Method for directly capturing carbon dioxide from air

Abstract

The embodiment of the invention provides a method for directly trapping carbon dioxide from air. The method comprises the following steps: capturing carbon dioxide in air through an adsorber; after the carbon dioxide is captured, the interior of the adsorber is vacuumized for the first time; introducing water vapor into the adsorber to increase the pressure in the adsorber and increase the temperature of an adsorbent in the adsorber so as to desorb the carbon dioxide; the adsorber is vacuumized for the second time, and mixed gas formed by water vapor and carbon dioxide is obtained; and carrying out gas-liquid separation on the mixed gas to obtain carbon dioxide. The regeneration energy consumption of the adsorbent is reduced, and the concentration of the carbon dioxide product gas is improved.

Description

Technical Field

[0001] The present application relates to the technical field of direct capture of carbon dioxide from air, and relates to a method for direct capture of carbon dioxide from air. Background Art

[0002] Direct Air Capture (DAC) is a technology used to capture carbon dioxide (CO2) from the atmosphere. DAC technology extracts CO2 directly from the air, rather than capturing it from industrial emission sources, with the goal of reducing atmospheric CO2 concentrations and thus helping mitigate climate change.

[0003] DAC technology is mainly divided into two categories: liquid absorption DAC technology and solid adsorption DAC technology. Among them, solid adsorption DAC technology is relatively mature. In related technologies, steam-assisted variable temperature vacuum adsorption cycle process is used to capture carbon dioxide, and steam-assisted regeneration and desorption of adsorbents are achieved. However, continuous steam purging results in a large demand for water vapor and high energy consumption for adsorbent regeneration. Summary of the invention

[0004] The present application provides a method for direct air capture of carbon dioxide, which is used to solve the problem of high energy consumption of adsorbent regeneration during the direct capture of carbon dioxide.

[0005] The direct air capture carbon dioxide method provided in the present application comprises:

[0006] Capture carbon dioxide from the air through an absorber;

[0007] Performing a first vacuum on the adsorber;

[0008] Introducing water vapor into the adsorber to increase the pressure in the adsorber and the temperature of the adsorbent in the adsorber to desorb carbon dioxide;

[0009] Vacuuming the adsorber for a second time to obtain a mixed gas formed by the water vapor and the carbon dioxide;

[0010] The mixed gas is subjected to gas-liquid separation to obtain carbon dioxide.

[0011] In some optional embodiments, the first vacuuming takes 5 to 8 minutes, and the vacuum pressure in the adsorber is evacuated to -80 to -90 kPa.

[0012] In some optional embodiments, the water vapor flow rate is 0.8-1.3 m 3 / h, the introduction time is 5 to 8 minutes.

[0013] In some optional embodiments, during the introduction of water vapor into the adsorber, the pressure in the adsorber is increased to 130-170 kPa, and the temperature of the adsorbent in the adsorber is increased to 80-110°C.

[0014] In some optional embodiments, the second vacuuming lasts for 5 to 8 minutes, so that the temperature of the adsorbent in the adsorber drops to 60 to 80°C.

[0015] In some optional embodiments, after the temperature of the adsorbent in the adsorber is reduced to 60-80° C., the process further includes reducing the temperature of the adsorbent in the adsorber to 10-30° C. by air purge.

[0016] In some optional embodiments, the adsorber is a radial split-flow adsorber, or a staggered flexible filler is provided in the adsorber.

[0017] In some optional embodiments, the adsorber captures carbon dioxide in the air for 1 to 2 hours.

[0018] In some optional embodiments, the sum of the time for capturing carbon dioxide in the air, the time for introducing water vapor, the time for the first vacuuming and the time for the second vacuuming is 1.5 to 2.5 hours.

[0019] In some optional embodiments, the adsorbent of the adsorber is a solid amine adsorbent or a metal organic framework compound.

[0020] The direct air capture carbon dioxide method provided in the present application removes most of the non-target gases in the adsorber after the first step of vacuuming, thereby increasing the concentration of the final product gas; by intermittently introducing steam to heat the adsorbent, the temperature and pressure conditions in the adsorber can be more effectively controlled, thereby reducing the regeneration energy consumption of the adsorbent and facilitating the desorption of carbon dioxide; through the second step of vacuuming, high-concentration water vapor and carbon dioxide mixed gas can be extracted, and it helps to reduce the temperature of the adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] Figure 1 This is a schematic structural diagram of the direct air carbon dioxide capture device provided in an embodiment of the present application.

