Hollow fiber reactor for carbon capture and method thereof

Abstract

A hollow fiber reactor (1301) comprises a hollow fiber module (1304) that includes a plurality of hollow fiber bundles (201, 201A, 201B), each hollow fiber bundle including a plurality of hollow fibers (101) capable of carbon dioxide sorption. The plurality of hollow fiber bundles comprises at least two bundles arranged in a parallel configuration (800) or in a V-shaped configuration (300). A method of operating the hollow fiber reactor (1301).

Description

[0001] P12679

[0002] 1

[0003] HOLLOW FIBER REACTOR FOR CARBON CAPTURE AND METHOD THEREOF

[0004] Field of the Invention

[0005] The present invention relates to a hollow fiber reactor for use in carbon capture, and more particularly within direct air capture technology.

[0006] Background of the Invention

[0007] Carbon capture technologies have been developed to address the need to capture and store fossil and process-related carbon dioxide (CO2), whether directly at industrial installations, before release into the atmosphere, or from the general atmosphere, into which carbon dioxide may be released from a moving source such as a vehicle.

[0008] A direct air carbon capture process typically involves the stages of atmospheric air being introduced, actively or passively, to a reactor, carbon dioxide being removed from the air through binding, for example through absorption into a liquid solvent or through adsorption onto a solid sorbent, and then carbon dioxide being released from the solvent or sorbent. The captured carbon dioxide can then be utilised in some way, for example, for synthetic fuel production or carbonation of beverages, or transported to a storage facility, or integrated into a desalination process, or integrated in a data center. Solvents or sorbents used in the carbon capture process may be reused or recycled.

[0009] A carbon capture process may include an adsorption phase, during which a gas mixture containing carbon dioxide contacts a carbon dioxide affine sorbent material so that at least part of the carbon dioxide is bound at the surface of the sorbent material until it is sufficiently enriched or saturated. Thereafter, in a second, desorption phase, the carbon dioxide enriched sorbent material may be heated, set under vacuum, subject to an electrical current, contacted with a humid steam, and / or a separate purge gas streamed along it, to remove the carbon dioxide therefrom. It may be appreciated that various other processes may be used to release carbon dioxide from the sorbent material. This separation may result in carbon dioxide being obtained in a concentrated form. The carbon dioxide may then be utilised in some way, for example, for synthetic fuel production, carbonation of beverages, use in a greenhouse, sequestered, or transported to a storage facility for later use or green concrete, integrated into a desalination process, or integrated in a data center. The process may be repeated to perform a cyclic adsorption and desorption of carbon dioxide. Following multiple cycles of adsorption and desorption, oxidative degradation, for example, may reduce the number of available amine sites that may react with carbon dioxide. As a result, the sorbent material may decrease its capacity to capture carbon dioxide and require replacement or regeneration.

[0010] Hollow fiber (HF) membranes are used extensively in the field of fluid separation and purification; with different applications including gas separation, water purification, desalination of seawater, and extracorporeal blood treatment.

[0011] Hollow fiber membranes are tubular, defining a lumen extending therethrough, through which a fluid can flow, and having an intricate porous surface. The efficacy of such hollow fiber membranes is governed by specific BET surface area, pore size distribution, and porosity. These surface parameters can be tuned to tailor hollow fiber membranes for different applications. For example, the pore structure distribution can be used to classify hollow fiber membranes into microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes. The bulk-scale production and manufacture of hollow fiber membranes and modules, respectively, has led to the commercialization of this technology in several fields; however, hollow fiber membrane research for the adsorption and desorption of carbon dioxide is in the nascent stage of development.

[0012] US 2023 / 0182081 discloses a contactor module for heating, cooling, humidifying, and / or dehumidifying air and that includes hollow fibers composed into panels having first and second ports and which are configured in a V-shaped arrangement about a structural support. When used for evaporative cooling, water flows through the lumens of the hollow fibers, while dry, hot air flows over the surfaces of the hollow fibers. When used for dehumidification, a liquid desiccant flows through the lumens of the hollow fibers, while humid air flows over the surfaces of the hollow fibers.

[0013] US 9316123 B2 discloses a reactor in which a flue gas including carbon dioxide flows over an array of zeolite tubes that are “packed” into an internal volume of the reactor. Carbon dioxide is adsorbed, thus generating heat, and feedwater introduced through the lumen of the tubes is heated by the adsorption process and usable in any system that requires preheated water. For desorption of carbon dioxide, hot water / steam is introduced into the lumen of the tubes.

[0014] US 8658041 B2 discloses a contactor in which a plurality of fibers, each comprising a sorbent material, a lumen, a plurality of tortuous pathways and a barrier layer that functions to prevent fluid communication between the sorbent material and a heat transfer medium, are fixed in a parallel array within a chamber by a binding material, which may be an epoxy or a resin. Use P12679

[0015] 3 of the contactor for adsorbing a component from a medium, including, but not limited to, air, water, fuels, chemicals, petrochemicals, soil, flue gas, natural gas, fuel gas, bio gas, town gas, waste gas, water, coal gas, air, or a carbon dioxide-containing fluid, is disclosed.

[0016] US 8133308 B2 discloses a cylindrical cross flow contactor that comprises a plurality of hollow fiber adsorbents, each including a polymer matrix, a sorbent material, a plurality of tortuous pathways, a lumen, and a barrier layer lining the lumen to prevent fluid communication between the lumen and the sorbent material. The fibers are fixed in a parallel array and the ends of the fibers may be potted or embedded in a binding material, which may be an epoxy or a resin.

