Rotating bed and method for direct capture of CO2 from air

Abstract

A system and method are provided for implementing direct air capture using a rotating sorbent bed configuration. The rotating sorbent bed is supported on wheels that function as a framework structure for supporting the sorbent bed. The sorbent bed can include one or more monoliths that form a support material for the sorbent bed, and sorbents supported on the one or more monoliths. The rotational path of the sorbent bed passes through an enclosure that allows for sealing of portions of the sorbent bed within the enclosure. Optionally, the enclosure can contain multiple subzones that facilitate temperature and / or pressure control within the enclosure while enabling recovery of a high-purity CO stream from the desorption zone. The rotating sorbent bed configuration can enable continuous or semi-continuous capture of CO while reducing or minimizing contact of the sorbent bed with oxygen at high temperatures.

Description

[Technical Field]

[0001] A system and method for using a rotating bed contactor for the direct capture of CO2 from air is provided. [Background technology]

[0002] CO2 capture and sequestration can contribute to efforts to reduce or minimize the amount of CO2 introduced into the atmosphere by various commercial, residential, and / or industrial processes. One option is to attempt to capture CO2 as it is produced at various types of point sources. Another option is to attempt to remove CO2 directly from the air.

[0003] Some of the difficulties with direct air capture relate to the relatively low CO2 concentration in the atmosphere. Typical CO2 concentrations in air are on the order of 400 parts per million by volume (vppm). Due to the relatively low CO2 concentration compared to other air components, achieving high CO2 loadings at fast adsorption rates in adsorbents can be difficult and lead to increased material costs. Additionally, the amount of energy used per captured CO2 molecule can also be high, in part due to the relatively low density of CO2 that can be adsorbed in typical adsorbents based on the low concentration of CO2 in the atmosphere. It would be beneficial to have improved systems and methods for capturing CO2 from air that can reduce or minimize associated capital costs and / or energy requirements.

[0004] There are two basic strategies for managing the multiple streams to which the adsorbent (or sorbent) is exposed. One strategy is to maintain the adsorbent at a constant volume corresponding to the adsorbent environment and then sequentially introduce various flow streams into the adsorbent environment to contact the adsorbent. This strategy requires complex process stream management to prevent the different flow streams from mixing, while still reducing or minimizing the time required to switch between the various flow streams. A further complication is that to have a continuous process in which air is continuously introduced for CO2 removal, multiple adsorbent beds are required in parallel. Each parallel bed increases the complexity of the piping and manifolds required to manage the process streams.

[0005] Another option is to allow the adsorbent to move, allowing the piping for the process stream to be fixed. This has the advantage of simplifying the transportation of the gas stream for the direct air capture process. However, previous methods for allowing the adsorbent to move into the gas stream have suffered from various mechanical and / or reliability challenges. What is needed is an improved method for performing direct air capture that can simplify the handling of the gas stream while still providing mechanical stability and reliability.

[0006] U.S. Patent No. 9,925,488 describes a direct air capture system with multiple monoliths arranged on a closed-loop track. As the monoliths move around the track, CO2 is adsorbed. One location on the track contains a box. If the box is at a different level from the track, the monolith is moved into the box, sealed to the box, and then exposed to conditions for CO2 desorption. Continuous removal and reinsertion of the monolith into the track creates the potential for mechanical and / or reliability challenges. If the box is at the track level, the monolith moves into the box and forms a seal with the box to provide a sealed environment for CO2 desorption. Achieving the seal necessary to maintain the separation environment poses various challenges. Additionally, scaling this type of design to a size appropriate for commercial-scale CO2 removal can present structural design challenges.

[0007] European Patent Publication No. 3725391 describes a direct air capture device using a linear array of vertical sorbent beds with start / stop movement of a sliding door surrounding the bed. The reliability of this type of design is reduced by the start / stop movement of the process equipment along the linear array of beds, which typically requires complex hoses and mechanical swivel joints in the piping system to accommodate the movement of the process equipment. Requiring such movement of process equipment is known to be less reliable than permanently installed, fixed piping and equipment. Because reliable mechanical swivel joints are limited to small diameters, this type of configuration is further limited by the fact that the hose, with one fixed end and one moving end, cannot rotate 360° without breaking. This explains why the equipment in this configuration moves in a linear fashion rather than a closed loop, thereby increasing process costs due to unproductive time while the process equipment moves from the end of the sorbent bed back to the beginning. It should be noted that this type of design can experience sealing challenges similar to those of the design in U.S. Pat. No. 9,925,488.

[0008] U.S. Patent No. 11,014,040 describes a horizontal adsorbent bed that rotates through zones defined by a stator. The configuration includes a floating seal with a metal bellows or diaphragm to bias the seal, which is known to be susceptible to mechanical fatigue failure in thermal cycling processes such as the adsorptive gas separation process described herein. The cost of this type of design is increased by the use of fluid passages with port connections to the rotor assembly, which inevitably have higher pressure drops and reduced uniformity in flow distribution, both of which would result in higher operating costs.

[0009] U.S. Patent No. 9,227,153 describes various configurations for implementing direct air capture. Some configurations involve the use of thin sheets of sorbent that are oscillated back and forth between positions outside and within the enclosure to allow for separation of the sorbent within the enclosure during CO2 adsorption. Other configurations involve the use of sorbent pellets that are circulated to allow for cyclical adsorption and desorption of CO2.

[0010] U.S. Patent No. 8,974,576 describes the use of a rotating monolith having an adsorbent material for the adsorption of CO from a mixture of gases, but does not describe a housing that allows different portions of the monolith to be exposed to adsorption and desorption conditions simultaneously.

[0011] U.S. Patent No. 8,052,783 describes a rotating adsorber for the continuous bulk separation of volatile organic carbons from a fluid stream. A majority of the adsorber is exposed to the fluid stream for adsorption of the volatile organic carbons. A small portion of the adsorber is in a desorption zone, where a desorption fluid is used to desorb the volatile organics. No structure or device is described for managing the fluid flow in the desorption zone. Desorption is further enhanced by the use of an electric current in the portion of the wheel that is in the regeneration zone. Note that the electric current is used to reduce or minimize the temperature change of the adsorber as it passes through the desorption zone.

[0012] U.S. Patent No. 9,120,049 describes a rotary valve assembly for performing a swing adsorption process in a sealed environment. The adsorbent material is disposed in a separately sealed chamber. The rotary valve includes both a rotor and a stator having an opening. When an opening in the rotor aligns with an opening in the stator, the valve is "opened" and gas can flow into the chamber corresponding to the aligned opening. It should be noted that passing large volumes of fluid through a valve of the type described in this reference can result in a significant additional pressure drop.

[0013] U.S. Patent No. 7,972,422 describes a system for continuous removal of gases from a gas mixture in a sealed environment. Cartridges containing adsorbent material are used for adsorption of H2S from a gas stream. The cartridges can be rotated to allow adsorption and desorption within the sealed environment.

[0014] It should be noted that U.S. Patent Nos. 9,120,049 and 7,972,422 are examples of rotating adsorbent configurations in which the entire adsorbent bed is located within one or more pressure-controlled volumes during operation. This type of configuration is characterized by multiple valves that control the flow of fluid into and out of the volume containing the adsorbent bed. It should be noted that air can be used as the input gas stream in this type of configuration. However, in this type of configuration, such air passes through multiple valves and conduits, and therefore, some type of compressor is used to maintain a target combination of flow rate and pressure. While this type of configuration is effective in maintaining control of pressure and flow rate during the adsorption / desorption cycle, practical considerations limit the possible size or scale of this type of configuration. For example, as a practical matter, this type of configuration requires valves, such as rotary valves or poppet valves, to maintain control over the fluid flow within the vessel. These types of commercially available valves are limited in size. Additionally, the pressure drop involved in delivering fluid flow through the valves and manifolds required by this type of configuration results in a large pressure drop at the volumetric flow rates required for direct air capture. Thus, even if the target pressure within the volume containing the adsorbent bed is near ambient, significant compression is required. Summary of the Invention

[0015] In one aspect, a system for CO2 sorption is provided. The system includes a sorbent bed housing. The system further includes a wheel framework structure within the sorbent bed housing. The system further includes a sorbent bed. The sorbent bed includes a support material corresponding to one or more monoliths, the one or more monoliths being supported by the wheel framework structure. The support material further includes a first surface, a second surface, and a plurality of channels providing a flow path between the first surface of the support material and the second surface of the support material. The sorbent bed further includes a sorbent having selectivity for CO2 sorption supported on the support material, at least a portion of the sorbent being supported on one or more surfaces within the plurality of channels. The system further includes at least one fan or blower associated with the sorbent bed housing, the at least one fan or blower being in fluid communication with a first portion of the plurality of channels. The system further includes at least one cover plate. The system further includes one or more cover plate seals attached to the one or more cover plates, wherein a second portion of the plurality of channels is within a desorption zone volume defined by the at least one cover plate and the one or more cover plate seals. Depending on the embodiment, the one or more cover plate seals provide a) a seal between the at least one cover plate and a first surface of the carrier material, b) a seal between the at least one cover plate and a second surface of the carrier material, or c) a combination of a) and b). The system further includes one or more input flow conduits providing fluid communication between the at least one or more gas sources and the desorption zone volume. Additionally, the system includes at least one output flow conduit in fluid communication with the desorption zone volume.