[0023] Description of reference numerals:

[0024] 100- adsorber; 101- air inlet; 102- steam inlet; 103- first air outlet; 104- second air outlet; 105- third air outlet; 110- air inlet pipe; 120- steam pipeline; 121- steam generator; 130- air pipeline; 131- air pump; 140- first vacuum pipeline; 141- first vacuum pump; 150- second vacuum pipeline; 151- heat exchanger; 152- gas-liquid separator; 153- second vacuum pump; 154- storage tank.

[0025] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0026] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0027] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein.

[0028] In the embodiments of the present application, words such as "exemplarily" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplarily" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplarily" or "for example" is intended to present related concepts in a specific way.

[0029] In the related art, an intermittent steam-assisted temperature-swing vacuum adsorption cycle process is used to capture carbon dioxide. Steam is used as a heating and purging medium. Steam purging can assist the desorption of the adsorbent. Although this method reduces power consumption to a certain extent, the continuous flow of steam increases the regeneration energy consumption of the adsorbent. In other related technologies, shell-and-tube adsorbers or adsorbers with enhanced heat transfer elements such as fins and coils built into the tower are used for indirect heating and cooling. The heat transfer effect is poor, which also increases the energy consumption of the adsorbent regeneration process.

[0030] The direct air capture carbon dioxide method provided in this application is intended to solve the above technical problems of the prior art.

[0031] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0032] The direct air capture carbon dioxide method provided in the embodiment of the present application includes the following steps: capturing carbon dioxide in the air through an adsorber; after capturing carbon dioxide, evacuating the adsorber for the first time; introducing water vapor into the adsorber to increase the pressure in the adsorber to 130-170 kPa, and raising the temperature of the adsorbent in the adsorber to 80-110°C to desorb carbon dioxide; evacuating the adsorber for the second time to obtain a mixed gas formed by water vapor and carbon dioxide; and performing gas-liquid separation on the mixed gas to obtain carbon dioxide. In some embodiments, the step of capturing carbon dioxide in the air through an adsorber is carried out at normal temperature and pressure, with an air flow rate of 200-250 m 3 / h, the concentration of carbon dioxide in the air is 200-500 ppm. At a lower temperature, the adsorbent in the adsorber can adsorb the gas containing carbon dioxide, thereby separating carbon dioxide from the gas. Exemplarily, air enters the adsorber through an airflow guiding device such as a suction pump and an air pump, so that the adsorbent quickly adsorbs carbon dioxide in the air.

[0033] After the adsorbent in the adsorber is saturated with adsorption, the adsorbed carbon dioxide needs to be desorbed in order to obtain high-purity product gas carbon dioxide. After the adsorbent is saturated with adsorption of carbon dioxide and before desorption of carbon dioxide, other remaining gases in the adsorber, such as oxygen and nitrogen, are sucked out by the first vacuum pumping, so that the concentration of the final product gas can be increased. At the same time, there is a certain carbon dioxide partial pressure difference in the negative pressure environment formed by vacuum pumping in the adsorber, which is conducive to promoting the desorption of carbon dioxide from the adsorbent. Among them, 130~170kPa is the safe pressure that the adsorption bed can withstand; 80~110℃ is the regeneration temperature of the adsorbent.

[0034] During the desorption of carbon dioxide, the required heat is provided for the regeneration of the adsorbent by increasing the temperature, thereby accelerating the desorption process. After the first vacuuming is completed, water vapor is introduced into the adsorber. The heat of the water vapor can quickly increase the temperature of the adsorbent, thereby promoting the release of carbon dioxide on the adsorbent and regenerating the adsorbent. The steam heating method is more uniform and can more effectively increase the temperature of the adsorbent, thereby promoting the desorption of carbon dioxide. In this process, it is not necessary to continuously introduce water vapor for purging. When the temperature of the adsorbent rises to 80-110°C, the introduction can be stopped. After that, the heat of the water vapor can still be effectively used to heat the adsorbent during the cooling process without the need for an additional heat source. At the same time, due to the reduction in the amount of water vapor, the proportion of carbon dioxide in the mixed gas is increased, which is conducive to increasing the concentration of carbon dioxide collected later. Exemplarily, water vapor is introduced to increase the pressure in the adsorber to 130 kPa, 140 kPa, 150 kPa, 160 kPa, 170 kPa, or a range consisting of any two thereof, and the temperature of the adsorbent rises to 80°C, 85°C, 90°C, 100°C, 105°C, 110°C, or a range consisting of any two thereof.

