Space division device

Abstract

The application relates to the field of air separation, in particular to an air separation device. The air separation device comprises a mixing tower, an upper tower, a lower tower and a reboiler, the bottom of the mixing tower is provided with the reboiler, liquid oxygen collected at the bottom of the upper tower is connected to a middle liquid inlet of the mixing tower through a first path, nitrogen at the top of the lower tower is connected to a top gas inlet of the mixing tower through a second path, and the reboiler can evaporate the liquid oxygen from the upper tower into gaseous oxygen. According to the air separation device, the obtained oxygen-rich gas is the oxygen-rich gas with a specific oxygen content when oxygen is prepared by the existing air separation device, and the problem that the oxygen content cannot be adjusted according to the actual demand of customers is solved.

Description

Technical Field

[0001] This application relates to the field of air separation, and in particular to an air separation device. Background Technology

[0002] An air separation unit is a device that uses air as raw material, transforms it into a liquid state through compression and deep freezing, and then gradually separates oxygen, nitrogen, and inert gases such as argon from the liquid air through distillation. An air separation unit is a large and complex system, mainly including a power system, purification system, refrigeration system, heat exchange system, distillation system, product conveying system, liquid storage system, and control system.

[0003] The core of an air separation unit is the distillation system, which achieves low-temperature separation of air components. It mainly includes a low-pressure column, a medium-pressure column, and a condenser / evaporator. The main products of existing equipment are liquid nitrogen, liquid argon, liquid oxygen, and oxygen and nitrogen. Conventional oxygen-enriched air separation units employ two-stage distillation. Oxygen-enriched gas is directly obtained from the bottom of the upper column, reheated by the main heat exchanger, and then pressurized to the required pressure by an oxygen compressor. Alternatively, oxygen-enriched liquid air is obtained from the bottom of the upper column, compressed internally by a liquid oxygen pump, or self-pressurized to the required pressure, and then reheated before exiting the fractionation column cold box.

[0004] In response, existing equipment obtains oxygen-enriched liquid air at the bottom of the upper tower, which is then vaporized to obtain oxygen-enriched gas. However, the oxygen-enriched gas obtained by the above method has a specific oxygen content and cannot be adjusted and supplied according to the specific oxygen content required by the actual customer. Summary of the Invention

[0005] The purpose of this application is to provide an air separation unit that solves the problem that existing air separation units produce oxygen-enriched gas with a specific oxygen content, which cannot be adjusted and supplied according to the specific oxygen content required by actual customers.

[0006] According to this application, an air separation unit is provided, which includes a mixing tower, an upper tower, a lower tower, and a reboiler. The reboiler is provided at the bottom of the mixing tower. Liquid oxygen collected at the bottom of the upper tower is connected to the middle liquid inlet of the mixing tower through a first path. Nitrogen gas at the top of the lower tower is connected to the top gas inlet of the mixing tower through a second path. The reboiler is capable of evaporating liquid oxygen from the upper tower into gaseous oxygen.

[0007] In any of the above technical solutions, the air separation unit further includes a main heat exchanger, compressed air is connected to the reboiler through a third path, and the compressed air is connected to the bottom liquid inlet of the lower column through a fourth path, both the third path and the fourth path passing through the main heat exchanger.

[0008] In any of the above technical solutions, the nitrogen gas at the top of the lower tower flows out through the second branch path, and the gas outlet at the top of the mixing tower flows out through the first branch path. The first branch path and the second branch path pass through the main heat exchanger.

[0009] In any of the above technical solutions, the air separation unit further includes a main condenser-evaporator and a storage tank. The main condenser-evaporator connects the upper column and the lower column and is located in the liquid oxygen collected at the bottom of the upper column. The nitrogen at the top of the lower column can be liquefied in the main condenser-evaporator. Part of the liquefied liquid nitrogen enters the storage tank and the top liquid inlet of the upper column through a fifth path, and part flows out through the main heat exchanger. The top gas outlet of the upper column flows out through a sixth path, which passes through the main heat exchanger. The liquid oxygen collected at the bottom of the upper column flows out through a first branch path.

