阅读说明：本技术 用于从空气中捕获co2的高通量直接空气捕获装置及其操作方法 (High flux direct air capture device for capturing CO2 from air and method of operation thereof ) 是由 罗格·苏特尔 本杰明·梅格勒 尼古拉斯·雷蓬 克里斯托夫·格巴尔德 扬·安德烈·维茨巴赫尔 于 2020-04-01 设计创作，主要内容包括：一种用于从气体混合物中分离至少一种气态组分的分离单元(1),或者这样的分离单元的布置,其中其包括至少一个周向壁元件(5),所述周向壁元件限定至少一个腔(3)的上游开口(31)和相反的下游开口(32),所述至少一个腔(3)包括用于在环境压力和/或温度条件下吸附所述气态组分的至少一个气体吸附结构(4),或者至少两个这样的腔(3)的阵列,其中所述分离单元(1)包括用于密封腔(3)的开口并且优选地允许将腔(3)抽空的一对相反的滑动门(12),并且其中这对相反的滑动门(12)可以在基本上平行于相应滑动门(12)的平面的方向上移动并且允许气体混合物经气体吸附结构(4)流过。(A separation unit (1) for separating at least one gaseous component from a gas mixture, or an arrangement of such separation units, wherein it comprises at least one circumferential wall element (5) defining an upstream opening (31) and an opposite downstream opening (32) of at least one cavity (3), said at least one chamber (3) comprising at least one gas adsorption structure (4) for adsorbing said gaseous component under ambient pressure and/or temperature conditions, or an array of at least two such chambers (3), wherein the separation unit (1) comprises a pair of opposite sliding doors (12) for sealing the opening of the cavity (3) and preferably allowing evacuation of the cavity (3), and wherein the pair of opposing sliding doors (12) is movable in a direction substantially parallel to the plane of the respective sliding door (12) and allows the gas mixture to flow through the gas adsorption structure (4).)

1. A separation unit (1) for separating at least one gaseous component from a gas mixture comprising the gaseous component,

wherein the separation unit (1) comprises

At least one continuous and sealed circumferential wall element (5), the at least one continuous and sealed circumferential wall element (5) circumferentially surrounding at least one cavity (3),

said at least one continuous and sealed circumferential wall element (5) defining an upstream opening (31) and an opposite downstream opening (32) of said at least one cavity (3),

the chamber (3) comprises at least one gas adsorption structure (4), the at least one gas adsorption structure (4) being adapted to adsorb the at least one gaseous component, preferably under ambient pressure and/or temperature conditions,

wherein the separation unit (1) further comprises a pair of opposite sliding doors (12), the pair of opposite sliding doors (12) being adapted to seal respectively the upstream opening (31) and the downstream opening (32) of at least one chamber (3) in a closed state,

and wherein, in order to open the closed cavity (3), each of said pair of opposite sliding doors (12) is moved in a direction substantially parallel to the plane of the respective sliding door (12) to expose said upstream opening (31) and said downstream opening (32), respectively, and allow the gas mixture to flow through said gas adsorption structure (4).

2. The separation unit (1) according to claim 1, wherein the separation unit (1) allows evacuating the at least one cavity (3) in a closed state to a pressure of at most 700 mbar (abs) or to a pressure of less than 500 mbar (abs), preferably to a pressure of less than 300 mbar (abs) or to a pressure of less than 150 mbar (abs) or at most 100 mbar (abs);

and/or wherein the separation unit (1) allows to place the at least one cavity (3) in a closed state at an overpressure of at most 0.1 bar (g), or at most 0.2 bar (g), or at most 0.5 bar (g).

3. The separation unit (1) according to any one of the preceding claims, wherein it comprises at least one group of four continuous and sealed circumferential wall elements (5): a lower wall element (5a), an opposite upper wall element (5b) and two opposite lateral circumferential wall elements (5c), said two opposite lateral circumferential wall elements (5c) engaging respective ends of said upper and lower wall elements and circumferentially surrounding said at least one cavity (3), said group of four consecutive and sealed circumferential wall elements defining said upstream opening (31) and said opposite downstream opening (32);

or wherein the separation unit comprises at least one group of eight continuous and sealed circumferential wall elements (5): at least one lower wall element (5a), at least one opposite upper wall element (5b) and at least two opposite lateral circumferential wall elements (5c), said at least two opposite lateral circumferential wall elements (5c) engaging corresponding ends of said upper and lower wall elements, either directly or via inclined further wall elements, preferably forming a hexagonal or octagonal structure, and circumferentially surrounding said at least one cavity (3), said group of eight consecutive and sealed circumferential wall elements defining said upstream opening (31) and said opposite downstream opening (32);

or wherein the separation unit comprises at least one single circular or elliptical circumferential wall element (5) circumferentially surrounding at least one cavity (3).

4. Separation unit (1) according to claim 3, wherein said upper and lower wall elements are arranged parallel to each other, said lateral wall elements are arranged parallel to each other, and preferably said pair of opposite sliding doors (12) are also arranged parallel to each other.

5. The separation unit (1) according to any one of the preceding claims, wherein the separation unit (1) comprises an inlet chamber (6) at the upstream opening (31) of at least one cavity (3) or, in case of a plurality of cavities (3), more than one cavity (3), an upstream sliding door (12a) being located in the inlet chamber (6); and an outlet chamber (7) at said downstream opening (32), a downstream sliding gate (12b) being located in said outlet chamber (7), wherein preferably, in case of more than one cavity (3), the inlet chamber (6) and/or the outlet chamber (7) are common to all cavities, and wherein preferably, -providing one or a set of preferably movable louvers (9) and/or at least one gas or air propulsion device (8) upstream of or to form an inlet to the intake chamber (6), and/or downstream of said outlet chamber or to form the outlet of said outlet chamber (7), preferably in an outlet manifold (33), at least one gas or air propulsion device (8), preferably in the form of a fan, and/or one or a set of preferably movable louvers (9) is/are provided.

6. The separation unit (1) according to any one of the preceding claims, wherein one or two sliding doors (12) are mounted on a pair of upper and lower guide rails (16), preferably C guide rails, wherein preferably the doors run in these guide rails (16) or on these guide rails (16) with rollers (21), and wherein further preferably means are provided for: allowing the respective door to be pressed against the respective axial face (13) of the respective opening (31, 32) in the position for closing and to be spaced again with respect to the sealing position to allow the door to slide so as to free the respective opening (31, 32).

7. Separation unit (1) according to claim 6, wherein the respective opening (31, 32) of at least one cavity (3) and/or the sliding door is provided with at least one circumferential sealing element (26), preferably in the form of at least one sealing ring and/or in the form of a sealing coating,

and/or wherein said means allowing to press the respective door to the corresponding axial face and to release the respective opening to space the door apart again are provided by said pair of upper and lower guide rails (16) mounted on the frame (30) or on the circumferential wall (5) in an axially movable manner, preferably via a hydraulic or pneumatic actuator (23),

and/or wherein the pair of sliding doors are each driven by a belt (18) on a pair of pulleys (17).

8. The separation unit (1) according to any one of the preceding claims, wherein the axial length of the circumferential wall element (5) is smaller than the minimum distance of the opposing circumferential wall element (5),

and/or wherein said circumferential wall encloses a rectangular or square section and said pair of sliding doors (12) are respectively rectangular or square,

and/or wherein the sliding drives of the pair of doors (12) are made so that the doors can move in synchronized pairs.