[0016] In another aspect, a method for adsorbing (or sorbing) CO2 is provided. The method includes rotating a wheel framework structure supporting an adsorbent (or sorbent) bed, the adsorbent bed including a support material including one or more monoliths and an adsorbent selective for adsorption of CO2 supported on the support material. The support material further includes a first surface, a second surface, and a plurality of channels providing a flow path between the first surface of the support material and the second surface of the support material, and at least a portion of the adsorbent is supported on one or more surfaces within the plurality of channels. The method further includes exposing a first gas stream comprising 15% to 25% by volume O2 and 100 vppm to 650 vppm CO2 to a first portion of the adsorbent bed outside the desorption zone volume, the first gas stream having a temperature between 0°C and 40°C. Additionally, the method includes exposing a plurality of gas streams to a second portion of the adsorbent bed within a desorption zone volume, the desorption zone volume being defined by at least one cover plate and one or more cover plate seals, the one or more cover plate seals providing a) a seal between the at least one cover plate and a first surface of the support material, b) a seal between the at least one cover plate and a second surface of the support material, or c) a combination thereof. In some embodiments, exposing the plurality of gas streams to the second portion of the adsorbent bed includes sequentially exposing the second portion of the adsorbent bed to a purge gas stream to form a purge exhaust and a steam stream having a temperature between 80°C and 180°C to form a CO2-containing output stream. In various embodiments, rotation of the wheel framework structure alternates between the first portion of the adsorbent bed outside the desorption zone volume and the portion of the adsorbent bed corresponding to the second portion of the adsorbent bed within the desorption zone volume. [Brief explanation of the drawings]

[0017] [Figure 1] 1 illustrates aspects of an exemplary configuration for the adsorption of CO2 from a gas stream using an adsorbent bed supported on a rotating wheel framework structure. [Figure 2] 2 shows a top view of a portion of the configuration shown in FIG. 1. [Figure 3]FIG. 1 shows a perspective view of the rotor assembly and the detachment zone cover plate. [Figure 4] 4 shows an exploded view of the configuration shown in FIG. 3. [Figure 5] 1 shows an example of the configuration of the desorption zone. [Figure 6] 1 shows an alternative configuration including two adsorbent beds supported on a rotating wheel framework structure. DETAILED DESCRIPTION OF THE INVENTION

[0018] All numerical values ​​within the detailed description and claims herein are modified by values ​​indicated as "about" or "approximately" to account for experimental error and variations that would be expected by one of ordinary skill in the art.

[0019] overview In various aspects, systems and methods are provided for performing direct air capture using a rotating adsorbent (or sorbent) bed configuration. The rotating adsorbent bed is supported on wheels, which serve as a framework structure for supporting the adsorbent bed. The adsorbent bed can include one or more monoliths that form the support material for the adsorbent bed, and adsorbents supported on the one or more monoliths. The adsorbent bed can be oriented in any convenient manner, such as a horizontal or vertical configuration. The rotational path of the adsorbent bed passes through a housing that allows for sealing of portions of the adsorbent bed within the housing. Optionally, the housing can contain multiple subzones that facilitate temperature and / or pressure control within the housing while enabling recovery of a high-purity CO stream from the desorption zone. The rotating adsorbent bed configuration can enable continuous or semi-continuous capture of CO while reducing or minimizing contact of the adsorbent bed with oxygen at high temperatures.

[0020] Traditionally, direct air capture using a rotating sorbent bed configuration has presented challenges due to competing considerations. For the adsorption portion of the adsorption (or sorption) / desorption process, the low concentration of CO in air necessitates exposing large volumes of air to the sorbent bed to achieve sufficient CO capture. However, due to the large volumes of air that need to be processed, it is desirable to reduce or minimize the energy associated with processing such air on a volumetric basis. To accomplish this, it is desirable to reduce or minimize the pressure drop associated with exposing air to the rotating sorbent bed, so as to reduce or minimize the amount of air-moving force required to maintain air flow for contact with the sorbent bed.

[0021] While the adsorption process benefits from reduced or minimized airflow, the desorption portion of the adsorption / desorption process cycle has different considerations. First, the desorption process must be carried out in a well-controlled manner to allow for desorption of CO while reducing or minimizing loss of CO back to the ambient environment. Second, for at least some types of adsorbents (such as some amine-based adsorbents), the adsorbent material can be sensitive to oxygen exposure at elevated temperatures. This generally does not pose any problems during the adsorption step, but higher temperatures are often used for desorption. For such adsorbents that are sensitive to the combination of oxygen at elevated temperatures, the desorption step must be sufficiently separated from the adsorption step so that decomposition of the adsorbent material during desorption is reduced or minimized.

[0022] In various aspects, systems and methods are provided that enable control over the desorption zone environment while reducing or minimizing the energy costs of implementing direct air capture. This is achieved by enabling control over the desorption zone environment using a desorption zone enclosure that is sealed to the adsorption zone. As part of sealing the desorption zone to the adsorption zone, a positive pressure can be maintained at the seal between the desorption zone and the adsorption zone, so that any gas flow that occurs across the seal corresponds to an outflow of gas from the desorption zone to the adsorption zone. Optionally, the desorption zone can accommodate multiple subzones. In addition to enabling further control over the desorption zone environment, the use of multiple purged seals within the desorption zone can enable configurations in which a desorption subzone is two or more purged seals separate from the adsorption zone. By using a desorption zone enclosure, a simplified configuration can be used to expose air to the adsorbent bed, thereby reducing or minimizing the amount of air movement force required. To reduce or minimize the amount of air movement force required, in some aspects, the airflow can be controlled using one or more fans as opposed to using higher energy input blowers or compressors.

[0023] Because the rotating sorbent bed is a continuous structure, concerns about maintaining a separate environment within the enclosure during sorbent bed movement are reduced or minimized. Specifically, because the sorbent bed's support material is always present, the support material (i.e., one or more monoliths) is always in close proximity to the cover plate seal. This allows a sealed condition to be continuously maintained, thereby reducing or minimizing the risk of air entering the enclosure. Additionally, a positive pressure can be continuously maintained within the sealed area to prevent air from entering the enclosure. As a result, the only air transported to the desorption zone volume is any air optionally carried to the desorption zone within the sorbent bed itself. By controlling the air inflow into the desorption zone volume, the flow within the desorption zone can be simplified. A first flow can correspond to a purge gas to remove any air remaining within the rotating wheel as the wheel enters the desorption zone. A second gas (e.g., steam) flow can then be used to increase the temperature and desorb CO2. A cooling gas (such as N2) can then be used to return the adsorbent to a lower temperature before the wheel rotates that portion of the adsorbent out of the desorption zone. Because substantially the only air in the desorption zone volume corresponds to the air in the adsorbent bed volume as it enters the zone, gas flow in the desorption zone can be maintained continuously. Note that additional seals can be present within the desorption zone volume to define different regions or subzones within the desorption zone so that mixing of the various streams within the desorption zone is reduced, minimized, or eliminated.

[0024] Additionally, the rotating adsorbent bed can rotate in a single direction, which avoids the need for the added complexity of having a reciprocating motion and / or some other type of counter-directional motion to move the adsorbent into and out of the enclosure.

[0025] It should be noted that the above temperature and oxygen management methods are in contrast to conventional designs in which separate adsorbent monolith pieces are moved into and out of an enclosure. In such contrasting designs, air can enter the enclosure as the monolith pieces are moved into and out of the enclosure. Therefore, a separate purge step is required to remove air from the enclosure. Additionally, having doors / openings that open and close increases the mechanical complexity of the system and reduces reliability.

[0026] In some embodiments, the housing can correspond to the cover plates above and below the adsorbent bed structure. The cover plates can also be referred to as regeneration plates. The cover / regeneration plates provide part of the definition of the desorption zone. The desorption zone corresponds to the volume within the cover / regeneration plate and the volume defined by the seal between the cover / regeneration plate and the rotating adsorbent bed. Typically, the seals on the two sides of the adsorbent bed will be aligned so that the desorption zone volume is defined based on drawing a connecting line between the seal on one side of the adsorbent bed and the seal on the other side of the adsorbent bed. If the seals are not aligned, the desorption zone volume can then be identified by starting from the seal on the side of the adsorbent bed that receives the airflow and then drawing a line parallel to the axis of rotation of the adsorbent bed from the seal until it reaches the other side of the adsorbent bed. This defines the portion of the adsorbent bed that is within the desorption zone volume. The portion of the adsorbent bed outside the desorption zone volume is within the adsorption zone. Note that temperature adjustment can also be performed in the desorption zone.