[0017] Several drawbacks are associated with the parallel array structuring of hollow fibers disclosed in US 8658041 B2 and US 8133308 B2, including high pressure drop and substantial downtime to remove the fixed hollow fibers for maintenance. Nonetheless, there are benefits to the parallel array structure as well, such as ease of manufacturing, scaling, and increased volumetric capacity. The present invention will be directed to parallel array structures as well as other configurations, to be described in detail below.

[0018] US 9751039 B2 discloses a gas separation unit for the separation of carbon dioxide from air using a cyclic adsorption / desorption process. Layers of particulate sorbent material are stacked in a zigzag manner. Heating for desorption is accomplished using tubing containing a heat exchange fluid; in the same manner, cooling of the sorbent can be accomplished with the tubing. The heat transfer infrastructure is bulky, enlarging the footprint of the overall structure.

[0019] It is desirable to provide a hollow fiber module for use in carbon capture, in particular in direct air capture, that provides efficiencies with regards to performance relative to carbon dioxide capture, reactor volume, and maintenance operations, among other advantages.

[0020] Summary of the Invention

[0021] According to a first aspect there is provided a hollow fiber reactor, comprising: a hollow fiber module including a plurality of hollow fiber bundles, each bundle including a plurality of hollow fibers that are capable of carbon dioxide sorption, wherein said plurality of hollow fiber bundles comprises at least two bundles arranged in a parallel configuration or in a V-shaped configuration in which first ends of the two bundles are adjacent with first sides of the two bundles forming an internal angle; a lumen side inlet for introducing a flow of a liquid heat transfer medium to the lumens of the hollow fiber bundles; and shell side inlet for introducing P12679

[0022] 4 a flow of a gas containing carbon dioxide to contact the hollow fiber bundles, whereby the flow of gas containing carbon dioxide gas is at a non-zero, non-straight angle with respect to the flow of a liquid heat transfer medium.

[0023] The parallel or V-shaped configuration of the hollow fiber bundles advantageously allows effective use of the volume available within the hollow fiber reactor for a hollow fiber module to be made. The internal angle can range from 0 degrees, but with the first sides not in contact, to 180 degrees. The internal angle can therefore range from close to 0 degrees to 180 degrees.

[0024] In an example, the hollow fibers are functionalized with nucleophilic groups. The nucleophilic groups may be amine groups.

[0025] In an example, the plurality of hollow fibers comprises coated hollow fibers, in which the inner surface of the lumen of the hollow fiber has a semi-permeable layer that is impermeable to liquid water but permeable to water vapor.

[0026] The hollow fiber module may have a shape that is generally rectangular cuboid or that is generally tubular.

[0027] Preferably, each of the plurality of hollow fiber bundles is independently removable from the hollow fiber module. This beneficially allows for reduced total reactor downtime.

[0028] The hollow fiber reactor may further comprise a vacuum chamber in which the hollow fiber module is hermetically sealable during a desorption phase.

[0029] According to a second aspect there is provided a method of operating a hollow fiber reactor, comprising: exposing a hollow fiber module to ambient air, the hollow fiber module including a plurality of hollow fiber bundles, each bundle including a plurality of hollow fibers, wherein said plurality of hollow fiber bundles comprises at least two bundles arranged in a parallel configuration or in a V-shaped configuration in which first ends of the two bundles are adjacent with first sides of the two bundles forming an internal angle, for adsorption of carbon dioxide from the ambient air into at least one of the plurality of hollow fibers; subsequently reducing exposure of the hollow fiber module to the ambient air; introducing a first flow of a liquid heat transfer medium, at a first temperature, to the lumen of at least one of the plurality of hollow fibers, in which the liquid heat transfer medium is prevented from flowing from the lumen P12679

[0030] 5 through the semi-permeable layer and wherein a vapor state of the heat transfer medium is allowed to pass from the lumen through the semi-permeable layer, the first temperature sufficient to elevate the temperature of the hollow fiber for desorbing adsorbed carbon dioxide therefrom; and subsequently introducing a second flow of a liquid heat transfer medium, at a second temperature that is lower than said first temperature, to the lumen of said at least one of the plurality of hollow fibers, the second temperature sufficient to cool the hollow fiber.

[0031] In an example, the second temperature is sufficient to cool the hollow fiber below 40 °C.

[0032] In an example, the liquid heat transfer medium is liquid water, and the vapor state of the heat transfer medium is water vapor. The flow of water vapor may lower a carbon dioxide concentration in the hollow fiber, and hence would enhance the desorption kinetics or reduce the desorption duration.

[0033] In an example, the liquid heat transfer medium is mixed with at least one of demineralized water, water dosed with a conditioning agent, a corrosion inhibitor, an anti-frost additive, a biocide treatment, a boiling point adjuster, silicone oil, propylene glycol, ethyl glycol, polyethylene glycol, a salt, m-Xylene, ethyl benzoate, o-Xylene, decamethyltetrasiloxane (MD2M), and undecane methanol, ethanol, t-butanol, 2-propanol, 1-propanol, 2-butanol, t- amyl alcohol, i-butanol, 1 butanol, i-amyl alcohol, 2 ethylbutanol, 2-ethylhexanol, heptane, octane, cholorobenzene, p-cymene, and tetralin to allow controlled steam permeation through the lumen wall of the hollow fiber.

