Unit design and method for direct capture of carbon dioxide from air

Abstract

Implementations of the disclosed subject matter provide a process for capturing carbon dioxide from a gaseous feed stream. The method may include a direct air capture unit including an inlet air section, a sorbent section, and an outlet air section. A gaseous feed stream may be received at the inlet air section, and the feed stream may be contacted with a sorbent material in the sorbent section. An exhaust gaseous outlet stream may be provided from the outlet air section. A total pressure loss across the inlet air section and the outlet air section may be maintained at less than 200 Pa. The feed stream may have a volumetric flow rate within the sorbent section, the volumetric flow rate having a maximum flow rate and a minimum flow rate. The unit may include at least one structural element for maintaining the minimum flow rate within a range of 0% to 20% lower than the maximum flow rate across the sorbent section.

Description

Technical Field

[0001] The present invention relates to a direct air capture (DAC) unit design and method for capturing carbon dioxide (CO2) from a gaseous feed stream. More specifically, the present invention relates to a module design and method for capturing carbon dioxide (CO2) from a gaseous feed stream, wherein the method may include a direct air capture (DAC) unit, the direct air capture unit including an inlet air section, an adsorbent section, and an outlet air section. The total pressure loss across the inlet air section and the outlet air section can be maintained at less than 200 Pa. The gaseous feed stream can have a volume flow rate within the adsorbent section, and the volume flow rate can have a maximum flow rate and a minimum flow rate. The minimum flow rate can be maintained in the range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section. Background Art

[0002] Direct air capture (DAC) of carbon dioxide from the air has been proposed as a solution to human-induced climate change. The current estimated global atmospheric carbon dioxide content is about 420 parts per million. It is expected that by the end of the 21st century, this ratio will rise to about 900 parts per million. Therefore, DAC represents one of a range of technologies that can be used to reduce the impact of greenhouse gases (such as carbon dioxide) on the environment and help the world transition to a low-carbon economy.

[0003] A typical DAC system uses a large amount of air (or gaseous atmosphere under other conditions) as a feed stream that is pumped through a unit containing an adsorbent material that removes carbon dioxide from the feed stream. Over time, the adsorbent is filled with captured carbon dioxide. Next, the carbon dioxide captured in the adsorbent is extracted from the adsorbent in a regeneration step. Regeneration may involve a thermal process or a chemical process, depending on the type of adsorbent material selected for the DAC method. During regeneration, the captured carbon dioxide is released from the adsorbent and can be used to make sustainable fuels, chemicals, for food and beverage production, or for carbon capture and storage (CCS) to create a net negative carbon process. The energy input to the DAC system may include thermal energy in the form of steam, as well as electrical energy for the absorption (passing air through the DAC unit) and regeneration (regenerating CO2 from the adsorbent) steps.

[0004] Generally, DAC is a capital intensive process due to the large volume of air that needs to be processed. Therefore, the production capacity of the DAC unit is very important in the total cost of the captured CO2. If the production capacity of the DAC unit is reduced, the cost of the captured CO2 will increase. Therefore, it is necessary to maintain an optimal (high) production capacity of the DAC unit to minimize the cost. Summary of the invention

[0005] According to one embodiment of the disclosed subject matter, a method for capturing carbon dioxide (CO2) from a gaseous feed stream may include a direct air capture (DAC) unit, the direct air capture unit comprising: an inlet air section, an adsorbent section, and an outlet air section. The total pressure loss across the inlet air section and the outlet air section may be maintained at less than 200 Pa. The gaseous feed stream may have a volume flow rate within the adsorbent section, and the volume flow rate may have a maximum flow rate and a minimum flow rate. The DAC unit may include at least one structural element, the at least one structural element being used to maintain the minimum flow rate within a range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section.