[0010] In any of the above technical solutions, the air separation unit further includes a pure argon tower and a crude argon tower. A pure argon evaporator is provided at the bottom of the pure argon tower, a pure argon condenser is provided at the top of the pure argon tower, and a crude argon condenser is provided at the top of the crude argon tower. The bottom outlet of the lower tower is connected to the inlet of the pure argon evaporator through a seventh path. The outlet of the pure argon evaporator is connected to the top inlet of the pure argon tower and the top inlet of the crude argon tower through an eighth path and a ninth path, respectively. The liquid air vapor and liquid air generated by the pure argon condenser and the crude argon condenser are returned to the upper tower.

[0011] In any of the above technical solutions, the air separation unit further includes a subcooler, and the liquid air in the middle of the lower column is transported to the upper column through the tenth path, and the tenth path, the seventh path, and the fifth path all pass through the subcooler.

[0012] In any of the above technical solutions, further, the argon fraction extracted from the upper column is deoxygenated by the crude argon column, and the resulting crude argon gas enters the pure argon column for denitrification, and liquid argon is generated from the bottom of the pure argon column.

[0013] In any of the above technical solutions, the air separation unit further includes a liquid argon storage tank. The argon fraction extracted from the upper column is connected to the bottom liquid inlet of the crude argon column through an eleventh path. The crude argon gas generated by the crude argon condenser is connected to the middle gas inlet of the pure argon column through a twelfth path. The liquid argon generated by the pure argon condenser enters the liquid argon storage tank.

[0014] In any of the above technical solutions, the air separation unit further includes a purification system, a precooling system, and a compressor. External air enters the precooling system for precooling, then enters the purification system for filtration, and the filtered air is compressed into compressed air by the compressor.

[0015] In any of the above technical solutions, the middle part of the upper column is connected to the precooling system and the purification system through a nitrogen-removing path to provide cooling nitrogen for the precooling system and the purification system. The nitrogen-removing path passes through the subcooler and the main heat exchanger.

[0016] According to the air separation unit of this application, the air separation unit includes a mixing tower, an upper tower, and a lower tower. A reboiler is provided at the bottom of the mixing tower. Liquid oxygen collected at the bottom of the upper tower is connected to the middle liquid inlet of the mixing tower through a first path, and nitrogen gas at the top of the lower tower is connected to the top gas inlet of the mixing tower through a second path. The reboiler can evaporate the liquid oxygen from the upper tower into gaseous oxygen. Specifically, when liquid oxygen enters the mixing tower, it falls into the reboiler from the top of the mixing tower. The liquid oxygen is heated by the medium-pressure air in the reboiler and becomes low-temperature gaseous oxygen. The low-temperature gaseous oxygen and nitrogen gas from the top of the lower tower are mixed in the mixing tower. Liquid oxygen flows downward through the packing layer by layer, and gaseous oxygen flows upward through the packing layer by layer. At the same time, nitrogen gas from the lower tower also flows upward through the packing layer by layer in the mixing tower. After passing through the packing, the two gases (oxygen and nitrogen) are uniformly mixed into oxygen-enriched gas at the top of the mixing tower. On-site personnel can adjust the nitrogen content entering the mixing tower according to needs to obtain oxygen-enriched gas with different oxygen contents.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the overall flow of an air separation unit according to an embodiment of this application is shown;

[0020] Figure 2 Show Figure 1 A partial schematic diagram;

[0021] Figure 3 Show Figure 1 A further part of the schematic diagram;

[0022] Figure 4 Show Figure 1 A schematic diagram of another part;

[0023] Figure 5 Show Figure 1 A schematic diagram of another part.