9. The separation unit (1) according to any one of the preceding claims, wherein the separation unit (1) comprises at least one stabilizing element, preferably in the form of at least one stabilizing strut (15), at or in the at least one cavity (3),

and/or wherein at least one sliding door (12), preferably both sliding doors (12), comprises a stabilizing element, preferably in the form of a rib.

10. The separation unit (1) according to any one of the preceding claims, said separation unit (1) comprising an array of at least two, preferably at least three, or at least four or in the range of 2 to 8 or 2 to 6 chambers, a circumferential wall element surrounding said chambers (3) and said chambers (3) each containing a respective gas adsorbing structure (4), wherein said pair of opposite sliding doors (12) is mounted to allow alternately sealing one chamber and the other chamber or chambers of said separation unit (1).

11. The separation unit (1) according to claim 10, wherein the cavities of the array are arranged adjacent to each other in one or more rows and wherein the circumferential wall elements (5) of adjacent cavities are formed by a common separation wall (14), wherein preferably the cavities of the array are arranged in one single horizontal or vertical row and directly adjacent to each other.

12. Separation unit (1) according to one of the preceding claims 10 to 11, wherein the separation unit (1) is attached to or comprises only one common evacuation unit, and/or only one common heating unit, and/or only one common collection unit for gaseous components, and/or only one common drive at the upstream and downstream sides of the door, and/or only one set of louvers at the upstream side, in each case common to all chambers (3), while preferably for each chamber, at the downstream side an individually controllable gas or air propulsion device (8) is provided,

and/or wherein the separation unit (1) comprises one single frame (30) of the circumferential wall elements forming all cavities.

13. Arrangement of two separation units (1) according to any of the preceding claims, wherein two separation units (1, 1') are arranged in a V-shaped orientation, with respective upstream openings (31) facing in an obliquely downward/lateral direction and respective downstream openings (31) facing in an obliquely upward/lateral direction and said respective downstream openings (31) facing in an oblique manner to each other, and at least one gas or air propulsion device (8) preferably being arranged to propel a gas mixture through the separation units in a substantially vertically upward direction.

14. A method of operating a separation unit (1) or an arrangement of separation units according to any one of the preceding claims and comprising an array of chambers, wherein a pair of sliding doors (12) is positioned to seal one chamber of the array while the other chambers are open to flow a gas mixture therethrough, the sealed chamber is exposed to conditions for desorption and extraction of gaseous components while the other chambers are driven by a gas or air propulsion device to adsorb at least one gaseous component from the gas mixture, and upon termination of the desorption in the sealed chamber, the pair of sliding doors (12) is moved to the next chamber, preferably the next chamber in the array that has been exposed to gas mixture adsorption for the longest period of time, to seal that next chamber, and then the next chamber is exposed to conditions for desorption and extraction of the gaseous components, and the other plurality of chambers are driven by a gas or air propulsion device to adsorb at least one gaseous component from the gas mixture, wherein preferably the sequence of steps is similarly continued to sequentially seal and extract all chambers in the array and cyclically repeat the sequence of adsorption and desorption steps equal to the number of chambers in the array at least once, preferably at least 100 times or at least 1000 times.

15. Use of a separation unit, arrangement or array according to any one of the preceding claims or a method according to claim 14 for separating carbon dioxide and/or water vapour from ambient air.

Technical Field

The present invention relates to a new high throughput device for gas separation, in particular for direct air capture, such as CO2 from air, which in particular provides large flow cross section, low pressure drop, low thermal mass, few/few structural components and high efficiency. Methods for operating such apparatus and components of such apparatus, such as a new movable door system for sealing a gas separation structure, are also provided.

Background

Gas separation by adsorption has many different applications in industry, such as the removal of specific components from a gas stream, where the desired product may be a component removed from the stream, a remaining depleted stream, or both. Thus, both the trace components as well as the main components of the gas stream can be targeted by the adsorption process. One important application is the capture of carbon dioxide (CO2) from gas streams, for example from flue gases, waste gases, industrial waste gases or atmospheric air.

Capturing CO2 directly from the atmosphere (known as Direct Air Capture (DAC)) is one of several means of mitigating anthropogenic greenhouse gas emissions and has attractive economic prospects as a non-fossil, location-independent source of CO2 for the commercial market and for the production of synthetic fuels.

One particular approach to DAC is based on a cyclic adsorption/desorption process with respect to solid chemically functionalized adsorbent materials. For example, in WO-A-2016005226 and WO-A-2017009241, A process based on steam assisted cycle adsorption/desorption and A suitable amine-functionalized adsorbent material for extracting carbon dioxide from ambient atmospheric air are disclosed, respectively. Furthermore, WO 2019/092128 describes another class of potassium carbonate functionalized adsorbent materials that are also suitable for use in the cyclic CO2 adsorption/desorption process.

The adsorption process typically occurs at ambient atmospheric conditions where air flows through the adsorbent material and a portion of the CO2 contained in the air is chemically and/or physically bound/adsorbed at or within the surface of the adsorbent. During subsequent desorption of CO2, the adsorbent material is typically heated, and optionally, the partial pressure of carbon dioxide around the adsorbent can be reduced by applying a vacuum or exposing the adsorbent to a purge gas stream (such as, but not limited to, steam) (PSA-pressure swing adsorption). Thereby, previously captured carbon dioxide is removed from the sorbent material and obtained in a concentrated form.

One of the major challenges in achieving energy and cost efficiency of DACs arises from the low concentration of CO2 in atmospheric gases (nominally about 400ppm in 2019) and the correspondingly necessary large volumes of atmospheric air delivered to suitable gas separation structures. Suitable gas separation structures comprising A closed adsorbent material are presented in US2017/0326494 and WO-A-2018083109 and may be applied to batch adsorption-desorption processes in which the structure comprising an adsorbent material needs to be alternately exposed to A high volumetric flow air stream (adsorption/contact) and then to desorption conditions characterized by elevated temperatures and/or vacuum pressures as low as, for example, 10 millibars (abs). This requires a chamber structure: which on the one hand exposes the adsorbent material to a high volumetric flow of atmospheric air to adsorb CO2, and which on the other hand can suitably isolate the adsorbent material from ambient air during desorption and withstand adsorbent material temperatures of up to 130 ℃, a mixture of CO2, air and water as vapor and liquid, and optionally a vacuum pressure as low as 10 millibars (abs) or less (vacuum is required if desorption). One such suitable structure is the unit disclosed in WO-A-2015185434. In general, therefore, an infrastructure is particularly advantageous: the pressure drop during the adsorption pass is firstly minimized and secondly the largest part of the pressure drop is attributed to the part of the unit that actually captures CO 2.

In the prior art, there are many examples of cyclic adsorption/desorption processes that are typically carried out in long, narrow, thick walled columns with small flow cross sections. The devices are used for gas separation based on pressure and/or vacuum oscillations and are typically operated with very short cycle times, in the order of seconds to minutes, during which their thermal mass or thermal inertia does not play a major role. Furthermore, the device is typically subjected to high pressure streams with high adsorbate concentrations, and therefore openings and flow conduits significantly smaller than their cross-sections may be used, because the pressure drop over the features is relatively small. For example, US 8,034,164 relates to multiple pressure swing adsorption columns operating in parallel and discloses details of column construction and assembly, flow control and cycle optimization. US 6,878,186 relates to a method and apparatus for pure vacuum pressure swing desorption in a classical adsorption column, and to a process and apparatus for a classical adsorption column. Certain prior art systems, such as WO-A-2013117827, describe parallel channel based gas separation structures that do attempt to reduce pressure drop when included in A cylindrical pressure vessel for A psA process.