[0027] In some embodiments, the adsorbent bed can be continuously rotated. In such embodiments, gas flow in both the adsorption and desorption zones can be continuous. In such embodiments, the seal for the cover plate can correspond to a "purged" seal, with part of the sealing function being provided by the higher pressure in the sealed region (i.e., in the desorption zone). Thus, the seal can correspond to a contactless seal, such as a wiper seal, that is close to, but does not contact, the surface of the monolith. The use of a contactless seal avoids the difficulties associated with mechanically biasing the seal, which can break down the seal over time and reduce reliability. In this type of embodiment, multiple gas streams can be used in the desorption zone, such that the adsorbent bed is sequentially exposed to multiple gas streams as it rotates through the desorption zone.

[0028] In other aspects, contact seals (such as roller seals) could potentially be used with continuously rotating adsorbent beds. While this may reduce the reliability of the seal, it can reduce or minimize the need to use purge gas at the seal interface. Roller seals and contact wiper seals are examples of seals that can be used in this type of configuration.

[0029] In yet other embodiments, the adsorbent bed can be rotated in fixed increments such that the adsorbent bed periodically starts and stops moving to reposition the portion of the wheel within the desorption zone (i.e., the sealed area defined by the cover plate). In this type of embodiment, because the adsorbent bed is not moving for a portion of the time, an inflatable seal or another type of contact seal (such as a roller seal) could potentially be used. Wiper seals could also be used in this type of embodiment. This could be combined with maintaining a higher pressure in the desorption zone to avoid introducing air into the desorption zone. In this type of embodiment, the multiple gas streams used in the desorption zone can be exposed to the adsorbent bed in a temporally sequential manner, as opposed to the spatially sequential exposure used during continuous movement of the adsorbent bed.

[0030] During operation, a portion of the adsorbent bed in the adsorption zone can be exposed to a flow of air (or another gas stream with a low concentration of CO) to enable adsorption of CO by the adsorbent supported on the monolith. The portion of the adsorbent bed in the desorption zone can be exposed to: a) an initial purge gas to remove air contained in the adsorbent bed as the bed rotates into the desorption zone; b) steam to increase the temperature of the adsorbent bed in the desorption zone and desorb CO; and c) a temperature-regulating gas, such as nitrogen, to cool the monolith before exiting the desorption zone. In some embodiments, the multiple gas streams can be substantially parallel flows to reduce or minimize mixing. In other embodiments, one or more additional seals can be present in the desorption zone to define separate regions (or subzones) for the adsorbent bed within the desorption zone. For example, additional seals can be used to maintain separate subzones exposed to steam and temperature-regulating gas. In this discussion, spatial regions within the desorption zone exposed to different gas streams are defined as subzones. Preferably, such subzones can be separated by internal seals within the desorption zone, thereby reducing, minimizing, or eliminating gas mixing for such volumes. Seals can be used to form subzones above or below the adsorbent bed. Note that for adsorbent beds constructed of porous materials, some mixing of gases between subzones can potentially occur within the adsorbent bed.

[0031] Generally, the adsorption and desorption zones can have any convenient size, although the adsorption zone will typically correspond to a larger portion of the adsorbent bed than the desorption zone. In various embodiments, the volume defined inside the enclosure defined by the cover plate and seal (i.e., the desorption zone) can contain no more than 50% by volume, or no more than 40% by volume, or no more than 30% by volume, or no more than 20% by volume of the adsorbent bed, such as a minimum of 5.0% by volume of the rotating wheel volume, or possibly even less.

[0032] In various embodiments, the systems and methods described herein can have one or more of the following features: 1) In some embodiments, a purged seal between the adsorption zone and the desorption zone can provide gas flow across the seal from the desorption zone to the adsorption zone. 2) In some embodiments, the enclosure for the desorption zone can be located within the adsorption zone volume. This means that the gas flow (e.g., air) in the adsorption zone can impinge on at least one surface of the desorption zone where the average flow direction of the gas flow in the adsorption zone is substantially perpendicular to the surface. This is in contrast to configurations where the enclosure corresponds to the full height of the separation between the fan or blower and the adsorbent bed, for example, so that air from the fan or blower does not impinge on the top surface of the enclosure. 3) In some embodiments, the adsorption zone can be in direct fluid communication with the fan or blower without an intervening valve between the fan or blower and the adsorption zone. Alternatively, the fan or blower can be in direct fluid communication with the rotating adsorbent bed without an intervening valve between the fan or blower and the rotating adsorbent bed. 4) In some embodiments where the desorption zone comprises multiple subzones, the desorption subzones may be separated from the desorption zone by at least two purged seals, such as at least one internal seal and a cover plate seal.

[0033] Adsorbent bed structure and wheel framework structure In various embodiments, the CO adsorption / desorption process can be carried out using a sorbent bed corresponding to the sorbent supported on a sorbent support material (such as one or more monoliths). The sorbent bed is supported by a wheel framework structure that functions as a rotor. The sorbent can be supported on the support material in any convenient manner, such as having the sorbent supported on the interior surface of channels that pass through the sorbent support material. The resulting sorbent bed can provide a high surface area for contact of the CO2-containing gas while still allowing air to pass through the sorbent bed with a reduced or minimized pressure drop.

[0034] One option for providing this type of structure is to use a sorbent bed that includes multiple channels that run through the sorbent bed generally parallel to the axis of rotation of the sorbent bed. The channels can have any convenient shape that allows for the loading of sorbent material on the inner surface of the channel. Based on packing density considerations, square, rectangular, or hexagonal shapes can be beneficial for multiple channels, although round or other convenient shapes can also be used.

[0035] The framework structure for supporting the adsorbent bed can correspond to a wheel. The wheel framework structure can be constructed from any convenient material that provides sufficient structural integrity. Stainless steel (or other types of steel) is an example of a suitable material for forming the framework structure. The support material of the adsorbent bed (e.g., one or more monoliths) can be placed on / within the wheel framework structure. In some embodiments, the adsorbent bed can be attached to the wheel. In other embodiments, wedges, pins, and / or other structures can be used to hold the adsorbent bed in place in the wheel framework structure through friction. In some embodiments, the wheel framework structure can also function as a rotor, with the wheel directly attached and / or part of the same shaft used to rotate the adsorbent bed. In other embodiments, the wheel framework structure can be mechanically coupled to the rotor via one or more gears. Note that if gears are used to rotate the adsorbent bed, the mechanical coupling of the gears to the wheel framework structure can be near the center of the wheel, or gears around the outer edge of the wheel framework structure can be used.

[0036] The one or more monoliths corresponding to the adsorbent support material can be constructed from a material that provides sufficient structural stability to the support material during rotation of the adsorbent bed. The size of the adsorbent bed can vary, but on a commercial scale, the diameter of the adsorbent bed can range from 1.0 meter to 25 meters, and the thickness (i.e., depth) can range from 0.2 meters to 2.0 meters. Suitable materials for forming the monolith (or for forming pieces that can be assembled to form an approximately disk-shaped piece of support material) can include refractory metal oxides, metals, and ceramics. Some polymer systems can also provide sufficient structural stability to form the adsorbent bed, provided the adsorbent bed has sufficient thickness. Examples of support materials include, but are not limited to, silica, alumina, titanium, steel (including stainless steel), and silicon carbide.

[0037] Preferably, the support material can be a monolith with the adsorbent supported on at least a portion of the surface within the channels passing through the support material. More generally, the one or more monoliths used as the support material can form any type of continuous structure with sufficient structural stability to rotate through the desorption zone. Thus, support materials that are assemblies of smaller monoliths (e.g., pie-shaped sections) can also be used to form the support material for the adsorbent bed. The support material (e.g., monolith, assembly of smaller pieces) can preferably have a high density of flow channels or cells, such as 20-2000 channels per square inch, 100-2000 channels per square inch, 20-1000 channels per square inch, or 100-1000 channels per square inch. Examples of several types of monoliths are commercially available, such as CELCOR® monoliths available from Corning. Adsorbents, such as amine-based adsorbents, can be supported on the interior surfaces of these channels. This type of structure can provide a high surface area of ​​adsorbent while reducing or minimizing the pressure drop as the gas passes through the adsorbent bed.

[0038] After forming the monolith or forming multiple pieces that can be assembled to form the support material, the adsorbent can be added to the surface of the support material. For example, a washcoat of an amine-based adsorbent can be applied to the surface of the channels in the monolith (or channels in multiple monolith pieces). This can provide a relatively uniform distribution of the adsorbent on the inner surface of the channel. Note that the adsorbent does not need to be incorporated into the entire length of the channel. While the thickness of the adsorbent support material can be selected based in part on structural stability considerations, the depth of the adsorbent in the channel (i.e., the adsorbent bed) can be any convenient value that is equal to or less than the thickness of the channels in the adsorbent support material.

[0039] In this discussion, reference may be made to the leading edge of the adsorbent bed and the trailing edge of the adsorbent bed. The leading edge of the adsorbent bed generally refers to the edge of the adsorbent bed that is first exposed to air (or another CO2-containing stream) when the adsorbent bed is in the adsorption zone. The trailing edge of the adsorbent bed corresponds to the opposite end of the adsorbent bed.