[0006] Implementations of the disclosed subject matter provide a method for capturing carbon dioxide (CO2) from a gaseous feed stream using a DAC unit, wherein the gaseous feed stream has an average CO2 concentration greater than 95% of the CO2 concentration of ambient air, and wherein the ambient air has any wind direction and any wind speed. The disclosed subject matter allows for improved efficiency and reduced costs throughout the DAC process. Additional features, advantages, and embodiments of the disclosed subject matter may be elaborated or may be apparent by considering the following detailed description, drawings, and claims. In addition, it should be understood that the foregoing summary of the invention and the following detailed description are examples and are intended to provide further explanation without limiting the scope of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings, which are included to provide a further understanding of the disclosed subject matter, are incorporated into and constitute a part of this specification. The drawings also illustrate one embodiment of the disclosed subject matter and, together with the detailed description, serve to explain the principles of the embodiments of the disclosed subject matter. No attempt is made to show more detailed structural details than are necessary for a basic understanding of the disclosed subject matter and the various ways in which it may be implemented.

[0008] Figure 1 An example method and side view are shown in accordance with one implementation of the disclosed subject matter.

[0009] Figure 2 An example method and side view are shown in accordance with one implementation of the disclosed subject matter.

[0010] Figure 3 An example method and side view are shown according to one embodiment of the disclosed subject matter.

[0011] Figure 4 An example method and side view are shown according to one embodiment of the disclosed subject matter.

[0012] Figure 5An example method and side view are shown in accordance with one implementation of the disclosed subject matter.

[0013] Figure 6 An example method and side view are shown in accordance with one implementation of the disclosed subject matter.

[0014] Figure 7 An example method and side view are shown in accordance with one implementation of the disclosed subject matter. DETAILED DESCRIPTION

[0015] Generally, a problem or disadvantage of DAC units known in the art is the reduction in CO2 production capacity of the module or DAC unit due to uneven distribution of gas flow through the unit. The present invention solves this problem by increasing the CO2 production capacity resulting in lower CO2 capture costs.

[0016] The present invention is a modular design of a DAC unit for capturing CO2 from air using solid or liquid adsorbents. During adsorption / absorption, air flows through the DAC unit via a fan and the air comes into contact with the adsorbent, which then captures CO2 from the air. The air depleted of CO2 is discharged into the atmosphere at the outlet. Since DAC is a process that can be used on a large scale and is subject to fluctuations in wind speed and direction at a particular location, it is important to prevent uneven distribution of airflow through the unit while maintaining a low pressure drop across the module. This is because uneven distribution of flow reduces CO2 production capacity - this invention solves this problem.

[0017] According to one embodiment, the present invention minimizes the intake of CO2-depleted air by the DAC unit by optimizing several design parameters. According to one embodiment, the method for capturing carbon dioxide from a gaseous feed stream as described herein may include a direct air capture (DAC) unit, which may include 1) an inlet air section, 2) an adsorbent section, and 3) an outlet air section. The DAC unit may receive a gaseous feed stream at the inlet air section. At least a portion of the gaseous feed stream may contact an adsorbent material located in the adsorbent section. An exhaust gaseous outlet stream may be provided from the outlet air section. The total pressure loss across the inlet air section and the outlet air section may be maintained at less than 200 Pa. The total pressure loss may be equal to the sum of the static pressure loss and the dynamic pressure loss. The static pressure loss is caused by frictional resistance, while the dynamic pressure loss is caused by accelerating flow and decelerating flow. For example, the total pressure loss may be the sum of the pressure loss in the inlet air section plus the pressure loss in the outlet air section. As a specific example, if the pressure loss in the inlet air section is 75 Pa, the pressure loss in the outlet air section may be maintained at 125 Pa or less. In this case, the total pressure loss across the inlet air section and the outlet air section is maintained at less than 200 Pa, i.e., for a total pressure loss of 200 Pa or less, a pressure loss of 75 Pa in the inlet air section plus a pressure loss of 125 Pa in the outlet air section.

