A device and method for capturing carbon dioxide from the atmosphere based on an air separation unit

Abstract

The present invention relates to a device and method for capturing carbon dioxide from the atmosphere based on an air separation unit, and relates to the technical field of CO2 capture. The device comprises an air filtration device, a compressor unit, a cooling device, a molecular sieve adsorption group, a gas buffer device, an amine absorption device, a liquid storage device, a first heating device, an amine regeneration device, and a carbon dioxide storage device, which are connected in sequence. The post-adsorption gas phase outlet of the molecular sieve adsorption group is connected to the air inlet of the air separation unit. The first air outlet of the air separation unit is connected to the cooling device via a liquid cooling device and a refrigeration device in sequence. The second air outlet of the air separation unit is connected to the desorbed gas inlet of the molecular sieve adsorption group via a second heating device. The device provided by the present invention uses the molecular sieve adsorption group to adsorb CO2. The adsorbed gas enters the air separation unit to produce high-purity nitrogen and liquid oxygen. The CO2-containing gas enters the amine absorption tower and the amine regeneration tower to obtain high-purity CO2, thereby achieving low-energy consumption and low-waste air capture and production of CO2.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 capture, and in particular to a device and method for capturing carbon dioxide from the atmosphere based on an air separation unit. Background Art

[0002] Currently, the amount of CO2 in the atmosphere has increased significantly. CO2 is the main component of the greenhouse effect. Direct air CO2 capture (DAC) is an important method for reducing atmospheric CO2 content. It not only recaptures already emitted CO2, but also reduces the need to extract fossil fuels by combining the captured CO2 with hydrogen to produce synthetic fuels such as methanol, thereby further reducing the amount of CO2 released into the atmosphere. Compared with CCUS technology, which relies on capturing CO2 from fossil fuel emissions, DAC technology has more stable and wider application scenarios.

[0003] Among them, DAC technology includes liquid DAC technologies such as alkaline hydroxide solution, amine solution, amino acid salt solution / BIGs and alkalinity concentration changes, as well as solid DAC technologies such as solid alkali / alkaline earth metals, solid amines, metal organic framework MOFs materials and variable wetting adsorption.

[0004] For example, CN118142325A discloses a method and system for directly absorbing carbon dioxide using alkaline industrial solid waste. By selecting alkaline industrial solid waste as the raw material for DAC, specifically a mixture of calcium carbide slag as the main material, other solid wastes as the auxiliary material, and a small amount of additives, a packaged loading system and an energy-saving absorption tower system are combined to form a complete set of efficient DAC absorption reaction and mineralization processes.

[0005] CN116212595A discloses a direct air carbon capture system and method based on tiny air bubbles. The system comprises at least: an induced draft fan, a converging nozzle, and a CO2 absorber. The induced draft fan is connected to a first end of the converging nozzle via a first pipeline, and a second end of the converging nozzle is connected to the bottom of the CO2 absorber. The converging nozzle is used to deliver gas into the CO2 absorber in the form of tiny bubbles. The CO2 absorber is used to accommodate a liquid absorbent, and an opening is provided at the top of the CO2 absorber for gas discharge.

[0006] However, while the alkaline hydroxide solution absorption method has strong CO2 binding capacity and is a relatively mature process, the thermal regeneration process requires high-quality heat sources (approximately 900°C) to calcine calcium carbonate at high temperatures, significantly limiting its application scenarios and increasing operating costs. Furthermore, since the partial pressure of CO2 in the atmosphere is only approximately 400 ppm, DAC technology also faces the problem of high gas adsorption flow and low CO2 production, while also generating a large amount of waste gas. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a device and method for capturing carbon dioxide from the atmosphere based on an air separation unit, so as to solve the problems of high energy consumption and large amount of waste gas in the process of capturing carbon dioxide.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a device for capturing carbon dioxide from the atmosphere based on an air separation unit, the device comprising an air filtration device, a compressor unit, a cooling device, a molecular sieve adsorption group, a gas buffer device, an amine absorption device, a liquid storage device, a first heating device, an amine regeneration device, and a carbon dioxide storage device connected in sequence;

[0010] The post-adsorption gas phase outlet of the molecular sieve adsorption group is connected to the air inlet of the air separation device;

[0011] The first air outlet of the air separation device is connected to the cooling device through the liquid cooling device and the refrigeration device in sequence;

[0012] The second gas outlet of the air separation unit is connected to the desorption gas inlet of the molecular sieve adsorption group through a second heating device;

[0013] The top gas outlet of the amine absorption device is connected to the air separation device through a washing device;

[0014] The washing liquid outlet of the washing device is connected to the liquid storage device.