[0035] After the temperature and pressure in the adsorber reach the predetermined values, a second vacuum pumping is performed. On the one hand, the mixed gas formed by water vapor and carbon dioxide is extracted from the adsorber for subsequent treatment; on the other hand, the second vacuum pumping can reduce the pressure in the adsorber and form a vacuum environment, which helps to cool and regenerate the high-temperature adsorbent so that the adsorbent can adsorb carbon dioxide in the air again.

[0036] Therefore, the embodiment of the present application performs vacuum treatment before and after the introduction of steam to achieve intermittent introduction of steam to heat the adsorbent, which can more effectively control the temperature and pressure conditions in the adsorber, thereby reducing the regeneration energy consumption of the adsorbent and facilitating the desorption of carbon dioxide; through the first step of vacuuming, most of the non-target gases in the adsorber are removed, thereby increasing the concentration of the final product gas; through the second step of vacuuming, the high-concentration water vapor and carbon dioxide mixed gas can be extracted, and it helps to reduce the temperature of the adsorbent.

[0037] In some embodiments, the first vacuuming time is 5 to 8 minutes, and the vacuum pressure in the adsorber is pumped to -80 to -90 kPa. For example, after the first vacuuming, the vacuum pressure in the adsorber is -80 kPa, -82 kPa, -84 kPa, -86 kPa, -88 kPa, -90 kPa, or a range consisting of any two of them. The purpose of the first vacuuming is to remove impurities, remove residual air (especially oxygen) in the adsorber, and avoid oxidation of the adsorbent; wherein, the vacuum time and pressure are empirical values, which means that within 5 to 8 minutes, the vacuum pump can pump the pressure in the adsorber to a minimum of about -90 kPa.

[0038] In some embodiments, the water vapor flow rate can be 0.8 to 1.3 m 3 / h, the introduction time can be 5 to 8 minutes, for example, the water vapor introduction flow rate is 0.8m 3 / h、0.9m 3 / h、1m 3 / h、1.1m 3 / h、1.2m 3 / h、1.3m 3 / h or any value between them, and the introduction time is 5min, 6min, 7min, 8min or any value between them. Within the above numerical range, the temperature of the adsorbent in the adsorber can be raised to the regeneration temperature range.

[0039] In some embodiments, the second vacuuming time is 5 to 8 minutes, so that the temperature of the adsorbent in the adsorber is reduced to 60 to 80°C, such as 60°C, 65°C, 70°C, 75°C, 80°C or any two thereof. The main purpose of the second vacuuming is to remove water vapor and product gas carbon dioxide in the tower, and quickly enrich the high-purity product gas carbon dioxide; wherein, pressure and temperature are proportional, and the lower gas partial pressure allows the adsorbent to cool down quickly. Therefore, compared with single vacuum cooling, the combination of vacuum cooling and air purge can not only save energy, but also shorten the adsorption-desorption cycle time.

[0040] In some embodiments, after the adsorbent temperature in the adsorber is reduced to 60-80°C, the adsorbent temperature in the adsorber is reduced to 10-30°C by air purge, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C or a range of any two thereof.

[0041] In some embodiments, the adsorber may capture carbon dioxide in the air for 1 to 2 hours, such as 1, 1.5, 2 hours, or any two thereof.

[0042] In some embodiments, the adsorber is a radial split-flow adsorber, or a fixed-bed adsorber with staggered flexible packing.

