Air separation precooling system and air separation device

Abstract

The invention discloses an air separation pre-cooling system and an air separation device, and relates to the technical field of air separation, the air separation pre-cooling system comprises a lithium bromide absorption refrigerator, and the lithium bromide absorption refrigerator comprises a generator, a condenser and an evaporator; the first compressed air pipeline is used for conveying compressed air; the first cold waste nitrogen pipeline is used for conveying waste nitrogen; high-temperature compressed air discharged by the air compressor serves as a driving heat source to heat a lithium bromide solution at the generator and then exchanges heat with a refrigerant in the evaporator at the evaporator, so that secondary cooling of the compressed air is achieved, the cooled compressed air enters the scrubber tower, dust, oil mist and other impurities are removed through spraying and washing, and then the lithium bromide solution is cooled. Continuously cooling at the time; cold waste nitrogen from the rectifying tower system exchanges heat with refrigerant steam at the condenser. Working medium circulation of the lithium bromide absorption refrigerator is promoted through the heat of the compressed air and the cooling capacity of the cold waste nitrogen at the same time, and system energy consumption is remarkably reduced.

Description

Technical Field

[0001] This application relates to the field of air separation technology, and more specifically, to an air separation precooling system and an air separation device. Background Technology

[0002] An air separation unit is an industrial device used to separate various components in air, mainly oxygen and nitrogen. It includes an air compression system, an air separation precooling system, a molecular sieve purification system, and a distillation column system. The air compression system pressurizes the ambient pressure feed air to the high pressure required for the process; the air separation precooling system cools and washes the high-temperature, high-pressure compressed air, significantly reducing its temperature and removing most of the moisture; the molecular sieve purification system deeply adsorbs and removes residual carbon dioxide, moisture, and other trace impurities from the air, preventing them from freezing at low temperatures; and the distillation column system separates oxygen and nitrogen into high-purity products at deep cryogenic temperatures, utilizing the difference in boiling points.

[0003] The air separation precooling system comprises an air-cooled tower, a water-cooled tower, a room-temperature water pump, and a cryogenic water pump, all connected by a water circulation system. The cryogenic water pump pressurizes chilled water from the water-cooled tower and sprays it onto the top of the air-cooled tower to cool the high-temperature compressed air entering from the bottom. The heated water flows out of the air-cooled tower and into the water-cooled tower, where it is cooled through evaporation and other methods before being returned to the air-cooled tower for reuse. During system startup, load fluctuations, or when water replenishment is needed, the room-temperature water pump draws room-temperature water from the raw water network to quickly establish initial operating conditions, regulate water temperature, or replenish water volume. This collaborative heat exchange process ensures that the air entering the molecular sieve purification system is low-temperature and clean, which is crucial for guaranteeing the efficiency of subsequent processes.

[0004] However, existing air separation precooling systems generally suffer from high energy consumption and large size. Therefore, how to reduce the energy consumption and reduce the overall size of air separation precooling systems has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide an air separation precooling system to reduce energy consumption and reduce volume.

[0006] Another objective of this application is to provide an air separation device including the above-described air separation precooling system.

[0007] An air separation precooling system includes a lithium bromide absorption chiller, which comprises a generator, a condenser, and an evaporator, and further includes:

[0008] The first compressed air line is used to connect to the air compression system and deliver compressed air;

[0009] The first cold waste nitrogen pipeline is used to connect to the distillation column system and transport waste nitrogen.

[0010] The air scrubbing tower is equipped with a second compressed air pipeline;

[0011] The generator has a first heat exchange pipeline, the condenser has a second heat exchange pipeline, and the evaporator has a third heat exchange pipeline. A first compressed air pipeline is connected to the first, third, and second heat exchange pipelines in sequence to introduce compressed air as a heat source medium for heat exchange with the lithium bromide solution in the generator, as a heat source medium for heat exchange with the refrigerant in the evaporator, and to cool the compressed air in the air scrubbing tower. A first cold nitrogen pipeline is connected to the second heat exchange pipeline to introduce waste nitrogen as a cold source medium for heat exchange with the refrigerant vapor in the condenser.

[0012] In some embodiments, the air separation precooling system further includes a second cold waste nitrogen pipeline for communication with the distillation column system;

[0013] The lithium bromide absorption chiller includes an absorber, inside which is a fourth heat exchange pipeline. The second cold nitrogen pipeline is connected to the fourth heat exchange pipeline to introduce nitrogen gas as a cold source medium for heat exchange with the lithium bromide solution in the absorber.