[0024] Icons: 1 - First path; 101 - First branch path; 102 - First fork in the road; 21 - Second branch path; 3 - Third path; 41 - Fourth branch path; 42 - Fourth fork in the road; 43 - Fourth branch path; 5 - Fifth path; 6 - Sixth path; 7 - Seventh path; 8 - Eighth path; 9 - Ninth path; 10 - Tenth path; 11 - Eleventh path; 12 - Twelfth path; 13 - Anti-nitrogen path; 131 - Anti-nitrogen branch; C1001 - Main air compressor; F1001 - Air filter; E1060 - Water cooling tower; E1007 - Air cooling tower; D1001 - First air purifier; D1002 - Second air purifier; E1008 - Heater; S1005 - Silencer; K1002 - Upper column; K1001 - Lower column; C1005 - Compressor; ET1020 - Thermal expander; E1103 - Subcooler; E1101 - Main heat exchanger; K1011 - Pure argon column; E1016 - Pure argon condenser; K1010 - Crude argon column; E1010 - Crude argon condenser; E1015 - Pure argon evaporator; 100 - Mixing column; 200 - Reboiler; E1002 - Main condenser-evaporator. Detailed Implementation

[0025] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0026] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0027] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0028] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0029] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0030] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0031] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0032] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0033] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0034] This application provides an air separation unit that solves the problem that existing air separation units produce oxygen-enriched gas with a specific oxygen content, which cannot be adjusted and supplied according to the specific oxygen content required by the actual customer.

[0035] An air separation unit is a device that uses air as raw material, transforms air into a liquid state through compression and deep freezing, and then gradually separates inert gases such as oxygen, nitrogen, and argon from the liquid air through distillation. An air separation unit is a large and complex system, mainly including a power system, purification system, refrigeration system, heat exchange system, distillation system, product conveying system, liquid storage system, and control system.

[0036] The power system mainly refers to the air compressor. The air separation equipment separates air at low temperature to obtain products such as oxygen and nitrogen. Essentially, this is accomplished through energy conversion, and the energy of the device is mainly input from the air compressor.

[0037] The purification system consists of an air precooling system and a molecular sieve purification system. The compressed raw material air is at a high temperature. The air precooling system reduces the air temperature through contact heat exchange and can also wash away harmful impurities such as acidic substances. The molecular sieve purification system further removes substances harmful to the operation of air separation equipment, such as moisture, carbon dioxide, acetylene, propylene, propane, and nitrous oxide.

[0038] The refrigeration system is achieved through an expander, and the refrigeration of the entire air separation unit strictly follows the classic refrigeration cycle; the thermal balance of the air separation unit is achieved through the joint operation of the refrigeration system and the heat exchange system, and the heat exchanger in the existing technology mainly uses aluminum plate-fin heat exchangers.

[0039] The core of an air separation unit is the distillation system, which achieves low-temperature separation of air components. It consists of a low-pressure tower, a medium-pressure tower, a condenser-evaporator, a crude argon tower, a pure argon tower, and various condensers-evaporators. The oxygen and nitrogen produced by the air separation unit require a certain pressure to meet the needs of subsequent systems, which is accomplished through various pipelines in the product delivery system. The liquid oxygen and liquid nitrogen produced by the air separation unit enter the liquid storage system. Existing large-scale air separation units all adopt a computer distributed control system to achieve automatic control.

[0040] Prior to this application, conventional oxygen-enriched air separation equipment employed a two-stage distillation process. Oxygen-enriched gas was directly obtained from the bottom of the upper column, reheated by the main heat exchanger, and then pressurized to the required pressure by an oxygen compressor. Alternatively, oxygen-enriched liquid air was obtained from the bottom of the upper column, compressed internally by a liquid oxygen pump, or self-pressurized to the required pressure, and then reheated before exiting the fractionation column cold box. In contrast, existing equipment obtains oxygen-enriched liquid air from the bottom of the upper column, which is then vaporized to obtain oxygen-enriched gas. However, the above methods result in oxygen-enriched gas with a specific oxygen content, making it impossible to adjust the oxygen content according to the actual needs of customers.