If the desorption step uses a vacuum, there is a problem of pressure drop over the gas control structures at the inlet and outlet. Many prior art systems disclose large actuated pendulum covers further designated as baffles or dampers, wherein the units are not typically designed for pressure differentials above about 0.2 bar. Some isolation valves are particularly suitable for vacuum applications, but must have a substantial material thickness and be limited in size to handle the large forces of vacuum applications. Thus, such valves have a high thermal mass when applied to alternating heating/cooling steps and do not provide the necessary flow area. Furthermore, some prior art systems may have an actuation mechanism. EP-0864819 discloses a rotary flap valve for a fume hood built into the duct for ventilation applications but not for vacuum. US2005/005609 relates to bypass/redirection dampers (valves) for gas turbine applications but not for vacuum. GB-a-621195 discloses curved vacuum caps which attempt to reduce the material thickness but are incompatible with the requirement of a minimum pressure drop over the flow cross-section due to the effective thickness of the cap in the duct. FR- A-1148736 and US 3,857,545 propose actuating vacuum caps and valves by which the container can be evacuated, but are not suitable for thousands of times the flow of large gas required in DAC applications.

A particular DAC container solution with A swinging lid is again found in WO-A-2015185434, however here the flow restriction may reduce the output. As shown in US 2012/0174779, US 2011/0296872 and WO-A-2013166432, some prior art systems for contacting and regenerating solid adsorbent materials in DAC applications involve transferring the adsorbent material and A gas separation structure between A first region for the flow of adsorbed air and A second region in the form of A chamber for regeneration.

JP- ｃA-2009172479 provides ｃA carbon dioxide removing agent that can effectively adsorb carbon dioxide from the atmosphere and, in addition, can eliminate carbon dioxide only by slight heating. The proposed carbon dioxide removing agent is provided with a carbon dioxide adsorbing film of perovskite structure whose surface is exposed to the atmosphere containing carbon dioxide molecules, a heater for heating the carbon dioxide adsorbing film, and an exhauster for exhausting the space around the carbon dioxide adsorbing film. The carbon dioxide adsorption film chemically adsorbs carbon dioxide molecules from the atmosphere, and the heater releases the carbon dioxide molecules adsorbed by the carbon dioxide adsorption film.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved structure for gas separation processes, in particular for DAC processes, which has as few/few components as possible, is easy to operate, allows an efficient gas separation process, and which is highly reliable during long-term use.

The invention therefore proposes a separation unit and an arrangement of separation units as claimed, and a method of operating such a separation unit or an arrangement of such separation units, and the use of these elements, in particular for a DAC process.

More specifically, the invention proposes a separation unit for separating at least one gaseous component from a gas mixture comprising the component, preferably adapted and adapted to separate carbon dioxide and/or water vapour from ambient air.

The proposed separation unit comprises at least one continuous and sealed circumferential wall element circumferentially surrounding at least one cavity and defining an upstream opening and an opposite downstream opening of the at least one cavity. The apparatus is configured such that the gas mixture in the adsorption phase passes through the upstream opening, then laterally through the interior of the chamber and through or past the gas adsorption structure located in the chamber, then exits again by passing through the downstream opening, the entire flow of air being preferably substantially linear except for turbulence and deflection in or at the gas adsorption structure.

At least one cavity may preferably be of rectangular or square cross-section, in which case four continuous and sealed sets of circumferential wall elements are provided: a lower wall element, an opposite upper wall element, and two opposite lateral circumferential wall elements engaging respective ends of the upper and lower wall elements and circumferentially surrounding the cavity. The set of four continuous and sealed circumferential wall elements defines an upstream opening and an opposite downstream opening of the cavity.

In the case of adjacent cavities of separate cells in the array, the adjacent walls of the adjacent cavities may be formed by wall elements common to the adjacent cavities.

When defining a lower wall element and an opposite upper wall element, this does not mean that the respective chambers have to be oriented in a horizontal flow direction. It may also be oriented at an angle to the horizontal or the flow direction may be vertical. A lower wall element and an opposite upper wall element in a viewing direction along a main flow direction through the cavity are generally understood as two wall elements joining two lateral circumferential wall elements.

At least one cavity may also be of polygonal cross-section, for example it may comprise a group of eight continuous and sealed circumferential wall elements: at least one lower wall element, at least one opposite upper wall element and at least two opposite lateral circumferential wall elements joining the respective ends of the upper and lower wall elements, either directly or via an inclined further wall element, preferably forming a hexagonal structure in this case, and circumferentially surrounding the cavity, the group of eight consecutive and sealed circumferential wall elements defining an upstream opening and an opposite downstream opening of the cavity.

The proposed principle can be applied to any polygonal or circular flow-through cross-sectional shape defined by a substantially cylindrical continuous and sealed circumferential wall element or group of wall elements forming a respective cavity. May be, for example, triangular, rectangular, square, pentagonal, hexagonal, octagonal cross-sectional shapes.

Circular configurations are also possible. In this case, at least one of the chambers comprises a single circular or elliptical circumferential wall element.

The at least one cavity comprises or at least allows to comprise at least one gas adsorption structure for adsorbing the at least one gaseous component, preferably under ambient pressure and/or temperature conditions. If the separation unit comprises more than one chamber, for example in an array, each chamber comprises or may comprise at least one separate gas adsorption structure of this type.

According to the invention, the separation unit comprises a pair of opposite sliding doors for sealing respectively the upstream and downstream openings of the at least one chamber in the closed condition of said at least one chamber. If only one chamber is present, a pair of opposing sliding doors seal the chamber. If more than one chamber is provided, a pair of opposing sliding doors may also seal more than one (but not necessarily all) of the chambers at a time.

Typically, a pair of opposing sliding doors are mounted such that the chambers are opened and closed synchronously depending on the operating state.

In the case where more than one chamber is part of a separate unit, for example in the case of an array of chambers, the pair of opposing sliding doors are preferably mounted to alternately close only one chamber at a time, then be moved to the next chamber, and so on, preferably in a cyclical manner as will be described in further detail below. In such an array, the pair of opposing sliding doors may also be mounted to allow locations where no chambers are sealed, and preferably all chambers may be used for flow-through or other functions that do not require sealing by the pair of opposing sliding doors, as will be described in further detail below.

To open at least one chamber, the pair of opposing sliding doors may be moved in a direction substantially parallel to the plane of the respective sliding door to expose the upstream and downstream openings, respectively, and allow the gas mixture to flow through the respective chamber and the gas adsorption structure located therein. To release the corresponding sealing mechanism, the sliding movement of the door may involve a phase in which the door is lifted out of the corresponding opening in addition to or accompanied by sliding.