[0014] In some embodiments, the air scrubbing tower outputs cooled compressed air through a third compressed air pipeline, and the third compressed air pipeline is connected to at least one of the first cold waste nitrogen pipeline and the second cold waste nitrogen pipeline.

[0015] In some embodiments, the scrubbing tower is provided with a liquid distributor and a production water delivery pipeline for delivering production water.

[0016] The evaporator is equipped with a fifth heat exchange pipeline. The production water delivery pipeline, the fifth heat exchange pipeline and the liquid distributor are connected in sequence so that the production water can be used as a heat source medium to exchange heat with the refrigerant in the evaporator and to cool the compressed air in the gas scrubbing tower.

[0017] In some embodiments, the gas scrubbing tower is provided with a packing layer and a wire mesh mist eliminator. The wire mesh mist eliminator, liquid distributor and packing layer are arranged in sequence from top to bottom in the vertical direction, and the packing layer is one layer.

[0018] In some embodiments, the production water delivery pipeline is connected to the raw water network.

[0019] In some embodiments, the air separation precooling system further includes a molecular sieve heater, a steam delivery pipeline, and a hot nitrogen output pipeline, wherein the steam delivery pipeline is used to deliver steam;

[0020] The molecular sieve heater is equipped with a sixth heat exchange pipeline and a seventh heat exchange pipeline. The first cold waste nitrogen pipeline is connected to the second heat exchange pipeline, the sixth heat exchange pipeline and the hot nitrogen output pipeline in sequence. The steam transmission pipeline is connected to the seventh heat exchange pipeline to introduce steam as a heat source medium for heat exchange with waste nitrogen.

[0021] In some embodiments, the air separation precooling system further includes a third cold waste nitrogen pipeline for communication with the distillation column system, and the third cold waste nitrogen pipeline is connected to the hot nitrogen output pipeline.

[0022] In some embodiments, the air separation precooling system further includes a post-molecular sieve air delivery pipeline for communicating with the molecular sieve purification system and delivering air purified by the molecular sieve purification system, the post-molecular sieve air delivery pipeline being connected to a sixth heat exchange pipeline.

[0023] An air separation device, comprising the air separation precooling system of any one of the above.

[0024] The air separation precooling system provided in this application includes a lithium bromide absorption chiller, which includes a generator, a condenser, and an evaporator. It also includes a first compressed air pipeline, a first cold nitrogen pipeline, and a scrubbing tower. The first compressed air pipeline is connected to an air compression system and supplies compressed air. The first cold nitrogen pipeline is connected to a distillation column system and supplies nitrogen gas. The scrubbing tower is equipped with a second compressed air pipeline. A first heat exchange pipeline is located inside the generator, a second heat exchange pipeline is located inside the condenser, and a third heat exchange pipeline is located inside the evaporator. The first compressed air pipeline is sequentially connected to the first heat exchange pipeline, the third heat exchange pipeline, and the second compressed air pipeline to introduce compressed air as a heat source medium for heat exchange with the lithium bromide solution in the generator, as a heat source medium for heat exchange with the low-pressure liquid refrigerant in the evaporator, and to cool the compressed air in the scrubbing tower. The first cold nitrogen pipeline is connected to the second heat exchange pipeline to introduce nitrogen gas as a cold source medium for heat exchange with the refrigerant vapor in the condenser. The high-temperature compressed air discharged from the air compressor of the air compression system can be used as a driving heat source to first heat the lithium bromide solution at the first heat exchange pipe of the generator, and then exchange heat with the refrigerant in the evaporator at the third heat exchange pipe of the evaporator, thereby achieving secondary cooling of the compressed air. The cooled compressed air enters the scrubbing tower to remove dust, oil mist and other impurities through spray washing, and continues to cool down here. After cooling, it is then sent to the subsequent molecular sieve purification system. The cold waste nitrogen from the distillation tower system exchanges heat with the refrigerant vapor after being heated and evaporated by the compressed air at the second heat exchange pipe of the condenser, thereby condensing it into a liquid state, so as to use the cold energy of the cold waste nitrogen to promote the circulation of the lithium bromide absorption chiller.

