Systems and methods for the direct capture of carbon dioxide

Abstract

A method for removing carbon dioxide (CO2) from ambient air and related systems are disclosed. In an embodiment, the method includes (a) coating supports with a calcium hydroxide (Ca(OH)2) slurry to form a sorbent on the supports, (b) conveying the supports into an air contactor in a row of cassettes, each cassette supporting a set of the supports, and (c) generating an ambient airflow. In addition, the method includes (d) transporting the row along a path such that: for a first leg of the path, the ambient airflow is directed from a first end of the row to a second end of the row, and for a second leg of the path, the ambient airflow is directed from the second end of the row to the first end of the row. Further, the method includes (e) absorbing CO2 from the ambient airflow into the sorbent during (d).

Description

SYSTEMS AND METHODS FOR THE DIRECT CAPTURE OF CARBON DIOXIDE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.BACKGROUND

[0002] There is an ongoing effort worldwide to address increasing concentrations of greenhouse gases, particularly carbon dioxide (CO2), in the atmosphere. Although much work has been done to decrease the amounts of such gases being released into the atmosphere, there is a growing understanding that decreased emissions alone may be insufficient to address concerns related to climate change.BRIEF SUMMARY

[0003] One or more embodiments disclosed herein are directed to a method for removing carbon dioxide (CO2) from ambient air. In one or more embodiments, the method includes (a) coating a plurality of supports with a calcium hydroxide (Ca(OH)2) slurry to form a sorbent on the plurality of supports, and (b) conveying the plurality of supports into a structure of an air contactor in a row of a plurality of cassettes, each of the plurality of cassettes supporting a set of the plurality of supports. In addition, the method includes (c) generating an ambient airflow through the structure. Further, the method includes (d) transporting the row along a path in the structure such that: for a first leg of the path, the ambient airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the ambient airflow is directed from the second end of the row to the first end of the row. Still further, the method includes (e) absorbing CO2from the ambient airflow into the sorbent during (d).

[0004] One or more embodiments disclosed herein are directed to a plant for removing carbon dioxide (CO2) from ambient air. In one or more embodiments, the plant includes a coating assembly that is configured to coat a plurality of supports with a sorbent, where the plurality of supports are supported in a plurality of cassettes. In addition, the plant includes an air contactor comprising a structure that is configured to receive the plurality of cassettes downstream from the coating assembly. The structure includes one or more fans that are configured to induce an ambient airflow through the structure. In addition, the structure includes a conveyance system that is configured to support the plurality of cassettes in a row and to transport the row along a path defined in the structure to expose the plurality of supports to the ambient airflow and thereby absorb CO2from the ambient airflow into the sorbent. Where the path is configured such that: for a first leg of the path, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the airflow is directed from the second end of the row to the first end of the row.

[0005] One or more embodiments disclosed herein are directed to an air contactor for contacting ambient air with a sorbent to produce a CO2-depleted airflow. In one or more embodiments, the air contactor comprises a structure including a first end, a second end spaced from the first end along a longitudinal axis, a first sidewall extending axially between the first end and the second end relative to the longitudinal axis, and a second sidewall extending axially between the first end and the second end and radially opposite the first sidewall relative to the longitudinal axis. In addition, the air contactor includes one or more fans that are configured to generate an ambient airflow that enters the structure through vents positioned along the first sidewall and the second sidewall. Further, the air contactor includes a conveyance system positioned in the structure that is configured to transport a row of cassettes along a path defined in the structure to expose the cassettes to the airflow such that: for a first leg of the path along the first sidewall, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path along the second sidewall, the airflow is directed from the second end of the row to the second end of the row. Each cassette of the row of cassettes is configured to support a plurality of vertically oriented and parallel supports that are coated with a calcium-based sorbent that is configured to absorb CO2from the ambient airflow.

[0006] Embodiments described comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features previously described, as well as others, will be readily apparent to those having ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. One should appreciate that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. One should also realize that such equivalent constructions do not depart from the spirit and scope of the principles disclosed.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For a detailed description of various embodiments, reference will now be made to the accompanying drawings in which:

[0008] FIG. 1 is a schematic diagram of a process for removing CO2from ambient air according to one or more embodiment disclosed;

[0009] FIG. 2 is a schematic diagram of a sorbent processing step of the process of FIG. 1 according to one or more embodiments disclosed;

[0010] FIG. 3 is a schematic illustration of a spray method for performing a sorbent application step of the process of FIG. 1 according to one or more embodiments disclosed;

[0011] FIG. 4 is a schematic illustration of a pour method for performing a sorbent application step of the process of FIG. 1 according to one or more embodiments disclosed;

[0012] FIG. 5 is a schematic illustration of a dip method for performing a sorbent application step of the process of FIG. 1 according to one or more embodiments disclosed;

[0013] FIG. 6 is a perspective, schematic view of a cassette for supporting a plurality of supports for receiving a sorbent during performance of the process of FIG. 1 according to one or more embodiments disclosed;

[0014] FIG. 7 is a side view of the cassette of FIG. 6 according to one or more embodiments disclosed;

[0015] FIGs. 8 and 9 are side and top views, respectively, of an air contactor for performing an air contacting step of the process of FIG. 1 according to one or more embodiments disclosed;

[0016] FIG. 10 is a cross-sectional view taken along section A-A in FIG. 9 according to one or more embodiments disclosed;

[0017] FIGs. 11 and 12 are schematic views illustrating a flow of a plurality of cassettes through the structure of the air contactor of FIGS. 8 and 9 according to one or more embodiments disclosed;

[0018] FIGs. 13 and 14 are perspective views illustrating airflow through a row of cassettes through a plurality of positions of the structure of the air contactor of FIGs. 8 and 9 according to one or more embodiments disclosed;

[0019] FIGs. 15A and 15B are sequential views illustrating a progression of cassettes through the structure of the air contactor of FIGs. 8 and 9 according to or more embodiments disclosed;

[0020] FIGs. 16A-16E are sequential views illustrating an unloading of cassettes from the structure of the air contactor of FIGs. 8 and 9 according to one or more embodiments disclosed;

[0021] FIG. 17 is a perspective view of a plant for performing the process of FIG. 1 according to one or more embodiments disclosed;

[0022] FIG. 18 is a schematic view of a system for performing one or more steps of the process of FIG. 1 according to one or more embodiments disclosed;

[0023] FIG. 19 is a is a perspective view of a plant for performing the process of FIG. 1 according to one or more embodiments disclosed;

[0024] FIG. 20 is a perspective view of an air contactor of the plant of FIG. 19 according to one or more embodiments disclosed;

[0025] FIG. 21 is a perspective view of an air contactor module of the air contactor of FIG. 20 according to one or more embodiments disclosed;

[0026] FIG. 22 is a top view of the air contactor module of FIG. 21 according to one or more embodiments disclosed;

[0027] FIGs. 23 and 24 are perspective views of a container of a stack of containers for use within the air contactor module of FIG. 21 according to one or more embodiments disclosed;

[0028] FIG. 25 is a cross-sectional view taken along section B-B in FIG. 22 according to one or more embodiments disclosed;

[0029] FIG. 26 is a perspective, cross-sectional view of the air-contactor of FIG. 20, showing a crane for loading and unloading cassettes into the containers of the containers stacks according to one or more embodiments disclosed;

[0030] FIG. 27 is a perspective, partial cut-away view of the central structure of the plant of FIG. 19 according to one or more embodiments disclosed;

[0031] FIG. 28 is a schematic view illustrating a ducting system that collects CO2-depleted airflow from the plant of FIG. 17 and passing the collected CO2-depleted airflow to a turbine system according to one or more embodiments disclosed;

[0032] FIGs. 29 and 30 are schematic top and side views, respectively, of a ducting system for collecting the CO2-depleted airflow in one of the air contactors of the plant of FIG. 17 according to one or more embodiments disclosed; and

[0033] FIG. 31 is a cross-sectional view of an air-contactor of the plant of FIG. 17, illustrating a ducting system with a vent hood inlet according to one or more embodiments disclosed.DETAILED DESCRIPTION

[0034] There is a continued desire for methods for not only reducing greenhouse gas emissions but also for removing such gases that are already present in the atmosphere. Conventional methods for CO2removal are saddled with inflated capital expenditures (CAPEX) and operating costs. For example, because the CO2concentrations in ambient air are relatively dilute, conventional removal methods have required greater specificity and efficiency in order to be cost effective. In addition, scaling conventional CO2removal methods to industrial sizes may not be economically feasible. Without an affordable technology for removing existing CO2from the atmosphere, the world will continue to struggle to reduce and reverse this component of climate change. Thus, there remains a need in the field for additional technologies effective for removal of greenhouse gases, including CO2, from ambient air.

[0035] Accordingly, one or more embodiments disclosed provide systems and methods for direct capture of CO2from ambient atmospheric air (or more simply “ambient air”) that are simpler and more cost-effective than existing methods. In one or more embodiments, the systems and methods may make use of a calcium-based sorbent to absorb CO2from ambient air and then controllably released into a capture system during regeneration or re-processing of the sorbent. In one or more embodiments, the formation, use, and processing of the sorbent may be arranged in a continuous, cyclical process that facilitates simple and economical scaling to industrial levels. Thus, through use of embodiments disclosed, an economically feasible industrial process for removing CO2from ambient air may be employed to meaningfully effect atmospheric CO2concentrations.

[0036] For instance, reference is now made to FIG. 1 in which a process 10 for removing CO2from ambient air is shown according to one or more embodiments. The process 10 may include a continuous, cyclical process for absorbing CO2from ambient air using a sorbent.