Such sliding sealing door mechanisms are known from other applications, however not from the field of gas separation processes, and have never been used for this particular arrangement: in which a pair of opposed parallel sliding doors are provided instead of one to act as sealing doors for a chamber having an upstream opening and a downstream opening. Indeed, doors of sealing mechanisms are known from these other fields and applications, for example in US2015/0157030, GB- A-2420711 and KR- A-20110095014, wherein in each case A single sliding door may alternatively isolate and provide access to the vacuum cavity and provide A completely unobstructed cross-section in the open state. However, these systems are not designed for airflow laterally through the vacuum chamber and accordingly lack a second such door and means to drive the airflow.

In particular, the proposed separation unit allows to provide an array of chambers as will be further described below, wherein a pair of sliding doors is used to alternately close and open adjacent chambers comprising the adsorption structure, and to allow a cyclic operation of the adjacent chambers. An appropriate number of chambers may be combined in such an array, especially according to the time profile between adsorption and desorption. If, for example, the ratio between the two phases is 2:1, a structure in the form of a separation unit comprising an array of three chambers and a pair of opposite sliding doors is installed so as to alternately close one of the chambers in the array for the desorption step, while subjecting the other two chambers in the array to a process of cross-flow and adsorption of air and/or gas mixture.

In another embodiment of the invention, the sliding door may be moved to a position outside of the array of chambers comprising the adsorber structure. In the case of such "intermediate" positions, the time profile of the adsorption-desorption process is separated from the geometric arrangement of the chambers and the array, since the gates can be arranged in this position if it is not necessary to close the chambers, thus allowing any desorption and adsorption time. Placing this "intermediate" position at the bottom or side of an array of such chambers will further provide a safe location for the door to be held while commissioning, maintaining or otherwise working the adsorbent structures within the array.

Thus, in the case of an array of chambers, the pair of sliding doors may be positioned adjacent to the array of chambers or in a trough between the chambers in such a way as not to seal any chambers and all chambers are open to the passage flow of the gas mixture, and then the sliding doors may be moved to a chamber that has been exposed to the adsorption of the gas mixture for the longest period of time to seal the next chamber, which is then exposed to conditions to desorb and extract the gaseous component that needs to be desorbed as needed, or to hold the sliding doors in an adjacent position to allow commissioning, maintenance or other work to be performed on the entire structure or array of chambers.

Preferably, the separation unit allows evacuating the cavity to a pressure of less than 700 mbar (abs) or less than 500 mbar (abs), preferably to a pressure of less than 300 mbar (abs) or to a pressure of less than 150 mbar (abs) or at most 100 mbar (abs), followed by a vacuum cavity. Preferably, the separation unit in the closed state evacuates the chamber to a pressure in the range of 500 mbar (abs) to 10 mbar (abs).

More preferably, the separation unit exposes the chamber to an overpressure of up to +0.1 bar (g), or up to +0.2 bar (g), or +0.5 bar (g) (typically relative to a normal external pressure of 1.01325 bar).

According to a preferred embodiment of the proposed separation unit, the upper and lower wall elements of at least one chamber are arranged parallel to each other, the lateral wall elements are arranged parallel to each other, and preferably, the pair of opposite sliding doors are also arranged parallel to each other.

The separation unit may further include: an inlet chamber at an upstream opening of at least one cavity comprising an adsorption structure or in case of more than one cavity of a plurality of cavities comprising an adsorption structure, an upstream sliding door being located in the inlet chamber; and an outlet plenum at the downstream opening, the downstream sliding door being located at the outlet plenum.

Preferably, in case more than one cavity comprising an adsorption structure, the inlet and/or outlet chambers are common to all cavities.

Preferably, the upstream of the inlet chamber or the inlet forming the inlet chamber is provided with one or a set of preferably movable louvers and/or at least one gas or air propulsion means, and/or the downstream of the outlet chamber or the outlet forming the outlet chamber is preferably fitted with at least one gas or air propulsion means, preferably in the form of a fan, in the outlet manifold and/or a set of preferably movable louvers is provided.

One or both sliding doors may be mounted on a pair of upper and lower rails, or may be mounted on a pair of rails at opposite sides of the unit. The rail may be a C-rail.

Preferably, the doors run in or on these rails with rollers, and wherein further preferably means are provided which can press the respective door to the corresponding axial face of the respective opening at a position closing, in particular with the purpose of creating a seal, and space the door again from this sealing position to allow the door to slide to free the respective opening, and wherein the upper and lower rails on which the doors run (or the lateral rails in the case of up-and-down movement of the doors) can extend beyond the array dimension to bring the doors into the above-mentioned intermediate position.

The sliding door and/or the respective cavity opening may be provided with at least one circumferential sealing element, preferably in the form of at least one sealing ring and/or in the form of a sealing coating.

The means allowing the respective door to be pressed to the respective axial face and allowing the respective opening to be released for the door to be spaced again may be provided, for example, by a pair of upper and lower guide rails mounted on the frame or the circumferential wall in an axially movable manner, preferably by pneumatic actuation.

Preferably, the pair of sliding doors are each or collectively driven by a belt, for example a belt mounted on a pair of pulleys.

The axial length of the circumferential wall (i.e. the length of the wall in the flow direction of the at least one chamber) is preferably smaller than the minimum distance of the opposing circumferential wall elements.

The circumferential wall may enclose a rectangular or square cross-section and the pair of sliding doors is rectangular or square, respectively.

The sliding actuation of the pair of doors may be configured to move the doors in parallel (only) synchronized pairs.

The separation unit may also comprise at least one stabilizing element, preferably in the form of at least one stabilizing strut, at or at least one or preferably all of the chambers to ensure that the structure is sufficiently strong to withstand vacuum or overpressure conditions (if required). For the same purpose, at least one sliding door, preferably both sliding doors, may comprise stabilizing elements, preferably in the form of ribs, preferably on the outside with respect to the cavity.

As indicated above, according to a particularly preferred further aspect of the invention, it relates to a separation unit having not only one cavity but also more than one cavity, preferably an array of cavities, i.e. comprising at least two, preferably at least three, or at least four or in the range of 2 to 8 or 2 to 6 cavities, the circumferential wall elements surrounding the cavities and the cavities each accommodating a respective gas adsorbing structure. Typically, the pair of opposite sliding doors is then installed to allow sealing alternately one chamber of the separation unit and the other chamber sequentially. Preferably, the pair of opposing sliding doors are mounted in such an array to allow for locations where no chambers are sealed, and preferably all chambers are available for flow-through or other functions that do not require sealing by the pair of opposing sliding doors.

The cavities in such an array may have any of the cavity structures as detailed above, i.e. may have a cross-sectional shape that is rectangular, triangular, square, hexagonal, octagonal or circular, and preferably all the cavities of the separation unit have the same cross-sectional shape and size to allow alternate sealing of each of them with the same pair of opposing sealing doors.

One benefit of this solution over the prior art is that the infrastructure of a pair of opposing moveable sealing doors can be used for many chambers, allowing cost savings and improving reliability for multiple doors or covers. Furthermore, the complexity and sensitivity of the moving elements is much lower compared to the prior art invention of moving the gas separation structure into and out of the regeneration chamber, thereby reducing the risk. Still further, in regeneration processes utilizing temperature swing, the doors remain hot as they move between the regeneration chambers, thereby reducing the effective thermal mass of the regeneration and, therefore, the energy requirements. Another unexpected benefit of the present invention with respect to prior art devices applied to variable and variable temperature processes is the amount of structural cavity material per unit enclosed volume, which in the present invention is significantly lower than any prior art device due to the common separating wall, the common gate and the mutually stabilizing circumferential walls, and results in significant cost, complexity and energy savings in the variable temperature process. Finally, a significant benefit of the present invention over prior art flow-through applications is that the complete cross-section of the chamber can be used as a flow area without obstructions common to baffles, caps, valves or other flow restrictions. Accordingly, given an allowable pressure drop "budget," this integrity value may be applied to gas adsorption structures held in cavities through which gas flow must pass, resulting in higher volumetric gas flow rates and higher absorption rates of associated species in gas separation applications.