[0025] Compared to existing technologies, the air separation precooling system provided in this application simultaneously promotes the working fluid circulation of the lithium bromide absorption chiller by utilizing the heat of compressed air and the cold energy of the cold nitrogen gas. This achieves efficient recovery and utilization of waste heat from the air compressor exhaust and the cold energy of the cold nitrogen gas, significantly reducing system energy consumption. Simultaneously, the lithium bromide absorption chiller can perform secondary cooling of the compressed air, achieving deep cooling so that its temperature is significantly reduced before entering the subsequent scrubbing tower. Therefore, only one scrubbing tower is needed to reduce the compressed air temperature to the process requirements, eliminating the need for air-cooled towers, water-cooled towers, ambient temperature water pumps, and cryogenic water pumps in traditional processes. This significantly reduces the consumption of circulating water, and the elimination of the air-cooled tower significantly reduces the flow resistance of compressed air, simplifies the system process and structure, and effectively reduces equipment investment costs and subsequent operation and maintenance costs.

[0026] The air separation device provided in this application includes the aforementioned air separation precooling system, and therefore also possesses the aforementioned structure and beneficial effects. Other structures refer to the prior art and will not be described in detail here. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of the air separation precooling system disclosed in the embodiments of this application;

[0029] Figure 2 This is a schematic diagram of the circulating flow path of the working fluid in the lithium bromide absorption chiller disclosed in the embodiments of this application;

[0030] Figure 3 This is a schematic diagram of the compressed air flow path in the air separation precooling system disclosed in the embodiments of this application;

[0031] Figure 4 This is a schematic diagram of the flow path of polluted nitrogen in the air separation precooling system disclosed in the embodiments of this application. Figure 1 ;

[0032] Figure 5 This is a schematic diagram of the flow path of polluted nitrogen in the air separation precooling system disclosed in the embodiments of this application. Figure 2 ;

[0033] Figure 6 This is a schematic diagram of the flow path of production water in the air separation precooling system disclosed in the embodiments of this application;

[0034] Figure 7This is a simplified structural diagram of the air separation device disclosed in the embodiments of this application.

[0035] Among them, 10 is the air compression system, 20 is the air separation precooling system, 30 is the molecular sieve purification system, and 40 is the distillation column system;

[0036] 100 is a lithium bromide absorption chiller, 110 is a generator, 120 is a condenser, 121 is the second heat exchange line, 130 is an evaporator, 131 is the third heat exchange line, 132 is the fifth heat exchange line, 140 is an absorber, 141 is the fourth heat exchange line, 150 is a heat exchanger, 160 is a solution pump, and 170 is a refrigerant pump.

[0037] 200 is the first compressed air line, 210 is the second compressed air line, and 220 is the third compressed air line;

[0038] 300 is the first cold waste nitrogen pipeline, 310 is the second cold waste nitrogen pipeline, and 320 is the third cold waste nitrogen pipeline.

[0039] 400 is the air scrubbing tower, 410 is the liquid distributor, 420 is the production water delivery pipeline, 430 is the wire mesh mist eliminator, and 440 is the packing layer.

[0040] 500 is the molecular sieve heater, 510 is the steam delivery pipeline, 520 is the hot nitrogen output pipeline, and 530 is the air delivery pipeline after the molecular sieve. Detailed Implementation

[0041] This application discloses an air separation precooling system to reduce energy consumption and shrink volume.

[0042] Another aspect of this application discloses an air separation device including the aforementioned air separation precooling system.

[0043] The embodiments will now be described with reference to the accompanying drawings. Furthermore, the embodiments shown below do not limit the scope of the invention as described in the claims. Additionally, the complete contents of the structures represented in the embodiments below are not limited to those necessary for the solution of the invention as described in the claims. It should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0044] Combination Figure 1The air separation precooling system 20 disclosed in this application includes a lithium bromide absorption chiller 100, which includes a generator 110, a condenser 120, a throttle valve, an evaporator 130, an absorber 140, a heat exchanger 150, a solution pump 160, and a refrigerant pump 170. The generator 110 is used to heat the concentrated lithium bromide solution to generate refrigerant vapor; the condenser 120 is used to condense the refrigerant vapor into liquid refrigerant; the throttle valve is used to throttle and reduce the pressure of the liquid refrigerant; the evaporator 130 is used to evaporate the low-pressure liquid refrigerant for cooling; the absorber 140 is used to absorb the refrigerant vapor from the evaporator 130; the heat exchanger 150 is used to exchange heat between the concentrated and dilute lithium bromide solutions; the solution pump 160 is located between the absorber 140 and the heat exchanger 150 and is used to drive the circulation of the dilute lithium bromide solution; the refrigerant pump 170 is located between the evaporator 130 and the absorber 140 and is used to pump the liquid refrigerant in the evaporator 130 to the absorber 140.