[0018] The gaseous feed stream may have a volume flow rate within the adsorbent section, and the volume flow rate may have a maximum flow rate and a minimum flow rate. The minimum flow rate may be maintained within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section. For example, if the volume flow rate within the adsorbent section has a volume flow rate of 25 m / s, the minimum flow rate may be maintained within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section. 3 / s, the minimum flow rate in the adsorbent section can be maintained at 20m 3 / s to 25m 3 / s, the minimum flow rate is less than 25m 3 / s is within a range of 0% to 20% lower than the maximum flow rate of / s. According to one embodiment, the DAC unit may include at least one structural element for maintaining the minimum flow rate within a range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section. The structural elements are further described below.

[0019] Typically, the difference between the minimum flow and the maximum flow within a DAC unit should be kept to the minimum value that is as low as possible. In some cases, for example, the DAC unit may be composed of a stack of multiple individual containers (e.g., shipping containers, shipping containers, etc.), and in this case the DAC unit may include internal floors at different levels. In the case where these floors are solid (i.e., impermeable to airflow) in the outlet air section, it is more difficult to minimize the difference between the minimum flow and the maximum flow. On the contrary, it is preferred to have a floor with a high open area (i.e., permeable to airflow), for example in the case where the floor is an open grille floor, or in the case where there is no floor in the outlet air section. By having a floor that is permeable to airflow or having no floor, this makes it easier to minimize the difference between the minimum flow and the maximum flow within the DAC unit.

[0020] According to one embodiment, the method may include a direct air capture (DAC) unit, the direct air capture unit comprising: a first inlet face and a second inlet face located on opposite sides of the DAC unit. The adsorbent material may be located inside the DAC unit, and at or behind each of the first inlet face and the second inlet face. The outlet may be located at the top of the DAC unit, and the outlet may provide an exhaust gaseous outlet stream. The exhaust gaseous outlet stream may have a flow generated by at least one fan. The method may include receiving a gaseous feed stream at the inlet face, and the gaseous feed stream may have an average CO2 concentration greater than 95% of the CO2 concentration of the ambient air by minimizing the re-intake of the exhaust gaseous outlet stream that may have any wind direction and any wind speed. According to one embodiment, the DAC unit according to the present invention is designed so that by minimizing the re-intake of the exhaust gaseous outlet stream for any and all wind directions and wind speeds, the average concentration of CO2 at all inlet faces is greater than 95% of the CO2 concentration of the ambient air, regardless of where the DAC unit is operated geographically.

[0021] In one embodiment, the gaseous feed stream may be accelerated once in the inlet air section, and the exhaust gaseous outlet stream may be accelerated once in the outlet air section. For example, the air may be accelerated in the inlet air section by establishing a reduced pressure in the adsorbent section, and in the outlet air section by reducing the area available for flow. This may be accomplished by a fan or by constricting a portion of the flow path upstream or downstream of the fan.

[0022] According to one embodiment, the DAC unit may also include at least one structural element for maintaining the minimum flow rate within a range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section. The at least one structural element may be inside or outside the DAC unit. In one embodiment, the DAC unit may also include at least one structural element, which is located in the inlet air section extending from the top of the DAC unit adjacent to at least one of the first inlet face and the second inlet face, and the structural element may be partially or completely impermeable to the gaseous feed stream. The partially impermeable structural unit may be, for example, a screen, a mesh material, a perforated material, a membrane, etc., or any other partially impermeable structure or material. The completely impermeable structural unit may be, for example, any material or structure that is impermeable to the gaseous feed stream and blocks the gaseous feed stream from flowing through the material or structure.

[0023] According to one embodiment, the DAC unit may further include at least one structural element located in the outlet air section and the structural element is partially or completely impermeable to the exhaust gaseous outlet stream. As described above, the partially impermeable structural element may be, for example, a screen, a mesh material, a perforated material, a membrane, etc., or any other partially impermeable structure or material. The completely impermeable structural element may be, for example, any material or structure that is impermeable to the exhaust gaseous outlet stream and blocks the exhaust gaseous outlet stream from flowing through the material or structure.

[0024] In one embodiment, the structural element may have a length, and the ratio of the length of the structural element to the total height of the DAC unit may be less than 0.3, may be less than 0.2, and may be less than 0.1. The structural element may be located in the inlet air section or the outlet air section or both. For example, if the total height of the DAC unit is 25m, the length of the structural element may be less than 7.5m (a ratio of 7.5:25 is 0.3), may be less than 5m (a ratio of 5:25 is 0.2), and may be less than 2.5m (a ratio of 2.5:25 is 0.1).