[0037] The process 10 may include processing a sorbent 14 at block 12 and applying the sorbent 14 onto a support at block 16. In addition, the process 10 includes contacting the sorbent-coated support with an ambient airflow 19 at block 20 to thereby remove CO2from the airflow 19 and produce a CO2-depleted airflow 21 . Following the air contact step of block 20, the used sorbent 15 may be removed from the support at block 24.

[0038] In one or more embodiments, at least some of the used and removed sorbent 15 may be recycled, re-processed, and re-applied to the support via blocks 12 and 16 as previously described. In one or more embodiments, the sorbent processing step of block 12 may utilize new, raw materials 13 alone or in combination with recycled sorbent 15 to form the sorbent 14 that is then applied to the support via block 16 as previously described.

[0039] In one or more embodiments, all of the blocks 12, 16, 20, 24 may be performed at a single site or location. Alternatively, in one or more embodiments, one or more of the blocks 12, 16, 20, 24 may be performed at different sites or locations. For instance, in one or more embodiments, the sorbent processing step at block 12 may be performed at a different site or location than each of the blocks 16, 20, 24 in FIG. 1.

[0040] In one or more embodiments, the sorbent 14 may comprise a calcium-based sorbent that is derived predominantly or entirely from calcium carbonate (CaCO3). If pure calcite is not utilized as the source of the calcium-based sorbent, then a minor portion (< 20 weight percent) may comprise magnesium carbonate (MgCO3), where the mixture of calcium and magnesium carbonates is commonly known as dolomite. For the purposes of this application, whenever calcium carbonate, CaCO3, limestone, or calcite is referred to, then one of ordinary skill in the art may also interpret that a mixed forms of calcium and magnesium carbonates may also be used. This is also true of other forms of calcium, including the hydroxides (OH ) and oxides (O2).

[0041] FIG. 2 at least partially illustrates the sorbent processing step of block 12 in FIG. 1 according to one or more embodiments. Specifically, in the sorbent processing step of block 12 shown in FIG. 2, raw CaCO313, or recycled CaCO315 from previously used sorbent 15, may be subjected to calcination in a calciner 17 and then slaking in a slaker 22 to form a calcium hydroxide (Ca(OH)2) slurry as the sorbent 14. The Ca(OH)2slurry may then be applied to a support (such as support 30 shown in FIGS. 3-5) to form the calcium-based sorbent via the sorbent application step at block 16 in FIG. 1 as previously described.

[0042] Calcination in the calciner 17 may include heating the CaCO3to a suitable temperature, such as in the range of about 700 °C to about 1200 °C, such as about 750 °C to about 1100 °C, or such as about 800 °C to about 1000 °C in one or more embodiments, which may be combined with other embodiments. The calciner 17 may heat the CaCO3via the combustion of a fuel 18. The fuel 18 may include a carbonaceous fuel, such as natural gas or a constituent thereof, such as methane, ethane, or propane; synthesis gas; or combinations thereof. Heating the CaCO3in the calciner 17 may liberate CO2from the CaCO3to form calcium oxide (CaO) 1 1 . The CO2may be captured viaany suitable technique and then output from the process as a CO2stream 23. In one or more embodiments, the CO2stream 23 may be sold, sequestered, or used in another process.

[0043] The CaO 11 may then be hydrated with a water (H2O) stream 25 in a slaker 22 to form a calcium hydroxide (Ca(OH)2) slurry. The Ca(OH)2slurry may then be applied to the support as the sorbent 14 via the sorbent application step of block 16 in FIG. 1 as previously described to form a calcium-based sorbent. When the calcium-based sorbent contacts an ambient airflow 19 during the air contact step at block 20 in FIG.1 , H2O may be evaporated from the Ca(OH)2, and CO2from the ambient airflow 19 may be absorbed into the sorbent via carbonation. Thereafter, the carbonated sorbent 15 may be removed from the support via the sorbent removal step at block 24 in FIG. 1 , and at least some of the removed, carbonated sorbent 15 may be recycled (for example, as CaCO3with at least some residual Ca(OH)2) back to the calciner 17 for further sorbent processing as previously described.

[0044] Referring to FIGs. 3-5, various techniques may be employed for applying the sorbent 14 to a support 30 in the sorbent application step at block 16 in FIG. 1 . In one or more embodiments, the support 30 may comprise a sheet of material that defines a pair of opposing, exterior-facing sides 30a, 30b. The support 30 may comprise any suitable material. For instance, in one or more embodiments, the support 30 may comprise a polymer material or a metallic material. Applying sorbent to the support 30 during the sorbent application step at block 16 (FIG. 1) may comprise at least partially coating one or both of the two sides 30a, 30b with the sorbent 14 formed by the sorbent processing step at block 12 (FIG. 1) by use of a coating assembly.

[0045] For instance, as shown in FIG. 3, the coating assembly may comprise a sprayer 32 may spray the sorbent 14, which may comprise a Ca(OH)2slurry as previously described, onto one or both of the sides 30a, 30b of the support 30. In addition, as shown in FIG. 4, the coating assembly may comprise an applicator 34 that is configured to pourthe sorbent 14 onto one or both of the sides 30a, 30b of support 30 while traversing laterally (as shown via arrow 36) relative to the support 30. Further, as shown in FIG. 5, the coating assembly may comprise a system for dipping the support 30 into a container 38 holding a volume of the sorbent 14 to coat one or both of the sides 30a, 30b of support 30. Still other coating assemblies may be used to coat or partially coat one or both of the sides 30a, 30b of support 30 as a part of the sorbent application step at block 16 in FIG. 1.

[0046] In one or more embodiments, one or both of the sides 30a, 30b of the support 30 may be configured with a surface treatment. In such instances, one or both of the sides 30a, 30b of the support 30 can be expressly configured through either or both a chemical or physical treatment to facilitate retaining at least a portion of the sorbent 14 (which may comprise a Ca(OH)2slurry as previously described). In such instances, the sides 30a, 30b may have a regular or randomly patterned texture or other surface treatment, such as an intermediate coating, which improves the retention of the sorbent . Potential surface treatments may include, but are not limited to, sanding, bead blasting, laser marking, acid etching, corona treatment, and painting.

[0047] In one or more embodiments, the support 30 may be heated to a temperature that is greater than ambient temperature when applying the sorbent 14 . For instance, in one or more embodiments, the temperature of the support 30 can be in a range of from about 0.1 °C to about 50 °C greater than ambient temperature, such as from about 0.5 °C to about 45 °C, such from as about 1 °C to about 40 °C greater than ambient temperature, such from as about 2 °C to about 35 °C greater than ambient temperature, such as from about 3 °C to about 30 °C greater than ambient temperature, such as about 5 °C to about 25 °C greater than ambient temperature, such as about 10 °C to about 20 °C greater than ambient temperature, such as about 15 °C greater than ambient temperature inclusive of all values and ranges ending and in-between. Without being limited to this or any other theory, preheating the support 30 may benefit the application and adhesion of the sorbent 14 to the sides 30a, 30b during operations. As an example, heat energy may expand surface defects or openings or activate any surface treatments on the sides 30a, 30b. Such expanded surface defects may be infiltrated by solid particles of the sorbent. Upon cooling, such defects or openings may contract, which may facilitate anchoring of the sorbent layer to the exterior surface of the sides 30a, 30b of support 30.

[0048] Referring now to FIG. 6, in one or more embodiments, which may be combined with other embodiments, a plurality of supports 30 be supported together in a cassette 40 and one or more of the support-supporting cassettes 40 may be progressed through the processing steps of the process 10 shown in FIG. 1 . Each cassette 40 may include a frame 42 that supports a plurality of supports 30 in a vertical orientation such that the sides 30a, 30b of the plurality of supports 30 are all generally parallel.

[0049] The frame 42 may be formed as an open cube or cuboid that defines a total of six orthogonal sides 43, 44, 45, 46, 47, 48. In one or more embodiments, the frame 42 may be oriented such that the side 43 is a top side, the side 44 is a bottom side, the side 45 is a front side, the side 46 is a back side, and the sides 47, 48 are opposing first and second lateral sides, respectively. Thus, the sides 43, 44, 45, 46, 47, 48 may be referred to as a “top side,” “bottom side,” “front side,” “back side,” “first lateral side,” and “second lateral side,” respectively. However, other orientations of the frame 42 are contemplated in one or more embodiments. Because the frame 42 may be formed as an open cube or cuboid, one or more of the sides 43, 44, 45, 46, 47, 48 may all be open to allow air to freely flow through the frame 42 and across the sides 30a, 30b of the plurality of supports 30 during operations.

[0050] The plurality of supports 30 may be supported in the frame 42 such that the sides 30a, 30b of each support 30 are generally oriented parallel to the front and rear sides 45 and 46, respectively, and are generally perpendicular to the both the top and bottom sides 43 and 44, respectively, and the first and second lateral sides 47 and 48, respectively. Air that flows through the frame 42 between the first and second lateral sides 46 and 47, respectively, or between the top and bottom sides 43 and 44, respectively, may flow between the parallel supports 30 and across the sides 30a and 30b thereof. Specifically, FIG. 7 illustrates a side view of a cassette 40 (with supports 30supported) along the second lateral side 48 of the frame 42. As shown in FIG. 7, airflow that is directed normally into (or out of) the viewpoint provided by this figure as well as vertically along the viewpoint provided by this figure (that is, between the top side 43 and bottom side 44) may freely flow along the sides 30a, 30b of each of the plurality of supports 30.

[0051] During operations, a plurality of cassettes 40, each supporting a separate plurality of supports 30 as shown in FIGs. 6 and 7, are cyclically subjected to the processing steps of blocks 16, 20, 24 of the process 10 illustrated in FIG. 1 to reduce the concentration of CO2in the surrounding ambient air by extracting carbon dioxide from the ambient air passing between the sorbent retained on the sides 30a and 30b of the supports 30. Further details of these implementations of the process 10 will now be described according to one or more embodiments.