[0045] Combination Figure 2 The working mechanism of the lithium bromide absorption chiller 100 is as follows: In the generator 110, an external heat source heats the concentrated lithium bromide solution, causing it to generate high-pressure refrigerant vapor. This vapor enters the condenser 120 and condenses into high-pressure liquid refrigerant, which is then depressurized by a throttling valve and enters the evaporator 130. In the evaporator 130, the low-pressure liquid refrigerant absorbs heat and evaporates, achieving refrigeration. Subsequently, the refrigerant pump 170 pumps the remaining liquid refrigerant and the generated vapor in the evaporator 130 into the absorber 140. In the absorber 140, the refrigerant vapor is absorbed by the concentrated lithium bromide solution from the generator 110 to form a dilute solution. This dilute solution is pressurized by the solution pump 160 and sent to the heat exchanger 150 to exchange heat with the high-temperature concentrated solution from the generator 110 and increase its temperature. Finally, it returns to the generator 110 to complete the solution cycle. The operating principle and specific structure of the lithium bromide absorption chiller 100 are existing technologies and will not be described in detail in this application.

[0046] Combination Figure 1 , Figure 3 and Figure 4The air separation precooling system 20 disclosed in this application embodiment further includes a first compressed air pipeline 200, a first cold waste nitrogen pipeline 300, and a scrubbing tower 400. The first compressed air pipeline 200 is used to connect to the air compression system 10 and transport compressed air; the first cold waste nitrogen pipeline 300 is used to connect to the distillation column system 40 and transport waste nitrogen; the scrubbing tower 400 is provided with a second compressed air pipeline 210; a first heat exchange pipeline is provided inside the generator 110, a second heat exchange pipeline 121 is provided inside the condenser 120, and a third heat exchange pipeline is provided inside the evaporator 130. The heat pipe 131 and the first compressed air pipe 200 are sequentially connected to the first heat exchange pipe, the third heat exchange pipe 131 and the second compressed air pipe 210, so as to introduce compressed air as a heat source medium to exchange heat with the lithium bromide solution in the generator 110, to exchange heat with the low-pressure liquid refrigerant in the evaporator 130, and to cool the compressed air in the scrubbing tower 400; the first cold nitrogen pipe 300 is connected to the second heat exchange pipe 121, and is used to introduce waste nitrogen as a cold source medium to exchange heat with the refrigerant vapor in the condenser 120.

[0047] Specifically, in combination Figure 3 The high-temperature compressed air discharged from the air compressor of the air compression system 10 is typically between 90℃ and 110℃. It can be used as a driving heat source to first heat the lithium bromide solution at the first heat exchange pipe of the generator 110, and then exchange heat with the refrigerant in the evaporator 130 at the third heat exchange pipe 131, thus achieving secondary cooling of the compressed air. The cooled compressed air enters the air scrubbing tower 400 where it is sprayed to remove dust, oil mist, and other impurities, and is further cooled to about 6℃ before being transported to the subsequent molecular sieve purification system 30. Figure 4 The cold nitrogen gas from the distillation column system 40 exchanges heat with the refrigerant vapor that has been heated and evaporated by compressed air at the second heat exchange pipe 121 of the condenser 120, thereby condensing it into a liquid state, so as to use the cold energy of the cold nitrogen gas to promote the circulation of the lithium bromide absorption chiller 100.

[0048] Compared to existing technologies, the air separation precooling system 20 disclosed in this application simultaneously promotes the working fluid circulation of the lithium bromide absorption chiller 100 by utilizing the heat of compressed air and the cold energy of the cold nitrogen gas. This achieves efficient recovery and utilization of waste heat from the air compressor exhaust and the cold energy of the cold nitrogen gas, significantly reducing system energy consumption. Simultaneously, the lithium bromide absorption chiller 100 can perform secondary cooling of the compressed air, achieving deep cooling so that its temperature is significantly reduced before entering the subsequent scrubbing tower 400. Therefore, only one-stage scrubbing tower 400 is needed to reduce the compressed air temperature to the process requirements, thus eliminating the need for air-cooled towers, water-cooled towers, ambient temperature water pumps, and cryogenic water pumps in traditional processes. This significantly reduces the consumption of circulating water, and by eliminating the air-cooled tower, it significantly reduces the flow resistance of compressed air, simplifies the system process and structure, and effectively reduces equipment investment costs and subsequent operation and maintenance costs.