In such an array, the cavities of the array may be arranged adjacent to each other in one or more rows, and the circumferential wall elements of adjacent cavities may be formed by a common separating wall. Preferably, the cavities of the array are arranged in a single horizontal or vertical row and are directly adjacent to each other.

Such an array of chambers is preferably attached to or comprises only one common evacuation unit, and/or only one common heating unit, and/or only one common collection unit for the gaseous components, and/or only one common drive at the upstream and/or downstream side of the door, and/or only one set of louvers at the upstream side, in each case common for all chambers, while preferably for each chamber individually controllable air propulsion means are provided at the upstream and/or downstream side.

Typically, such an array of cavities comprises one single frame of circumferential wall elements forming all cavities.

As indicated above, according to one particularly preferred aspect of the invention, it relates to an arrangement of two separation units as detailed above, wherein the two separation units are arranged in a V-orientation, with the respective upstream opening facing downwards or in an obliquely downwards/sideways direction and the respective downstream opening facing upwards or in an obliquely upwards/sideways direction and facing each other in an oblique manner, and at least one or a pair of gas or air impelling means are preferably arranged to impel the gas mixture to travel in a vertically upwards direction through the separation units.

The separation units may thus be oriented in a downward direction with a face normal orientation between 30 ° and 60 ° downward, optionally with adjacent separation units abutting each other in a horizontally mirrored manner. Thereby, in particular, the gas separation structure is protected from the sediment and the falling atmospheric impurities (leaves, snow, etc.). Furthermore, in the angled orientation, the diagonal formed by the axial depth and the height of the maximum envelope dimension may be best used for the largest possible flow cross section.

Furthermore, the invention relates to a method of operating a separation unit or arrangement as detailed above, wherein the pair of sliding doors is positioned to seal one chamber in the array or in an intermediate position outside the array, while the other chambers in the array are open to lateral passage of the gas mixture, the sealed chamber is exposed to conditions for desorption and extraction of the gaseous component, while the other chambers are driven by the air propulsion means to adsorb the gaseous component from the passing gas mixture, and upon termination of desorption in the sealed chamber, the pair of sliding doors is moved to the next chamber, preferably the next chamber in the array that has been exposed to the gas mixture adsorption for the longest period of time at that moment to seal the next chamber, which is then exposed to conditions for desorption and extraction of the gaseous component, while the other chambers are driven by the air propulsion means to adsorb the gaseous component from the gas mixture, wherein preferably the sequence of steps is similarly continued to sequentially seal and extract all chambers in the array and cyclically repeat the sequence of adsorption and desorption steps equal to the number of chambers in the array at least once, preferably at least 100 times, or at least 500 or 1000 times.

Last but not least, the invention relates to the use of a separation unit or arrangement as detailed above, or a method according to the preceding paragraph, for separating carbon dioxide and/or water vapour from ambient air.

It is therefore a preferred object of the present invention to provide a DAC system based on flow-through cells that provide the largest possible unobstructed flow area, are individually sealable for gas separation processes, have low possible thermal mass, and can be effectively grouped in repeating units.

Accordingly, a separation unit for gas separation is proposed, said separation unit enclosing at least one and preferably a plurality of enclosed spaces designated as chambers, said chambers being separated from each other by a separation wall and further being enclosed by a transverse circumferential wall, and having at least one pair of axial gates, wherein one gate of each pair of gates is on a gas inlet face and a gas outlet face of the unit, respectively, wherein said gates can be moved in pairs and transversely between the chambers, sealing the spaces enclosed thereby and passing gas through the chambers which are not isolated thereof, and further wherein the spaces within the chambers can be occupied by gas adsorption structures through which a gas stream is passed for adsorbing the components to be separated. In the case of a single chamber, the separation unit and the chamber essentially form a device.

For the case where the separation unit allows to evacuate the cavity to a pressure below atmospheric pressure, this is intended to mean that if the structure is in an environment of ambient atmospheric pressure (about 1 atmosphere, i.e. about 101325kPa), it is capable of withstanding an internal pressure below 1000 mbar (abs), preferably capable of withstanding an internal pressure of 700 mbar (abs), or 500 mbar (abs) or 100 mbar (abs), or more preferably less than 10 mbar (abs). Thus, the structure is provided to be able to withstand a pressure, for example as in the range of 5 to 350 or 5 to 200 mbar (abs) or even lower than this, for example 10 or 5 mbar (abs). The structure is thus preferably generally capable of withstanding a negative pressure difference between the external space and the internal space in the range of-0.3 bar (g) or-0.5 bar (g), preferably-0.95 bar (g), or-0.99 bar (g), or even-0.9999 bar (g), so close to or even about-1 bar (g), and an overpressure difference of up to +0.1 bar (g) or up to +0.5 bar (g).

In the above description, axial means the overall direction of gas flow through the separation unit, which may be any direction of depth direction leading through the separation unit, including from bottom to top of the unit or also from top to bottom and all other variants, irrespective of whether the fluid changes direction locally in the unit, transverse means substantially perpendicular to the overall flow of gas through the separation unit and the chamber, irrespective of local flow direction deviations, and thus may mean substantially horizontal or vertical, or indeed any direction in between. Furthermore, in the above description, gas separation is understood to be the separation of miscible gaseous species from a gaseous mixture and thus includes gaseous streams such as air, flue gas, biogas or geothermal gases or indeed any gaseous mixture.

The movable door may have characteristic dimensions (width, height and thickness) of 0.6m x 0.05m, up to 12m x 3.8m x 0.3m, preferably 2m x 0.14m, and may be made of metal (in particular aluminium, iron, steel, stainless steel, carbon steel), composite material, ceramic or plastic, or a combination thereof, as the circumferential wall forming the cavity.

Likewise, in the case where the chamber is not sealed against the flow by means of a moving door, i.e. is open to the flow, it is characterized by a flow section with characteristic dimensions of 0.55m x 0.55m up to 11.75m x 3.8m, and by a depth-the axial extension of the chamber: 0.1m to 1.8m, preferably 0.2m to 1.2 m. In general, the envelope size of the separation unit including the door may be substantially limited by the envelope size of the ISO 668 standard high top shipping container, thereby enabling standardized, cost effective transportation. It will be appreciated by those skilled in the art that such separation units may be combined to form a larger system by placing multiple separation units together and operating them as one device.

The cross-section of the moving gate and cavity may be circular, hexagonal or rectangular, and optionally the gate may have reinforcing ribs to prevent excessive deformation under pressure loads, wherein such ribs may have a pitch of 50mm to 500mm and a rib thickness of 2mm to 20 mm.