[0015] The device provided by the present invention utilizes a molecular sieve adsorption group to adsorb CO2. The air that does not contain CO2 enters the air separation unit to produce high-purity nitrogen and liquid oxygen products. The CO2-containing gas is stored in a gas buffer bag at a certain concentration. The CO2 of a certain concentration enters the amine absorption tower and the amine regeneration tower, and finally high-purity CO2 is obtained, thereby realizing low-energy consumption and low-waste air capture to produce CO2.

[0016] As a preferred technical solution of the present invention, the compressor unit includes at least one stage of compressor.

[0017] Preferably, the cooling method of the cooling device includes liquid cooling.

[0018] As a preferred technical solution of the present invention, the molecular sieve adsorption group includes at least two molecular sieve adsorption devices connected in parallel.

[0019] Preferably, a carbon dioxide concentration detection device and an exhaust branch are provided on the pipeline between the molecular sieve adsorption group and the gas buffer device.

[0020] As a preferred technical solution of the present invention, the first heating device includes a heat exchange device or a direct heating device.

[0021] Preferably, the cold medium inlet of the heat exchange device is connected to the liquid storage device.

[0022] Preferably, the cold medium outlet of the heat exchange device is connected to the liquid inlet of the amine regeneration device.

[0023] Preferably, the heat medium inlet of the heat exchange device is connected to the liquid outlet of the amine regeneration device.

[0024] Preferably, the heat medium outlet of the heat exchange device is connected to the amine absorption device through a cooler.

[0025] In a second aspect, the present invention provides a method for capturing carbon dioxide from the atmosphere based on an air separation unit, the method comprising using the atmospheric carbon dioxide capture device based on an air separation unit as described in the first aspect.

[0026] As a preferred technical solution of the present invention, the method comprises: filtering, compressing and cooling the air in sequence, adsorbing the air, desorbing the air, absorbing the desorbed gas with an amine liquid to obtain an absorption liquid, and separating the absorption liquid to obtain a carbon dioxide product;

[0027] Among them, the adsorbed gas is collected as oxygen or nitrogen as product gas after air separation, and the remaining gas is divided into two paths, one as a cooling source and the other as desorption gas; the absorbed gas obtained by amine liquid absorption is eluted, and the elution liquid is used as the absorption liquid, and the eluted gas enters the air separation.

[0028] As a preferred technical solution of the present invention, the compression is to compress the gas to 4-6 bar.

[0029] As a preferred technical solution of the present invention, the temperature of the gas obtained after cooling is 10-15°C.

[0030] As a preferred technical solution of the present invention, the temperature of the desorption gas used in the desorption is 180-200°C.

[0031] As a preferred technical solution of the present invention, the feeding temperature of the absorption liquid in the separation is 95-100°C.

[0032] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0033] The device provided by the present invention can produce high-purity CO2 gas using air as raw material, and avoids the high-temperature regeneration process generated by the traditional use of strong alkali to absorb CO2 gas. In addition, the air separation unit reuses the remaining gas for air separation production, greatly improving the problem of low output of valuable products. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of a device for capturing carbon dioxide from the atmosphere based on an air separation unit provided in an embodiment of the present invention.

[0035] In the figure: 1-air filtration equipment, 2-compressor unit, 3-cooling equipment, 4-molecular sieve adsorption group, 5-gas buffer equipment, 6-amine absorption equipment, 7-liquid storage equipment, 8-first heating equipment, 9-amine regeneration equipment, 9.1-steam reboiler, 9.2-condenser, 10-carbon dioxide storage equipment, 11-air separation unit, 12-liquid cooling equipment, 13-refrigeration equipment, 14-second heating equipment, 15-washing equipment, 16-carbon dioxide concentration detection equipment, 17-exhaust branch, 18-valve, 19-pump, 20-cooling equipment;

[0036] I-air, II-water.