[0049] In some embodiments disclosed in this application, combined with Figure 4 The air separation precooling system 20 also includes a second cold nitrogen pipeline 310 for connection to the distillation column system 40; the absorber 140 is provided with a fourth heat exchange pipeline 141, and the second cold nitrogen pipeline 310 is connected to the fourth heat exchange pipeline 141 for introducing nitrogen gas as a cold source medium to exchange heat with the concentrated lithium bromide solution in the absorber 140, thereby further cooling the concentrated lithium bromide solution, that is, combined with Figure 4 The cold nitrogen gas from the distillation column system 40 is divided into two paths. One path is transported by the first cold nitrogen gas pipeline 300 to the condenser 120 to exchange heat with the refrigerant vapor. The other path is transported by the second cold nitrogen gas pipeline 310 to the absorber 140 to exchange heat with the lithium bromide solution, thereby promoting the working fluid circulation of the lithium bromide absorption chiller 100 and improving its cooling effect on compressed air.

[0050] Combination Figure 1 and Figure 3 The gas scrubbing tower 400 outputs cooled compressed air to the molecular sieve purification system 30 through the third compressed air pipeline 220. The third compressed air pipeline 220 is connected to at least one of the first cold waste nitrogen pipeline 300 and the second cold waste nitrogen pipeline 310, so as to achieve temperature regulation by neutralizing the cold waste nitrogen with the cooled compressed air.

[0051] Combination Figure 6The air scrubbing tower 400 is equipped with a liquid distributor 410 and a production water delivery pipeline 420 for conveying production water. The evaporator 130 has a fifth heat exchange pipeline 132. The production water delivery pipeline 420, the fifth heat exchange pipeline 132, and the liquid distributor 410 are sequentially connected, allowing the production water to act as a heat source medium for heat exchange with the low-pressure liquid refrigerant in the evaporator 130, thereby effectively cooling the production water. The cooled production water then cools the compressed air within the air scrubbing tower 400. In other words, in addition to cooling the compressed air from the air compression system 10, the evaporator 130 also cools the production water, which serves as the scrubbing liquid in the air scrubbing tower 400, ensuring that the production water has a low temperature to meet the cooling requirements of the compressed air. Furthermore, the air scrubbing tower 400 also includes a drain pipeline, a production water return pipeline, and corresponding control valves, which will not be described in detail here.

[0052] Combination Figure 6 The scrubbing tower 400 is equipped with a packing layer 440 and a wire mesh precipitator 430. Vertically, from top to bottom, the wire mesh precipitator 430, liquid distributor 410, and packing layer 440 are arranged sequentially. During operation, compressed air enters from the bottom of the scrubbing tower 400 and flows upward. The scrubbing liquid, evenly sprayed by the liquid distributor 410, forms a liquid film on the surface of the packing layer 440, making full contact with the compressed air for cooling and scrubbing. After scrubbing, the compressed air continues to rise and finally passes through the wire mesh precipitator 430 at the top. The wire mesh precipitator 430 intercepts and removes tiny liquid droplets entrained in the compressed air, ensuring the cleanliness of the discharged gas. The packing layer 440 can use high-efficiency packing materials such as stepped rings or Pall rings. Taking stepped rings as an example, their structure enhances gas-liquid contact and improves heat exchange efficiency. Simultaneously, their low pressure drop advantage reduces air compressor energy consumption and helps achieve a more compact and low-cost design.

