the second liquid nitrogen delivery main pipe (13), the oxygen-enriched liquid air delivery pipe (17) and the finished nitrogen gas delivery pipe (16) are provided with a first subcooler (21), and the finished nitrogen gas delivery pipe (16) and the liquid oxygen delivery pipe (20) are provided with a second subcooler (22).

3. The liquid air separation distillation apparatus according to claim 1, characterized in that: The lower tower (3) is provided with a compressed air delivery main pipe (23). The compressed air delivery main pipe (23) is provided with the outlet end of the liquefied air delivery pipe (24), the inlet end of the first expansion air return pipe (25), the fifth regulating valve (26), the expansion end of the first turbine expander (27), the inlet end of the liquefied air delivery pipe (24), the boosting end of the first turbine expander (27), the circulating air compressor unit (28), and the outlet end of the first expansion air return pipe (25) in sequence along the direction from near the lower tower (3) to far away from the lower tower (3). The expansion end of the first turbine expander (27) and the first expansion air return pipe (25) are provided with a sixth regulating valve (29). The compressed air delivery main pipe (23), the first expansion air return pipe (25), and the liquefied air delivery pipe (24) are provided with a main heat exchanger (30).

4. The liquid air separation distillation apparatus according to claim 3, characterized in that: The main compressed air supply pipe (23) and the main heat exchanger (30) are provided with compressed air supply branch pipes (31). The inlet end of the first turboexpander (27) is connected to the inlet end of the compressed air supply pipe (23) and the compressed air supply branch pipe (31) between the first turboexpander (27) and the circulating air compressor unit (28). The inlet end of the compressed air supply pipe (23) between the first turboexpander (27) and the main heat exchanger (30) is provided with the inlet end of the second turboexpander (32). The outlet end of the compressed air supply branch pipe (31) and the first turboexpander (32) are connected to the inlet end of the second turboexpander (32). The expansion end inlets of the two turbo expanders (32) are connected. The first expansion air return pipe (25) between the outlet end of the first expansion air return pipe (25) and the main heat exchanger (30), the main heat exchanger (30) and the expansion end outlet of the second turbo expander (32) are provided with a second expansion air return pipe (33). The compressed air delivery main pipe (23) between the compressed air delivery branch pipe (31) and the pressurization end of the first turbo expander (27) and the compressed air delivery branch pipe (31) are each provided with a seventh regulating valve (34).

5. The liquid air separation distillation apparatus according to claim 4, characterized in that: The compressed air delivery main pipe (23) between the booster end of the first turbo expander (27) and the booster end of the second turbo expander (32), and the compressed air delivery branch pipe (31) between the booster end of the second turbo expander (32) and the main heat exchanger (30) are respectively provided with heat source channels for the organic post heat exchanger (35).

6. The liquid air separation distillation apparatus according to claim 1, characterized in that: The liquid nitrogen graduated cylinder (9) is equipped with a liquid level sensor (36).

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