[0037] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0038] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0039] This embodiment provides a device for capturing carbon dioxide from the atmosphere based on an air separation unit, such as Figure 1 As shown, the atmospheric carbon dioxide capture device based on the air separation unit includes an air filtration device 1, a compressor unit 2, a cooling device 3, a molecular sieve adsorption group 4, a gas buffer device 5, an amine absorption device 6, a liquid storage device 7, a first heating device 8, an amine regeneration device 9, and a carbon dioxide storage device 10 connected in sequence;

[0040] The post-adsorption gas phase outlet of the molecular sieve adsorption group 4 is connected to the air inlet of the air separation device 11;

[0041] The first air outlet of the air separation device 11 is connected to the cooling device 3 through the liquid cooling device 12 and the refrigeration device 13 in sequence;

[0042] The second gas outlet of the air separation device 11 is connected to the desorption gas inlet of the molecular sieve adsorption group 4 through the second heating device 14;

[0043] The top gas outlet of the amine absorption device 6 is connected to the air separation device 11 through the scrubbing device 15;

[0044] The washing liquid outlet of the washing device 15 is connected to the liquid storage device 7 .

[0045] In the present invention, the air filtering device 1 is used to remove particulate matter and pollutants in the air.

[0046] The compressor unit 2 includes at least one stage of compressor.

[0047] In the present invention, the design of the compressor unit 2 is to compress the gas to meet the subsequent operation requirements. The specific setting of the compressor of the compressor unit 2 can be set in multi-stage parallel, multi-stage series, or multi-stage series-parallel, and is also equipped with an inter-stage heat exchanger for cooling.

[0048] The cooling method of the cooling device 3 includes liquid cooling.

[0049] In the present invention, the cooling device 3 cools the compressed air by liquid cooling to ensure that the operating temperature of the molecular sieve adsorption is reached and the efficiency of the adsorption process is guaranteed.

[0050] The molecular sieve adsorption group 4 includes at least two molecular sieve adsorption devices connected in parallel.

[0051] In the present invention, part of the molecular sieve adsorption towers and another part of the molecular sieve adsorption towers in the molecular sieve adsorption group 4 take turns as CO2 adsorption towers and molecular sieve regeneration towers during the adsorption and regeneration process to improve the operating efficiency of the molecular sieve adsorption group 4 and facilitate continuous operation.

[0052] A carbon dioxide concentration detection device 16 and an exhaust branch 17 are provided on the pipeline between the molecular sieve adsorption group 4 and the gas buffer device 5 .

[0053] In the present invention, the carbon dioxide concentration detection device 16 is used to detect the concentration of carbon dioxide in the gas after adsorption. When a certain concentration is reached, it can be fed into the gas buffer device 5. If the required concentration is not reached, it can be discharged through the exhaust branch 17 or fed into the molecular sieve adsorption group 4 for recycling, thereby ensuring that the requirements of subsequent operations are met and the absorption efficiency of carbon dioxide is guaranteed.

[0054] Exemplarily, the carbon dioxide concentration detection device 16 includes an online CO2 gas concentration detector and a CO2 gas pump.

[0055] In the present invention, the gas buffer device 5 includes an outer air bag and an inner air bag connected to the concentration detection and control device. When the air intake of the inner air bag increases or the exhaust volume decreases, the pressure of the inner air bag is higher than the set pressure value, and the outer air bag is exhausted to reduce the gas storage pressure of the inner air bag until the inner layer pressure stabilizes at the set pressure value. When the air intake of the inner air bag decreases or the exhaust volume increases, the pressure of the inner air bag is lower than the set pressure value, and the outer air bag is exhausted to increase the gas storage pressure of the inner air bag until the inner layer pressure stabilizes at the set pressure value, thereby ensuring the stability of the gas pressure of the CO2 gas at the outlet of the gas buffer bag.

[0056] The first heating device 8 includes a heat exchange device or a direct heating device.

[0057] In the present invention, the first heating device 8 is used to heat the amine absorption liquid so that it is easier to reach the operating temperature required by the amine regeneration device 9, thereby improving the efficiency of amine regeneration.

[0058] The cold medium inlet of the heat exchange device is connected to the liquid storage device 7.

[0059] The cold medium outlet of the heat exchange device is connected to the liquid inlet of the amine regeneration device 9.

[0060] The heat medium inlet of the heat exchange device is connected to the liquid outlet of the amine regeneration device 9.

[0061] The heat medium outlet of the heat exchange device is connected to the amine absorption device 6 through a cooler.