[0040] Configuration example FIG. 1 shows a cross-sectional view of an example of a configuration for implementing direct air capture using a rotating adsorbent bed. The example shown in FIG. 1 corresponds to a horizontal rotating adsorbent bed configuration. In FIG. 1, a rotor assembly 110 (including a wheel framework structure) is contained within a rotor housing 101. The rotor assembly 110 provides support for one or more monoliths corresponding to an adsorbent support material 115. The CO2 adsorbent material (such as an amine-based adsorbent) is supported on one or more surfaces of the support material 115, such as on the inner surfaces of channels that pass through the support material 115 in a direction generally perpendicular to the axis of rotation of the adsorbent bed. The CO2 adsorbent material can be supported on the support material 115 in any convenient manner. For example, the adsorbent material can be applied as a washcoat. In the example shown in FIG. 1, the wheel framework structure / rotor assembly 110 is attached to a central rotor support 105, such as by using a bearing assembly 107.

[0041] In the exemplary configuration shown in FIG. 1 , rotor support 105 rotates rotor assembly 110 so that the portion of the adsorbent bed contained within desorption zone 130 changes over time. In other embodiments, movement of the adsorbent bed can be accomplished by mechanically coupling the adsorbent bed to the rotor using gears. For example, in another embodiment, the central support can function primarily as a support but cannot provide a force to rotate the adsorbent bed. Instead, gears along the outer edge of the framework structure can engage the framework structure to provide rotation of the adsorbent bed. More generally, any convenient method for rotating the adsorbent bed can be used.

[0042] In the example shown in FIG. 1 , the rotor housing 101 includes an upper fan shroud 102 and a lower fan shroud 103. The upper fan shroud 102 and the lower fan shroud 103 help provide a higher degree of laminar airflow within the rotor housing during operation. In other configurations, one or both of the upper fan shroud 102 and the lower fan shroud 103 may be optional. In FIG. 1 , a fan 108 is shown below the rotor assembly 110 to drive air through the sorbent bed (such as through channels in the support material 115). Depending on the configuration, the fan 108 can alternatively be located above the sorbent bed and draw air through the bed, or at least one fan can be located both above and below the sorbent bed. Yet another option could be to use ductwork to direct air from the fan to the sorbent bed. After passing through the sorbent bed, the air (partially depleted of CO2) exits the upper fan shroud 102. Depending on the configuration, any convenient number of fans, blowers, and / or other systems for generating air movement can be used to facilitate air flow through the adsorbent bed (e.g., through the channels of the support material 115).

[0043] Note that in the example shown in FIG. 1 , the diameter of the rotor assembly 110 (and / or the diameter of the adsorbent bed) appears to be smaller than the diameter / length of the rotor housing 101. This is primarily for convenience in illustrating the different components shown in FIG. 1 . In various embodiments, air bypass around the adsorbent bed can be reduced or minimized by either matching the size of the adsorbent bed to the rotor housing and / or adding additional structural / design features to minimize air flow bypassing the bed. However, it should also be noted that in embodiments where air is the gas stream for the adsorption zone, small amounts of CO2 bypass are less of a concern compared to applications where flue gas or other high CO2 concentration streams are used as the gas stream for the adsorption zone.

[0044] 1, the desorption zone 130 is the volume defined by the upper regenerative cover 132, the lower regenerative cover 138, and the seals (not shown) support material 115 and the upper regenerative cover 132 and the lower regenerative cover 138. To minimize or prevent gas migration from outside the desorption zone into the desorption zone (except for air carried into the desorption zone within the adsorbent bed 115), in some embodiments, the seals for the upper regenerative cover 132 and the lower regenerative cover 138 can be aligned.

[0045] In the example shown in FIG. 1 , the flow within the desorption zone 130 is countercurrent to the flow outside the desorption zone. In other words, outside the desorption zone 130, air moves from bottom to top through the adsorbent bed 115. Within the desorption zone 130, the various flows move from top to bottom through the adsorbent bed 115. In other embodiments, co-current flow inside and outside the desorption zone can be used. In still other configurations, counter-current flow can be used, with the flow in the adsorption zone moving from top to bottom and the flow in the desorption zone moving from bottom to top. It should be further noted that the adsorbent beds can be mounted in any other convenient manner. For example, the adsorbent beds can be mounted vertically, with the axis of rotation perpendicular to the direction of gravitational attraction.

[0046] 1 , the desorption zone 130 includes at least one gas distribution manifold 142 and at least one collection manifold 148. The gas distribution manifold 142 provides various gases used in the desorption zone. Depending on the embodiment, these may include one or more of: a) an initial seal purge gas 153 for maintaining a positive pressure within the desorption zone relative to the volume outside the desorption zone; b) steam 155 for heating the adsorbent bed 115 to facilitate desorption of CO; c) a temperature adjustment gas 157 (such as N) for cooling the adsorbent bed 115 after desorption of CO; and d) a final seal purge gas for maintaining a positive pressure within the desorption zone relative to the volume outside the desorption zone. Generally, the streams in the desorption zone will include at least steam and a temperature adjustment gas. In various embodiments where air is potentially carried to the desorption zone within the wheel, an initial purge gas may also be present both to maintain a positive pressure within the desorption zone relative to the volume outside the desorption zone and to purge any air (oxygen-containing gas) within the wheel prior to exposing the supported adsorbent to the vapor.

[0047] The collection manifold 148 can collect the fluid streams passing through the channels in the support material 115. The first collection manifold and / or a first portion of the collection manifold can collect air exiting the adsorbent bed during the purge gas flow 153. The second collection manifold and / or a second portion of the collection manifold can collect steam, liquid water, and CO2 during the vapor flow 155. Note that part of the heat transfer from the vapor to the adsorbent bed during desorption is based on condensation of the vapor. Therefore, even if liquid water is not introduced, some liquid water will typically be present in the product of the desorption zone. Optionally, separate manifolds / collection troughs can be provided for separate collection of the liquid product (water) and the gas-phase products (water vapor and CO2) exiting the adsorbent bed during exposure to the vapor flow 155. In some preferred embodiments, liquid water is not introduced into the desorption zone as part of the vapor flow to limit the possibility of water forming a continuous liquid phase across the width of the channel, which could restrict air flow through the channels in the support material 115. The collected liquid water, steam, and CO2 output 165 produced in vapor stream 155 can be further processed in any convenient manner. For example, separation can be performed to recover CO2 as a higher purity stream. The CO2 can then be sequestered and / or used as input for another process. A third collection manifold and / or a third portion of the collection manifold can collect the output stream produced during exposure of temperature conditioning gas 157 to the adsorbent bed for cooling of the bed. The output stream can typically have a higher water vapor content than the initial water vapor content of the temperature conditioning gas due to evaporation of water from the bed during the cooling step. The evaporation of water further assists in cooling the bed.

[0048] In the exemplary configuration shown in Figure 1, various elements may be in fluid communication. For example, in Figure 1, input streams 153, 155, and 157 are in fluid communication with desorption zone 130 through upper manifold 142. Upper manifold 142 is in direct fluid communication with desorption zone 130. Input streams 153, 155, and 157 are in indirect fluid communication with desorption zone 130. As another example, channels in support material 115 (and thus, adsorbent beds) may be in direct fluid communication with fan 108. Other examples of direct and indirect fluid communication are described herein and illustrated in the figures.

[0049] FIG. 2 shows a plan (top-down) view of the configuration shown in FIG. 1. As shown in FIG. 2, the majority of the adsorbent bed (and therefore the majority of the support material 115) is in the adsorption zone 270, and a smaller portion of the adsorbent bed is in the desorption zone 130. As the adsorbent bed rotates, the portion of the support material 115 in the desorption zone 130 changes over time. In the view shown in FIG. 2, the upper regenerator cover 132 and the upper manifold 142 are shown. Because of the top-down view, the lower regenerator cover and the lower manifold are not shown in FIG. 2. FIG. 2 also shows an input flow pipe 250. One or more input flow pipes 250 can be used to provide various input flows to the upper manifold 142. Similar pipes (not shown) can be used to carry product or wastewater collected by the lower manifold.

[0050] 3 shows a perspective view of the rotor assembly 110, the carrier material 115, and the upper regenerative cover 132. The upper regenerative cover 132 defines the upper volume of the desorption zone 130 from FIG.

[0051] Figure 4 shows an exploded view of the configuration shown in Figure 3. The exploded view of Figure 4 is provided to illustrate the location of the seal 432 between the upper regenerative cover 132 and the rotor assembly 110 / carrier material 115. Similarly, a seal (not shown) can be provided between the lower regenerative cover and the rotor assembly / carrier material.

[0052] Adsorption Zone Operation The processes during operation of a rotating adsorbent bed can be broadly divided into processes in the adsorption zone and processes in the desorption zone.

[0053] In the adsorption zone, the adsorbent bed is exposed to a CO2-containing gas stream. In various embodiments, the CO2-containing gas stream is air. More generally, the CO2-containing gas stream can be a gas stream having a CO2 content of 650 vppm or less, or 500 vppm or less, or 400 vppm or less, such as a minimum of 50 vppm, or possibly even lower.