In particular, in the case of rectangular doors and chambers, the planes of the axial faces at the inlet and outlet of the separation unit may be reinforced with intersecting tensile struts such as, but not limited to, cables, chains, rods or slats spanning the flow area and fixed to the load-bearing structure-the circumferential wall of the chamber and the separation wall-wherein the cross-flow of the feature is reduced to less than 10%, preferably less than 1% of the chamber flow area compared to the complete chamber cross-section. In this way, the known truss structure prevents the separation unit from tilting laterally under pressure loads or loads caused by its own weight. In another preferred embodiment of this same aspect, the gas separation structure may be fixed to the chamber along its circumferential wall and the separation wall, the inner periphery of the chamber further optionally having a non-load bearing wire or plastic mesh or a substantially gas permeable material having pores in the range of 0.5mm to 10 mm. In this way, since no greater depth has to be foreseen for the stabilizing structure, the tilting loads can be carried by the gas separation structure without the need for additional stabilizing structures, thereby preventing deformation of the entire separation unit, while allowing a greater depth of the gas separation structure in the cavity.

The doors may be moved in pairs in the lateral direction by different types of drive systems including, but not limited to, belts, gears, or winches with stepper or other motors, wherein the position of the doors is controlled to stop at the cavities to be isolated.

The inlet face may be provided with a gas plenum having the dimensions of the characteristic dimensions of the separation unit and a depth only slightly greater than the depth of the movable door, and characterized by a set of angled plates (louvers) extending from one side of the inlet gas flow along the entire transverse length of the separation unit or array, with the main plane optionally adjustable downward at an angle of 30 ° to 60 ° from the horizontal position or from the horizontal position to the fully vertical position. In this way, the shutter may effectively close the gas inlet of the separation unit.

A fan for propelling the movement of gas, preferably atmospheric air, may be placed in the axial wall of the gas plenum, preferably on the gas outlet side of the separation unit, wherein the minimum flow area of the plenum cross-section is at least 20%, preferably at least 50%, of the flow cross-section of the non-isolated chamber and the plenum is gas tight to the gas flow, but not to a pressure differential of more than 1000Pa, wherein no further separation of the gas flow occurs, and wherein the plenum may be made of a material such as metal, plastic, composite or ceramic, and may optionally be internally reinforced to resist external loads such as snow, ice, rain, wind, etc.

One or both movable doors may be provided with a contact ring which encloses a shape having the same shape as the cavity but having a characteristic dimension only slightly larger than the dimension of the cavity and which in the isolated state is brought into contact with the axial face of the separation unit in the axial direction. The contact ring can be provided on its axial surface with a full-circumference elastic sealing element, for example an O-ring, a contour seal on the edge contour, a sealing profile fixed via an adhesive or any common sealing profile. The core diameter of the resilient sealing element is in the range of 2mm to 25mm, preferably 3mm to 15 mm. Furthermore, all or part of the axial face of the door axially opposite to the axial face of the cavity may be coated with an elastic material. An advantage of this preferred embodiment is that it is not necessary to manufacture a well-defined sealing structure (i.e. an O-groove), which allows for cost savings. Another advantage of the preferred embodiment is the thermal insulation provided by such coatings, thereby reducing the effective thermal mass of the door during temperature swing adsorption/desorption cycles.

At least one actuator for establishing a seal of the movable door on the axial chamber wall may be foreseen on the movable door and engage with a catch, lever or guide rail on the separation unit, so as to translate the door axially towards the outward axial wall of the separation unit, so as to affect the airtight seal. Preferably, these means may include, but are not limited to, pneumatic or hydraulic actuators or solenoids, wherein preferably, gas may be evacuated from each chamber by any common vacuum system to achieve a pressure of less than 1000 millibars (abs), preferably less than 200 millibars (abs), wherein in another preferred embodiment of the apparatus, the initial rapid application of the vacuum system may provide sufficient suction to achieve the initial seal and enable further evacuation.

The separation unit may comprise further inlet/outlet elements for attaching at least one vacuum pump and/or for extracting gas and/or liquid from the chamber and/or for introducing further process media, in particular water and/or steam, into the chambers of the separation unit separated by the gate, wherein preferably two inlet/outlet elements of a chamber each having the size DN40-DN500 may be fixed on the circumferential horizontal wall of the separation unit, and wherein furthermore optionally said inlet/outlet elements are further connected to a header extending over the entire length of a single separation unit, thereby connecting all chambers in said separation unit.

In other embodiments, the header extending the entire length of a single separation unit is formed by first upper and lower circumferential horizontal walls and a second circumferential horizontal wall surrounding the space between the two circumferential walls, with more openings in the first circumferential wall to create channels to the respective chambers.

Thus, according to yet another preferred embodiment, at least one, or preferably at least both, of the wall elements or parts thereof forming the above-mentioned continuous and sealed circumferential wall is double-walled, so that the gap between the two walls can be used as an inlet/outlet element for introducing or extracting medium from the cavity. Preferably, in the case of a rectangular circumferential wall structure, the upper wall element and/or the lower wall element or preferably both are constructed as a double-walled structure, the gap between the two walls being available for this function. The advantages of this are: the gaps between the double-walled upper wall elements of adjacent chambers and the gaps between the double-walled lower wall elements of adjacent chambers may be interconnected so as to have one single conduit in the upper and/or lower space of the chamber.

The use of a separation unit as outlined above may be used in a direct carbon dioxide capture process involving a cycle between adsorption of carbon dioxide at ambient atmospheric temperature and pressure and desorption of carbon dioxide at reduced pressure below ambient atmospheric pressure, preferably at pressure levels of up to 1200 millibars (abs) and at elevated sorbent material temperatures of 60 ℃ to 130 ℃, preferably 80 ℃ to 120 ℃.

Further embodiments of the invention are defined in the dependent claims.

Drawings

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, which are for the purpose of illustrating the presently preferred embodiments of the invention, and not for the purpose of limiting the same. In the drawings, there is shown in the drawings,

fig. 1 shows a cross section of an arrangement of separation units/two possible orientations: (a) a single vertically aligned separation unit, and (b) an arrangement of two obliquely, symmetrically adjoining separation units;

FIG. 2 shows a perspective view of a separation unit comprising an array of six chambers and a pair of horizontally translating doors (only the front one shown) and no gas adsorbing structure to show the positions of the movable doors, chambers and louvers;

FIG. 3 shows a perspective view of a separation unit comprising an array of six chambers and a pair of horizontally translating doors (only the front one shown) without a gas adsorption structure and with different stabilizers in/at each chamber;

FIG. 4 shows the voltage drop distribution in the direction of gas flow for a prior art DAC cell and a DAC cell of the present invention;

FIG. 5 shows details of the mechanism for lateral movement of the sliding door between the various chambers of the array within the separation unit;

FIG. 6 shows details of a mechanism for providing an airtight seal between the door and the axial face of the separation unit;

figure 7 shows the pressure increase within the chamber of a separation unit with a movable door operating under repeated vacuum evacuations and maintained over 1000 cycles; and

fig. 8 shows the use of a double circumferential horizontal wall as a header for conveying medium to or from the chambers of the separation unit.

Detailed Description

Fig. 1a shows a vertical section through a separation unit 1 for e.g. direct air capture of atmospheric CO2, wherein the air stream 2 through the separation unit 1 is substantially horizontal. The air flow 2 passes through the shutter 9, through the first inlet chamber 6, through the upstream opening 31 at the upstream axial face 13a and into the chamber 3 comprising the gas adsorption structure 4, then through the downstream opening 32 at the downstream axial face 13b into the second outlet chamber 7 and as outlet air flow 2⁺Leaving the separation unit driven by a fan 8 mounted in or at the outlet manifold 33.