[0062] In the present invention, the second heating device 14 can optionally be set as a heat exchange device and / or a direct heating device. The heat source of the heat exchange device comes from the inside of the device or other process systems to ensure that the desorbed gas can meet the desorption operation requirements of the molecular sieve adsorption group 4.

[0063] Illustratively, the amine absorption equipment 6 includes an amine absorption tower body, an absorption tower sprayer, a liquid distributor, a packing layer, and inlet and outlet pipes. The CO2-containing gas enters the bottom of the amine absorption tower body, and the amine absorption liquid enters the top of the amine absorption tower body and is evenly sprayed on the packing layer through the absorption tower sprayer. The CO2-containing gas reacts with the amine absorption liquid to obtain the amine absorption liquid after absorbing CO2, which is called rich liquid. The rich liquid enters the rich liquid storage tank from the bottom of the amine absorption tower, and the gas that is not absorbed is discharged from the top of the amine absorption tower body. The packing layer uses layered packing to increase the contact surface area, so that the contact between the CO2-containing gas and the amine absorption liquid is more sufficient. The liquid distributor is arranged between the layered packings so that the amine absorption liquid is evenly distributed on the packing layer to ensure the smooth progress of the absorption process.

[0064] Exemplarily, the amine regeneration equipment 9 includes an amine regeneration tower, a regeneration tower sprayer, a liquid distributor, a packing layer, a steam reboiler, a condenser, and inlet and outlet pipes. Hot rich liquid enters the top of the amine regeneration tower and is evenly sprayed onto the packing layer through the regeneration tower sprayer. The steam reboiler provides heat to promote CO2 desorption from the amine solution. The condenser condenses water vapor and amine entrained in the gas at the top of the amine regeneration tower and refluxes them back to the top of the amine regeneration tower. The high-purity CO2 product at the condenser outlet is collected and stored. The amine absorption liquid after CO2 separation is called lean liquid. The lean liquid is discharged at the bottom of the amine regeneration tower and then cooled to become cold lean liquid. The cold lean liquid is reused as amine absorption liquid for CO2 absorption. The packing layer uses layered packing, and the liquid distributor is arranged between the layered packing.

[0065] In the present invention, the CO2 in the CO2-containing gas is captured by the amine absorption device and the amine regeneration device through the absorption and regeneration cycle of the amine absorption liquid.

[0066] In the present invention, the lean liquid coming out of the amine regeneration tower device 9 flows into the first heating device 8 such as a heat exchanger through the lean liquid pump, and serves as the heat source of the lean-rich liquid heat exchanger. The rich liquid coming out of the bottom of the amine absorption device 6 serves as the cold source of the lean-rich liquid heat exchanger. The rich liquid is heated by the first heating device 8 to become a hot rich liquid and then enters the amine regeneration device 9 for CO2 desorption, which can reduce the heat load of the steam reboiler of the amine regeneration device. The lean liquid is cooled by the first heating device 8 and then enters the cooler for further cooling, which can reduce the cooling water consumption of the cooler.

[0067] In the present invention, the devices in the apparatus are also equipped with connecting pipes, a pump 19 for material transmission, a valve 18 for controlling the flow of materials and other equipment; further, each device in the apparatus is equipped with sensors or detectors of relevant key control parameters, and then the intelligent operation of the apparatus is realized with the help of control equipment such as an industrial computer.

[0068] The exemplary usage process is as follows:

[0069] Air I is piped into an air filter to remove particulate matter such as dust. The gas at the air filter outlet is piped into compressor unit 2, compressed to 4-6 bar, and then piped into cooling equipment 3.

[0070] The gas is cooled in cooling device 3, and the water in cooling device 3 is discharged and then treated as waste liquid. The cooled gas at the top outlet of cooling device 3 is passed through a pipeline to molecular sieve adsorption group 4. At this time, the CO2 in the gas is adsorbed in molecular sieve adsorption group 4, and the remaining gas is passed through a pipeline to air separation unit 11.

[0071] Air separation unit 11 separates oxygen and / or nitrogen from the gas as product gas. The remaining gas is split into two paths: one path is piped into liquid cooling unit 12, and the other path is piped into second heating unit 14. Water II is fed into the upper side of liquid cooling unit 12. The water at the bottom outlet is compressed by a pump and piped into refrigeration unit 13. After being cooled in refrigeration unit 13, it is piped into cooling unit 3. The other path of gas from air separation unit 11 enters second heating unit 14, where it is heated and then piped into molecular sieve adsorption group 4 for CO2 desorption.