[0043] The radial split-flow adsorber has radial channels inside, which allows the gas to flow radially in the adsorption bed, that is, the gas enters from the center or periphery of the adsorption bed, then passes through the adsorbent bed and flows out from the other end, which helps to reduce bed resistance, reduce energy consumption, and improve adsorption efficiency. At the same time, it is equipped with multiple adsorption beds arranged in parallel along the axial direction, and each adsorption bed can be adsorbed and regenerated, which helps to expand the air processing capacity, improve the utilization efficiency of adsorption particles, and optimize the adsorption process.

[0044] Staggered flexible packing has excellent mass transfer performance and high specific surface area. Its structural feature is that the packing units are staggered to form a complex channel structure, which helps the gas to be evenly distributed and fully contacted in the packing layer. At the same time, the flexible packing also has a certain elasticity and plasticity, which can adapt to the changes in the stress of the bed and prevent the bed from collapsing and clogging.

[0045] Exemplarily, the adsorber is a fixed bed adsorber, a fluidized bed adsorber or a moving bed adsorber. Among them, a fixed bed adsorber is an adsorption device in which the adsorbent is fixed at certain parts of the adsorber to form a stationary bed. When the gas passes through the bed, the adsorbent can capture and remove impurities or pollutants therein. The fixed bed adsorber has the advantages of simple structure, simple operation, easy maintenance and adsorbent replacement.

[0046] In some embodiments, the sum of the time for capturing carbon dioxide in the air, the time for introducing water vapor, the time for the first vacuuming, and the time for the second vacuuming is 1.5 to 2.5 hours.

[0047] In some embodiments, the adsorbent of the adsorber is a solid amine adsorbent or a metal organic framework compound.

[0048] The present invention is further described below through specific embodiments.

[0049] Example 1

[0050] Adsorption: Under normal temperature and pressure, air is introduced into the adsorber for 1 hour.

[0051] The first vacuuming: After the adsorption of the adsorbent is completed, the residual gas in the adsorber is discharged by vacuuming. The vacuuming time is 5 minutes. After vacuuming, the vacuum pressure in the adsorber is -80kPa~-90kPa.

[0052] Steam purge: After the first vacuuming is completed, water vapor is introduced into the adsorber at a flow rate of 0.8 m 3 / h, the introduction time is 5min, the pressure in the adsorber is increased to 130kPa~170kPa, and the temperature of the adsorbent in the adsorber is raised to 80℃~110℃.

[0053] Second vacuuming: The adsorber is vacuumed for a second time for 8 minutes to reduce the temperature of the adsorbent in the adsorber to 60°C, and a mixed gas of water vapor and carbon dioxide is obtained. The mixed gas is separated into gas and liquid to obtain carbon dioxide.

[0054] Air purge: After the temperature of the adsorbent in the adsorber drops to 60°C, the air is purged into the adsorber for 15 minutes to drop the temperature of the adsorbent in the adsorber to 10°C.

[0055] Example 2 to Example 3: The difference from Example 1 is that the conditions such as adsorption time, first vacuuming time, water vapor flow rate, water vapor introduction time, second vacuuming time, air purge time, etc. are different, see Table 1 for details.

[0056] Comparative Example:

[0057] Comparative Example 1: The difference from Example 1 is that the second vacuuming and air purge are not performed.

[0058] Comparative Example 2: The difference from Example 1 is that desorption is carried out by indirect coil heat exchange.

[0059] The specific steps are as follows:

[0060] Adsorption: The air is introduced into the fixed bed through the fan and fully contacts with the evenly loaded adsorbent particles. Most of the carbon dioxide in the air is effectively captured in the adsorbent particles, and the rest of the air is sent into the atmosphere through the adsorption outlet by the adsorption fan. When the adsorbent is saturated or reaches the breakthrough point of the breakthrough curve, the fan is stopped and the adsorption process stops.

[0061] Vacuuming: Start the vacuum pump to extract the residual air in the tower and discharge it into the environment. After the pressure in the tower drops to the target value, stop the vacuum pump and the vacuuming process of the device is completed.

[0062] Coil indirect heat exchange desorption: Start the steam generator, open the steam valve after steam preparation, and allow high-temperature steam to pass into the heat exchange pipe inside the adsorbent bed to indirectly heat and desorb carbon dioxide.