[0034] In an example, the reducing exposure of the hollow fiber module to the ambient air comprises closing a shell side inlet of the hollow fiber reactor.

[0035] In an example, the method comprises hermetically sealing the hollow fiber reactor and reducing a pressure within the hollow fiber reactor prior to introducing the first flow of a liquid heat transfer medium, at the first temperature, to the lumen of the least one of the plurality of hollow fibers to enhance the operation standards and the lifetime of the hollow fiber-based sorbents.

[0036] In an example, the method further comprises (i) removing a hollow fiber bundle from the hollow fiber module; and(ii) replacing the hollow fiber bundle removed from the hollow fiber module at (')■ P12679

[0037] 6

[0038] In an example, the hollow fiber bundle removed from the hollow fiber module at (i) is inserted back into the hollow fiber module at (ii).

[0039] The method may further comprise (iii), performing at least one treatment step on the hollow fiber bundle removed from the hollow fiber module at (i).

[0040] In an example, the method comprises treating one or more hollow fiber bundles of the hollow fiber module with an amine grafting solution.

[0041] Further particular and preferred aspects of the present invention are set out in the dependent claims.

[0042] Brief Description of the Drawings

[0043] The present invention will now be more particularly described, with reference to the accompanying drawings, in which:

[0044] Figure 1 shows an example hollow fiber;

[0045] Figure 2 is an exploded view of a hollow fiber bundle according to a first example;

[0046] Figure 3 illustrates a V-shaped configuration of hollow fiber bundles;

[0047] Figure 4 shows a plurality of hollow fiber bundles according to the first example of Figure

[0048] 1 , arranged in a V-shaped configuration series according to a first specific example;

[0049] Figure 5 illustrates a 3-dimensional shape created by the hollow fiber bundles of the V- shaped configuration series according to a first specific example of Figure 4;

[0050] Figure 6 shows a plurality of hollow fiber bundles according to a second example and arranged in a V-shaped configuration series according to a second specific example;

[0051] Figure 7 illustrates a 3-dimensional shape created by the hollow fiber bundles of the V- shaped configuration series according to a second specific example of Figure 6;

[0052] Figure 8 shows a top view of a plurality of hollow fiber bundles arranged in a parallel configuration series according to a third specific example;

[0053] Figure 9 shows a side view of a reinforced hollow fiber screen according to a first specific example;

[0054] Figure 10 shows a perspective view of the reinforced hollow fiber screen according to a first specific example of Figure 9;

[0055] Figure 11 shows a plurality of hollow fiber screens aligned to construct a bundle;

[0056] Figure 12 shows a hollow fiber bundle according to the first example of Figure 2;

[0057] Figure 13 shows a schematic of an example reactor provided with a hollow fiber module that comprises a plurality of hollow fiber bundles arranged in a V-shaped configuration; P12679

[0058] 7

[0059] Figure 14 illustrates an adsorption phase;

[0060] Figure 15 illustrates a desorption phase; and

[0061] Figure 16 illustrates a cooling phase.

[0062] Description

[0063] Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the apparatus, systems and processes described herein. It is to be understood that embodiments can be provided in many alternate forms and the invention should not be construed as limited to the specific embodiments and examples set forth herein but by the scope of the appended claims.

[0064] With respect to terminology of inexactitude, the terms “about” and “approximately” may be used, interchangeably, to refer to a measurement that includes the stated measurement and that also includes any measurements that are reasonably close to the stated measurement. Measurements that are reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount as understood and readily ascertained by individuals having ordinary skill in the relevant arts. Such deviations may be attributable to measurement error, differences in measurement and / or manufacturing equipment calibration, human error in reading and / or setting measurements, minor adjustments made to optimize performance and / or structural parameters in view of differences in measurements associated with other components, particular implementation scenarios, imprecise adjustment and / or manipulation of objects by a person or machine, and / or the like, for example. In the event it is determined that individuals having ordinary skill in the relevant arts would not readily ascertain values for such reasonably small differences, the terms “about” and “approximately” can be understood to mean plus or minus 10% of the stated value.

[0065] As used herein "hollow fiber" refers to a semi-permeable tubular element with an axial lumen. The hollow fiber has a lumen side and a shell side. The hollow fiber may have a cross-sectional shape that is cylindrical, but may have an alternative cross-sectional shape, which may be symmetrical or asymmetrical, providing that it defines a lumen within.

[0066] As used herein, a “hollow fiber bundle” refers to a plurality of hollow fibers arranged in a unitary structure.

[0067] As used herein, a “hollow fiber module” refers to a plurality of hollow fiber bundles arranged in a configuration. P12679

[0068] 8

[0069] As used herein, “additives” may refer to the reagents added to a dope mixture to tune the surface morphology of the hollow fiber during the spinning process via non-solvent induced phase separation. Examples of surface morphology include without limitation pore size and surface area of the hollow fiber.