[0052] Referring again to FIG. 1 , in one or more embodiments the carbonated sorbent 14 may be removed from the supports 30, such as the supports 30 supported in the cassette 40 shown in FIGs. 6 and 7, by any suitable method during the sorbent removal step of block 24 in FIG. 1 . For instance, the sorbent removal step of block 24 may include scaping the sorbent off the supports 30, dislodging the sorbent 14 from the supports 30 using vibration or fluids, or other methods. In one or more embodiments, a pressurized air flow may be directed on the sides 30a, 30b of the support 30 dislodge the carbonated sorbent during the sorbent removal step of block 24 in FIG. 1 . In one or more embodiments, which may be combined with other embodiments, a liquid, such as water, may be used to dislodge the carbonated sorbent from the supports 30 during the sorbent removal step of block 24 in FIG. 1 . Still other methods of removing the carbonated sorbent are contemplated.

[0053] Referring now to FIGs. 8 and 9, an air contactor 50 that may be utilized to contact ambient airflow 19 with the sorbent-coated supports 30 during the air contact step of block 20 in the process 10 (FIG. 1) is shown according to one or more embodiments. In particular, in one or more embodiments, the air contactor 50 may comprise an elongate building or structure 51 having a first end 52 and a second end 54 that are spaced from one another along a longitudinal axis 55. The elongate structure 51 (or more simply “structure 51 ”) may be at least partially enclosed by a roof 56 and a pair of sidewalls 58, 59 extending axially between the ends 52, 54 along axis 55.

[0054] The structure 51 may be configured to channel the ambient airflow 19 (FIG. 1) therethrough during operations. Specifically, the sidewalls 58, 59 may each include a plurality of openings or vents 60 that are configured to allow surrounding ambient airto enterthe structure 51 as the ambient airflow 19 illustrated in FIG. 1. After entering the structure 51 via the vents 60, the ambient airflow 19 may contact the sorbent-coated supports, such as supports 30, arranged in the cassettes 40 (FIGS. 6 and 7) to form the CO2-depleted airflow 21 as previously described.

[0055] In addition, the roof 56 includes a plurality of exhaust fan stacks 62 that are axially spaced from one another relative to the axis 55. As shown in FIG. 9, each of the fan stacks 62 may include an air driver, such as a fan 64. During operations, the fans 64 may draw the ambient airflow 19 into the structure 51 via the vents 60 and may exhaust the CO2-depleted airflow 21 out of the structure 51 via the fan stacks 62 on the roof 56.

[0056] Referring now to FIG. 10, a cross section of the structure 51 taken along section A-A in FIG. 9 is shown according to one or more embodiments. A plurality of cassettes 40 may be positioned in the structure 51 , each cassette supporting a plurality of sorbent-coated supports 30 (FIGs. 6 and 7) as previously described. The cassettes 40 may be supported on a pair of racks 70, 71 that are positioned in the structure 51 . The racks 70, 71 include a first rack 70 and a second rack 71. The racks 70, 71 may be laterally or horizontally spaced from one another within the structure 51 . Thus, the racks 70, 71 may be radially spaced from one another relative to the longitudinal axis 55. The first rack 70 is laterally more proximate the second sidewall 59 than the first sidewall 58, and the second rack 71 is laterally more proximate the first sidewall 58 than the second sidewall 59. As a result, a central opening or space 73 is laterally or radially (relative to axis 55) positioned between the racks 70, 71 within the structure 51 . The central space 73 may be useful for allowing personnel or equipment to traverse axially through the structure 51 of air contactor 50 for repairs, maintenance, or other operations without having to remove or reposition the cassettes 40 relative to their position on the racks 70, 71 during extraction.

[0057] The racks 70, 71 may extend axially along the axis 55 between the ends 52, 54, and may each define a plurality of lateral oriented rows 72 of cassettes 40 that are stacked vertically within the structure 51 . Each of the cassettes 40 may be positioned on the racks 70, 71 so that the lateral sides 47, 48 of the cassettes 40 generally face toward the sidewalls 58, 59 of the structure 51 . Thus, as may be appreciated from FIGs. 6, 7, and 10, the sides 30a, 30b of the supports 30 supported in the cassettes 40 may be generally oriented perpendicularly to the sidewalls 58, 59 of structure 51 .

[0058] Referring again to FIG. 10, each fan 64 may rotate about a vertically oriented axis 65 that may be oriented perpendicularly (or orthogonally) relative to the longitudinal axis 55 of structure 51 . Rotating the fans 64 may draw the ambient airflow 19 into the structure 61 via the vents 60 positioned on the sidewalls 58, 59. Upon being introduced into the structure 51 , the ambient airflow 19 is directed laterally or horizontally across through the sides 30a, 30b (FIGS. 6 and 7) of the supports 30 supported in the cassettes 40. As the ambient airflow 19 contacts the sorbent 14 (FIG. 1) coated on the sides 30a, 30b of supports 30, the concentration of CO2in the airflow 19 is reduced to produce the CO2-depleted airflow 21 as previously described. The CO2-depleted airflow 21 is then drawn upward toward the fans 64 and is passed back into the surrounding atmosphere via the fan stacks 62. In one or more embodiments, which may be combined with other embodiments, the fans 64 and fan stacks 62 may be configured and positioned to push the ambient airflow 19 into and through the structure 51 rather than drawing the airflow 19 through the structure 51 as previously described.

[0059] Referring now to FIG. 1 1 , the structure 51 of the air contactor 50 may be connected or positioned adjacent to additional structures or facilities to carry out one or more of the other steps of the process 10 in FIG. 1 (such as blocks 12, 16, 24). For instance, the structure 51 may be connected to another structure or area 75 that is configured to carry out one or more of the sorbent processing step of block 12, the sorbent application step of block 16, and the sorbent removal step of block 24. In one or more embodiments, the area 75 may be configured to carry out the sorbentapplication step of block 16 and the sorbent removal step of block 24, while the sorbent processing step of block 12 may be performed in yet another location, structure, or area as previously described.

[0060] During operations, the cassettes 40 may be cyclically moved into, through, and out of the structure 51 of air contactor 50 when performing the steps of process 10 (FIG. 1). Specifically, after the supports 30 (FIGs. 6 and 7) supported in the cassettes 40 are coated with the sorbent 14 via the sorbent application step of block 16, the cassettes 40 may be transferred into and through the structure 51 so as to contact the ambient airflow 19 generated by the fans 64 as previously described. Thereafter, the cassettes 40 may be progressed back out of the structure 51 and into the area 75 so that the now carbonated sorbent 14 may be removed from the supports 30 via the sorbent removal step of block 24. The cassettes 40 may then progress back to the sorbent application step of block 16 within the area 75 so that the supports 30 may be re-coated with sorbent 14 and progressed back into the structure 51 to contact the ambient airflow 19 as previously described. This progression of the cassettes 40 through this sequence may be continuous so that at any point in time during operations, cassettes 40 may be positioned in each of the sorbent application step of block 16, the structure 51 , the sorbent removal step of block 24, and locations in between. As is previously described, the removed sorbent 14 may be at least partially recycled back to the sorbent processing step of block 12 prior to re-applying the sorbent 14 to the supports 30 supported in the cassettes 40 via the sorbent application step of block 16.

[0061] While the cassettes 40 are positioned in the structure 51 of air contactor 50, the cassettes 40 (and the sorbent-coated supports 30) may be moved along a path 77 through the structure 51 by a conveyance system 78 to expose the cassettes (and supports 30) to the airflow 19. The path 77 may at least partially follows along a perimeter of the structure 51. Specifically, relative to the longitudinal axis 55, the path 77 may have a first portion or leg 77a that extends axially from the first end 52 of the structure 51 to the second end 54 along the sidewall 59, a second portion or leg 77b that extends radially from the sidewall 59 to the opposing sidewall 58, and a third portion or leg 77c that extends axially from the second end 54 back to the first end 52 along the sidewall 58.

[0062] The racks 70, 71 may comprise at least a portion of the conveyance system 78, and may guide and move the cassettes 40 along at least a portion of the path 77. Specifically, the first rack70 may guide and move the cassettes 40 along the first leg 77a of the path 77, and the second rack71 may guide and move the cassettes 40 along the third leg 77c of the path 77. In addition, the conveyance system 78 may also include a third rack 76 that guides the cassettes 40 along the second leg 77b of the path 77. The racks 70, 71 , 76 may include any suitable structures or systems for imparting movement to the cassettes 40 and for guiding the cassettes 40 along the path 77 during operations. For instance, in one or more embodiments, the racks 70, 71 , 76 may include or be coupled to tracks, rails, rollers, belts, chains, motors, cables, carts, or any other components that may be used to move the cassettes 40 along the path 77.

[0063] Referring now to FIG. 12, the progression of a single row 72 of cassettes 40a, 40b, 40c, 40d along the path 77 though the structure 51 of air contactor 50 is illustrated to generally describethe progression of all of the cassettes 40 along the path 77 during operations. The row 72 may represent one of the plurality of vertically stacked rows 72 supported by the racks 70, 71 as shown in FIG. 10 and previously described. In addition, the row 72 may include a first cassette 40a, a second cassette 40b, a third cassette 40c, and a fourth cassette 40d arranged sequentially adjacent one another in a radial direction relative to the longitudinal axis 55. This row 72 of cassettes 40a, 40b, 40c, 40d may be progressed along the path 77 through the positions (i), (ii), (iii), and (iv) noted in FIG. 12 within the structure 51 as a part of the air contacting step of block 20 in process 10 (FIG. 1).