[0025] In order to promote an understanding of the principles of the invention, reference will now be made to the embodiments shown in the accompanying drawings, which will be described in more detail below. The embodiments disclosed herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. The present invention includes any changes and further modifications to the illustrated apparatus and described methods and further applications of the principles of the invention set forth in the claims.

[0026] Figure 1 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 1 1 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 1 As shown, a method for capturing carbon dioxide from a gaseous feed stream 5 may include a direct air capture (DAC) unit 10. The DAC unit 10 may include an inlet air section 300, an adsorbent section 310, and an outlet air section 320. The gaseous feed stream 5 may be received at the inlet air section 300. At least a portion of the gaseous feed stream 5 may be contacted with an adsorbent material 40 located within the adsorbent section 310. An exhaust gaseous outlet stream 60 may be provided from the outlet air section 320. Although not given a reference numeral, Figure 1 Also shown are the fans and chimneys located in the outlet air section 320 .

[0027] The total pressure loss across the inlet air section 300 and the outlet air section 320 may be maintained at less than 200 Pa. In addition, the gaseous feed stream 5 has a volume flow rate within the adsorbent section 310, and the volume flow rate may have a maximum flow rate and a minimum flow rate. The minimum flow rate may be maintained in the range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section 310.

[0028] Figure 2 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 2 1 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 2 As shown, a method for capturing carbon dioxide from a gaseous feed stream 5 may include a direct air capture (DAC) unit 10. The DAC unit 10 may include an inlet air section 300, an adsorbent section 310, and an outlet air section 320. The gaseous feed stream 5 may be received at the inlet air section 300. At least a portion of the gaseous feed stream 5 may be contacted with an adsorbent material 40 located within the adsorbent section 310. An exhaust gaseous outlet stream 60 may be provided from the outlet air section 320. Also as shown in FIG. Figure 2 As shown, the DAC unit 10 may include a void space 80 beneath the DAC unit 10 that separates the DAC unit 10 from a support plane 90 .

[0029] like Figure 2As further shown, the DAC unit 10 may also include a first inlet face 20 and a second inlet face 30. As shown, the first inlet face 20 and the second inlet face 30 may be on opposite sides of the DAC unit 10 within the inlet air section 300. The adsorbent material 40 may be located at or behind each of the first inlet face 20 and the second inlet face 30. The DAC unit 10 may also include an outlet 50 located at the top of the DAC unit 10 within the outlet air section 320 for providing an exhaust gaseous outlet stream 60. The exhaust gaseous outlet stream 60 may have a flow generated by at least one fan 70. The gaseous feed stream 5 may be received at each of the first inlet face 20 and the second inlet face 30. By minimizing the re-intake of the exhaust gaseous outlet stream, the gaseous feed stream 5 may have an average CO2 concentration greater than 95% of the CO2 concentration of the ambient air, and the ambient air may have any wind direction and any wind speed.

[0030] Figure 3 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 3 1 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 3 As shown, a method for capturing carbon dioxide from a gaseous feed stream 5 may include a direct air capture (DAC) unit 10. The DAC unit 10 may include an inlet air section 300, an adsorbent section 310, and an outlet air section 320. The gaseous feed stream 5 may be received at the inlet air section 300. At least a portion of the gaseous feed stream 5 may be contacted with an adsorbent material 40 located within the adsorbent section 310. An exhaust gaseous outlet stream 60 may be provided from the outlet air section 320. Although in Figure 3 Not shown, but the gaseous feed stream 5 may be accelerated once in the inlet air section 300 , and the exhaust gaseous outlet stream 60 may be accelerated once in the outlet air section 320 .