[0053] Furthermore, since this application uses a lithium bromide absorption chiller 100 to perform secondary cooling of compressed air, the air-cooled tower in the current process can be replaced by a more structurally optimized scrubbing tower 400. Existing air-cooled towers typically have three layers of packing, while this invention only requires one layer to meet the same process requirements. This improvement not only reduces equipment manufacturing costs but also reduces water consumption, primarily spray water, to 25% of the current process. Simultaneously, the resistance of compressed air passing through the scrubbing tower 400 is significantly reduced, resulting in a reduction of approximately 4 kPa in the air compressor outlet resistance. For centrifugal air compressors, the main type of air separator, their pressure rating is typically between 0.5 MPaG and 1.0 MPaG. Based on their operating characteristics, for every 1 kPa reduction in system resistance, shaft power will decrease by approximately 0.15% to 0.25%, and the closer the operating conditions are to the design point, the closer the power reduction is to the upper limit. Taking an air compressor with a shaft power of 15,000 kW as an example, if the system resistance is reduced by 4 kPa, the shaft power can decrease by approximately 0.6% to 1.0%. Based on 8,000 hours of operation per year, the annual electricity savings can reach 720,000 to 1,200,000 kWh, demonstrating significant economic benefits. The air scrubbing tower 400 disclosed in this application has a simple structure and significantly reduces system resistance, creating favorable conditions for energy-saving operation of air compressors and other equipment.

[0054] The aforementioned production water delivery pipeline 420 can be connected to the raw water network to use raw water as production water to cool compressed air, which can effectively reduce costs compared to using circulating water.

[0055] In some embodiments disclosed in this application, combined with Figure 5 The air separation precooling system 20 also includes a molecular sieve heater 500, a steam conveying pipeline 510, and a hot nitrogen output pipeline 520. The steam conveying pipeline 510 is used to convey steam. The molecular sieve heater 500 is equipped with a sixth heat exchange pipeline and a seventh heat exchange pipeline. The first cold waste nitrogen pipeline 300 is connected in sequence to the second heat exchange pipeline 121, the sixth heat exchange pipeline, and the hot nitrogen output pipeline 520. The steam conveying pipeline 510 is connected to the seventh heat exchange pipeline to introduce steam as a heat source medium to exchange heat with the waste nitrogen gas, thereby further heating the waste nitrogen gas that has been heated after exchanging heat with the condenser 120. This high-temperature nitrogen gas is then used to regenerate the molecular sieve, thereby recovering waste heat and reducing regeneration energy consumption.

[0056] In some embodiments disclosed in this application, combined with Figure 5 The air separation precooling system 20 also includes a molecular sieve post-air delivery pipeline 530 for communicating with the molecular sieve purification system 30 and delivering air purified by the molecular sieve purification system 30. The molecular sieve post-air delivery pipeline 530 is connected to the sixth heat exchange pipeline to introduce molecular sieve post-air so that it is heated by steam together with the waste nitrogen and acts on the regeneration of the molecular sieve.

[0057] Combination Figure 5 The air separation precooling system 20 also includes a third cold waste nitrogen pipeline 320 for connection to the distillation column system 40, and the third cold waste nitrogen pipeline 320 is connected to the hot nitrogen output pipeline 520 for regulating the temperature of the output hot nitrogen. In addition, the waste nitrogen that has been heated after heat exchange in the condenser 120 can also be drawn out as cold blowing nitrogen.

[0058] Combination Figure 7 The air separation device disclosed in this application includes the air separation precooling system 20 described above, so it also has the above-mentioned structure and beneficial effects. Other structures refer to the prior art and will not be described in detail here.

[0059] Specifically, the air separation device includes an air compression system 10, an air separation precooling system 20, a molecular sieve purification system 30, and a distillation column system 40. The outlet of the air compression system 10 is connected to the first compressed air pipeline 200 of the air separation precooling system 20 to send compressed air into it for deep cooling. The third compressed air pipeline 220 of the air separation precooling system 20 is connected to the inlet of the molecular sieve purification system 30 so that the low-temperature high-pressure air is purified by adsorption of impurities by the molecular sieve purification system 30. The purified dry air is introduced into the bottom of the distillation column system 40 from the outlet of the molecular sieve purification system 30 and used as raw material gas to achieve efficient separation of components such as oxygen and nitrogen through continuous distillation in the column. The cold waste nitrogen gas fractionated at the distillation column system 40 acts on the air separation precooling system 20 and the molecular sieve purification system 30 through the first cold waste nitrogen gas pipeline 300, the second cold waste nitrogen gas pipeline 310, and the third cold waste nitrogen gas pipeline 320, thereby reducing energy consumption.