[0054] Air also contains O. Air typically contains approximately 20% O by volume. However, CO-containing gas streams can contain other amounts of O. In some embodiments, CO-containing gas streams can contain 10% to 25% O by volume, or 15% to 25% O by volume. For this type of CO-containing stream, the rotating wheel adsorber described herein provides the advantage of reducing or minimizing the unexpected influx of O into the desorption zone, thereby reducing or minimizing the potential for degradation of the adsorbent material during the desorption process. In other embodiments, CO-containing streams can have any convenient O content. In optional embodiments, CO-containing streams can have an O content of 1.0% or less by volume, or 0.1% or less by volume.

[0055] In various aspects, the length of the adsorption process is determined in part by the rotational speed of the adsorbent bed. In other words, for a given portion of the adsorbent bed, the adsorption process begins when the portion of the adsorbent bed exits the desorption zone and continues until the adsorbent bed re-enters the desorption zone. Thus, the length of the adsorption process can be selected based on the rotational speed of the rotating wheel.

[0056] In some embodiments, the adsorption process can be carried out for a time sufficient to approach equilibrium loading, based on the adsorbent temperature and the CO2 concentration in the air. In other embodiments, the initial adsorption can be stopped further away from equilibrium loading. For example, one of the difficulties in fully loading the adsorbent with CO2 during a direct air capture process is that the adsorption rate decreases as the loading approaches equilibrium loading. One option can be to terminate the initial adsorption step when the adsorption rate falls below a target rate. This target rate can be an absolute adsorption rate, an adsorption rate corresponding to a percentage of the adsorption rate at the start of initial adsorption, an adsorption rate corresponding to a percentage of the adsorption rate of a fully desorbed adsorbent, or another convenient target rate. Yet another option can be to carry out the initial adsorption step for a fixed period of time. For example, selecting a fixed time can serve as a proxy for selecting a target adsorption rate without requiring in situ detection of the adsorption rate.

[0057] During the adsorption process, the adsorbent bed may be at a temperature of 0°C to 70°C, or 0°C to 40°C, or 0°C to 30°C, or 10°C to 60°C, or 10°C to 40°C, or 10°C to 30°C. Note that when the adsorbent bed initially exits the desorption zone, it may still be at a temperature of 40°C to 70°C due to only partial cooling of the adsorbent bed prior to exiting the desorption zone. Because the rate of adsorption of CO from air is relatively slow, heating of the adsorbent bed due to CO adsorption is relatively low compared to the ability of air to carry heat away from the adsorbent bed. Thus, in some embodiments, the temperature of the adsorbent bed will tend to equilibrate with the temperature of the air or other CO2-containing stream during the adsorption process. In other embodiments, a sufficiently low air flow rate and / or a sufficiently high adsorbent bed rotation rate may be used so that the adsorbent bed does not equilibrate with the air temperature during the adsorption process.

[0058] The average or superficial gas velocity of the CO2-containing stream along the direction of the flow channel in the adsorbent bed as it passes through the adsorbent bed can be 0.02 m / s to 0.5 m / s, or 0.02 m / s to 0.2 m / s, or 0.05 m / s to 0.5 m / s, or 0.05 m / s to 0.2 m / s. In some embodiments, the temperature of the CO2-containing stream can be 0°C to 40°C, or 0°C to 30°C, or 10°C to 40°C, or 10°C to 30°C. Such temperatures correspond approximately to the temperature of ambient air. In other embodiments, heated or cooled air streams can be used, so long as condensation of water on the bed is reduced, minimized, or avoided during the adsorption process. The adsorption process can typically be carried out at pressures near ambient conditions (approximately 100 kPa-a). Thus, a typical pressure range for the adsorption zone can be 90 kPa-a to 120 kPa-a, or 90 kPa-a to 110 kPa-a. However, operating near ambient pressure is primarily driven by cost and / or convenience. Pressures of 50 kPa-a to 10 MPa-a or even higher can be used if desired.

[0059] Desorption Zone Operation In various embodiments, one or more gas streams can be used in the desorption zone to facilitate desorption of at least a portion of the CO2 adsorbed on the portion of the adsorbent bed within the desorption zone. One or more gas streams can also be used for temperature control, including raising the temperature of the adsorbent bed to a desorption temperature. Optionally, additional temperature control streams can be used to cool the adsorbent bed before exiting the desorption zone. Optionally, one or more additional gas streams can also be used at the boundary between the adsorption and desorption zones (e.g., at the seal location) so that the pressure within the desorption zone is greater than the pressure outside the desorption zone.

[0060] Figure 5 shows an example of the interior of a desorption zone. Adsorbent bed section 530 is located within the desorption zone. Seals 533 on either side of adsorbent bed section 530 help minimize the passage of air into the desorption zone. The portion of the adsorbent bed corresponding to adsorbent bed section 530 changes as the rotating wheel rotates during the adsorption / desorption process.

[0061] The example desorption zone shown in Figure 5 includes four subzones: Subzone 582 corresponds to an initial purge subzone; Subzone 584 corresponds to a desorption subzone; Optional subzone 586 corresponds to a temperature adjustment subzone; and Optional subzone 588 corresponds to another purge subzone.

[0062] In some embodiments, a subzone can represent a general volume and / or portion of the adsorbent bed where a corresponding gas stream is introduced into the desorption zone. Optionally, one or more additional internal seals can be used such that one or more of the subzones are separated by the additional internal seal. Due to the presence of a gas stream in the desorption zone 530, such internal seals can also correspond to purged seals. In some embodiments, an internal seal can exist between each subzone in the desorption zone 530. As an example, FIG. 5 shows additional seals 591, 593, and 595 dividing the desorption zone 530 into subzones 582, 584, 586, and 588. These internal seals can help maintain temperature and / or pressure differentials between the subzones.

[0063] Optionally, a similar seal can be used below the adsorbent bed portion 530 to create a subzone below the adsorbent bed (not shown). Creating a separate subzone below the bed can be beneficial to form a CO2 product stream containing reduced or minimized amounts of nitrogen and / or other gases used as purge or temperature adjustment streams. The large difference between the condensation points of water and CO2 allows for relatively easy removal of water from a gas stream containing both water and CO2. Reducing or minimizing the presence of other gases that condense less readily than water can simplify subsequent processing of the collected CO2 to form a high-purity CO2 stream.

[0064] In some embodiments in which seals are used, the amounts of gas flow can be independently selected so that the relative pressures in subzones 582, 584, 586, and 588 can have any convenient relationship. In some embodiments in which seals are used, the gas flow rate in desorption subzone 584 can be lower than the gas flow rate in subzone 582 and / or subzone 586 to reduce or minimize leakage of CO from the high CO concentration product formed by subzone 584 to the low CO concentration product formed by subzone 582 and / or subzone 586.

[0065] The gas flow in subzone 582 corresponds to a purge flow. Nitrogen can be used as the purge flow, or any other convenient gas flow with an O concentration of 650 vppm or less (or, at a minimum, 400 vppm or less, such as substantially no O content). The purge flow in subzone 582 can perform two functions. First, as the adsorbent bed rotates, adsorbent bed portion 530 will typically contain a certain amount of air that is within the flow channels of the adsorbent bed. The purge flow in subzone 582 allows this air, carried to the desorption zone within the adsorbent bed, to be exhausted before heating the adsorbent bed. Second, the purge flow in subzone 582 can be used to create a positive pressure differential with respect to the pressure in the adsorption zone on the other side of seal 533. The portion of the purge gas flow in subzone 582 that passes through the channels of the rotating wheel and exits the opposite surface can be referred to as the purge flow exhaust.

[0066] The temperature of the gas stream in subzone 582 can be any convenient temperature between 0°C and 50°C, or between 10°C and 40°C. One option can be to use a temperature similar to ambient temperature to minimize the cost of providing the gas stream in subzone 582. The average or superficial gas velocity through the channels of the adsorbent bed in subzone 582 can generally be greater than the gas velocity through the channels of the adsorbent bed in the adsorption zone. In some embodiments, the gas velocity through the channels of the adsorbent bed in subzone 582 can be between 0.04 m / s and 5.0 m / s, or between 0.04 m / s and 2.2 m / s, or between 0.1 m / s and 5.0 m / s, or between 0.1 m / s and 2.2 m / s. By using a higher gas velocity in subzone 582 relative to the gas velocity of the CO2-containing gas (e.g., air) in the adjacent portion of the adsorption zone, a higher pressure can be maintained within the desorption zone. In some embodiments, the pressure in the desorption zone (or at least in subzone 582 of the desorption zone) may be 0.15 kPa or more, or 0.5 kPa or more, or 1.0 kPa or more higher than the pressure in the adsorption zone, such as up to 15 kPa, or possibly even higher.