[0070] As used herein, a “filler” may refer to a non-polymeric matrix material added, dispersed through, or otherwise incorporated into a hollow fiber structure. Non-limiting examples of fillers include, but are not limited to, an ion exchange resin, such as a strongly basic anion exchange resin (e.g., Dowex™ Marathon™ A, di- and multi-amines, polyethyleneimine, or another suitable carbon dioxide adsorbing material, such as desiccant, carbon molecular sieve, carbon adsorbent, graphite, activated alumina, molecular sieve, aluminophosphate, silicoaluminophosphate, zeolite adsorbent, ion exchanged zeolite, hydrophilic zeolite, hydrophobic zeolite, modified zeolite, natural zeolites, faujasite, mordenite, metal-exchanged silico-aluminophosphatable from Dow Chemical Company, etc.), zeolite, activated carbon, alumina, metal-orge, uni-polar resin, bi-polar resin, aromatic cross-linked polystyrenic matrix, ion exchange resins, anion exchange resins, brominated aromatic matrix, methacrylic ester copolymer, graphitic adsorbent, carbon fiber, carbon nanotube, nano-materials, metal salt adsorbent, perchlorate, oxalate, alkaline earth metal particle, metal oxide, chemisorbent, amine, organo-metallic reactant, hydrotalcite, silicalite, zeolitic imadazolate framework, covalent organic framework (COF) and metal organic framework (MOF) adsorbent compounds, and combinations thereof.

[0071] As used herein, “mixed matrix hollow fibers” refer to the fibers including filler materials. The filler materials (both aminated and non-aminated variants) may be dispersed throughout the hollow fiber structure during the fiber production process.

[0072] As used herein, “liquid heat transfer medium” may comprise water or any suitable liquid that takes part in heat transfer by serving as an intermediary in cooling one side of a process, transporting and storing thermal energy, and heating on another side of a process. For example, demineralized water, water dosed with a conditioning agent, which may be or comprise a corrosion inhibitor, an anti-frost additive, a biocide treatment, a boiling point adjuster, for example silicone oil, propylene glycol, ethyl glycol, polyethylene glycol, a salt, or other water miscible ingredient may be added to water or used alone. Other examples of chemical fluids that may be suitable include m-Xylene, ethyl benzoate, o-Xylene, decamethyltetrasiloxane (MD2M), and undecane. Alcohols that may be suitable include but P12679

[0073] 9 are not limited to methanol, ethanol, t-butanol, 2-propanol, 1 -propanol, 2-butanol, t-amyl alcohol, i-butanol, 1 butanol, i-amyl alcohol, 2 ethylbutanol, 2-ethylhexanol, other alcohol, mixtures thereof, and mixtures thereof with water. Hydrocarbons that may be suitable include but are not limited to heptane, octane, cholorobenzene, p-cymene, and tetralin.

[0074] As used herein, a “coated hollow fiber” refers to a hollow fiber where an inner surface of the hollow fiber structure adjacent to the lumen has a semi-permeable layer that is impermeable to a liquid heat transfer medium but permeable to a vapor state of the heat transfer medium.

[0075] As used herein "nucleophile” is a chemical species that forms bonds by donating an electron pair. Examples of nucleophilic groups include amines, amide salts, alcohols, alkoxides, thiols, and metal alkyls.

[0076] As used herein, an “unfunctionalized hollow fiber” refers to a hollow fiber as prepared after spinning, which does not have additional functional or reactive groups apart from those present in the polymer skeleton, fillers, on either the lumen side or the shell side of the hollow fiber.

[0077] As used herein, a “functionalized hollow fiber” refers to a hollow fiber as obtained after reaction with nucleophilic groups, such as amines.

[0078] As used herein, the term "ambient air" is defined herein as air at pressure, temperature, and carbon dioxide presence conditions that the hollow fiber reactor of the present disclosure is exposed to when outside. Ambient air pressure conditions typically include pressures in the range from 0.8 to 1.1 bar absolute. Ambient air temperature conditions typically include temperatures in the range of -40 to 60 °C, more typically -30 to 45 °C. Carbon dioxide conditions present in ambient air typically include concentrations ranging between 380 ppm and 1000 ppm.

[0079] As used herein, “rectangular” includes square.

[0080] As used herein, “screen” refers to a unitary structure of reinforced hollow fibers that are matted or woven and structurally stabilized via reinforcing materials.

[0081] An example hollow fiber 101 is shown in Figure 1. The hollow fiber 101 comprises a structure for capture of carbon dioxide sorption, indicated at 102, and a lumen, indicated at 103, P12679

[0082] 10 extending axially therethrough. A lumen side 104 and a shell side 105 of the hollow fiber 101 are indicated. The lumen side 104 may be considered an “interior” side and the shell side 105 an “exterior” side. Optionally, and in this illustrated example, the hollow fiber 101 comprises a semi-permeable barrier layer 106, shown radially disposed between the structure for capture of carbon dioxide sorption 102 and the lumen 103.

[0083] In some embodiments, the structure for capture of carbon dioxide sorption may include a polymer matrix functionalized with nucleophilic groups. Examples of polymer matrices that may be suitable for functionalization by nucleophilic groups include without limitation polyetherimide, polyvinylchloride (PVC), polyimides (Pls), polybenzylchloride, polybenzimidazole, and polyphenyleneoxide.

[0084] In some embodiments, the structure for capture of carbon dioxide sorption may include a polymer and one or more fillers, for example, metal-organic frameworks (MOFs), aromatic cross-linked polystyrenic matrix including but not limited to poly-styrene based ion-exchange resins and amine functionalized resins, zeolites, ion-exchange resins, activated carbon, alumina, silica, inorganic nanoparticles, and any other suitable filler. Such structures may rely on polymers for structural properties rather than for sites where functionalization may occur. In these cases, functionalization may occur on the filler instead of the polymer matrix. As such, the polymer for structures with fillers may be different from structures that include a polymer matrix functionalized with nucleophilic groups. Polymers that may be suitable for structural support of fillers may include but not be limited to polypropylene (PP), polybenzimidazole (PBI), polyvinylenedifluoride (PVDF), polysulfone (PSU), polyethersulfone (PES), polyphenyleneoxide (PPO), or any other suitable polymer may be used.