[0063] Air purge: Turn on the fan to introduce air to cool the adsorbent bed after steam regeneration so that it reaches ambient temperature as quickly as possible.

[0064] The regeneration energy consumption and carbon dioxide concentration of the above embodiments were tested respectively, and the results are shown in Table 2.

[0065] Table 1

[0066]

[0067]

[0068] Table 2

[0069] Example <![CDATA[Regeneration energy consumption (GJ / t CO2)]]> <![CDATA[CO2 concentration (%)]]> Example 1 2.6 95 Example 2 2.6 95 Example 3 2.6 95 Comparative Example 1 3.013 95％ Comparative Example 2 9.284 95％

[0070] Comparative analysis and summary:

[0071] By comparison, the regeneration time of the adsorbent in the embodiments of the present application is significantly shortened compared with the comparative examples, and the regeneration heat consumption is greatly reduced. Among them, the regeneration energy consumption of the adsorbent is reduced by 15.88% and 257.08% compared with comparative examples 1 and 2, which can help achieve a regeneration energy consumption of less than 3 GJ / t.

[0072] For example, the present application provides a direct air capture carbon dioxide device for implementing the above-mentioned direct air capture carbon dioxide method, see Figure 1 The device comprises an adsorber 100, an air inlet pipe 110, a steam pipeline 120, an air pipeline 130, a first vacuum pipeline 140 and a second vacuum pipeline 150. The adsorber 100 is provided with an air inlet 101, a steam inlet 102, a first air outlet 103, a second air outlet 104 and a third air outlet 105.

[0073] The air inlet pipe 110 is connected to the adsorber 100 through the air inlet 101, so that air enters the adsorber 100. The steam pipeline 120 is connected to the adsorber 100 through the steam inlet 102. The steam pipeline 120 is used to pass water vapor into the adsorber 100 to purge the adsorbent in the adsorber 100, thereby raising the temperature of the adsorbent. Exemplarily, a water vapor generator 121 is provided on the steam pipeline 120 to provide water vapor to the adsorber 100.

[0074] The air pipeline 130 is connected to the adsorber 100 through the first air outlet 103, and an air pump 131 is provided on the air pipeline 130. The air pipeline 130 cooperates with the air inlet 101, and the air pump 131 on the air pipeline 130 allows air to form convection in the adsorber 100 between the air inlet 101 and the air pipeline 130, thereby accelerating the adsorption of CO2 by the adsorbent.

[0075] The first vacuum pipeline 140 is connected to the adsorber 100 via the second gas outlet 104 . It can be understood that the first vacuum pipeline 140 is provided with a first vacuum pump 141 for discharging non-target gas in the adsorber 100 .

[0076] The second vacuum pipeline 150 is connected to the adsorber 100 via the third gas outlet 105 , and a heat exchanger 151 , a gas-liquid separator 152 , a second vacuum pump 153 and a storage tank 154 are sequentially disposed on the second vacuum pipeline 150 .

[0077] The second pipeline extracts the water vapor and CO2 desorbed in the adsorber 100 through the second vacuum pump 153 on the pipeline. The extracted high-temperature desorbed gas and water vapor are cooled and condensed through the heat exchanger 151, and most of the water vapor in the desorbed gas is removed through the gas-liquid separator 152. The outlet of the gas-liquid separator 152 may be provided with an analyzer connected thereto. Part of the product gas enters the analyzer to detect the CO2 concentration, and the remaining product gas is collected and stored.

[0078] It can be understood that the air intake pipe 110, the steam pipeline 120, the air pipeline 130, the first vacuum pipeline 140 and the second vacuum pipeline 150 are all provided with switch valves for controlling the opening and closing of the pipelines, thereby controlling the wall of each pipeline to ensure that each step of the above method can be implemented.

[0079] Exemplarily, a plurality of adsorbers 100 may be provided, and the plurality of adsorbers 100 are arranged in parallel to improve the CO 2 capture efficiency.

[0080] During actual operation, firstly, external air is introduced into the adsorber 100 through the air pump 131 on the air pipeline 130. The air forms convection inside the adsorber, and when it flows through the adsorbent, carbon dioxide in the air is captured by the adsorbent.