[0067] The gas stream in subzone 584 corresponds to the steam used to facilitate desorption of CO from the adsorbent bed. This results in the formation of a CO2-containing gas stream exiting the channels of the rotating wheel. Preferably, the input gas stream in subzone 584 can consist essentially of steam alone (less than 3.0% by volume, or less than 1.0% by volume, of other gases), although in some alternative embodiments, the steam stream can include other gases, such as nitrogen. The steam provides heat to raise the temperature of the adsorbent bed to the target temperature for desorption. In addition to the heat transferred directly from the gas-phase steam stream, additional heat can be transferred to the adsorbent based on condensation of the steam on the adsorbent surface. This can allow the temperature of the adsorbent bed in at least a portion of the desorption zone (such as at least a portion of subzone 584) to increase to a temperature of 70°C to 200°C, or 80°C to 200°C, or 100°C to 200°C, or 70°C to 170°C. The steam used to heat the adsorbent bed can be at a sufficient temperature so that the steam is substantially entirely in the gas phase before entering the channels of the adsorbent bed. At pressures of approximately 100 kPa-a, this would correspond to having the steam at a temperature of 100°C or greater. More typically, the temperature of the steam can be between 90°C and 200°C, or between 100°C and 200°C, or between 120°C and 200°C. Preferably, the steam stream is substantially free of liquid water before entering the adsorbent bed. This can correspond to having less than 0.1% by weight of the steam stream corresponding to liquid water droplets.

[0068] The vapor also functions as a sweep gas to carry the desorbed CO2 into a collection manifold. The average or superficial gas velocity of the vapor through the channels of the adsorbent beds in subzone 584 can be generally similar to the gas velocity through the channels of the adsorbent beds in subzone 582. In some embodiments, the gas velocity of the vapor through the channels of the adsorbent beds in subzone 584 can be between 0.04 m / s and 5.0 m / s, or between 0.04 m / s and 2.2 m / s, or between 0.1 m / s and 5.0 m / s, or between 0.1 m / s and 2.2 m / s. In some embodiments in which subzone 582 and subzone 584 are separated by a seal, the average gas flow velocity of the vapor through the channels of the adsorbent beds in subzone 584 can be lower than the average gas flow velocity through the channels of the adsorbent beds in subzone 582.

[0069] The gas flow in subzone 586 corresponds to the temperature conditioning flow. Nitrogen and air are examples of gases suitable for the temperature conditioning flow. The portion of the temperature conditioning gas flow in subzone 586 that passes through the channels of the rotating wheel and exits the opposite surface can be referred to as the temperature conditioning flow exhaust.

[0070] Evaporative cooling can occur for a temperature adjustment stream having any favorable moisture content, so long as the moisture content of the temperature adjustment stream is less than the vapor pressure of water at the temperature of the temperature adjustment stream. During exposure of the adsorbent bed to the temperature adjustment stream in subzone 586, the adsorbent bed will have a higher temperature than the temperature adjustment stream. Thus, even if the temperature adjustment stream is initially saturated, heat transfer from the bed to the temperature adjustment stream will increase the temperature of the gas, thus allowing some evaporative cooling to occur.

[0071] In some embodiments, the temperature conditioning stream can correspond to a "dry" temperature conditioning stream. Using a dry temperature conditioning stream can enhance the amount of evaporative cooling that occurs during exposure of the temperature conditioning stream to the adsorbent bed. One way to designate a "dry" gas stream is to designate the humidity of the gas stream at the temperature of the gas stream. In such embodiments, the humidity of the gas stream (relative to the temperature of the gas stream) can be, at a minimum, 50% or less, or 40% or less, or 30% or less, or 20% or less, such as having substantially no humidity. Additionally or alternatively, the temperature conditioning stream can, at a minimum, comprise 10% or less by volume of HO, or 5.0% or less by volume, or 1.0% or less by volume, such as having substantially no moisture content.

[0072] The temperature-adjusted stream can have a temperature between 0°C and 60°C, or between 0°C and 50°C, or between 10°C and 60°C, or between 10°C and 40°C before entering the channels of the adsorbent bed. Based on the low humidity of the temperature-adjusted stream, the temperature-adjusted stream can provide two types of cooling to the adsorbent bed. In addition to direct heat transfer from the gas-phase stream, the adsorbent bed can also be cooled by evaporation of water present in the liquid phase above the adsorbent bed. As mentioned above, liquid water can be present above the adsorbent bed due to condensation of vapor during the vapor desorption step in subzone 584.

[0073] The average or superficial gas velocity of the temperature adjustment stream through the adsorbent bed channels in subzone 586 can be generally similar to the gas velocity through the adsorbent bed channels in subzone 582. In some embodiments, the gas velocity of the temperature adjustment stream passing through the adsorbent bed channels in subzone 586 can be between 0.04 m / s and 5.0 m / s, or between 0.04 m / s and 2.2 m / s, or between 0.1 m / s and 5.0 m / s, or between 0.1 m / s and 2.2 m / s. In some embodiments in which subzone 586 and subzone 584 are separated by a seal, the average gas flow velocity through the adsorbent bed channels in subzone 584 can be lower than the average gas flow velocity through the adsorbent bed channels in subzone 586.

[0074] In some embodiments, the temperature adjustment stream can function as a final purge gas for the desorption zone. In other embodiments, a second optional purge gas stream can be provided in optional subzone 588. The use of a second purge gas stream can allow the temperature and velocity of the temperature adjustment stream to be selected independently of the conditions required to provide a positive pressure inside the edge of the desorption zone relative to the adsorption zone. When a separate second purge gas is provided in optional subzone 588, the gas velocity of the second purge gas stream through the channels of the adsorbent bed in subzone 588 can be 0.04 m / s to 5.0 m / s, or 0.04 m / s to 2.2 m / s, or 0.1 m / s to 5.0 m / s, or 0.1 m / s to 2.2 m / s. The temperature of the second purge gas can be 0°C to 60°C, or 0°C to 50°C, or 10°C to 60°C, or 10°C to 40°C.

[0075] The temperature adjustment stream and any optional second purge gas stream can be used to reduce the temperature of the adsorbent bed before exiting the desorption zone, which can allow the temperature of the desorbent bed in at least a portion of the desorption zone (such as at least a portion of subzones 586 and / or 588) to be reduced to a temperature between 10°C and 70°C, or between 10°C and 50°C, or between 30°C and 70°C.

[0076] It should be noted that the combination of the vapor flow in subzone 584, the temperature adjustment flow in subzone 586, and the optional second purge flow in subzone 588 results in a temperature profile within the desorption zone in which the portion of the adsorbent bed in subzone 584 has a higher temperature than the portion of the adsorbent bed in subzone 582, subzone 586, or optional subzone 588.

[0077] Adsorbent Materials The adsorbent bed on the rotating wheel can correspond to a monolith (or an assembly of smaller pieces) used to support an adsorbent, such as an amine-based adsorbent. Generally, the adsorbent can be one that provides CO adsorption at temperature and pressure conditions near ambient conditions (e.g., approximately 0°C to 40°C and pressures of approximately 90 kPa-a to 110 kPa-a). Such adsorbents are defined herein as adsorbents selective for CO adsorption. The adsorbent can be supported on the monolith in any convenient manner. One option is to impregnate the monolith material / other support structure with an amine adsorbent compound and / or polymer. This allows the amine adsorbent to be incorporated into the surface and / or pores of the porous support structure. Another option is to chemically bond the adsorbent to the surface of the support structure. Yet another option is to form in situ a polymer layer with CO adsorption capacity (such as a polymer layer with amine functionality) on the inner surface of the channels in the support structure. Yet another option may be to incorporate the adsorbent into a support layer applied to the support structure by incorporating the adsorbent into an alumina layer that is deposited onto the surface of the support structure.

[0078] Various amines can potentially be used as sorbent materials for CO2 capture. Some amines can correspond to polymers with amine functionality, such as polyethyleneimine and / or polypropyleneimine. Polyethyleneimine, polypropyleneimine, or a combination thereof are examples of amine systems that can be deposited on and / or impregnated into the monolith surface. Another example of an amine is 3-aminopropyltrimethoxysilane. For monoliths with a suitable amount of oxygen functionality available on the monolith surface, this type of amine can be grafted onto the monolith surface.

[0079] Other examples of adsorbent materials include, but are not limited to, metal-organic framework materials (MOFs) and materials with zeotype framework structures. It should be noted that the adsorption capacity of some MOF and zeotype adsorbents can be modified and / or enhanced by adding amine adsorbents to the MOF or zeotype.

[0080] Additional configurations - sorbent bed variations Figures 2-4 generally illustrate one example of an adsorbent bed configuration. Figure 1 illustrates an example of incorporating an adsorbent bed such as the adsorbent beds of Figures 2-4 into an adsorber in which a single adsorbent bed is used in a horizontal orientation. In other embodiments, other configurations for the adsorber may be used.

[0081] One type of alternative configuration is to use an adsorbent bed mounted in an orientation other than substantially horizontal relative to the direction of gravitational attraction. For example, in some embodiments, the adsorbent bed can be mounted on a vertically oriented wheel framework structure so that the direction of gravitational attraction is approximately perpendicular to the axis of rotation of the adsorbent bed. In still other embodiments, any convenient orientation for the adsorbent bed / wheel framework structure can be used. Because the majority of the flow in the adsorbent bed is gas-phase flow with sufficient initial velocity, the operation of the adsorption and desorption zones in a vertically mounted adsorbent bed can be substantially similar to that in a horizontally mounted adsorbent bed. Note that any liquid water formed by vapor condensation may require different handling. One option for handling liquid water can be to position the desorption zone at the bottom of the adsorbent bed relative to the direction of gravitational attraction. This can simplify the placement of a collection trough in the desorption zone at a suitable location to collect any liquid water that exits the adsorbent bed.