[0031] like Figure 3 As further shown, the DAC unit may include at least one structural element 400 for maintaining a minimum flow rate within a range of 0% to 20% below a maximum flow rate across the adsorbent section 310. Figure 3 As shown, the DAC unit may include more than one structural element, for example, as shown, the DAC unit 10 may include two or more structural elements 400. According to one embodiment, the structural element 400 may be located within the inlet air section 300. As described above, the structural element 400 may be partially or completely impermeable to the gaseous feed stream 5.

[0032] Figure 4 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 41 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 4 As shown, a method for capturing carbon dioxide from a gaseous feed stream 5 may include a direct air capture (DAC) unit 10. The DAC unit 10 may include an inlet air section 300, an adsorbent section 310, and an outlet air section 320. The gaseous feed stream 5 may be received at the inlet air section 300. At least a portion of the gaseous feed stream 5 may be contacted with an adsorbent material 40 located within the adsorbent section 310. An exhaust gaseous outlet stream 60 may be provided from the outlet air section 320. As shown in FIG. Figure 4 As shown, the DAC unit 10 may include more than one structural element 410, for example, as shown, the DAC unit 10 may include two or more structural elements 410. According to one embodiment, the structural element 410 may be located within the inlet air section 300. Figure 4 As shown, the structural element 410 may be located in the inlet air section 300 extending from the top of the DAC unit 10 adjacent to the first inlet face 20 and the second inlet face 30. In addition, the structural element 410 may be partially or completely impermeable to the gaseous feed stream 5.

[0033] Figure 5 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 5 1 shows a side view of a DAC unit 10 according to one embodiment of the present invention. Figure 5 As shown, a method for capturing carbon dioxide from a gaseous feed stream 5 may include a DAC unit 10. The DAC unit 10 may include an inlet air section 300, an adsorbent section 310, and an outlet air section 320. The gaseous feed stream 5 may be received at the inlet air section 300. At least a portion of the gaseous feed stream 5 may be contacted with an adsorbent material 40 located within the adsorbent section 310. An exhaust gaseous outlet stream 60 may be provided from the outlet air section 320. As shown in FIG. Figure 5 As shown, the DAC unit 10 may include more than one structural element 420, for example, as shown, the DAC unit 10 may include two or more structural elements 420. According to one embodiment, and as shown Figure 5 As shown, the structural element 420 can be located within the outlet air section 320. In addition, the structural element 420 can be partially or completely impermeable to the gaseous feed stream 5. In addition, the structural element 420 can be partially or completely impermeable to the exhaust gaseous outlet stream 60.

[0034] Figure 6 An example method according to one implementation of the disclosed subject matter is shown. In particular,

[0035] Figure 61 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 6 As shown, the DAC unit 10 may include an inlet air section 300 , a sorbent section 310 , and an outlet air section 320 . Figure 6 Also shown is an adsorbent material 40 located within the adsorbent section 310, and the DAC unit 10 may include two or more structural elements 400. According to one embodiment, the structural element 400 may be located within the inlet air section 300. Further, as shown in FIG. Figure 6 As shown, DAC cell 10 may have an overall height 510, and structural element 400 may have a length 500. According to one embodiment of the present invention, the ratio of length 500 of structural element 400 to the overall height 510 of the DAC cell may be less than 0.3.

[0036] Figure 7 An example method according to one implementation of the disclosed subject matter is shown. In particular, Figure 7 1 shows a side view of a DAC unit according to one embodiment of the present invention. Figure 7 As shown, the DAC unit 10 may include an inlet air section 300 , a sorbent section 310 , and an outlet air section 320 . Figure 7 Also shown is an adsorbent material 40 located within the adsorbent section 310, and the DAC unit 10 may include two or more structural elements 420. According to one embodiment, the structural element 420 may be located within the outlet air section 320. Further, as shown in FIG. Figure 7 As shown, DAC cell 10 may have an overall height 530, and structural element 420 may have a length 520. According to one embodiment of the present invention, the ratio of length 520 of structural element 420 to the overall height 530 of the DAC cell may be less than 0.3.