[0085] Nucleophilic groups that may be suitable for functionalization of the polymer matrix and I or the fillers include without limitation amines, amide salts, alcohols, alkoxides, thiols, and metal alkyls.

[0086] In one exemplary embodiment, the nucleophilic groups may include amine groups. Polymeric amines may benefit from more sites for chemisorption of carbon dioxide; however, such polymeric amines may be branched and I or bulky, which may impede reaction conversion to the nucleophilic group due to pore blockages and potential for crosslinking. Subsequently, the surface underneath the aminated region of polymeric amines may have reduced access to free amines to allow further functionalization. Oppositely, small molecule amines may demonstrate faster diffusion coefficients compared to the polymeric amines, leading to a more P12679

[0087] 11 complete functionalization. As such, functionalization using a mixture of two or more amines may be beneficial. For example, the polymer matrix and I or the fillers may be functionalized with a mixture of small molecule and polymeric amines. Small molecule amine groups may include ethylenediamine (EDA), 1 ,3-propylenediamine (PDA), mefa-xylylenediamine (meta- XyDm), para-xylylenediamine (para-XyDm), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) or pentaethylenehexamine (PEHA), mono-, di-, tri-, tetra- or polyamino functionalized amino- alkoxy-silanes aminosilanes, any other suitable small molecule amine group, or combinations thereof. Polymeric amine groups may include branched polyethyleneimine, polyallylamine, any other suitable polymeric groups, or combinations thereof.

[0088] Furthermore, in some embodiments, hollow fibers may be coated, such that an inner surface adjacent to the lumen of the hollow fiber has a barrier layer. In one example, the barrier layer may be a semi-permeable layer that is impermeable to a liquid heat transfer medium but permeable to a vapor state of the heat transfer medium. For instance, the liquid heat transfer medium may be liquid water, and a vapor state of the heat transfer medium may be water vapor. As such, the semi-permeable layer may be formed of a material that substantially prevents the passage of the liquid heat transfer medium (e.g., liquid water, etc) but allows for the passage of a vapor state of the heat transfer medium (e.g., water vapor, etc). Suitable materials include non-polar polymers, particularly non-polar polymers which are rubbery or glassy at ambient conditions. As examples, suitable materials may include ethylene propylene diene monomer (EPDM) rubber (ethylene propylene diene monomer cross-linked with organic peroxides such as Di-(4-methylbenzoyl)-peroxide, Dibenzoyl peroxide, 1 ,1-Di-(tert- butylperoxy)-3,3,5-trimethylcyclohexane, te / Y-Butyl dicumyl peroxide, tertbutylperoxybenzoate, lauroyl peroxide, radical initiators or combinations thereof), polychloroprene, polystyrene, and styrene-butadiene. Other suitable materials will be apparent to the skilled person. In certain examples, the water vapour permeability of the semi- permeable layer is selected to be less than 100-3000 Barrer (1 Barrer = 3.348 x 10-16 mol.m / (m2.s.Pa)). A semi-permeable layer having a thickness of between 10 -500 micrometers has been determined to be particularly suitable in the processes of the present invention.

[0089] An exploded view of a hollow fiber bundle 201 , according to a first example, is shown in Figure 2. The hollow fiber bundle 201 includes a plurality of hollow fibers, such as hollow fibers 202, 203, 204, that are capable of carbon dioxide sorption. The hollow fibers in the bundle may be arranged into an array. According to the array shown in Figure 2, the hollow fibers are arranged 12 in a series of rows and columns that are staggered; however, it is to be appreciated that the hollow fibers may be arranged in any suitable arrangement.

[0090] As shown in this Figure, the hollow fiber bundle 201 is generally rectangular in shape, having a length in a length direction L between a pair of opposed first and second sides 205, 206, a depth in a depth direction D between a pair of opposed first and second ends 207, 208 and a width in a width direction W between a pair of opposed third and fourth sides 209, 210. It is to be understood however that the hollow fiber bundle may have any suitable alternative shape and / or relative dimensions.

[0091] As indicated in Figure 2, the hollow fiber bundle 201 can receive a flow 211 of a first fluid, such as a liquid heat transfer medium, therethrough, flowing through the lumens of the hollow fibers, and a flow 212 of a second fluid, such as a gas containing carbon dioxide, flowing between the hollow fibers and across the flow 211 of a first fluid.

[0092] For example, the flow 211 of a first fluid may be introduced to the hollow fiber bundle 201 from a lumen inlet side, indicated at 213, at one end 205 thereof, from which the flow 211 is directed to first ends of the lumens of the hollow fibers, and to a lumen outlet side, indicated at 214, at the opposed end 206 thereof, to which the flow 211 is directed from the second ends of the lumens of the hollow fibers, the first fluid flowing through the hollow fiber bundle 201 , along the lumen sides of the hollow fibers, generally in the depth direction D, and the flow 212 of a second fluid may come into contact with the hollow fiber bundle 201 from one side 209 thereof, and may pass through the hollow fiber bundle 201 to the opposed side 210 thereof, the second fluid flowing through the hollow fiber bundle 201 , across the shell sides of the hollow fibers, generally in the width direction W.