The inlet and outlet collecting ducts 10 are connected to the individual chamber inlet/outlet elements to the single chamber 3 by inlet and outlet ducts 11 and are in this example included in the lower circumferential wall 5a of the separation unit 1 or attached to the lower circumferential wall 5a of the separation unit 1.

It is also possible to tilt the separation unit shown in fig. 1a by 90 deg. so that the air flow through the separation unit 1 is substantially vertical in the upward or downward flow direction.

Another possible orientation of the separation unit 1 is shown in fig. 1 b. Here, the outlet air flow 2⁺Is substantially vertical and the separation unit 1 is oriented (tilted) at an angle to the vertical. Such a separation unit 1 mayCombined with another horizontally mirrored and adjacent separation unit 1'.

In this case, the louvers 9 may also be omitted, and the inlet air flow 2 may enter directly via the inlet plenum 6, the upstream opening 31 at the upstream axial face 13a, and the gas adsorption structure 4 inside the chamber 3.

A substantially triangular outlet plenum 7 is provided starting at the downstream axial face 13b at the downstream opening 32 to provide the necessary outlet area and propulsion means-in this case a fan 8-is accommodated at the outlet of the outlet plenum 7 in the outlet manifold 33.

In fig. 1b, two outlet plenums 7 and 7' are shown; however, the two outlet plenums 7 and 7' may also be combined into one combined outlet plenum, i.e. without a separating wall between them, instead of two propelling means (8, 8 ') or two rows of corresponding propelling means (8, 8 ') in the viewing direction, there may also be one single, central propelling means (or one row of propelling means in the viewing direction).

As in fig. 1a, the separation unit 1 is connected with an inlet and outlet collection duct 10 connected by an inlet and outlet duct 11 to the cavity 3 in or at the lower circumferential wall 5 a.

It will be understood that the pair of movable sliding doors 12 are not shown in these views of fig. 1, since they are not in the plane of the cross-section shown. The pair of movable sliding doors 12 will move within inlet plenum 6 and outlet plenum 7, will be oriented perpendicular to inlet airflow directions 2 and 2⁺And in the case of the arrangement of figure 1b, the upstream movable slide gate is located in inlet plenum 6 and 6', and the downstream movable slide gate is arranged in parallel with the upstream movable slide gate in the slide gate region 27 of outlet plenum 7 substantially immediately downstream of gas adsorption structure 4.

Furthermore, in fig. 1a and 1b, a separation unit 1', respectively, is shown, each having only one cavity 3, but typically there are at least two cavities per separation unit, adjacent in a direction parallel to the viewing direction and substantially adjacent to each other. Furthermore, the concept can be extended to any number of separate units by stacking units in the case of a vertically aligned arrangement or abutting units in the case of an inclined arrangement.

In particular, in the case of the arrangement of fig. 1b, if at least two cavities are used per separation unit, the outlet plenums 7 and 7' (or the combined outlet plenum as described above) may be formed in such a way that they form one (or two parallel) combined outlet plenum above each separation unit, and in this case there is no need to allocate the individual air pushers to one cavity each, and the number of air pushers per separation unit does not necessarily need to match the number of cavities in that separation unit.

Fig. 2 shows a perspective view of a possible separation unit 1 comprising an array 28 of six adjacent chambers 3 formed by circumferential walls 5a, 5b and 5c, the latter in the case of adjacent chambers given by partition walls 14, wherein, in the illustration, the second chamber from the left is sealed by a pair of square-shaped movable doors (only upstream door 12a is shown) located in the inlet plenum, and the remaining five chambers are exposed to an airflow 2 which in this case passes through louvers 9 fixed on side walls 29 and driven by fans 8. A downstream door 12b (not shown) is located in downstream plenum 7. At the bottom of the separation unit, in or at the bottom circumferential wall 5a, a pair of lead-in and lead-out collection tubes 10 are provided to convey media to or from the respective chamber 3.

In this particular preferred embodiment, the side walls of each of the cavities 3 as shown are made of steel or stainless steel or carbon steel having a thickness of 8mm and have an axial length (in the flow direction) in the range of 1.8 m. In this case, the cavity has an internal height of typically 2.1m and an internal width of 2.1 m. The sliding door can be realized in dimensions of height and width of 2.2m x 2.2m, made of steel, stainless steel or carbon steel with a material thickness of 8mm, with ribs with a depth of 0.16m and a material thickness of 5mm, wherein the ribs are welded to the door panel with a spacing of 0.2m between the ribs in both axes of the plane of the door.

The separation unit 1 as shown in fig. 2 can be operated as follows: in this solution as given in the figure, the second chamber from the left is sealed by an upstream sliding door 12a and a downstream sliding door 12 b. The inlet line 11 is closed by a valve and the outlet line 11 is used to evacuate the chamber. At the same time, the cavity may be heated, which may be done by introducing a heated liquid into corresponding conduits located in the cavity and/or in the gas adsorption structure 4 and/or by introducing hot steam via the introduction conduit 11.

Steam or other gas may also be introduced as a purge gas stream during or after evacuation and/or heating or in lieu of evacuation and/or heating, and for extracting carbon dioxide, extraction line 11 is used and carbon dioxide is extracted from the chamber. Thus, the extraction of carbon dioxide can be performed with or without vacuum depending on the process configuration. Although this process occurs in the second chamber from the left, the fan 8 of the second chamber from the left is not operated, or, preferably, at a reduced speed as described further below, while the other fans are operating, and the first chamber from the left and the four chambers from the right are open to flow and serve to adsorb carbon dioxide.

Once the carbon dioxide extraction step in the second from left chamber is terminated and, optionally, the second from left chamber has been brought to ambient temperature and/or ambient pressure again, the pair of sliding doors are moved, for example, to cover the first from left chamber and manipulated to seal the first from left chamber. The fan flux of the first chamber from the left decreases and the fan flux of the second chamber from the left increases. This preferably reduces the power to the active adsorption cavity adjacent the fan without a complete stop, otherwise air will be drawn into the outlet plenum 7 by the stopped fan, thereby reducing the adsorbate absorption.

The first chamber from the left is now subjected to the operations described above for the second chamber from the left, while the other chambers are subjected to the circulation to adsorb carbon dioxide from the ambient air. In the next cycle, the pair of sliding doors is typically moved to seal the cavity at the rightmost position in the illustration, assuming that the cavity is the one that has been exposed to the circulation of ambient air for the longest time at that moment.

The cycle continues so that the sliding door, after having sealed the first chamber from the right, then travels to the second chamber from the right and seals that chamber, to the third chamber from the right, and so on. Considering that in general the adsorption step takes longer than the desorption step, the cyclic process is likewise carried out in an optimal manner, wherein as few structural elements as possible are present to operate as many adsorption chambers as possible. In fact, the number of chambers arranged in such an array may be adapted to the time ratio of adsorption and desorption. For example, if adsorption and desorption take the same amount of time, an array of two chambers adjacent to each other may be most suitable. If the ratio of time for adsorption and desorption is 5:1, optimum forward operation is given as shown in FIG. 2.