[0037] Example

[0038] Commercially available multi-physics modeling software StarCCM+ was used to calculate the fluid flow pattern of the air flow inside the direct air capture unit. The length of the inlet face was set to 12.19 m. The height of the DAC unit was set to 10.36 m. The direction of the incoming wind was set to be perpendicular to the two inlet faces of the unit. The total air flow rate through the module was fixed in all embodiments. The following Table 1 shown below summarizes the simulation results for different comparative examples according to the implementation of the disclosed subject matter.

[0039] For each of the multiple simulations, the wind direction was set to be perpendicular to the two inlet faces of the DAC unit. It was assumed that the air flow rate through each of the multiple inlet faces was equal. The adsorbent thickness was set to 0.5m. Columns 2 and 3 in Table 1 compare the minimum volume flow rate and the maximum volume flow rate of air through the adsorbent section for different comparative examples. Column 4 in Table 1 shows the flow maldistribution across the entire adsorbent for different comparative examples. Flow maldistribution is defined as the difference between the maximum air flow rate and the minimum air flow rate across the adsorbent section, expressed as a percentage of the maximum air flow rate. Finally, column 5 in Table 1 is the sum of the pressure drops in the inlet air section and the outlet air section for different comparative examples.

[0040] Base case embodiment A is a DAC unit without an internal floor in the outlet air section.

[0041] Comparative Example 1 is a DAC unit similar to Base Case Example A, except that it includes two completely impermeable structural elements adjacent to the inlet face and located in the inlet air section. As shown in Table 1, Base Case Example A provides a flow maldistribution of 14.5%, while Comparative Example 1 provides a flow maldistribution of 11.1%. This shows that by including two completely impermeable structural elements adjacent to the inlet face and located in the inlet air section, a DAC unit according to the disclosed subject matter provides improved (i.e., lower flow maldistribution) flow maldistribution, as 11.1% (Comparative Example 1) is less than 14.5% (Base Case Example A).

[0042] Base case embodiment B is a DAC unit similar to base case embodiment A, except that it includes a solid internal floor in the outlet air section.

[0043] Comparative Example 2 is a DAC unit similar to Comparative Base Case Example B, except that it includes two partially impermeable structural elements adjacent to the inlet face and located in the inlet air section. As shown in Table 1, Base Case Example B provides a flow maldistribution of 27.6%, while Comparative Example 2 provides a flow maldistribution of 14.8%. This shows that by including two partially impermeable structural elements adjacent to the inlet face and located in the inlet air section, the DAC unit according to the disclosed subject matter provides improved (i.e., lower flow maldistribution) flow maldistribution, because 14.8% (Comparative Example 2) is less than 27.6% (Base Case Example B). This also shows that the present invention according to Comparative Example 2 achieves a minimum flow rate maintained within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section, i.e., a flow maldistribution of 14.8%. This is not the case with Base Case B, which has a flow maldistribution of 27.6%, i.e., not within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section.

[0044] Comparative Example 3 is a DAC unit similar to Base Case Example B, except that it also includes a completely impermeable structural element located in the outlet air section. As shown in Table 1, Base Case Example B provides a flow maldistribution of 27.6%, while Comparative Example 3 provides a flow maldistribution of 8.3%. This shows that by including two completely impermeable structural elements located in the outlet air section, the DAC unit according to the disclosed subject matter provides improved (i.e., lower flow maldistribution) flow maldistribution because 8.3% (Comparative Example 3) is less than 27.6% (Base Case Example B). This also shows that the present invention according to Comparative Example 3 achieves a minimum flow rate maintained within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section, i.e., a flow maldistribution of 8.3%. This is not the case for Base Case B, which has a flow maldistribution of 27.6%, i.e., not within a range of 0% to 20% below the maximum flow rate over the entire adsorbent section.

[0045] In summary, Comparative Examples 1, 2, and 3 achieve less than 20% flow maldistribution as indicated and shown in columns 3 and 4 of Table 1. All Comparative Examples have a pressure drop of less than 200 Pa across the inlet and outlet air sections, demonstrating the results achieved by the disclosed subject matter.