[0093] A lumen side inlet 215 and a lumen side outlet 216 are indicated in this Figure. Any suitable number and type of fluid inlet / outlet may be used at any suitable location or locations. Any suitable type of flow guiding arrangement, for example comprising one or more manifolds, baffles and / or channels, may be used to direct, restrain and / or regulate the flow of a fluid through the hollow fiber bundle.

[0094] Hollow fiber bundle 201 is shown in Figure 3 arranged with a second, like hollow fiber bundle 102B in a V-shaped configuration 300, according to a first example, in which first ends 205, 205 respectively of the two bundles 201 , 201 B are adjacent, with the second and the first sides 210, 209B respectively of the two bundles 201 , 201 B forming an internal angle 301. Thus, the 13 second and the first sides 210, 209B respectively of the two bundles 201 , 201 B face inwardly towards each other, with the respective first and second sides 209, 21 OB of the two bundles 201 , 201 B facing outwardly of each other. According to the illustrated example V-shaped configuration 300, the internal angle 301 between the inwardly facing sides 210, 209B of the respective hollow fiber bundles 201 , 201 B is acute.

[0095] A plan view of a plurality of hollow fiber bundles according to the first example of Figure 1 and comprising bundles arranged in a V-shaped configuration series 400, according to a first specific example, is shown in Figure 4.

[0096] The V-shaped configuration series 400 comprises the V-shaped configuration 300 of the arrangement of the hollow fiber bundle 201 and the second, like hollow fiber bundle 201 B shown in Figure 3. According to this first example, a cover element 401 is arranged to extend across the adjacent ends 205, 205B of the first and second hollow fiber bundles 201 , 201 B of the V-shaped configuration 300.

[0097] With reference to Figure 2 and the accompanying description, the cover element 401 functions to prevent the passage of a flow 212 of a second fluid, such as a gas containing carbon dioxide, between the adjacent ends 205, 205B of the first and second hollow fiber bundles 201 , 201 B and to direct the second fluid to instead flow across the shell side of the hollow fibers of the hollow fiber bundles 201 , 201 B, whereby carbon dioxide may be adsorbed by the hollow fibers (as described in detail below). The cover element 401 may have any suitable dimensions and may comprise any suitable material or combination of materials. For example, the cover element may comprise a plastic material and / or a metal.

[0098] The V-shaped configuration series 400 further comprises third and fourth hollow fiber bundles 201 C, 201 D arranged in a second, like V-shaped configuration 300B, and fifth and sixth hollow fiber bundles 201 E, 201 F arranged in a third, like V-shaped configuration 300C. According to this first example, the magnitude of the internal angle 301 B, 301 C of each of the second and third V-shaped configurations 300B is substantially the same as that of the internal angle 301 of V-shaped configuration 300. In this example also, the adjacent ends 205C, 205D of the second V-shaped configuration 300B and the adjacent ends 205E, 205F of the third V-shaped configuration 300B are provided with a respective cover element 401 B, 401 C like cover element 401 closing off any gap between the adjacent ends 205, 205B of the V-shaped configuration 300. P12679

[0099] 14

[0100] As shown, the second V-shaped configuration 300B is located adjacent to the V-shaped configuration 300, with the second end 206C of the third hollow fiber bundle 201 C adjacent the second end 206B of the second hollow fiber bundle 201 B. An internal angle 301 D between the second and third hollow fiber bundles 201 B, 201 C is formed, which in this example has substantially the same magnitude as the internal angle 301 of V-shaped configuration 300. In addition, in this example, a cover element 401 D is provided to block off any gap between the adjacent ends 206B, 206C of the second and third hollow fiber bundles 201 B, 201 C to fluid flow.

[0101] As also shown, the third V-shaped configuration 300C is located adjacent to the second V- shaped configuration 300B, with the second end 206E of the fifth hollow fiber bundle 201 E adjacent the second end 206D of the fourth hollow fiber bundle 201 D. An internal angle 301 E is formed between the fourth and fifth hollow fiber bundles 201 D, 201 E. In this example, the internal angle 401 E has substantially the same magnitude as that of the internal angle 301 of V-shaped configuration 300. Further, according to this example, a cover element 401 E is provided across the adjacent ends 206D, 206E of the second and third hollow fiber bundles 201 B, 201 C to prevent the passage of a fluid therebetween.

[0102] The hollow fiber bundles within the hollow fiber module can be arranged at any angle relative to one another, allowing for flexibility in design and optimization of the reactor's performance. As illustrated in Figure 8, the bundles may be configured in a parallel arrangement, in which the first sides of the bundles are aligned without forming an internal angle. This parallel configuration can be advantageous in certain applications, as the design becomes less complex while maintaining efficient fluid flow and heat transfer. The ability to adjust the angle between the bundles, including the option for a parallel arrangement, provides versatility in tailoring the reactor to specific operational requirements and spatial constraints, ensuring performance is optimized in various carbon capture scenarios, as will be described below.

[0103] It is important to understand that while the hollow fiber bundles are arranged in a series, they are independent components. Thus, each hollow fiber bundle may be provided with its own individual fluid inflow / outflow arrangement. In addition, each hollow fiber bundle may be removable from the series separately from each other hollow fiber bundle.