[0064] Initially, following the sorbent application step of block 16, the row 72 of cassettes 40a, 40b, 40c, 40d may enter the structure 51 at first end 52 at position (i), and then may be translated axially (relative to longitudinal axis 55) along the first leg 77a of the path 77 via first rack 70 from position (i) to position (ii) at second end 54 of structure 51 . While the row 72 translates along the first leg 77a, the first cassette 40a is positioned closest to the outer wall or perimeter of the structure 51 relative to the other cassettes 40b, 40c, 40d. Specifically, as the row 72 translates along the first leg 77a, the first cassette 40a is closest to the sidewall 59 relative to the other cassettes 40b, 40c, 40d, and the fourth cassette 40d is positioned relatively closest to the central space 73 (and thus farthest from the sidewall 59) relative to the other cassettes 40a, 40b, 40c. Accordingly, as shown in FIG. 13, while the row 72 of cassettes 40 is translating along the first leg 77a of path 77, the ambient airflow 19 entering the structure 51 via the vents 60 in the sidewall 59 may generally flow laterally or radially relative to the longitudinal axis 55 (FIG. 12) across the row 72. Specifically, while the row 72 is translating along the first leg 77a, the ambient airflow 19 may be directed from a first end 72a of the row 72 positioned at the first cassette 40a toward a second end 72b of the row 72 positioned at the fourth cassette 40d (and thus opposite the first end 72a), where it then emerges as the CO2-depleted airflow 21 as previously described.

[0065] Referring again to FIG. 12, once the row 72 of cassettes 40a, 40b, 40c, 40d reaches the position (ii) at the second end 52 of structure 51 , the row 72 may be translated in a radial direction (relative to longitudinal axis 55) along the second leg 77b of path 77 via the third rack 76 to thereby locate the row 72 at the position (iii) at the second end 52. Thereafter, the row 72 of cassettes 40a, 40b, 40c, 40d is translated along the third leg 77c of path 77 axially from position (iii) to position (iv). When the row 72 of cassettes 40a, 40b, 40c, 40d is translated along the second leg 77b of path between positions (ii) and (iii) via third rack 76, the radial or lateral order and orientation of the row 72 of cassettes 40a, 40b, 40c, 40d is maintained. As a result, when the row 72 is in the position (iii) and while the row 72 is translated along the third leg 77c of path 77 between the positions (iii) and (iv), the fourth cassette 40d is positioned closest to the outer wall or perimeter of the structure 51 relative to the other cassettes 40b, 40c, 40d. Specifically, as the row 72 translates along the third leg 77c, the fourth cassette 40d is closest to the sidewall 58 relative to the other cassettes 40a, 40b, 40c, and the first cassette 40a is positioned relatively closest to the central space 73 (and thus farthest from the sidewall 58) relative to the other cassettes 40b, 40c, 40d. Accordingly, as shownin FIG. 14, while the row of cassettes 40a, 40b, 40c, 40d is traversing along the third leg 77c of path 77, the ambient airflow 19 entering the structure 51 via the vents 60 in the sidewall 58 may generally flow laterally or radially relative to the longitudinal axis 55 from the second end 72b of the row 72 to the first end 72a of the row 72, where it then emerges as the CC>2-depleted airflow 21 as previously described.

[0066] Thus, the progression of the row 72 of cassettes 40a, 40b, 40c, 40d along the path 77 and between the positions (i), (ii), (iii), (iv) may be configured to contact substantially evenly the supports 30 supported in the cassettes 40a, 40b, 40c, 40d with the ambient airflow 19. Without being limited to this or any other theory, cassettes 40a, 40b, 40c, 40d of the row 72 that are more closely positioned to a vent 60 along the sidewalls 58, 59 may receive a greater volume of airflow than cassettes 40a, 40b, 40d, 40d that are positioned fartherfrom the vent 60. As a result, by maintaining the radial order and orientation of the row 72 of cassettes 40a, 40b, 40c, 40d when moving from the first rack 70 to the second rack 71 along the second leg 77b of path 77, each of the cassettes 40a, 40b, 40c, 40d may see a more even volume and distribution of airflow over the entire time that the cassettes 40a, 40b, 40c, 40d are traversed along the path 77 in the structure 51 of air contactor 50. Moreover, still without being limited to this or any other theory, evenly contacting the supports 30 in the cassettes 40a, 40b, 40c, 40d with the ambient airflow 19 while in the structure 51 of air contactor 50 may help to increase the amount of CO2that is absorbed by the sorbent coated on the supports 30 by forcing exposure of each row of cassettes to an equivalent amount of air flow from opposing directions, and thereby increase the operating efficiency for the process 10 (FIG. 1). Although not wanting to be bound by theory, by maintaining the group of cassettes in the same relative order to one another while repositioning the group such that the air flowing through the group for equivalent periods flows in a first direction and then a second, opposite direction, should utilize the sorbent in each grouping along a row in a more even manner than if the same was utilized only in a single air flow direction. As the ambient air is introduced into a grouping of cassettes, a leading, exterior- adjacent edges of the supports of the exterior-adjacent cassettes are exposed to the greatest concentration of carbon dioxide in the ambient air introduced into the facility; similarly, a trailing, interior-adjacent edge of the supports of the interior-adjacent cassettes are exposed to the least concentration of carbon dioxide in the not-completely but somewhat CO2-depleated air traversing the interior of the facility. One of skill in the art would expect the greatest amount of carbonate conversion would be expected along the sorbent in the most-exterior positioned cassette; the least along the sorbent in the most-interior positioned cassette. One of skill in the art would also expect any intermediate-positioned cassettes with sorbent material to have relevant degrees of conversion relative to their positions to the exterior-adjacent cassette and interior-adjacent cassette. Therefore, in embodiment processes, when the group of cassettes are re-positioned such that the ambient air flow changes from the first direction to the second, opposite direction, the formerly trailing, interior- adjacent edges of the formerly interior-adjacent cassettes are now the leading, exterior-adjacent edges of the supports of the exterior-adjacent cassettes and vice versa. This exposes these formerlytrailing, interior-adjacent edges to the greatest concentration of carbon dioxide in the ambident air introduced into the facility, and again vice versa. As well, the intermediate-positioned cassettes also see a shift in degree of carbon dioxide exposure relative to their positioning among the group. As previously stated, this should more effectively utilize the active sorbent on all the supports in all the cassettes. At the same time, because of the better utilization of sorbent, the concentration of carbon dioxide in the spent ambident air should be reduced versus maintaining a merely static group of sorbent supports. Additionally, one may hypothesize that the amount of carbon dioxide in the spent ambient air should also be relatively steady, as the reversal of relative air flow should avoid situations where some of the sorbent in each grouping still has a significant removal capacity but is reprocessed, leading to reduced captured carbon dioxide removal and production, as well as preventing “breakthrough” of CO2 due to over-exposed sorbent, leading to greater concentrations of CO2in the spent ambient air.

[0067] Referring still to FIG. 12, after the row 72 reaches the position (iv) at the first end 52 of the structure 51 , the row 72 of cassettes 40a, 40b, 40c, 40d may be removed from the structure 51. Thereafter, the cassettes 40a, 40b, 40c, 40d may be returned to the sorbent removal step at block 24 where the carbonated sorbent (that is, spent) is removed (and potentially recycled), and then progressed to the sorbent application step of block 16 to receive a new coating of sorbent 14 on the supports 30 as previously described.

[0068] In addition, as was previously described and shown in FIG. 10, the racks 70, 71 may support a plurality of vertically stacked rows 72 of cassettes 40. As a result, it should be appreciated that a plurality of vertically stacked rows 72 of cassettes 40, may be progressed together along the path 77 and through the positions (i), (ii), (iii), (iv) during operations. Specifically, FIGS. 15A and 15B show sequential views of a plurality of vertically stacks rows 72 of cassettes 40 moving together as a unit along the second leg 77b of path 77 from the position (ii) to the position (iii) at the second end 54 of the structure 51 of air contactor 50 according to one or more embodiments. A portion of the structure 51 at the second end 54 is shown cut-away in the view of FIGs. 15A and 15B to illustrate the cassettes 40.

[0069] Each of the rows 72 may include a corresponding set of cassettes 40a, 40b, 40c, 40d as previously described. As shown in FIGS. 15A and 15B, the third rack 76 is connected between the first rack 70 and second rack 71 . The third rack 76 is configured to transfer the vertically stacked rows 72 of cassettes 40a, 40b, 40c, 40d along the second leg 77b of path 77 from the position (ii) to the position (iii). During operations, the cassettes 40 positioned on the second rack 71 are progressed forward toward the position (iv) at first end 52 (FIG. 12) via the third leg 77c of path 77 so as to create an opening in the second rack at the position (iii). As a result, the vertical stack of rows 72 of cassettes 40a, 40b, 40c, 40d may be progressed along the second leg 77b of path 77 from the first rack 70 at the position (ii) to the second rack 71 at the position (iii) via the third rack 76. In addition, the cassettes 40 positioned on the first rack 70 are progressed forward along the first leg 77a of path 77 to place another stack of rows 72’ of cassettes 40a, 40b, 40c, 40d at theposition (ii). The process of FIGs. 15A and 15B may be repeated to continuously progress the vertically stacked rows 72 of cassettes 40 along the path 77 through the structure 51 .

[0070] Referring now to FIGs. 16A-16E, once the plurality of vertically stacked rows 72 of cassettes 40 illustrated in FIGS. 15A and 15B reaches the position (iv) in the structure 51 via the third leg 77c of path 77, each row 72 may be offloaded from the second rack 71 and progressed back out of the structure 51 and to the sorbent removal step of block 24 and sorbent application step of block 16. A portion of the structure 51 at the first end 54 is shown cut-away in the views of FIGs. 16A-16E so as to illustrate the cassettes 40.