[0046] In addition, the results and effects of the present invention are demonstrated by comparing the results of various comparative examples as provided in Table 1 below. Adding a completely impermeable structural unit (e.g., Comparative Example 1) or a partially impermeable structural element (Comparative Example 2) adjacent to the inlet face in the inlet air section results in less flow maldistribution. In addition, including a completely impermeable structural element located in the outlet air section (Comparative Example 3) also results in lower flow maldistribution.

[0047] Table 1 below shows the minimum and maximum air flow rates (and therefore flow maldistribution) through the adsorbent sections and the pressure drop across the inlet and outlet air sections for different examples according to various embodiments of the disclosed invention. The flow maldistribution is the difference between the minimum and maximum air flow rates through the adsorbent section, expressed as a percentage of the maximum air flow rate.

[0048]

[0049] For the purpose of explanation, the foregoing specific embodiments have been described with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the embodiments of the disclosed subject matter to the disclosed precise forms. In view of the above teachings, many modifications and variations are possible. The embodiments are selected and described to explain the principles of the embodiments of the disclosed subject matter and their practical applications, so that other persons skilled in the art can utilize those embodiments and various embodiments with various modifications that may be suitable for the particular use under consideration.

Claims

1. A method for capturing carbon dioxide from a gaseous feed stream, the method comprising: a) a direct air capture (DAC) unit, said direct air capture unit comprising: 1) Inlet air section, 2) an adsorbent section, and 3) Outlet air section, b) receiving a gaseous feed stream at said inlet air section, c) contacting at least a portion of the gaseous feed stream with an adsorbent material located within the adsorbent section, d) providing an exhaust gaseous outlet stream from said outlet air section, wherein the total pressure loss across the inlet air section and the outlet air section is maintained at less than 200 Pa; wherein the gaseous feed stream has a volume flow rate within the adsorbent section, and the volume flow rate has a maximum flow rate and a minimum flow rate, and The DAC unit further comprises at least one structural element for maintaining the minimum flow rate within a range of 0% to 20% lower than the maximum flow rate over the entire adsorbent section.

2. A method for capturing carbon dioxide from a gaseous feed stream according to claim WRONG! Citation source not found, wherein the direct air capture (DAC) unit further comprises: 1) a first inlet face and a second inlet face, wherein the first inlet face and the second inlet face are on opposite sides of the DAC unit within the inlet air section, wherein the adsorbent material is located at or behind each of the first inlet face and the second inlet face; as well as 2) an outlet located at a top of the DAC unit within the outlet air section for providing the exhaust gaseous outlet stream, and wherein the exhaust gaseous outlet stream has a flow generated by at least one fan; wherein the gaseous feed stream is received at each of the first inlet face and the second inlet face, wherein the gaseous feed stream has an average CO2 concentration greater than 95% of the CO2 concentration of ambient air by minimizing re-intake of the exhaust gaseous outlet stream, and wherein the ambient air has any wind direction and any wind speed.

3. A process for capturing carbon dioxide from a gaseous feed stream according to claims 1 and 2, wherein the gaseous feed stream is accelerated once in the inlet air section, and wherein the exhaust gaseous outlet stream is accelerated once in the outlet air section.

4. A method for capturing carbon dioxide from a gaseous feed stream according to claim 1, wherein the at least one structural element is located in the inlet air section extending from the top of the DAC unit adjacent to at least one of the first inlet face and the second inlet face, and wherein the structural element is partially or completely impermeable to the gaseous feed stream.

5. The method for capturing carbon dioxide from a gaseous feed stream according to claim 4, wherein the structural element has a length, and wherein the ratio of the length of the structural element to the overall height of the DAC unit is less than 0.

3.

6. The method for capturing carbon dioxide from a gaseous feed stream according to claim 1, wherein the at least one structural element is located in the outlet air section, and wherein the structural element is partially or fully impermeable to the exhaust gaseous outlet stream.

7. A method for capturing carbon dioxide from a gaseous feed stream according to claim 6, wherein the structural element has a length, and wherein the ratio of the length of the structural element to the overall height of the DAC unit is less than 0.3.

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