[0082] FIG. 6 shows another type of alternative configuration in which two adsorbent beds are used. In the exemplary configuration shown in FIG. 6, rotor housing 601 includes rotor assembly 610 (containing support material 615 for supporting the adsorbent) and rotor assembly 620 (containing support material 625 for supporting the adsorbent). In the example shown in FIG. 6, fan or blower 608 is positioned to the side of rotor assembly 610 and rotor assembly 620 instead of above or below the beds. In other embodiments, fan or blower 608 can be in any convenient location, and ductwork can be used to provide fluid communication between fan or blower 608 and the adsorbent beds. Fan or blower 608 forces air into the volume between adsorbent beds 615. Partition wall 604 is an interior wall in rotor housing 601 that reduces, minimizes, or eliminates the gap between rotor assemblies 610 and 620 and the nearest wall. As a result, airflow is forced through channels in support material 615 and support material 625 with reduced or minimized ability to bypass the adsorbent beds. Desorption zone gas streams 653 (nitrogen purge), 655 (steam), and 657 (temperature control stream) can also be introduced between the beds so that a single flow source for each gas stream can provide gas flow for both adsorbent beds. Product effluent 665 from the adsorbent on support material 615 can be collected separately from product effluent 667 from the adsorbent on support material 625. Manifolds for managing the input and output streams to the adsorbent beds, such as a manifold similar to that shown in FIG. 1, can be used. Note that a water collection trough can be included in the lower regeneration cover of the upper adsorbent bed, even though the lower regeneration cover corresponds to the input flow side of the upper adsorbent bed.

[0083] Additional configuration - separate movement of the rotating adsorbent bed In some embodiments, instead of continuously rotating the rotating sorbent bed, the sorbent bed can be moved in discrete amounts, with pauses between movements. By moving the sorbent bed in discrete amounts and then stopping, additional processing options are available. Specifically, moving the sorbent bed in discrete amounts can enable the use of a seal that forms a completely sealed contact with the surface of the support material for the sorbent. An inflatable seal is one example of this type of seal. By using an inflatable seal, or another type of seal that provides a completely sealed contact with the support material, a larger pressure difference between the desorption zone and the adsorption zone can be achieved. This can allow pressures below 100 kPa-a to be used in the desorption zone to support CO2 desorption.

[0084] During the individual transfers of the adsorbent bed (and corresponding wheel framework structure), the adsorbent bed can be rotated any convenient amount during each transfer step. In some embodiments, the size of each transfer step can correspond to the amount of adsorbent bed located in the desorption zone. In other words, during a transfer step, a portion of the adsorbent bed in the desorption zone is completely transferred into the adsorbent zone. In other embodiments, individual transfer steps can be used to partially transfer a portion of the adsorbent bed from the desorption zone to the adsorption zone. In such embodiments, multiple individual transfer steps are required to transfer a portion of the bed in the desorption zone into the adsorption zone. Of course, transferring a portion of the bed in the desorption zone into the adsorption zone also results in transferring another portion of the adsorbent bed from the adsorption zone into the desorption zone.

[0085] In operation, the steps of the adsorption / desorption process are similar, and operation in the adsorption zone can be substantially the same as operation in the adsorption zone when continuous movement of the adsorbent beds is used. However, there are various options for how the desorption zone can be operated in conjunction with separate movement of the adsorbent beds.

[0086] One option for operating the desorption zone during individual transfers of the adsorbent beds is to use a strategy similar to that used during continuous transfer of the adsorbent beds. In this type of option, the desorption zone can still include multiple subzones for different gas flows, and seals can even be present within the desorption zone to further define the subzones. In this type of embodiment, the subzones can be substantially uniform in size, and the size of the wheel's movement step can match the size of the subzones. Optionally, one or more subzones can have a size that is a multiple of the size of the movement step, as opposed to each subzone having substantially the same size as the movement step. In this type of embodiment, the process sequence can begin with the wheel moving through the movement step to a new position. The seal can then engage with the surface of the adsorbent bed (such as the surface of the support material). Next, the gas flow in the desorption zone can be turned on for a certain period of time. The gas flow can then be stopped, the seal can be disengaged, and the next movement of the wheel can occur.

[0087] Alternatively, when using individual transfer of the adsorbent beds, the gas streams in the desorption zone can be used sequentially, as opposed to having simultaneous gas flows. In this type of embodiment, the adsorbent beds can be transferred by a transfer step. In some embodiments, the transfer step will correspond to the size of the desorption zone, so that the entire portion of the adsorbent bed in the desorption zone is transferred to a position in the adsorption zone. This also results in a new portion of the adsorbent being in the desorption zone. However, other types of transfer steps can also be used. After the transfer step, the seal engages the surface of the adsorbent bed. The gas stream for the desorption step can then be applied sequentially to all of the adsorbent beds in the desorption zone. In various embodiments, this can mean exposing the portion of the adsorbent bed in the desorption zone to an initial purge gas stream, a desorption gas stream, an optional second purge stream, and an optional temperature adjustment gas stream. These gas streams can be similar to the gas streams described herein. The difference is that all of the adsorbent beds are exposed to the gas streams sequentially, as opposed to exposing different subzones of the adsorbent bed to each of the gas streams simultaneously.

[0088] In embodiments where the adsorbent bed is moved a modest amount and a surface-engaging seal is used, a larger pressure difference between the desorption zone volume and the adsorption zone can be maintained. Optionally, in such embodiments, the pressure in the desorption zone volume during at least a portion of the desorption step may be 10 kPa or more, or 20 kPa or more, or 40 kPa or more lower than the pressure in the adsorption zone (outside the desorption zone volume), such as up to 99 kPa, or possibly even higher, than the pressure in the adsorption zone.

[0089] Additional Embodiments Embodiment 1. A system for sorption of CO2, comprising: a sorbent bed housing; a wheel framework structure within the sorbent bed housing; a support material including one or more monoliths, the one or more monoliths being supported by the wheel framework structure, the support material including a first surface, a second surface, and a plurality of channels providing a flow path between the first surface of the support material and the second surface of the support material; and a sorbent bed including a sorbent having selectivity for sorption of CO2 supported on the support material, at least a portion of the sorbent being supported on one or more surfaces within the plurality of channels; and at least one fan or blower associated with the sorbent bed housing and in fluid communication with a first portion of the plurality of channels. a fan or blower; at least one cover plate; one or more cover plate seals attached to the one or more cover plates, wherein a second portion of the plurality of channels is within a desorption zone volume defined by the at least one cover plate and the one or more cover plate seals, the one or more cover plate seals providing a) a seal between the at least one cover plate and a first surface of the carrier material, b) a seal between the at least one cover plate and a second surface of the carrier material, or c) a combination of a) and b); one or more input flow conduits providing fluid communication between at least one or more gas sources and the desorption zone volume; and at least one output flow conduit in fluid communication with the desorption zone volume.

[0090] Embodiment 2. The system of embodiment 1, further comprising at least one internal seal within the desorption zone volume, wherein the at least one internal seal provides a seal between an inner surface of one or more cover plates and at least one of the first surface and the second surface of the carrier material, and wherein the at least one internal seal defines a plurality of subzones within the desorption zone volume.

[0091] Embodiment 3. A system as described in embodiment 2, wherein at least a first input flow conduit of the one or more input flow conduits is in fluid communication with a first subzone of a plurality of subzones within the desorption zone volume, and at least a second input flow conduit of the one or more input flow conduits is in fluid communication with a second subzone of a plurality of distinct subzones within the desorption zone volume.

[0092] Embodiment 4. A system according to embodiment 2 or 3, wherein at least one subzone of the desorption zone volume is separated from the first portion of the plurality of channels by at least one internal seal and at least one cover plate seal.

[0093] Embodiment 5. A system described in any one of the preceding embodiments, wherein the one or more cover plate seals include one or more purged seals or the one or more cover plate seals include one or more inflatable seals.

[0094] Embodiment 6. A system described in any one of the preceding embodiments, wherein one or more input flow conduits are in fluid communication with the desorption zone volume via at least one input manifold, or at least one output flow conduit is in fluid communication with the desorption zone volume via at least one output manifold, or a combination thereof, and wherein at least one output manifold optionally includes a liquid collection trough.

[0095] Embodiment 7. A system according to any one of the preceding embodiments, wherein the wheel framework structure is supported by a central support, the central support optionally being configured for rotation of the wheel framework structure by a motor.

[0096] Embodiment 8. A system according to any one of the preceding embodiments, wherein the wheel framework structure is mechanically engaged by one or more gears configured for rotation of the wheel framework structure.

[0097] Embodiment 9. A system according to any one of the preceding embodiments, wherein a first portion of the plurality of channels is in direct fluid communication with at least one fan or blower.