[0071] Initially, as shown in the sequence from FIGs. 16A to 16B, when the plurality of vertically stacked rows 72 reaches the position (iv) in the structure 51 , a first of the rows 72, such as a topmost row 72, is removed from the stack and progressed out of the structure 51 via an elevator 49. Thereafter, as shown in the sequence from FIGs. 16C to 16D, the removed row 72 may be progressed to a first station 80 to perform the sorbent removal step of block 24 in FIG. 1 , and then to a second station 82 to perform the sorbent application step of block 16 in FIG. 1. Finally, as shown in FIG. 16E, another row 72, such as the next top-most row in the stack, is removed via the elevator 49 and progressed toward the stations 80 and 82.

[0072] After progressing through the stations 80, 82, the rows 72 of cassettes 40, which have been re-coated with processed sorbent 14 via the station 82, may be re-introduced into the structure 51 at the position (i) (FIG. 12) to thereby restart the process previously described. A similar elevator 49 may be used to restack the rows 72 as shown when re-introducing the cassettes 40 back into the structure 51 .

[0073] Referring now to FIG. 17, a perspective view of a plant 90 for conducting the process 10 illustrated in FIG. 1 is shown according to one or more embodiments. The plant 90 may include a central building or structure 92, and one or more air contactors 50 connected to and extending outward from the central structure 92. Specifically, in the embodiment illustrated in FIG. 17, there are two air contactors 50, each having a corresponding elongate structure 51 extending from opposite sides of the central structure 92 so as to increase the volumetric flow rate of the CO2- depleted airflow 21 (FIG. 1) that may be output from the plant 90 during operations.

[0074] The central structure 92 may at least partially house equipment configured for performing one or more steps of the process 10 shown in FIG. 1 . For instance, in one or more embodiments, the central structure 92 may be house equipment that is configured to perform the sorbent application and sorbent removal steps of blocks 16 and 24, respectively, in FIG. 1. The plant 90 may also include an additional unit 94 that is adjacent to but separate from the central structure 92 that includes equipment that is configured to perform the sorbent processing steps of block 12 in FIG. 1 . Once the supports 30 supported in the cassettes 40 are coated with sorbent, the cassettes 40 may be progressed through the structures 51 to perform the air contacting step of block 20 in FIG. 1 as previously described.

[0075] In one or more embodiments, the cassettes 40 may be held generally stationary while one or more of the steps of process 10 illustrated in FIG. 1 are performed. For instance, referring to FIG. 18, in one or more embodiments, a plurality of cassettes 40 may be maintained substantially static in rows or other suitable organizational patterns during the air contacting step in block 20 of FIG. 1 . A plurality of assemblies 100, 101 may traverse along the static cassettes 40 to perform one or more of the sorbent application and sorbent removal steps of blocks 16 and 20, respectively. A first assembly 100 may traverse along the cassettes 40 to remove carbonated sorbent from the supports 30 in the manner previously described. The first assembly 100 may include a collection bin 102 that is configured to collect the carbonated sorbent removed from the supports 30 during operations.

[0076] In addition, a second assembly 101 may also be traversed along the cassettes 40 behind or after the first assembly 100 to re-coat the supports 30 supported in the cassettes 40 with processed sorbent. In particular, the second assembly 101 may include an applicator 34 that is configured to pour sorbent slurry onto the supports 30 as previously described, and a collection bin 104 to collect excess sorbent slurry; however, other coating methods are contemplated for the second assembly 101.

[0077] Referring now to FIG. 19, a perspective view of a plant 200 for conducting the process 10 illustrated in FIG. 1 is shown according to one or more embodiments. The plant 200 may include a central building or structure 292 from the plant 90 of FIG. 19. In addition, the plant 200 may include one or more air contactors 250 in place of the previously described air contactors 50. The air contactors 250 may connect to and extend outward from the central structure 292.

[0078] As previously described, the central structure 292 may house equipment that is configured to perform the sorbent application and sorbent removal steps of blocks 16 and 24, respectively, in FIG. 1. Additionally, the central structure 292 may include additional equipment configured to perform the sorbent processing steps of block 12 in FIG. 1 , or an additional unit (such as additional unit 94) may be included for these purposes as previously described. Further details of one or more embodiments of the central structure 292 are provided later.

[0079] Similar to the air contactors 50, previously described, the air contactors 250 of plant 200 may be utilized to contact ambient airflow 19 with the sorbent-coated supports 30 during the air contact step of block 20 in the process 10 (FIG. 1). However, the air contactors 250 may be configured differently from the previously described air contactors 50.

[0080] Specifically, with reference to FIG. 20, the air contactor 250 may comprise an elongate structure 251 having a first end 251a and a second end 251 b that are spaced from one another along a longitudinal axis 255. The first end 251a may be connected to the central structure 292, and the second end 251 b may be projected outward and away from the central structure 292 along the longitudinal axis 255.

[0081] The structure 251 may comprise one or more, such as one or a plurality of, air contactor modules 252 (or “modules” 252) that are arranged axially adjacent one another along the longitudinal axis 255 between the ends 251 a, 251 b. As is described later, each of the modules 252may be configured to facilitate the air contact step of block 20 in the process 10 (FIG.1) once connected to eitherthe central structure 292 or another module 252. As a result, construction of the structure 251 via one or more of the modules 252 may allow for simultaneous scale up and operation of the plant 200.

[0082] Referring now to FIGs. 21 and 22, one of the modules 252 of an air contactor 250 of plant 200 (FIG. 19) is shown connected to the central structure 292. The module 252 includes a central canopy 260 having a first end 260a and a second end 260b spaced apart from one another along the longitudinal axis 255. When the air contactor 250 (FIG. 20) comprises a single module 252, such as shown in FIG. 21 , the first end 260a may comprise the first end 251 a of structure 251 , and the second end 260b may comprise the second end 251 b of structure 251 . Thus, the first end 260a is connected to the central structure 292, and the second 260b is projected away from central structure 292 along longitudinal axis 255.

[0083] The canopy 260 may comprise a roof 262, but may otherwise be open on all lateral sides. Specifically, the ends 260a, 260b of canopy 260 may be open so that a central opening or space 263 is defined beneath the roof 262 and between the ends 260a, 260b. The canopy 260 may also include a pair of lateral sides 264, 266 that extend axially between the ends 260a, 260b along longitudinal axis 255. The lateral sides 264, 266 may also be open to thereby provide access into the central space 263.

[0084] The central space 263 may be open to the interior of the central structure 292 (or the central space 263 of an adjacent module 252) via the first end 260a and may be open to the outside environment (or the central space 263 of an adjacent module 252) at the second end 260b. As is shown in FIG. 20, a door 265 may be positioned at the second end 260b of the last, or most distal, module 252 from the central structure 292 so that the central space(s) 263 of the adjacent modules 252 of structure 251 may be closed off to the outer environment via the second end 251 b.

[0085] Referring again to FIGs. 21 and 22, the roof 260 may include one or more of the fan stacks 62, which are previously described. For instance, in one or more embodiments, each module 252 may include a single fan stack 62 positioned on roof 262. However, in one or more other embodiments, each module 252 may include a plurality of fan stacks 62 that are axially spaced from one another along the longitudinal axis 255. As previously described, the fan stack(s) 62 may include an air driver, such as a fan 64 (FIG. 20) that is configured to generate an airflow from the central space 263 and out of the fan stack 62.

[0086] A stack 270 of air contactor containers 272 (or “containers 272”) may be positioned along and coupled to one or both of the lateral sides 264, 266. The containers 272 may hold one or more cassettes 40 (FIG. 6) that are in turn contain a plurality of sorbent-coated supports 30 for facilitating the air contact step of block 20 in the process 10 (FIG. 1) as previously described.

[0087] Referring now to FIGs. 23 and 24, one of the containers 272 is shown according to one or more embodiments. Note that the exterior surfaces of the container 272 illustrated in FIGs. 23 and 24 are transparent in order to show the interior thereof. The container 272 may comprise anelongate structure that is shaped as a rectangular parallelepiped. Thus, the container 272 includes a central or longitudinal axis 275, a first end 272a, and a second end 272b opposite first end 272a. The first end 272a may comprise an opening 274, and the second end 272b may comprise a vent 276. In one or more embodiments, the vent 276 may comprise a plurality of louvers that may be actuated so as to adjust an airflow through the container 272 during operations.

[0088] A rack 278, or other suitable structure, may be included within the container 270 that is configured to support a plurality of cassettes 40 therein. Specifically, as shown in FIGs. 23 and 24, the rack 278 may support a plurality, such as four (4), rows 280 each including four (4) cassettes 40 arranged axially adjacent one another relative to the longitudinal axis 275. Thus, for the example of FIGs. 23 and 24, the container 270 may be configured to hold a total of sixteen (16) cassettes 40; however, other sizes and capacities are contemplated for the containers 270.

[0089] In one or more embodiments, the container 270 may be constructed from a shipping container. For instance, the container 270 may comprise a CONEX shipping container that has been modified so as to be configured as described. Thus, the stack 270 of containers 272 may be largely constructed from recycled materials so that the overall construction costs of module 252 are relatively low.

[0090] Referring now to FIG. 25, a cross section of the module 252 taken along section B-B in FIG. 25 is shown according to one or more embodiments. During operations, the fan(s) 64 may rotate about the corresponding vertical axis 65 to draw the ambient airflow 19 into the containers 270 of stacks 270 via the vents 260 at second ends 272b. Upon being introduced into the containers 262, the ambient airflow 19 is directed laterally or horizontally across through the sides 30a, 30b of the supports 30 supported in the cassettes 40 (FIGS. 6 and 7). As the ambient airflow 19 contacts the sorbent 14 (FIG. 1) coated on supports 30, the concentration of CO2in the airflow 19 is reduced to produce the CO2-depleted airflow 21 as previously described. The CO2-depleted airflow 21 is then drawn out of the open first ends 272a of containers 272 into the central space 263 of canopy 260. Thereafter, the CO2-depleted airflow 21 is drawn upward toward the fans 64 and is passed back into the surrounding atmosphere via the fan stack(s) 62. In one or more embodiments, which may be combined with other embodiments, the fans 64 and fan stacks 62 may be configured and positioned to push the ambient airflow 19 into and through the module 252 rather than drawing the airflow 19 through the module 252 as previously described.