[0072] The CO2-containing gas formed after desorption enters the carbon dioxide concentration detection device 16, such as a concentration detection control device, through a pipeline. The device controls the opening and closing of the exhaust branch 17 by detecting the CO2 content in the CO2-containing gas.

[0073] When the CO2 concentration in the gas is greater than a certain value, the exhaust branch 17 is closed, the gas is passed into the gas buffer device 5, and the gas with a higher CO2 concentration is collected; when the CO2 concentration in the gas is less than a certain value, the exhaust branch 17 is opened, and the gas with a lower CO2 concentration is discharged.

[0074] The CO2 gas stored in the gas buffer device 5 is passed into the amine absorption device 6 through a pipeline. The CO2 in the gas reacts with the amine absorption solution in the gas buffer device 5 and is enriched in the amine solution in the form of reaction products. This solution is called absorption liquid.

[0075] Furthermore, the absorption liquid produced by the amine absorber 6 is fed into the liquid storage device 7 via a pipeline from the bottom. The residual gas at the top of the amine absorber 6 is passed through a pipeline to the scrubbing device 15. Water is added to the top of the scrubbing device 15 for scrubbing. The residual gas produced at the top of the scrubbing device 15 is treated for water removal and then passed through a pipeline to the air separation unit 11 for further conversion into air separation products. The liquid at the bottom of the scrubbing device 15 is collected through a pipeline into the liquid storage device 7. The absorption liquid in the liquid storage device 7 is passed through a pipeline to a first heating device 8, such as a lean-rich liquid heat exchanger, for heating. After heating, it flows through a pipeline to the amine regeneration device 9.

[0076] The bottom of the amine regeneration unit 9 is equipped with a steam reboiler 9.1. The absorption liquid is heated in the amine regeneration unit 9.1, and the solution after desorbing CO2 is called the lean liquid. The lean liquid flows out of the bottom of the amine regeneration unit 9 and is cooled, such as by passing it into a lean-rich liquid heat exchanger. It is then cooled by further cooling equipment 20, such as a heat exchanger or direct cooler, and then flows through a pipeline into the amine absorption unit 6 for the CO2 absorption reaction.

[0077] The gas at the top of the amine regeneration device 9 is condensed by the condenser 9.2, and the condensed water flows back to the amine regeneration device 9. The condensed gas is a high-concentration CO2 product gas, which is passed through a pipeline to the carbon dioxide storage device 10 for storage.

[0078] In the present invention, the water used in cooling and washing can be replaced by other commonly used gas cooling and gas washing media in the art.

[0079] Furthermore, the present invention provides a method for capturing carbon dioxide from the atmosphere based on an air separation unit. The method is performed using the aforementioned atmospheric carbon dioxide capture unit based on an air separation unit, comprising: filtering, compressing, and cooling the air in sequence, followed by adsorption, followed by desorption, absorbing the desorbed gas with an amine liquid to obtain an absorption liquid, and separating the absorption liquid to obtain a carbon dioxide product;

[0080] Among them, the adsorbed gas is collected as oxygen or nitrogen as product gas after air separation, and the remaining gas is divided into two paths, one as a cooling source and the other as desorption gas; the absorbed gas obtained by amine liquid absorption is eluted, and the elution liquid is used as the absorption liquid, and the eluted gas enters the air separation.

[0081] The compression is to compress the gas to 4-6 bar, for example, it can be 4 bar, 4.2 bar, 4.4 bar, 4.6 bar, 4.8 bar, 5 bar, 5.2 bar, 5.4 bar, 5.6 bar, 5.8 bar or 6 bar, etc., but is not limited to the listed values. Other values not listed in this range also meet the requirements.

[0082] The temperature of the gas obtained after cooling is 10-15°C, for example, it can be 10°C, 10.5°C, 11°C, 11.5°C, 12°C, 12.5°C, 13°C, 13.5°C, 14°C, 14.5°C or 15°C, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0083] Wherein, the adsorption is performed using molecular sieve.

[0084] The molecular sieves used include 13X APG molecular sieves and other molecular sieves that adsorb carbon dioxide from the air.