[0098] Embodiment 10. A method of sorbing CO using the system of any one of embodiments 1-9, comprising: rotating a wheel framework structure; and exposing a first gas stream comprising 15% to 25% by volume O and 100 vppm to 650 vppm CO to a first portion of a sorbent bed outside a desorption zone volume, wherein the first gas stream has a temperature between 0°C and 40°C; and exposing a plurality of gas streams to a second portion of the sorbent bed within the desorption zone volume, wherein the second portion of the sorbent bed is sequentially exposed to a purge gas stream to form a purge exhaust and a steam stream having a temperature between 80°C and 180°C to form a CO2-containing output stream, wherein the rotation of the wheel framework structure changes the portion of the sorbent bed corresponding to the first portion of the sorbent bed outside the desorption zone volume and the second portion of the sorbent bed within the desorption zone volume.

[0099] Embodiment 11. The method of embodiment 10, wherein the desorption zone volume comprises a plurality of subzones, each subzone comprising at least one of a plurality of gas streams.

[0100] Embodiment 12. The method of embodiment 10 or 11, wherein the temperature of the leading edge of the second portion of the sorbent bed is 70°C or higher after exposure to the vapor stream and the temperature of the trailing edge of the second portion of the sorbent bed is 60°C or lower before being rotated out of the desorption zone volume.

[0101] Embodiment 13. The method of any one of embodiments 10-12, wherein exposing the plurality of gas streams to the second portion of the sorbent bed further comprises exposing the second portion of the sorbent bed to a temperature conditioning stream after the steam stream, wherein the temperature conditioning stream has a temperature between 0°C and 50°C to form a temperature conditioning stream exhaust; and wherein exposing the plurality of gas streams to the second portion of the sorbent bed optionally further comprises exposing the second portion of the sorbent bed to a second purge gas stream after the temperature conditioning stream, wherein the temperature conditioning stream optionally comprises a humidity of 25% or less relative to the temperature of the temperature conditioning stream.

[0102] Embodiment 14. The method of any one of embodiments 10-13, wherein exposing the second portion of the sorbent bed to the vapor stream further forms a liquid output product, or the vapor stream is substantially free of liquid water content, or a combination thereof.

[0103] Embodiment 15. The method of any one of embodiments 10 to 14, wherein the pressure inside the desorption zone volume is at least 2.0 kPa greater than the pressure outside the desorption volume, or the pressure inside the desorption zone volume is at least 20 kPa less than the pressure outside the desorption zone volume, or a combination thereof.

[0104] Additional Embodiment A. The method of any one of embodiments 10-15, wherein exposing the second portion of the sorbent bed to a plurality of gas streams comprises exposing the second portion of the sorbent bed to the plurality of gas streams in a time-sequential manner.

[0105] Additional Embodiment B. The method of any one of embodiments 10-15, wherein the first gas stream comprises air.

[0106] Additional Embodiment C. The method of any one of embodiments 10-15, wherein the first gas stream impinges on at least one surface of at least one cover plate in the desorption zone, and wherein the average flow direction of the first gas stream in the sorption zone is substantially perpendicular to at least one surface of the at least one cover plate in the desorption zone.

[0107] Additional Embodiment D. The method of any one of embodiments 10-15, wherein rotating the wheel framework structure comprises continuously rotating the wheel framework structure.

[0108] Certain features are described using a set of upper numerical limits and a set of lower numerical limits. It is understood that ranges from any lower limit to any upper limit are contemplated unless otherwise indicated. Certain lower limits, upper limits, and ranges are set forth in one or more claims below. All numerical values ​​account for experimental error and variations that would be expected by one of ordinary skill in the art.

[0109] The foregoing description of the present disclosure illustrates and describes the present methodology. Additionally, while the present disclosure illustrates and describes exemplary methods, it should be understood that various other combinations, modifications, and environments may be employed, and that the method is capable of change or modification commensurate with the above teachings and / or skill or knowledge of the relevant art, within the scope of the concepts expressed herein.

Claims

1. CO ２ 1. A system for sorption of CO2, comprising: a sorbent bed housing; a wheel framework structure within the sorbent bed housing; and a support material including one or more monoliths, the one or more monoliths being supported by the wheel framework structure, the support material including a first surface, a second surface, and a plurality of channels providing a flow path between the first surface of the support material and the second surface of the support material. ２ a sorbent bed including a sorbent having selectivity for sorption of at least one of the gases, wherein at least a portion of the sorbent is supported on one or more surfaces within the plurality of channels; at least one fan or blower associated with the sorbent bed housing, the at least one fan or blower in fluid communication with a first portion of the plurality of channels; at least one cover plate; one or more cover plate seals attached to the one or more cover plate, wherein a second portion of the plurality of channels is within a desorption zone volume defined by the at least one cover plate and the one or more cover plate seals, the one or more cover plate seals providing a) a seal between the at least one cover plate and the first surface of the carrier material, b) a seal between the at least one cover plate and the second surface of the carrier material, or c) a combination of a) and b); one or more input flow conduits providing fluid communication between at least one or more gas sources and the desorption zone volume; and at least one output flow conduit in fluid communication with the desorption zone volume.

2. 2. The system of claim 1, further comprising at least one internal seal within the desorption zone volume, the at least one internal seal providing a seal between an inner surface of the one or more cover plates and at least one of the first surface and the second surface of the carrier material, the at least one internal seal defining a plurality of subzones within the desorption zone volume.

3. 3. The system of claim 2, wherein at least a first input flow conduit of the one or more input flow conduits is in fluid communication with a first subzone of the plurality of subzones within the desorption zone volume, and at least a second input flow conduit of the one or more input flow conduits is in fluid communication with a second subzone of the plurality of distinct subzones within the desorption zone volume.

4. 4. The system of claim 2 or 3, wherein at least one sub-zone of the desorption zone volume is separated from the first portion of the plurality of channels by at least one internal seal and at least one cover plate seal.

5. 10. The system of any one of the preceding claims, wherein the one or more cover plate seals include one or more purged seals or the one or more cover plate seals include one or more inflatable seals.

6. 10. The system of claim 9, wherein the one or more input flow conduits are in fluid communication with the desorption zone volume via at least one input manifold, or the at least one output flow conduit is in fluid communication with the desorption zone volume via at least one output manifold, or a combination thereof, wherein the at least one output manifold optionally includes a liquid collection trough.

7. 10. A system according to any one of the preceding claims, wherein the wheel framework structure is supported by a central support, the central support optionally configured for rotation of the wheel framework structure by a motor.

8. 10. A system according to any one of the preceding claims, wherein the wheel framework structure is mechanically engaged by one or more gears configured for rotation of the wheel framework structure.

9. 10. The system of any one of the preceding claims, wherein the first portion of the plurality of channels is in direct fluid communication with the at least one fan or blower.

10. Using the system according to any one of embodiments 1 to 9, ２ 1. A method for adsorbing a surface of a wheel comprising: rotating the wheel framework structure; and adsorbing 15% to 25% by volume of O ２ and 100 vppm to 650 vppm CO ２ to a first portion of the sorbent bed outside the desorption zone volume, the first gas stream having a temperature between 0° C. and 40° C.; and exposing a plurality of gas streams to a second portion of the sorbent bed within the desorption zone volume, the second portion of the sorbent bed being exposed to a purge gas stream to form a purge exhaust, and a CO ２ exposing the second portion of the sorbent bed to a plurality of gas streams, including sequentially exposing the second portion of the sorbent bed to a steam stream having a temperature of 80°C to 180°C to form a contained output stream, wherein the rotation of the wheel framework structure changes a portion of the sorbent bed corresponding to the first portion of the sorbent bed outside the desorption zone volume and the second portion of the sorbent bed within the desorption zone volume.

11. The method of claim 10 , wherein the desorption zone volume comprises a plurality of subzones, each subzone comprising at least one of the plurality of gas streams.

12. 12. The method of claim 10 or 11, wherein the temperature of the leading edge of the second portion of the sorbent bed is 70°C or higher after the exposure to the vapor stream and the temperature of the trailing edge of the second portion of the sorbent bed is 60°C or lower before being rotated out of the desorption zone volume.

13. 13. The method of any one of claims 10-12, wherein exposing the plurality of gas streams to the second portion of the sorbent bed further comprises exposing the second portion of the sorbent bed to a temperature conditioning stream after the vapor stream, the temperature conditioning stream having a temperature between 0°C and 50°C to form a temperature conditioning stream exhaust, and wherein the exposing of the plurality of gas streams to the second portion of the sorbent bed optionally further comprises exposing the second portion of the sorbent bed to a second purge gas stream after the temperature conditioning stream, and the temperature conditioning stream optionally comprises a humidity of 25% or less relative to the temperature of the temperature conditioning stream.

14. 14. The method of any one of claims 10-13, wherein exposing the second portion of the sorbent bed to the vapor stream further forms a liquid output product, or the vapor stream is substantially free of liquid water content, or a combination thereof.

15. 15. The method of any one of claims 10 to 14, wherein the pressure inside the desorption zone volume is at least 2.0 kPa greater than the pressure outside the desorption volume, or the pressure inside the desorption zone volume is at least 20 kPa less than the pressure outside the desorption zone volume, or a combination thereof.

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