[0091] Without being limited to this or any other theory, directing the ambient airflow 19 through the plurality of containers 272 of the stacks 270 may help to channel the airflow 19 across the cassettes 40. As a result, the containers 272 may form individual “wind-tunnels” that promote contact and interaction between the airflow 19 and the sorbent-coated supports 30 in the cassettes 40 (FIGS. 6 and 7) during operations. In one or more embodiments, the vents 276 at the second ends 272b of containers 272 may be adjusted so as to adjust the volume or velocity of ambient airflow 19 through one or more of the containers 272 during operations. For instance, the vents 276 may be adjusted, such as manually or via a suitable controller, based on feedback from one or moresensors, such as flow sensors, anemometers, etc., so as to ensure a desired volume or rate of the ambient airflow 19 through the containers 272 during operations.

[0092] Thus, each module 252 may be a self-contained unit that is configured to facilitate the air contact step of block 20 in the process 10 (FIG. 1) once connected to either the central structure 292 or another module 252. As a result, as may be appreciated from FIGs. 19-21 , increasing the capacity of plant 200 may be relatively simple, and may involve the installation of additional modules 252 to increase the axial length of each of the air contactors 250 along the corresponding axes 255. Because each module 252 is a self-contained unit, the installed modules 252 may operate to thereby conduct the air contact step of block 20 in the process 10 (FIG. 1) while additional modules 252 are being installed.

[0093] Referring now to FIG. 26, one or more cranes 290 may be traversed axially along the central space 263 of each air contactor 250 so as to load and unload the rows 280 of cassettes 40 from the containers 272 in the stacks 270. The crane 290 may be configured to load and unload all of the cassettes 40 from a particular container 272 during operations. Thus, the crane 290 may be configured to load and unload a total of at least sixteen (16) cassettes 40 in one or more embodiments.

[0094] In one or more embodiments, within each air contactor 250, one crane 290 may be utilized to unload all of the cassettes 40 from a particular container 272 and a second crane 290 may be utilized to load new cassettes 40, into the particular container 272. In one or more other embodiments, a single crane 290 may be configured to hold or support enough cassettes 40 so that the single crane 290 may be configured to both unload all of the cassettes 40 from a container 272 and then load new cassettes 40 into the container 272.

[0095] Each crane 290 may traverse axially through the central space 263 of the corresponding air contactor 250 via tracks 294. However, other conveyance systems are contemplated, such as belts, floor-mounted rollers, sliders, etc. Likewise, the crane(s) 290 may include any suitable structures or systems for imparting movement to the cassettes 40 and for guiding the cassettes 40 into and out of the containers 272 during operations. For instance, in one or more embodiments, the crane(s) 290 may include or be coupled to tracks, rails, rollers, belts, chains, motors, cables, carts, or any other components that may be used to move the cassettes 40 into and out of the containers 272.

[0096] Once cassettes 40 are unloaded from a container 272 onto the crane 290, the crane 290 may traverse axially along the central space 263 relative to axis 255 to bring the unloaded cassettes 40 back to the central structure 292. As previously described, within the central structure 292, the removed cassettes 40 undergo the sorbent removal and applications steps of blocks 24 and 16, respectively, in FIG. 1. Thereafter, the cassettes 40, with newly coated supported therein may be transported and loaded into another container 272 via crane 290.

[0097] Referring now to FIG. 27, an example layout of the central structure 292 of plant 200 (FIG. 19) is shown according to one or more embodiments. As shown, the tracks 292 from the aircontactors 250 may extend into the central building 292 so that cranes 290 can traverse from the air contactors 250 to the central structure 292 and within the central structure 292 during operations. The central structure 292 may include equipment or stations that are configured to one or more of the sorbent application, sorbent removal, and sorbent processing steps of blocks 16, 24, and 12, respectively, in the process 10 of FIG. 1. For instance, as shown in FIG. 27, the central structure 292 may include removal station 295, one or more dipping stations 296, and a drying station 293.

[0098] The removal station 295 may be configured to perform or facilitate the removal of spent sorbent from cassettes 40 (FIGs. 6 and 7) following the air contact step of block 20 in FIG. 1 . Any suitable removal method may be used to remove the spent sorbent at the removal station 295 as previously described, such as scaping, vibrating, an air knife, etc.

[0099] The one or more dipping stations 296 may be configured to perform the sorbent application step of block 16 in FIG. 1 . In one or more embodiments, the dipping station 296 may be configured to facilitate dipping of cassettes 40, with supports 30 contained therein, into tanks or vats of liquid (or semi-liquid) sorbent to facilitate the sorbent application step. However, in one or more other embodiments, the dipping station(s) 296 may be replaced with other application stations that are configured to perform alternative sorbent application methods, such as spraying, pouring, etc. The dipping station(s) 296 may include one or more gantry cranes 297 and a loading zone 298. For instance, in the particular example of FIG. 27, the central structure 292 includes two dipping stations 296 with the loading zone 298 arranged therebetween. The gantry crane(s) 297 may pick up one or more cassettes 40 from the loading zone 298 and then dip the cassettes 40 into a tank or vat of sorbent within the dipping station 296, to thereby coat supports 30 loaded into the cassettes 40 with sorbent as previously described. Each dipping station 296 may also include an unloading zone 299 within which the gantry crane(s) 297 may deposit cassettes 40 following dipping.

[0100] The drying station 293 may be configured to facilitate the dusting of fresh lime powder (or other substances) onto the surfaces of supports 30 contained within cassettes 40. In one or more embodiments, the drying station 293 may facilitate dusting of the supports 30 after the supports 30 (and their corresponding cassettes 40) have been coated with sorbent via the dipping station(s) 296 as previously described. Without being limited to this or any other theory, dusting the wet supports 30, such as with lime powder as previously described, may help to at least partially dry the sorbent coated onto supports 30 prior to transporting the cassettes 40 back into one of the air contactors 250 via crane(s) 290.

[0101] The buffer stations 291 may comprise staging areas where cranes 290 may transfer cassettes 40 that are progressing both into and out of one of the air contactors 250. Thus, the buffer stations 291 may comprise areas where the travel paths of one or more cranes 290 overlap via tracks 294.

[0102] During operations, a crane 290 may move cassettes 40 containing supports 30 coated with spent sorbent from one of the air contactors 250 to one of the buffer zones 291 within the central structure 292. Another crane 290 positioned within the central structure 292 may pick up thecassettes 40 at the buffer zone 291 and then transport the cassettes 40 to the removal station 295, where the spent sorbent is removed as previously described. Thereafter, a crane 290 transfers the cassettes 40 to the loading zone 298 so that the gantry crane 297 (or one of the gantry cranes 297) may pick up the cassettes 40 and dip them into a tank or vat of sorbent in one of the dipping station 296 as previously described. Thereafter, the gantry crane 297 may deposit the cassettes 40 (now with freshly coated supports 30 contained therein) into the corresponding unloading zone 299. Next, a crane 290 may pick up the cassettes 40 from the unloading zone 299 and may transfer them to the drying station 293 for dusting with additional lime powder as previously described. Finally, a crane 290 may retrieve the cassettes 40 from the drying station 293 and may then deposit them back into one of the buffer zones 291 , from which another crane 290 may retrieve the cassettes 40 and then load them into one of the containers 272 in one of the air contactors 250 as previously described.

[0103] Referring now to FIG. 28, in one or more embodiments, which may be combined with other embodiments, systems for direct capture of CO2 from ambient air disclosed herein may be used to reduce CO2, and potentially other impurities, from an airflow for another industrial system or process. For instance, in one or more embodiments, the system for direct capture of CO2may be used to reduce CO2and other potential impurities for an airflow that is passed to a gas turbine system, a compressor, a furnace, a heat exchanger, or some other industrial system or process. Specifically, as shown in FIG. 28, the air contactors 50 of plant 90 (or an air-contactors 250 of the plant 200 in FIG. 19) may output some or all of the CO2-depleted airflow 21 to a gas turbine system 300 as an oxidant stream.

[0104] As shown in FIG. 28, in lieu of or in addition to venting the CO2-depleted airflow 21 to the atmosphere via exhaust fan stacks 62, the air contactors 50 may include a ducting system 302 that is configured to capture some or all of the CO2-depleted airflow 21. The collected, CO2-depleted airflow 21 may then be passed via pipe(s), hose(s), or other conduit(s) to the gas turbine system 300.

[0105] The gas turbine system 300 may include a turbine 304 that is configured to expand combustion products derived from the combustion of a fuel stream 308 by use of the captured portion of the CO2-depleted airflow 21 as an oxidant. The fuel stream 308 may comprise a carbonaceous fuel, such as natural gas or syngas. The fuel stream 308 may be combusted in the turbine 304 or in a separate combustor (not shown).

[0106] The expansion of the combustion products via the turbine 304 may be used to perform mechanical work. For instance, in the example of FIG. 28, the expansion of the combustion products via the turbine 304 may be used to actuate an electrical generator 306.