[0060] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed. Additionally, in the description of embodiments in this application, "a plurality of" means two or more.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Specific technical means in some embodiments may be incorporated, in whole or in part, into another embodiment unless explicitly excluded by another embodiment. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An air separation precooling system, comprising a lithium bromide absorption chiller (100), said lithium bromide absorption chiller (100) comprising a generator (110), a condenser (120) and an evaporator (130), characterized in that, Also includes: A first compressed air line (200) is used to connect to the air compression system (10) and deliver compressed air; The first cold waste nitrogen pipeline (300) is used to connect to the distillation column system (40) and to transport waste nitrogen. Air scrubbing tower (400), wherein the air scrubbing tower (400) is provided with a second compressed air pipeline (210); The generator (110) is provided with a first heat exchange pipeline, the condenser (120) is provided with a second heat exchange pipeline (121), and the evaporator (130) is provided with a third heat exchange pipeline (131). The first compressed air pipeline (200) is connected to the first heat exchange pipeline, the third heat exchange pipeline (131), and the second compressed air pipeline (210) in sequence to introduce the compressed air as a heat source medium to exchange heat with the lithium bromide solution in the generator (110), to exchange heat with the refrigerant in the evaporator (130), and to cool the compressed air in the gas scrubbing tower (400). The first cold nitrogen pipeline (300) is connected to the second heat exchange pipeline (121) to introduce the nitrogen as a cold source medium to exchange heat with the refrigerant vapor in the condenser (120).

2. The air separation precooling system as described in claim 1, characterized in that, The air separation precooling system (20) also includes a second cold waste nitrogen pipeline (310) for communication with the distillation column system (40). The lithium bromide absorption chiller (100) includes an absorber (140), and the absorber (140) is provided with a fourth heat exchange pipeline (141). The second cold waste nitrogen pipeline (310) is connected to the fourth heat exchange pipeline (141) and is used to introduce the waste nitrogen as a cold source medium to exchange heat with the lithium bromide solution in the absorber (140).

3. The air separation precooling system as described in claim 2, characterized in that, The air scrubbing tower (400) outputs cooled compressed air through a third compressed air pipeline (220), and the third compressed air pipeline (220) is connected to at least one of the first cold waste nitrogen pipeline (300) and the second cold waste nitrogen pipeline (310).

4. The air separation precooling system as described in claim 1, characterized in that, The gas scrubbing tower (400) is equipped with a liquid distributor (410) and a production water conveying pipeline (420) for conveying production water. The evaporator (130) is equipped with a fifth heat exchange pipeline (132). The production water delivery pipeline (420), the fifth heat exchange pipeline (132) and the liquid distributor (410) are connected in sequence so that the production water can be used as a heat source medium to exchange heat with the refrigerant in the evaporator (130) and to cool the compressed air in the gas scrubbing tower (400).

5. The air separation precooling system as described in claim 4, characterized in that, The gas scrubbing tower (400) is provided with a packing layer (440) and a wire mesh mist eliminator (430). The wire mesh mist eliminator (430), the liquid distributor (410) and the packing layer (440) are arranged in sequence from top to bottom in the vertical direction, and the packing layer (440) has one layer.

6. The air separation precooling system as described in claim 4, characterized in that, The production water delivery pipeline (420) is connected to the raw water pipeline network.

7. The air separation precooling system as described in claim 1, characterized in that, The air separation precooling system (20) also includes a molecular sieve heater (500), a steam conveying pipeline (510), and a hot nitrogen output pipeline (520), wherein the steam conveying pipeline (510) is used to convey steam; The molecular sieve heater (500) is provided with a sixth heat exchange pipeline and a seventh heat exchange pipeline. The first cold waste nitrogen pipeline (300) is connected in sequence to the second heat exchange pipeline (121), the sixth heat exchange pipeline and the hot nitrogen output pipeline (520). The steam conveying pipeline (510) is connected to the seventh heat exchange pipeline to introduce steam as a heat source medium to exchange heat with the waste nitrogen.

8. The air separation precooling system as described in claim 7, characterized in that, The air separation precooling system (20) also includes a third cold waste nitrogen pipeline (320) for communication with the distillation column system (40), and the third cold waste nitrogen pipeline (320) is connected to the hot nitrogen output pipeline (520).

9. The air separation precooling system as described in claim 7, characterized in that, The air separation precooling system (20) also includes a molecular sieve post-air delivery pipeline (530) for communicating with the molecular sieve purification system (30) and delivering air purified by the molecular sieve purification system (30), the molecular sieve post-air delivery pipeline (530) being connected to the sixth heat exchange pipeline.

10. An air separation device, characterized in that, Includes the air separation precooling system (20) as described in any one of claims 1-9.

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