[0085] In the present invention, the amine medium used in the amine liquid absorption includes monoethanolamine, methyldiethanolamine or 2-amino-2-methyl-1-propanol, which are commonly used amine media for carbon dioxide absorption in the art. The amine medium can be diluted with water or other commonly used solvents in the art, or the amine medium can be directly used for absorption.

[0086] The temperature of the desorption gas used in the desorption is 180-200°C, for example, it can be 180°C, 182°C, 184°C, 186°C, 188°C, 190°C, 192°C, 194°C, 196°C, 198°C or 200°C, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0087] The feeding temperature of the absorption liquid in the separation is 95-100°C, for example, it can be 95°C, 95.5°C, 96°C, 96.5°C, 97°C, 97.5°C, 98°C, 98.5°C, 99°C, 99.5°C or 100°C, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0088] Furthermore, in order to illustrate that the device for capturing carbon dioxide from the atmosphere based on an air separation unit provided by the present invention can achieve a good carbon dioxide capture effect, a specific practical example is used for illustration, as follows:

[0089] Example 1

[0090] This embodiment provides a practical application process of a device for capturing carbon dioxide from the atmosphere based on an air separation unit, as follows:

[0091] Air I is piped into an air filter to remove particulate matter such as dust. The gas at the air filter outlet is piped into a compressor unit 2, compressed to 5 bar, and then piped into a cooling device 3.

[0092] The gas is cooled in cooling device 3, and the water in cooling device 3 is drained and then treated as waste liquid. The cooled gas (temperature 12°C) at the top outlet of cooling device 3 is piped into molecular sieve adsorption group 4, where the CO2 in the gas is adsorbed. The molecular sieve adsorption group 4 consists of two molecular sieve adsorption devices connected in parallel, and the molecular sieve used is 13XAPG molecular sieve. The remaining gas is piped into air separation unit 11.

[0093] Air separation unit 11 separates oxygen and / or nitrogen from the gas as product gas. The remaining gas is split into two paths: one path is piped into liquid cooling unit 12, and the other path is piped into second heating unit 14. Water II is fed into the upper side of liquid cooling unit 12. The water at the bottom outlet is compressed by a pump and piped into a refrigeration unit. After cooling in the refrigeration unit, it is piped into cooling unit 3. The other path of gas from air separation unit 11 enters second heating unit 14, where it is heated and then piped into molecular sieve adsorption group 4 as desorbed gas at 190°C for CO2 desorption.

[0094] The CO2-containing gas formed after desorption enters the carbon dioxide concentration detection device 16 through the pipeline, and the switch of the exhaust branch 17 is controlled by detecting the CO2 content in the CO2-containing gas; when the CO2 concentration in the gas is ≥2000ppm, the exhaust branch 17 is closed, and the gas is passed into the gas buffer device 5, and the gas with a higher CO2 concentration is collected; when the CO2 concentration in the gas is <2000ppm, the exhaust branch 17 is opened, and the gas with a lower CO2 concentration is discharged.

[0095] The CO2 gas stored in the gas buffer device 5 is passed through a pipeline into the amine absorption device 6, where methyldiethanolamine is used to absorb the CO2. The CO2 in the gas reacts with the amine absorption solution in the gas buffer device 5 and is enriched in the amine solution in the form of reaction products. This solution is called the absorption solution.

[0096] The absorption liquid produced by the amine absorber 6 is piped into the liquid storage device 7 through the bottom. The residual gas at the top of the amine absorber 6 is piped into the scrubbing device 15. Water is added to the top of the scrubbing device 15 for scrubbing. After the residual gas produced at the top of the scrubbing device 15 is dehydrated, it is piped into the air separation unit 11 for further conversion into air separation products. The liquid at the bottom of the scrubbing device 15 is piped into the liquid storage device 7. The absorption liquid in the liquid storage device 7 is piped into a first heating device 8, such as a lean-rich liquid heat exchanger, where it is heated to 100°C. After heating, it flows through a pipe into the amine regeneration device 9.

[0097] The bottom of the amine regeneration unit 9 is equipped with a steam reboiler 9.1. The absorption liquid is heated in the amine regeneration unit 9.1, and the solution after desorbing CO2 is called the lean liquid. The lean liquid flows out of the bottom of the amine regeneration unit 9 and is cooled, such as by passing it into a lean-rich liquid heat exchanger. It is then cooled by further cooling equipment 20, such as a heat exchanger or direct cooler, and then flows through a pipeline into the amine absorption unit 6 for the CO2 absorption reaction.