[0107] The CO2-depleted airflow 21 may have a higher oxygen concentration relative to the ambient airflow 19. For instance, in one or more embodiments, the CO2-depleted airflow 21 may have a CO2content of 50 to 100 parts per million (ppm) whereas the CO2content of the ambient airflow 19 may be more than about 400 ppm, such as 427 ppm in one or more embodiments. As aresult, the reduced CO2content of CO2-depleted airflow 21 may correlate with a higher oxygen concentration. Without being limited to this or any other theory, providing a higher oxygen concentration in the oxidant stream provided to the gas turbine system 300 which may, in turn, result in more complete and efficient combustion of the fuel stream 308.

[0108] In addition, again without being limited to this or any other theory, passing an airflow through an embodiment of an air-contactor, such as air contactor 50 or air contactor 250 (FIG. 19), may also reduce other impurities in the CO2-depleted airflow 21 provided to the gas turbine system 300 as an oxidant stream. Specifically, during operations SOX, such as sulfur dioxide (SO2) or sulfur trioxide (SO3), in the ambient airflow 19 may react with Ca or Mg in the sorbent coating on the supports 30 in cassettes 40 (FIGs. 6 and 7), to form calcium sulfite and magnesium sulfite, respectively, on the supports 30 and thereby reduce these SOXspecies in the CO2-depleted airflow 21. The reduction of SOXin the CO2-depleted airflow 21 may further increase the oxygen content provided to the gas turbine system 300, thereby further improving the combustion reaction performed therein as previously described.

[0109] In one or more embodiments, the ducting system 302 for collecting the CO2-depleted airflow 21 may comprise one or more air-inlet tubes of ducts that are at least partially installed in the structure 51 of the air contactor 50 (or within the canopies 260 of the modules 252 of air-contactor 250 of FIGS. 19-21). For instance, with reference to FIGS. 29 and 30, in one or more embodiments, the ducting system 302 may include an elongate inlet tube assembly 310 that extends at least partially within the structure 51 in an axial direction relative to the axis 55 from a first or upstream end 310a to a second or downstream end 310b. The terms “upstream” and “downstream” for the ends 310a, 310b refer to the direction of flow for the CO2-depleted airflow 21 within the inlet tube assembly 310 during operations.

[0110] The upstream end 310a may be positioned within the structure 51 , proximate the second end 54, and the downstream end 310b may be either positioned outside or inside the structure 51 , proximate the first end 52. The inlet tube assembly 310 may include a plurality of tube sections 312 that are coupled to one another and arranged end-to-end between the ends 310a, 310b. Each tube section 312 may include a plurality of axially-spaced inlets 314 that are configured to collect the CO2-depleted airflow 21 into the inlet tube assembly 310 during operations. In addition, the upstream end 310a of inlet tube assembly 310 may also comprise a terminal opening 316 that is also configured to collect CO2-depleted airflow 21 into the inlet tube assembly 310. The downstream end 310b may include an outlet 318 that is configured to communicate the CO2-depleted airflow 21 into a pipe, hose, conduit, etc. (not shown) that is configured to pass the collected, CO2-depleted airflow 21 to the gas turbine system 300 (FIG. 28) as previously described.

[0111] Generally speaking, the accumulated volume or flow rate of CO2-depleted airflow 21 increases in the inlet flow assembly 310 when moving toward from the upstream end 310a the downstream end 310b. Thus, the inner diameter of the inlet flow assembly 310 may generally increase when moving from the upstream end 310a to the downstream end 310b in order to avoidor at least reduce a backpressure on the CO2-depleted airflow 21 in the inlet tube assembly 310 during operations. Specifically, while each tube section 312 may have a constant inner diameter along its length, the tube sections 312 may have progressively increasing inner diameters when moving from the upstream end 310a to the downstream end 310b. Thus, each tube section 312 may include a smaller inner diameter than the immediately axially adjacent tube section 312 in the downstream direction (that is, toward the downstream end 310b) and may include a larger inner diameter than the immediately axially adjacent tube section 312 in the upstream direction (that is, toward the upstream end 310a).

[0112] Referring now to FIG. 31 , in one or more embodiment, inlets 314 of the inlet tube assembly 310 may be configured as one or more vent hoods 316 that are coupled to one or more of the tube sections 312 (FIGs. 29 and 30). For instance, each tube section 312 may include one or more vent hoods 316 that open downward within the structure 51 and are configured to collect and funnel CO2- depleted airflow into the corresponding tube section 312 during operations. Without being limited to this or any other theory, use of the vent-hoods 316 may help to increase the volume of CO2-depleted airflow 21 that is collected into the inlet tube assembly 310 during operations.

[0113] As explained previously and reiterated here, the present disclosure includes, without limitation, the following embodiments and example implementations.

[0114] Clause 1 : A method for removing carbon dioxide (CO2) from ambient air, the method comprising: (a) coating a plurality of supports with a calcium hydroxide (Ca(OH)2) slurry to form a sorbent on the plurality of supports; (b) conveying the plurality of supports into a structure of an air contactor in a row of a plurality of cassettes, each of the plurality of cassettes supporting a set of the plurality of supports; (c) generating an ambient airflow through the structure; (d) transporting the row along a path in the structure such that: for a first leg of the path, the ambient airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the ambient airflow is directed from the second end of the row to the first end of the row; and (e) absorbing CO2 from the ambient airflow into the sorbent during (d).

[0115] Clause 2: The method of any of the clauses, further comprising: (f) processing calcium carbonate (CaCO3) to form the Ca(OH)2 slurry.

[0116] Clause 3: The method of any of the clauses, where (e) comprises: (f1) calcining the CaCO3 to produce calcium oxide (CaO); and (f2) slaking the CaO to form the Ca(OH)2 slurry.

[0117] Clause 4: The method of any of the clauses, further comprising: (g) removing the sorbent from the plurality of supports after (d); and (h) recycling at least some of the sorbent removed from the plurality of supports to the processing in (f).

[0118] Clause 5: The method of any of the clauses, where (d) comprises: (d1) moving the row along a first sidewall of the structure in the first leg; and (d2) moving the row along a second sidewall of the structure in the second leg.

[0119] Clause 6: The method of any of the clauses, where (c) comprises drawing the ambient airflow into vents in both the first sidewall and the second sidewall and expelling the ambient airflow out of one or more fan stacks positioned on a roof of the structure.

[0120] Clause 7: The method of any of the clauses, where (d) comprises transporting a plurality of vertically stacked rows of cassettes as a unit along the path in the structure, where the row is one of the plurality of vertically stacked rows.

[0121] Clause 8: The method of any of the clauses, where (a) comprises pouring the Ca(OH)2slurry onto the set of supports supported in each of the plurality of cassettes.

[0122] Clause 9: A plant for removing carbon dioxide (CO2) from ambient air, the plant comprising: a coating assembly that is configured to coat a plurality of supports with a sorbent, where the plurality of supports are supported in a plurality of cassettes; and an air contactor comprising a structure that is configured to receive the plurality of cassettes downstream from the coating assembly, the structure comprising: one or more fans that are configured to induce an ambient airflow through the structure; and a conveyance system that is configured to support the plurality of cassettes in a row and to transport the row along a path defined in the structure to expose the plurality of supports to the ambient airflow and thereby absorb CO2from the ambient airflow into the sorbent, where the path is configured such that: for a first leg of the path, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the airflow is directed from the second end of the row to the first end of the row.

[0123] Clause 10: The plant of any of the clauses, where each of the plurality of cassettes is configured to support a set of the plurality of supports in a parallel and vertical orientation.

[0124] Clause 11 : The plant of any of the clauses, where the conveyance system is configured to transport the plurality of cassettes along the path in the structure as a unit of a plurality of vertically stacked rows of cassettes.

[0125] Clause 12: The plant of any of the clauses, where the conveyance system comprises one of more racks to support the plurality of vertically stacked rows of cassettes along the path in the structure.

[0126] Clause 13: The plant of any of the clauses, where the structure of the air contactor is an elongate structure including: a first end; a second end spaced from the first end along a longitudinal axis; a first sidewall extending axially between the first end and the second end; and a second sidewall extending axially between the first end and the second end that is radially opposite the first sidewall relative to the longitudinal axis, where the first leg of the path extends along the first sidewall and the second leg of the path extends along the second sidewall.

[0127] Clause 14: The plant of any of the clauses, where the conveyance system is configured to transport the row along the first leg of the path such that the first end of the row is closer to the first sidewall than the second end and to transport the row along the second leg of the path such that the second end of the of the row is closer to the second sidewall than the first end of the row.

[0128] Clause 15: The plant of any of the clauses, where the first sidewall and the second sidewall each include a plurality of vents, where the structure further includes a roof extending axially between the first end and the second end, and where the one or more fans are supported in one or more fan stacks positioned in the roof such that the ambient airflow enters the structure via the plurality of vents and exits the structure via the one or more fan stacks.

[0129] Clause 16: The plant of any of the clauses, further comprising: a calcinerthat is configured to heat calcium carbonate (CaCO3) to liberate CO2and produce calcium oxide (CaO); and a slaker that is configured to hydrate the CaO to form a calcium hydroxide (Ca(OH)2) slurry, where the coating assembly is configured to coat the Ca(OH)2slurry onto the plurality of supports as the sorbent.

[0130] Clause 17: An air contactor for contacting ambient air with a sorbent to produce a CO2- depleted airflow, the air contactor comprising: a structure including: a first end; a second end spaced from the first end along a longitudinal axis; a first sidewall extending axially between the first end and the second end relative to the longitudinal axis; a second sidewall extending axially between the first end and the second end and radially opposite the first sidewall relative to the longitudinal axis; one or more fans that are configured to generate an ambient airflow that enters the structure through vents positioned along the first sidewall and the second sidewall; and a conveyance system positioned in the structure that is configured to transport a row of cassettes along a path defined in the structure to expose the cassettes to the airflow such that: for a first leg of the path along the first sidewall, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path along the second sidewall, the airflow is directed from the second end of the row to the second end of the row, where each cassette of the row of cassettes is configured to support a plurality of vertically oriented and parallel supports that are coated with a calcium-based sorbent that is configured to absorb CO2from the ambient airflow.