[0041] In view of this, an air separation unit is provided according to this application. The air separation unit includes a mixing tower 100, an upper tower K1002, and a lower tower K1001. A reboiler 200 is provided at the bottom of the mixing tower 100. Liquid oxygen collected at the bottom of the upper tower K1002 is connected to the middle liquid inlet of the mixing tower 100 through a first path 1. Nitrogen gas at the top of the lower tower K1001 is connected to the top gas inlet of the mixing tower 100 through a second path 2. The reboiler 200 can evaporate the liquid oxygen from the upper tower K1002 into gaseous oxygen. Specifically, the liquid oxygen side of the reboiler 200 is connected to the bottom of the easing tower, and the liquid oxygen enters the mixing tower 100. During the process, liquid oxygen is drawn from the top of mixing tower 100 into reboiler 200. The liquid oxygen is heated by the medium-pressure air in reboiler 200, becoming low-temperature gaseous oxygen. This low-temperature gaseous oxygen mixes with nitrogen from the top of lower tower K1001 within the mixing tower. Liquid oxygen flows downwards through the packing layer, while gaseous oxygen flows upwards. Simultaneously, nitrogen from lower tower K1001 also flows upwards through the packing layer of mixing tower 100. After passing through the packing, the two gases (oxygen and nitrogen) are uniformly mixed at the top of mixing tower 100, resulting in oxygen-enriched gas. On-site personnel can adjust the nitrogen content entering mixing tower 100 as needed to obtain oxygen-enriched gas with different oxygen contents. During this process, medium-pressure air is liquefied by liquid oxygen into medium-pressure liquid air. This liquid air is then throttled by a throttling valve and sent to the lower tower as one of its feed liquids. The specific structure and separation process of the air separation unit will be described in detail below.

[0042] In the embodiments of this application, such as Figure 2As shown, the air separation unit may also include a main heat exchanger E1101. Compressed air is connected to the reboiler 200 via a third path 3, specifically to the air inlet of the reboiler 200, to provide a heat source. Compressed air is also connected to the bottom liquid inlet of the lower column via a fourth path 4. Both the third path 3 and the fourth path 4 pass through the main heat exchanger E1101. Here, the fourth path 4 may include a fourth branch path 41, a fourth fork path 42, and a fourth branch path 43.

[0043] like Figure 2 As shown, nitrogen gas at the top of the lower column flows out through the second branch path 21, and the gas outlet at the top of the mixing column 100 flows out through the first branch path 101. After being reheated by the main heat exchanger E1101, it enters the oxygen-enriched gas pipeline network. Both the first branch path 101 and the second branch path 21 pass through the main heat exchanger E1101.

[0044] Furthermore, such as Figure 2 As shown, the air separation unit also includes a main condenser-evaporator E1002, which connects the upper tower K1002 and the lower tower K1001 and is located in the liquid oxygen collected at the bottom of the upper tower K1002. The nitrogen at the top of the lower tower K1001 can be liquefied in the main condenser-evaporator E1002 (the main condenser-evaporator E1002 includes an inlet pipe and an outlet pipe connected to the top of the lower tower K1001). The liquefied liquid nitrogen enters the storage tank (to obtain liquid nitrogen product) and the top inlet of the upper tower K1002 through the fifth path 5, and some flows out through the main heat exchanger E1101. Before entering the main heat exchanger E1101, it can be adjusted by three regulating valves to produce nitrogen at different pressures, such as 0.6 MPa nitrogen, 2.55 MPa nitrogen, and 3.0 MPa nitrogen.

[0045] In addition, the top outlet of the upper tower K1002 flows out through the sixth path 6, which passes through the main heat exchanger E1101. The liquid oxygen collected at the bottom of the upper tower flows out through the first branch 102 to produce liquid oxygen products.