[0081] Then, when the carbon dioxide in the adsorber reaches a certain saturation, the valve on the air inlet pipe 110 is closed, the valve on the first vacuum pipeline 140 is opened, and the non-target gas remaining in the adsorber is discharged through the first vacuum pump 141 on the first vacuum pipeline 140, in preparation for the subsequent desorption step;

[0082] Then, only the valve on the steam pipeline 120 is opened, the valves of other pipelines are closed, and water vapor is introduced into the adsorber 100 through the steam pipeline 120. The water vapor not only plays a purging role to remove the impurities adsorbed on the adsorbent, but also raises the temperature of the adsorbent to 80-110° C. by heating, thereby promoting the desorption of carbon dioxide. Under the combined effect of high temperature and water vapor, the carbon dioxide adsorbed on the adsorbent is gradually desorbed and forms a mixed gas with the water vapor.

[0083] Next, the valve on the steam pipeline 120 is closed, and the valve on the second vacuum pipeline 150 is opened. The water vapor and carbon dioxide mixed gas desorbed from the adsorber is pumped out through the second vacuum pump 153 on the second vacuum pipeline 150, thereby obtaining pure carbon dioxide gas.

[0084] Finally, the extracted high-temperature mixed gas is first cooled and condensed through the heat exchanger 151. This step helps to separate water vapor from carbon dioxide and reduces the difficulty of subsequent processing. The condensed mixed gas enters the gas-liquid separator 152. In the gas-liquid separator 152, most of the water vapor is removed to obtain a relatively pure carbon dioxide gas. The outlet of the gas-liquid separator 152 can be connected to an analyzer for real-time monitoring of the concentration of carbon dioxide. The treated carbon dioxide gas is collected and stored in a storage tank 154. These carbon dioxide gases can be used in a variety of industrial and environmental applications, such as geological storage, chemical raw materials, etc.

[0085] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0086] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for direct air capture of carbon dioxide, characterized in that: The following steps are involved: Capture carbon dioxide from the air through an absorber; Performing a first vacuum on the adsorber; Introducing water vapor into the adsorber to increase the pressure in the adsorber and the temperature of the adsorbent in the adsorber to desorb carbon dioxide; Vacuuming the adsorber for a second time to obtain a mixed gas formed by the water vapor and the carbon dioxide; The mixed gas is subjected to gas-liquid separation to obtain carbon dioxide.

2. The direct air capture carbon dioxide method according to claim 1, characterized in that: The first vacuuming takes 5 to 8 minutes, and the vacuum pressure in the adsorber is reduced to -80 to -90 kPa.

3. The direct air capture carbon dioxide method according to claim 1, characterized in that: The water vapor flow rate is 0.8-1.3 m 3 / h, the introduction time is 5 to 8 minutes.

4. The direct air capture carbon dioxide method according to claim 1, characterized in that: During the introduction of water vapor into the adsorber, the pressure in the adsorber is increased to 130-170 kPa, and the temperature of the adsorbent in the adsorber is increased to 80-110°C.

5. The direct air capture carbon dioxide method according to any one of claims 1 to 4, characterized in that: The second vacuuming time is 5 to 8 minutes, so that the temperature of the adsorbent in the adsorber is reduced to 60 to 80°C.

6. The direct air capture carbon dioxide method according to claim 5, characterized in that: After the temperature of the adsorbent in the adsorber is reduced to 60-80° C., the method further comprises: The temperature of the adsorbent in the adsorber is reduced to 10-30° C. by air purge.

7. The direct air capture carbon dioxide method according to claim 5, characterized in that: The adsorber is a radial split-flow adsorber, or a staggered flexible filler is arranged in the adsorber.

8. The direct air capture carbon dioxide method according to claim 5, characterized in that: The adsorber captures carbon dioxide in the air for 1 to 2 hours.

9. The direct air capture carbon dioxide method according to claim 8, characterized in that: The sum of the time for capturing carbon dioxide in the air, the time for introducing water vapor, the time for the first vacuuming and the time for the second vacuuming is 1.5 to 2.5 hours.

10. The direct air capture carbon dioxide method according to claim 5, characterized in that: The adsorbent of the adsorber is a solid amine adsorbent or a metal organic framework compound.

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