[0104] As illustrated, hollow fiber bundles 201 and 201 B of V-shaped configuration 300, and hollow fiber bundles 201 C and 201 D of the second V-shaped configuration 300B together form a W- shaped configuration (or M-shaped configuration, depending on the direction of viewing). P12679

[0105] 15

[0106] Within the V-shaped configuration series 400, N-shaped configurations of hollow fiber bundles can be identified, such as is formed by hollow fiber bundles 201 B, 201 C and 201 D and by hollow fiber bundles 201 D, 201 E and 201 F. The V-shaped configuration series 400 extends, in the manner of forming knife (or accordion) pleats, in a generally linear direction as indicated by arrow 402.

[0107] Although the first example of a V-shaped configuration series 400 is illustrated to contain 6 hollow fiber bundles, it is to be appreciated that other examples may contain any plural even or odd number of hollow fiber bundles. Further, although the first example of a V-shaped configuration series 400 is illustrated to contain hollow fiber bundles arranged such that substantially similar internal angles are formed between each pair of adjacent hollow fiber bundles, it is to be appreciated that other examples may contain hollow fiber bundles arranged differently so that at least two different internal angles are formed between different pairs of adjacent hollow fiber bundles.

[0108] The hollow fiber bundles of the V-shaped configuration series 400 create a 3-dimensional shape that is generally rectangular cuboid, such as the generally rectangular cuboid shape indicated by outline 501 in Figure 5.

[0109] In Figure 5, arrow 211 indicates a lumen side direction of flow of a first fluid to the lumens of the hollow fiber bundles, and arrow 212 indicates a shell side direction of flow to the hollow fiber bundles. The shown shell side direction of flow crosses the lumen side direction of flow substantially perpendicularly but may extend relative to the lumen side direction at any suitable alternative angle (non-zero, non-straight, in other words between 0 and 180 degrees).

[0110] A plan view of a plurality of hollow fiber bundles according to a second example and comprising bundles arranged in a V-shaped configuration series 600 according to a second specific example is shown in Figure 6.

[0111] The V-shaped configuration series 600 comprises a plurality of like, hollow fiber bundles, including bundles 601 , 601 B, 601 C and 601 D, which are similar to, but dimensioned differently from, the hollow fiber bundles 201 , 201 B, 201 C and 201 D shown in Figure 4, and which are also arranged to form a W-shaped configuration (or M-shaped configuration); however, as shown, the W-shaped configuration (or M-shaped configuration) is curved around a central axis 602. The hollow fiber bundles of the V-shaped configuration series 600 create a 3-dimensional shape that is generally tubular, such as the generally tubular shape indicated by outline 701 in Figure 7. As can be seen, the cross-sectional shape in a plane through which the central axis 402 extends perpendicularly is generally star-polygonal.

[0112] Although the first example of a V-shaped configuration series 600 is illustrated to contain 16 hollow fiber bundles, it is to be appreciated that other examples may contain any other suitable plural number of hollow fiber bundles, with any suitable internal angle formed between adjacent pairs of hollow fiber bundles.

[0113] In Figure 7, arrow 211 indicates a lumen side direction of flow of a first fluid to the lumens of the hollow fiber bundles, and arrow 212 indicates a shell side direction of flow to the hollow fiber bundles. The shown shell side direction of flow crosses the lumen side direction of flow substantially perpendicularly but may extend relative to the lumen side direction at any suitable alternative angle (non-zero, non-straight, in other words between 0 and 180 degrees).

[0114] A perspective view of a plurality of hollow fiber bundles arranged in a parallel configuration series 800 according to a third specific example is shown in Figure 8. The hollow fiber bundles of the parallel configuration series 800 create a 3-dimensional shape that is generally rectangular cuboid, such as that indicated by outline 801 .

[0115] The parallel configuration comprises a plurality of like, hollow fiber bundles, which may be similar to, or dimensioned differently from, the hollow fiber bundles 201 , 201 B shown in Figure 2.

[0116] A module can comprise a plurality of hollow fibers bundles, in the form of substantially planar plates, in a parallel configuration in which the hollow fiber bundles are spaced apart to define an inter-bundle flow channel for a first fluid. For example, bundles 802 and 802B are spaced apart to define inter-bundle flow channel 803 between them. The first fluid can be a CO2 containing gas or air, and can be directed through the inter-bundle flow channel along a first flow direction. A second fluid that is a heat-transfer fluid can be flowed through the lumen of the hollow fibers inside the bundles. The second fluid can be directed along the longitudinal axes of the bundles in a second direction. The second direction can be substantially orthogonal to the first direction and substantially parallel to the longitudinal axes of the bundles. P12679

[0117] 17

[0118] In Figure 8, a lumen side direction of flow of a first fluid to the lumens of the hollow fiber bundles is not indicated, but a shell side direction of flow to the hollow fiber bundles is indicated by arrow 212. The shown shell side direction of flow crosses the lumen side direction of flow substantially perpendicularly but may extend relative to the lumen side direction at any suitable alternative angle (non-zero, non-straight, in other words between 0 and 180 degrees).

[0119] In some embodiments, bundles configured in a parallel configuration can provide favorable hydrodynamics, thermal control, manufacturability, and operability under low pressure drop, high-throughput conditions typical of capture units.

[0120] In some examples, the hollow fiber bundles are separated by spacers, which may also function as end-closures, as described below. For example, bundles 802 and 802B are spaced apart by spacer 804. When operated at typical face velocities for adsorption or desorption steps, the straight channels between the bundles may promote near plug-flow behavior and minimize secondary flows. As a result, the bed may exhibit reduced pressure drop for a given flow rate, attributed to the absence of corrugation-induced tortuosity and recirculation observed in the pleated V- or W- geometries. The reduction in pressure drop directly lowers blower and / or vacuum power requirements, enabling improved energy efficiency at system level.