[0046] In the embodiments of this application, such as Figure 3 and Figure 5 As shown, the air separation unit also includes a pure argon column K1011 and a crude argon column K1010. A pure argon evaporator E1015 is installed at the bottom of the pure argon column K1011, and a pure argon condenser E1016 is installed at the top of the pure argon column K1011. A crude argon condenser E1010 is installed at the top of the crude argon column K1010. The bottom outlet of the lower column is connected to the inlet of the pure argon evaporator E1015 through the seventh path 7. The outlet of the pure argon evaporator E1015 is connected to the top inlet of the pure argon column K1011 and the top inlet of the crude argon column through the eighth path 8 and the ninth path 9, respectively. The liquid air vapor and liquid air generated by the pure argon condenser E1016 and the crude argon condenser E1010 are returned to the middle of the upper column.

[0047] like Figure 3 As shown, the air separation unit also includes a subcooler E1103. The liquid air in the middle of the lower column K1001 is transported to the upper column through the tenth path 10. Here, the tenth path 10, the seventh path 7, and the fifth path 5 all pass through the subcooler E1103.

[0048] In embodiments of this application, a step of preparing liquid argon is also included, such as... Figure 3 As shown, the argon fraction extracted from the upper column K1002 is deoxygenated in the crude argon column K1010, and the resulting crude argon gas enters the pure argon column K1011 for denitrification, where liquid argon is generated at the bottom. Specifically, the argon fraction extracted from the upper column K1002 is connected to the bottom liquid inlet of the crude argon column K1010 via the eleventh path 11, and the crude argon gas generated by the crude argon condenser E1010 is connected to the middle gas inlet of the pure argon column K1011 via the twelfth path 12. The liquid argon generated by the pure argon condenser E1016 enters the liquid argon storage tank. The specific heat exchange process and air separation process of the above structure will be described in detail below.

[0049] In the embodiments of this application, such as Figure 1 and Figure 4 As shown, the air separation unit also includes a purification system, a precooling system, and a compressor. External air enters the precooling system for precooling, then enters the purification system for filtration (removing CO2, H2O, and some hydrocarbons). The filtered air is then compressed into compressed air by the compressor. The middle section of the upper column K1002 connects the precooling system and the purification system via a nitrogen-removing path 13 (two nitrogen-removing branches 131). (Here, the sixth path 6 can connect to nitrogen-removing path 13) to provide cooling nitrogen gas for the precooling and purification systems. Nitrogen-removing path 13 passes through the subcooler E1103 and the main heat exchanger.

[0050] The argon-enriched air separation unit of this application includes an air compression system, an air precooling system, a molecular sieve purification system, an air booster system, an expander system, a heat exchange system, an air oxygen-nitrogen distillation system, and an argon distillation system.

[0051] like Figure 4 As shown, the air compression system includes a self-cleaning air filter F1001 and a main air compressor C1001 (centrifugal three-stage compressor).

[0052] The air precooling system includes an air-cooled tower E1007, a water-cooled tower E1060, a normal temperature water pump, a low temperature water pump, and a chiller unit.

[0053] The air purification system includes two air purifiers, D1001 and D1002, which are used interchangeably, as well as a regeneration heater E1008 and a silencer S1005.

[0054] The air booster system mainly consists of an air booster compressor C1005.

[0055] The expander system, heat exchange system, oxygen-nitrogen distillation system, and argon distillation system mainly include a thermal expander ET1020, a plate-fin heat exchanger, a high-pressure tower (lower tower K1001), a low-pressure tower (upper tower K1002), a main condenser-evaporator E1002, a crude argon condenser E1010, a crude argon tower K1010, a pure argon evaporator E1015, a pure argon condenser E1016, a pure argon tower K1011, a circulating liquid argon pump, a process oxygen pump, a mixing tower 100, and a mixing-reboiler 200.