[0131] Clause 18: The air contactor of any of the clauses, where the conveyance system comprises one or more racks that are configured to transport a plurality of vertically stacked rows of cassettes along the path in the structure, where the row is one of the plurality of vertically stacked rows of cassettes.

[0132] Clause 19: The air contactor of any of the clauses, where the conveyance system comprises one or more racks positioned in the structure, and where the one or more racks comprises: a first rack extending along the first sidewall; a second rack extending along the second sidewall; and a third rack extending between the first rack and the second rack at the second end of the structure, where the first rack, the second rack, and the third rack are configured to transport the row of cassettes along the path while maintaining a radial order and orientation of the row of cassettes.

[0133] Clause 20: The air contactor of any of the clauses, where the first rack is configured to translate the row of cassettes axially from the first end of the structure to the second end of the structure along the first sidewall relative to the longitudinal axis; where the third rack is configuredto translate the row of cassettes radially from the first sidewall to the second sidewall relative to the longitudinal axis; and where the second rack is configured to translate the row of cassettes axially from the second end of the structure to the first end of the structure along the second sidewall relative to the longitudinal axis.

[0134] Embodiments disclosed provide systems and methods for direct capture of CO2from ambient atmospheric air (or more simply “ambient air”) that are simpler and more cost-effective than existing methods. In one or more embodiments, the systems and methods may make use of a calcium-based sorbent to absorb CO2from ambient air. The absorbed CO2may then be captured during regeneration or re-processing of the spent sorbent. In one or more embodiments, the formation, use, and processing of the sorbent may be arranged in a continuous, cyclical process that facilitates simple and economical scaling to industrial levels. Thus, through use of embodiments disclosed, an economically feasible industrial process for removing CO2from ambient air may be employed to meaningfully effect atmospheric CO2concentrations.

[0135] While one or more embodiments described have described use of a sorbent for absorbing CO2from ambient air, it should be appreciated that one or more embodiments of the process 10 of FIG. 1 may be utilized to removed other pollutants from ambient air.

[0136] The preceding description is directed to various embodiments. However, one of ordinary skill in the art will understand that the examples disclosed have broad application. The discussion of any embodiment is meant only to be descriptive of that embodiment is not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0137] The drawing figures are not necessarily to scale. Certain features and components may be shown exaggerated in scale or in somewhat schematic form. Some details of conventional elements may not be shown in interest of clarity and conciseness.

[0138] In the description and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to ....” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. As used, the terms “axial” and “axially” generally mean along or parallel to a given axis, such as a central axis of a body or a port. The terms “radial” and “radially” generally mean perpendicular to the given axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. When used (including in the claims), the words “about,” “generally,” “substantially,” “approximately,” and the like, when used in reference to a stated value mean within a range of plus or minus (±) 10% of the stated value.

[0139] Ranges may be expressed as from about one value to about another value and are inclusive unless otherwise indicated. When such a range is expressed, one will appreciate thatanother embodiment is from the one value to the other value, along with all combinations of values within the given range.

[0140] Throughout this application, where patents or publications are referenced, the disclosures of these references in their entireties are intended to be incorporated by reference into this application to more fully describe the state of the art to which the invention pertains, except when these references contradict the statements made here.

[0141] While example embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the provided scope or teachings. The embodiments described are examples only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

Claims

CLAIMSWhat is claimed is:1 . A method for removing carbon dioxide (CO2) from ambient air, the method comprising:(a) coating a plurality of supports with a calcium hydroxide (Ca(OH)2) slurry to form a sorbent on the plurality of supports;(b) conveying the plurality of supports into a structure of an air contactor in a row of a plurality of cassettes, each of the plurality of cassettes supporting a set of the plurality of supports;(c) generating an ambient airflow through the structure;(d) transporting the row along a path in the structure such that: for a first leg of the path, the ambient airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the ambient airflow is directed from the second end of the row to the first end of the row; and(e) absorbing CO2from the ambient airflow into the sorbent during (d).

2. The method of claim 1 , further comprising:(f) processing calcium carbonate (CaCO3) to form the Ca(OH)2 slurry.

3. The method of claim 2, where (f) comprises:(f1) calcining the CaCO3 to produce calcium oxide (CaO); and(f2) slaking the CaO to form the Ca(OH)2 slurry.

4. The method of claim 3, further comprising:(g) removing the sorbent from the plurality of supports after (d); and(h) recycling at least some of the sorbent removed from the plurality of supports to the processing in (f).

5. The method of claim 1 , where (d) comprises:(d1) moving the row along a first sidewall of the structure in the first leg; and(d2) moving the row along a second sidewall of the structure in the second leg.

6. The method of claim 5, where (c) comprises drawing the ambient airflow into vents in both the first sidewall and the second sidewall and expelling the ambient airflow out of one or more fan stacks positioned on a roof of the structure.

7. The method of claim 6, where (d) comprises transporting a plurality of vertically stacked rows of cassettes as a unit along the path in the structure, where the row is one of the plurality of vertically stacked rows.

8. The method of claim 7, where (a) comprises pouring the Ca(OH)2slurry onto the set of supports supported in each of the plurality of cassettes.

9. A plant for removing carbon dioxide (CO2) from ambient air, the plant comprising: a coating assembly that is configured to coat a plurality of supports with a sorbent, where the plurality of supports are supported in a plurality of cassettes; and an air contactor comprising a structure that is configured to receive the plurality of cassettes downstream from the coating assembly, the structure comprising: one or more fans that are configured to induce an ambient airflow through the structure; and a conveyance system that is configured to support the plurality of cassettes in a row and to transport the row along a path defined in the structure to expose the plurality of supports to the ambient airflow and thereby absorb CO2from the ambient airflow into the sorbent, where the path is configured such that: for a first leg of the path, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path, the airflow is directed from the second end of the row to the first end of the row.

10. The plant of claim 9, where each of the plurality of cassettes is configured to support a set of the plurality of supports in a parallel and vertical orientation.11 . The plant of claim 10, where the conveyance system is configured to transport the plurality of cassettes along the path in the structure as a unit of a plurality of vertically stacked rows of cassettes.

12. The plant of claim 11 , where the conveyance system comprises one of more racks to support the plurality of vertically stacked rows of cassettes along the path in the structure.

13. The plant of claim 10, where the structure of the air contactor is an elongate structure including: a first end;a second end spaced from the first end along a longitudinal axis; a first sidewall extending axially between the first end and the second end; and a second sidewall extending axially between the first end and the second end that is radially opposite the first sidewall relative to the longitudinal axis, where the first leg of the path extends along the first sidewall and the second leg of the path extends along the second sidewall.

14. The plant of claim 13, where the conveyance system is configured to transport the row along the first leg of the path such that the first end of the row is closer to the first sidewall than the second end and to transport the row along the second leg of the path such that the second end of the of the row is closer to the second sidewall than the first end of the row.

15. The plant of claim 13, where the first sidewall and the second sidewall each include a plurality of vents, where the structure further includes a roof extending axially between the first end and the second end, and where the one or more fans are supported in one or more fan stacks positioned in the roof such that the ambient airflow enters the structure via the plurality of vents and exits the structure via the one or more fan stacks.

16. The plant of claim 15, further comprising: a calcinerthat is configured to heat calcium carbonate (CaCO3) to liberate CO2and produce calcium oxide (CaO); and a slaker that is configured to hydrate the CaO to form a calcium hydroxide (Ca(OH)2) slurry, where the coating assembly is configured to coat the Ca(OH)2slurry onto the plurality of supports as the sorbent.

17. An air contactor for contacting ambient air with a sorbent to produce a CO2-depleted airflow, the air contactor comprising: a structure including: a first end; a second end spaced from the first end along a longitudinal axis; a first sidewall extending axially between the first end and the second end relative to the longitudinal axis; a second sidewall extending axially between the first end and the second end and radially opposite the first sidewall relative to the longitudinal axis; one or more fans that are configured to generate an ambient airflow that enters the structure through vents positioned along the first sidewall and the second sidewall; anda conveyance system positioned in the structure that is configured to transport a row of cassettes along a path defined in the structure to expose the cassettes to the airflow such that: for a first leg of the path along the first sidewall, the airflow is directed from a first end of the row to a second end of the row, the second end of the row being opposite the first end of the row; and for a second leg of the path along the second sidewall, the airflow is directed from the second end of the row to the second end of the row, where each cassette of the row of cassettes is configured to support a plurality of vertically oriented and parallel supports that are coated with a calcium-based sorbent that is configured to absorb CO2 from the ambient airflow.

18. The air contactor of claim 17, where the conveyance system comprises one or more racks that are configured to transport a plurality of vertically stacked rows of cassettes along the path in the structure, where the row is one of the plurality of vertically stacked rows of cassettes.

19. The air contactor of claim 17, where the conveyance system comprises one or more racks positioned in the structure, and where the one or more racks comprises: a first rack extending along the first sidewall; a second rack extending along the second sidewall; and a third rack extending between the first rack and the second rack at the second end of the structure, where the first rack, the second rack, and the third rack are configured to transport the row of cassettes along the path while maintaining a radial order and orientation of the row of cassettes.

20. The air contactor of claim 19, where the first rack is configured to translate the row of cassettes axially from the first end of the structure to the second end of the structure along the first sidewall relative to the longitudinal axis; where the third rack is configured to translate the row of cassettes radially from the first sidewall to the second sidewall relative to the longitudinal axis; and where the second rack is configured to translate the row of cassettes axially from the second end of the structure to the first end of the structure along the second sidewall relative to the longitudinal axis.

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