[0098] The gas at the top of the amine regeneration device 9 is condensed by the condenser 9.2, and the condensed water flows back to the amine regeneration device 9. The condensed gas is a high-concentration CO2 product gas, which is passed through a pipeline to the carbon dioxide storage device 10 for storage.

[0099] When the air intake volume is 150000Nm 3 / h, based on the total output of oxygen and liquid oxygen produced by the air separation unit at 25000Nm 3 / h-32000Nm 3 / h. The gas volume entering the amine absorption equipment through the gas buffer equipment is 30000-35000Nm 3 / h, the CO2 content is 2000ppm-3000ppm. The purity of CO2 entering the storage tank is above 95%, and the output is 40Nm 3 / h~60Nm 3 / h, and the system energy consumption is 5.36GJ / tCO2.

[0100] It should be noted that the present invention uses the above-described embodiments to illustrate the detailed structural features of the present invention. However, the present invention is not limited to these detailed structural features, and this does not mean that the present invention must rely on these detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0101] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0102] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0103] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A device for capturing carbon dioxide from the atmosphere based on an air separation unit, characterized in that: The device includes an air filtration device, a compressor unit, a cooling device, a molecular sieve adsorption group, a gas buffer device, an amine absorption device, a liquid storage device, a first heating device, an amine regeneration device, and a carbon dioxide storage device connected in sequence; The post-adsorption gas phase outlet of the molecular sieve adsorption group is connected to the air inlet of the air separation device; The first air outlet of the air separation device is connected to the cooling device through the liquid cooling device and the refrigeration device in sequence; The second gas outlet of the air separation unit is connected to the desorption gas inlet of the molecular sieve adsorption group through a second heating device; The top gas outlet of the amine absorption device is connected to the air separation device through a washing device; The washing liquid outlet of the washing device is connected to the liquid storage device; A carbon dioxide concentration detection device and an exhaust branch are provided on the pipeline between the molecular sieve adsorption group and the gas buffer device.

2. The device according to claim 1, characterized in that The compressor unit includes at least one compressor stage.

3. The device according to claim 1, wherein: The cooling method of the cooling device includes liquid cooling.

4. The device according to claim 1, wherein The molecular sieve adsorption group includes at least two molecular sieve adsorption devices connected in parallel.

5. The device according to claim 1, wherein: The first heating device includes a heat exchange device or a direct heating device.

6. The device according to claim 5, characterized in that The cold medium inlet of the heat exchange device is connected to the liquid storage device.

7. The device according to claim 5, characterized in that The cold medium outlet of the heat exchange device is connected to the liquid inlet of the amine regeneration device.

8. The device according to claim 5, characterized in that The heat medium inlet of the heat exchange device is connected to the liquid outlet of the amine regeneration device.

9. The device according to claim 5, characterized in that The heat medium outlet of the heat exchange device is connected to the amine absorption device through a cooler.

10. A method for capturing carbon dioxide from the atmosphere based on an air separation unit, characterized in that: The method comprises capturing carbon dioxide using the atmospheric carbon dioxide capture device based on an air separation unit as described in any one of claims 1 to 9.

11. The method according to claim 10, wherein: The method comprises: filtering, compressing and cooling the air in sequence, adsorbing the air, desorbing the air, absorbing the desorbed gas with an amine liquid to obtain an absorption liquid, and separating the absorption liquid to obtain a carbon dioxide product; Among them, the adsorbed gas is collected as oxygen or nitrogen as product gas after air separation, and the remaining gas is divided into two paths, one as a cooling source and the other as desorption gas; the absorbed gas obtained by amine liquid absorption is eluted, and the elution liquid is used as the absorption liquid, and the eluted gas enters the air separation.

12. The method according to claim 11, wherein: The compression is to compress the gas to 4-6 bar.

13. The method according to claim 11, wherein: The temperature of the gas obtained after the cooling is 10-15°C.

14. The method according to claim 11, wherein: The temperature of the desorption gas used in the desorption is 180-200°C.

15. The method according to claim 11, wherein: The feeding temperature of the absorption liquid in the separation is 95-100°C.

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