[0056] like Figure 1 As shown, the air first passes through the self-cleaning air filter F1001, then is compressed by the main air compressor C1001 and washed and cooled in the air-cooled tower E1007. When the air temperature is cooled to about 13°C, the air enters the molecular sieve adsorber (first air purifier D1001 and second air purifier D1002) for switching. After removing H2O and CO2 in the adsorber, the air is divided into two paths. One path enters the main heat exchanger E1101 through the fourth sub-path 41, and after heat exchange, it enters the lower tower K1001. The other path enters the air booster compressor C1005. After the first stage of compression, a portion of the air in the booster compressor is extracted as instrument air for the air separation unit. A portion of the medium-extraction air is extracted from the second stage of compression of the booster compressor and enters the main heat exchanger for heat exchange (through the third path 3). At a suitable position in the main heat exchanger E1101, the medium-extraction air is extracted and enters the reboiler 200 of the mixing tower 100 as the heat source for the mixing reboiler 200.

[0057] like Figure 2 As shown, the air output pressure of the air booster C1005 is 3.0 MPa. All the air drawn out from the end enters the booster end of the thermal expander ET1020, where it is further compressed. After being cooled to room temperature by the booster cooler, it enters the main heat exchanger E1101, where it is cooled. A portion of the air is drawn out from the middle of the main heat exchanger E1101 and enters the expansion end of the thermal expander ET1020. The expanded air re-enters the main heat exchanger through the fourth branch path 43, where it is further cooled and enters the lower tower K1001. The other portion continues to be cooled to liquid state in the main heat exchanger E1101, and then enters the lower tower K1001 after being throttled through the fourth branch path 42.

[0058] The oxygen-enriched liquid air at the bottom of the lower column K1001 is subcooled by the subcooler E1103 and enters the pure argon evaporator E1015 via the seventh path 7. After being subcooled again by the pure argon evaporator E1015, it is throttled through the eighth path 8 and the ninth path 9 into the pure argon condenser E1016 and the crude argon condenser E1010, respectively, providing a cold source for the pure argon column K1011 and the crude argon column K1010. The throttled liquid air undergoes gas-liquid separation and energy exchange in the pure argon condenser E1016 and the crude argon condenser E1010. The resulting liquid air vapor and part of the liquid air reflux liquid are returned to the upper column K1002 to participate in rectification.

[0059] like Figure 2 As shown, nitrogen is generated at the top of the lower tower K1001. Part of the nitrogen is sent to the gas mixing tower 100 (through the second path 2), and the remaining nitrogen is liquefied in the main condenser-evaporator E1002. Part of the liquefied liquid nitrogen is used as the reflux liquid of the lower tower K1001, and the remaining part is pressurized by the liquid nitrogen pump and then reheated by the main heat exchanger E1101 before being sent to the gas pipeline network as product nitrogen. The remaining liquid nitrogen is further cooled by the subcooler E1103 in the fifth path 5. The cooled liquid nitrogen enters the gas-liquid separator. Part of the liquid nitrogen in the gas-liquid separator is sent to the storage tank as product liquid nitrogen, and the remaining part is used as the reflux liquid of the upper tower K1002 and enters the top of the upper tower K1002.

[0060] like Figure 1 and Figure 4 As shown, low-pressure nitrogen and waste nitrogen are extracted from the top of the upper tower K1002. The low-pressure nitrogen and waste nitrogen pass through the anti-nitrogen path 13 and are reheated by the subcooler E1103 and the main heat exchanger E1101 before exiting the cold box. The low-pressure nitrogen can be used as product gas and can be pressurized and sent to the user's pipeline network, or the low-pressure nitrogen can be sent to the water-cooled tower E1060 for further recovery of cold energy.

[0061] The liquid oxygen generated at the bottom of the upper tower K1002 is partly cooled by the subcooler E1103 and sent to the storage tank as a product, and partly pressurized by the liquid oxygen pump and sent to the mixing tower 100 through the first path 1.

[0062] Finally, the top of the mixing tower 100 outputs oxygen-enriched gas with different oxygen contents.