This optimal time ratio can be abandoned or relaxed by providing a hold or intermediate position outside the array, which allows to separate the process time from the configuration of the chamber and the array, since the gate can be placed in this position if it is not necessary to close the chamber, thus allowing any desorption and adsorption time.

Fig. 3 shows a detail of a variant of the frame element 30 of a possible separation unit 1 comprising an array 28 of six chambers 3 separated by a separation wall 14 and therefore each surrounded by a circumferential wall 5a, 5b and 5c, sealed with a pair of movable gates 12a and 12b (only the upstream gate shown) respectively abutting against an upstream face 13a and a downstream face 13b, in this case the second chamber from the left. In or at some cavities, different embodiments of the stabilizer 15 based on a truss structure formed by various combinations of transversal struts fixed in the cavity 3 to the circumferential wall 5 and the separation wall 14 are shown, or, as in the first cavity from the left, the gas permeable sheet crossing the cavity cross section may also be an element of the gas adsorbing structure. Optionally, depending on the desired pressure range and size of the separation unit 1, there may be no need for a stabilizer to be present as in the rightmost chamber.

Fig. 4a and 4b show the relevant positions (0 to iv) for a prior art DAC cell and a separation cell of the invention, respectively, under the conditions of the gas stream 2, taking into account the pressure drop. Fig. 4c) shows the resulting pressure curves for two units operated with the same fan 8 and the same gas adsorption structure 4. Both units start to draw air at point 0 at atmospheric pressure, whereas in the prior art unit a) the inclusion of a duct immediately creates a pressure drop, whereas the unit of the invention keeps the pressure level almost unchanged up to point i where the air hits the gas adsorption structure 4. Above the gas adsorption structure (point i to point ii), the main pressure drop occurs before the fan 8 increases the pressure to atmospheric level again. Since the fan 8 of unit a) must overcome the pressure drop constituted by the pressure drop of the gas adsorbing structure 4 and the ducts-including any covers, actuators and flow restrictions-the generated gas flow is defined by the constituted pressure drop and is accordingly larger than the case of b) where the fan must substantially overcome only the pressure drop of the gas adsorbing structure. Accordingly, the gas flow rate and the CO2 absorption rate in case b) are higher than in case a).

Fig. 5 shows a detail of a possible drive mechanism of the separation unit 1 for the lateral movement of the door 12 in this case between the three chambers 3 of the array 28, with the two outer parts of the chambers 3 exposed to the air flows 2 each pushed by a fan 8. The door 12 is guided and carried in upper and lower tracks 16, 16 fixed to a frame 30 of the array 28 to limit its movement only in the lateral direction, and is further attached to a drive belt 18 by one or a pair of catches 20. The belt 18 travels over two pulleys 17, at least one of which is driven by an electric stepper motor 19. Door 12 may move to the left and right as shown.

Fig. 6 shows a detail of one possible mechanism for sealing the movable door 12 against the upstream face 13 of the frame of the separation unit 1. In this figure, the unit is depicted from the side and only the upstream movable door 12a is shown with the upper and lower rollers 21 housed in the C-shaped guide rail 16, said C-shaped guide rail 16 being fixed by means of a rod 22 to a pneumatic drive 23, said pneumatic drive 23 being further fixed by means of an L-bracket 24 to the circumferential wall 5 of the separation unit 1, wherein the contraction of the pneumatic drive 23 pulls the C-shaped guide rail 16 and the respective upstream door 12a towards the upstream face 13a, bringing a sealing ring 26 (shown in cross-section) into contact with the upstream face 13a and providing a seal for sealing the cavity 3 inside the separation unit 1. The C-rail 16 is further supported and guided in its movement by a pair of rods 25 forming a 4-rod linkage. Although only one door is shown (only on one side of the separation unit, for example the gas inlet upstream side in this case), it will be appreciated that the same mirror image mechanism may be applied to the other side of the separation unit.

Fig. 7 shows the long-term test results of one possible arrangement of a separation unit consisting of an array of two vacuum chambers and a movable door of size 2.2m x 2.2 m. The pair of doors are repeatedly moved between the chambers by the belt drive with the seals set on the axial faces of the separation units with a set of pneumatic drives. In addition, the chamber was evacuated from atmospheric pressure to 100 millibar (abs), after which the pressure was maintained for 15 minutes before re-pressurizing the chamber, the door was moved to a second chamber and the evacuation and pressure maintenance were repeated. The separation unit was run in the ambient atmosphere for more than 1000 cycles and fig. 7 shows the resulting increase in pressure at the end of the pressure hold-hence air leakage into the evacuated vacuum chamber. It is seen firstly that this rise is less than 10 mbar in all cycles and well within the range specified by the system, and secondly that it remains almost unchanged between the first and the last cycle, demonstrating the cycle stability and robustness of the separation unit.

Example 1. material amount and material strength for a temperature variable vacuum direct air capture device.

Table 1 shows the material amount and material strength of one possible implementation of a separation unit comprising an array of six adjacent chambers and a pair of horizontally sliding doors. This is compared with A prior art separation device according to WO-A-2015185434 consisting of six individual units. In this embodiment, both variants are implemented within the envelope dimensions of a 40 foot ISO 668 shipping container.

TABLE 1

	Closed volume (m3)	Mass of structural material (kg)	Strength of material (kg/m3)
				The invention	26	9000	350
Prior Art	21	12000	570

It is seen that the material strength of the present invention is reduced by 40% (where the material strength describes the specific amount of structural material mass required to enclose a certain volume that can be used for the adsorbent structure), resulting in significant manufacturing cost savings. Furthermore, the corresponding reduced thermal mass represents a significant energy savings, particularly for direct air capture processes utilizing temperature swing.

Fig. 8 shows a possible variant of the separation unit 1, said separation unit 1 comprising a cavity 3 formed by a circumferential wall 5. The lower circumferential wall 5a and the upper circumferential wall 5b form a space in the form of a double-walled element (which forms a header 10) with the second lower circumferential wall 5a 'and the second upper circumferential wall 5 b', respectively, wherein the medium can flow to and from the chamber 3 via an inlet 11 or an outlet 11. In this way, the structure of the separation unit can be dually used for carrying structural loads and containing media.

List of reference numerals

1 separation unit

2 inlet gas/air flow

2⁺Outlet gas/air flow

3 cavities

4 gas adsorption structure

55 of the circumferential wall

5a 5 lower circumferential wall

5 a' 5 second lower circumferential wall

5b 5 upper circumferential wall

5 b' 5 second upper circumferential wall

5c 5 lateral circumferential wall

6 air inlet chamber

7 air outlet chamber

8 air propulsion device, fan

9 shutter

10 lead-in and lead-out collecting ducts/gaps

11 introduction and extraction ducts of the various chambers

12 sliding door

12a 6 upstream sliding door

12b 7 downstream sliding door

13a upstream axial face

13b downstream axial face

14 separating wall

15 stabilizer

16 guides, e.g. C guides

17 belt pulley

18 belt

19 stepping motor

20 catch

21 wheel

22 rod

23 pneumatic driver

24L section bar

254-bar linkage mechanism bar

26 sealing ring

277 sliding door region

28 separation unit with an array of cavities

296 side wall

30 frame of array 28

31 upstream opening

32 downstream opening

33 outlet manifold