[0063] Furthermore, changes to the oxygen content and extraction rate of the oxygen-enriched gas in existing equipment alter the argon distillation sections of the upper column, leading to reduced argon production and poor economic efficiency. Existing conventional air separation units cannot produce pure argon products that meet standards when producing oxygen-enriched gas.

[0064] Therefore, in the embodiments of this application, such as Figure 3 and Figure 5As shown, the feed gas for the argon system is the argon fraction extraction port of the upper tower K1002. The extracted argon fraction is deoxygenated in the crude argon tower, and the resulting crude argon gas is sent to the pure argon tower K1011 for denitrification. Then, high-purity liquid argon is generated at the top of the pure argon tower K1011, and the liquid argon is sent to the liquid argon storage tank.

[0065] Specifically, the argon fraction extracted from the upper column K1002 is connected to the bottom inlet of the crude argon column K1010 via the eleventh path 11. The crude argon gas generated by the crude argon condenser E1010 is connected to the middle inlet of the pure argon column K1011 via the twelfth path 12 (the inlet of the crude argon condenser E1010 is connected to the top of the crude argon column). The liquid argon generated by the pure argon condenser E1016 enters the liquid argon storage tank (the inlet of the pure argon condenser E1016 is connected to the top of the pure argon column K1011, and the outlet is connected to the top of the pure argon column K1011). The liquid argon collected at the bottom of the pure argon column K1011 is collected in the liquid argon storage tank. Furthermore, the bottom of the crude argon column K1010 is connected to the upper column K1002 via a reflux path.

[0066] This application obtains oxygen-enriched gas without affecting the distillation process in the column, ensuring that the argon content at the argon fraction extraction port remains stable at the design level, and that argon production is stable and reliable.

[0067] According to the air separation unit of this application, the air separation unit includes a mixing tower, an upper tower, and a lower tower. A reboiler is provided at the bottom of the mixing tower. Liquid oxygen collected at the bottom of the upper tower is connected to the middle liquid inlet of the mixing tower through a first path, and nitrogen gas at the top of the lower tower is connected to the top gas inlet of the mixing tower through a second path. The reboiler can evaporate the liquid oxygen from the upper tower into gaseous oxygen. Specifically, when liquid oxygen enters the mixing tower, it falls into the reboiler from the top of the mixing tower. The liquid oxygen is heated by the medium-pressure air in the reboiler and becomes low-temperature gaseous oxygen. The low-temperature gaseous oxygen and nitrogen gas from the top of the lower tower are mixed in the mixing tower. Liquid oxygen flows downward through the packing layer by layer, and gaseous oxygen flows upward through the packing layer by layer. At the same time, nitrogen gas from the lower tower also flows upward through the packing layer by layer in the mixing tower. After passing through the packing, the two gases (oxygen and nitrogen) are uniformly mixed into oxygen-enriched gas at the top of the mixing tower. On-site personnel can adjust the nitrogen content entering the mixing tower according to needs to obtain oxygen-enriched gas with different oxygen contents. In other words, this application allows for adjusting the proportion of nitrogen entering the mixing tower, enabling the production of oxygen-enriched air with a specific oxygen content, unrestricted by the upper and lower towers or the main condenser-evaporator. Furthermore, variable oxygen production is possible, allowing for quantitative adjustment of the oxygen-enriched gas within a certain production range. Cooling balance is achieved through the coupled control of the mixing-reboiler, main heat exchanger, and expander. Additionally, the liquid oxygen in the main condenser-evaporator meets standard requirements. Simultaneously with the production of oxygen-enriched air, the high-pressure expander provides sufficient cooling capacity, enabling the large-scale extraction of liquid oxygen products.

[0068] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An air separation unit, characterized in that, The air separation unit includes a mixing column, an upper column, a lower column, and a reboiler, with the reboiler located at the bottom of the mixing column. The liquid oxygen collected at the bottom of the upper tower is connected to the middle inlet of the mixing tower via a first path. The nitrogen gas at the top of the lower column is connected to the top inlet of the mixing column via a second path. The reboiler is capable of evaporating liquid oxygen from the upper column into gaseous oxygen. The liquid oxygen side of the reboiler is connected to the bottom of the mixing tower. When liquid oxygen enters the mixing tower, it falls from the mixing tower into the reboiler. The liquid oxygen is heated by the reboiler and becomes low-temperature gaseous oxygen. The low-temperature gaseous oxygen and nitrogen from the top of the lower tower are mixed in the mixing tower. The gaseous oxygen and nitrogen from the lower tower pass through the packing of the mixing tower upward and are mixed into oxygen-enriched gas at the top of the mixing tower.

2. The air separation unit according to claim 1, characterized in that, The air separation unit also includes a main heat exchanger, and compressed air is connected to the reboiler via a third path. The compressed air is connected to the bottom liquid inlet of the lower tower via a fourth path. Both the third path and the fourth path pass through the main heat exchanger.

3. The air separation unit according to claim 2, characterized in that, The nitrogen gas at the top of the lower column flows out through the second branch path. The gas flows out through the top outlet of the mixing tower via the first branch path. The first branch path and the second branch path pass through the main heat exchanger.

4. The air separation unit according to claim 2, characterized in that, The air separation unit also includes a main condenser-evaporator and a storage tank. The main condenser-evaporator connects the upper and lower columns and is located in the liquid oxygen collected at the bottom of the upper column. The nitrogen gas at the top of the lower column can be liquefied in the main condenser-evaporator. The liquefied liquid nitrogen partially enters the storage tank and the top inlet of the upper column via the fifth path, and partially flows out through the main heat exchanger. The gas outlet at the top of the upper column flows out through the sixth path, which passes through the main heat exchanger, and the liquid oxygen collected at the bottom of the upper column flows out through the first branch path.

5. The air separation unit according to claim 4, characterized in that, The air separation unit also includes a pure argon column and a crude argon column. The bottom of the pure argon tower is equipped with a pure argon evaporator, the top of the pure argon tower is equipped with a pure argon condenser, and the top of the crude argon tower is equipped with a crude argon condenser. The bottom outlet of the lower column is connected to the inlet of the pure argon evaporator via a seventh path. The outlet of the pure argon evaporator is connected to the top inlet of the pure argon column and the top inlet of the crude argon column via an eighth path and a ninth path, respectively. The liquid air vapor and liquid air generated by the pure argon condenser and the crude argon condenser are returned to the upper column.

6. The air separation unit according to claim 5, characterized in that, The air separation unit also includes a subcooler, and the liquid air in the middle of the lower column is transported to the upper column via a tenth path. The tenth path, the seventh path, and the fifth path all pass through the subcooler.

7. The air separation unit according to claim 5, characterized in that, The argon fraction extracted from the upper column is deoxygenated in the crude argon column, and the resulting crude argon gas enters the pure argon column for denitrogenation, where liquid argon is generated from the bottom of the pure argon column.

8. The air separation unit according to claim 7, characterized in that, The air separation unit also includes a liquid argon storage tank. The argon fraction extracted from the upper column is connected to the bottom liquid inlet of the crude argon column through the eleventh path. The crude argon gas generated by the crude argon condenser is connected to the middle gas inlet of the pure argon column through the twelfth path. The liquid argon generated by the pure argon condenser enters the liquid argon storage tank.

9. The air separation unit according to claim 6, characterized in that, The air separation unit also includes a purification system, a precooling system, and a compressor. External air enters the precooling system for precooling, then enters the purification system for filtration, and the filtered air is compressed into compressed air by the compressor.

10. The air separation unit according to claim 9, characterized in that, The middle section of the upper column is connected to the precooling system and the purification system via a nitrogen-removing path to provide cooling nitrogen to the precooling system and the purification system. The nitrogen-removing path passes through the subcooler and the main heat exchanger.

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