[0121] To inhibit bypass (short-circuit) flow of the first fluid (CO2 / air) outside the active sorbing region of the module, the module can include a fluid-tight end closure at one lateral end of the configuration of bundles. The end closure blocks through-routing at that end so that the first fluid entering the inter-bundle channel is constrained to spread laterally and traverse across substantially the full width prior to discharge. By eliminating peripheral leakage paths, the end closure promotes uniform cross-sectional loading and substantially even residence-time distribution across the width of the channels.

[0122] A parallel configuration may provide improved flow uniformity, residence-time distribution across channels, which may sharpen the mass-transfer zone, yielding more predictable breakthroughs, higher sorbent utilization, and tighter process control across cyclic operation.

[0123] Manufacturing, sealing, and manifolding are simplified when the bundles are in a parallel configuration, which simplifies scalability, reduces leak paths and assembly variability.

[0124] In another embodiment, the hollow fibers are constructed in a reinforced woven mat structure. The woven hollow fiber mats are defined as screens. A plurality of hollow fibers are stacked P12679

[0125] 18 parallel to each other followed by reinforcement at the ends and / or the body of the hollow fibers. Reinforced hollow fiber screens are more robust to mechanical stress induced fatigues caused by continuous contact with air. Enhanced hydraulic stability can be realized as the reinforcement holds the HFs in place and reduces HF breakages. A screen configuration, as compared to staggered or otherwise configured hollow fibers, can result in reduced pressure drop. Hollow fiber can have controlled spacings and extended durability and may offer more predictable mass transfer phenomena. Reinforced HF screens may create micro-vortices and secondary flow without adding separate spacers or baffles and the integrated turbulence may enhance the mass transfer kinetics. With respect to scale-up and quality control, a hollow fiber screen structure can deliver lot-to-lot uniformity in fiber count, spacing, and tension within the bundle with simpler upscaling protocols.

[0126] Figures 9 & 10 show a reinforced hollow fiber screen 901 according to a specific example. According to the shown example, thirty-two hollow fibers, such as hollow fiber 902, are laid parallel to each other at a predetermined spacing distance between them. The hollow fibers are then reinforced with support materials. These support materials may include polymeric threads, synthetic thread-like materials, and / or metal plate or wire based supports. The reinforcement threat / material holds the hollow fiber in a stable configuration through wrapping around the hollow fiber or weaving across the hollow fiber to ensure the stability of the hollow fibers. The reinforcement material can be, but not limited to, textile yarns (e.g. polyester) or composed of the same polymer as the hollow fiber material. These reinforced hollow fiber screens are then potted to have channels for the lumen heat transfer fluid. The screens are potted at the top and bottom with epoxy. The illustrated specific example comprises five reinforcements or wefts, such as weft 903, along the body of the hollow fiber structure.

[0127] Figure 11 shows a plurality of the hollow fiber screens, such as hollow fiber screen 901 , aligned parallel to each other to construct a hollow fiber bundle 1101. In this illustrated specific example, six hollow fiber screens are aligned parallel to each other inside the bundle. In this configuration, CO2 / air is flowed / passed in between the screens during the adsorption phase. Passing CO2 / air through the direct face of the hollow fiber screen may result in significant pressure drop, therefore, CO2 / air transfer through the mats ensures reduced pressure drop. This design supports an increase in the volumetric capacity of the capture unit. Since the CO2 / air passes between the screens, the distance between the screens may be reduced, to pack more screens in each module. In this way. more sorbent materials are loaded in each bundle, and the capture unit. This increases the CO2 volumetric capacity of the capture unit. P12679

[0128] 19

[0129] The hollow fiber bundles containing the screens may be arranged in W- / V- or parallel configuration as described above. Since the CO2 / air is flowing in between the screens and does not go through the stack of the hollow fibers, the parallel module configurations with or without end closures may be used. A W- or V- shaped configuration may alternatively be used for the reinforced hollow fiber screens in the bundles.

[0130] Advantageously, arranging the bundles in a parallel or a V-shaped configuration makes effective use of the volume available in which to locate a hollow fiber module. Beneficially, each bundle of the parallel V-shaped configuration series is removable independently from the hollow fiber module for replacement, which reduces the total reactor downtime.

[0131] A hollow fiber bundle 201 ’ is shown in Figure 12, which is like the hollow fiber bundle 201 of Figure 2 but in which the lumen side inflow and outflow openings 215’, 216’ are in different positions.

[0132] A hollow fiber reactor 1301 according to a first example is illustrated in Figure 13. The hollow fiber reactor 1301 comprises a casing, indicated at 902 that defines an interior chamber 1303 for housing a hollow fiber module 1304 that comprises a plurality of hollow fiber bundles, such as hollow fiber bundles 201 , 201 B, 201 C, arranged in a V-shaped configuration as disclosed herein.

[0133] The hollow fiber reactor 1301 comprises at least one lumen side inlet 1305 for selectively introducing a flow 211 of a liquid heat transfer medium to the lumens of the hollow fiber bundles, and at least one a shell side inlet 906 for selectively introducing a flow of a gas containing carbon dioxide to contact the hollow fiber bundles, whereby the flow 212 of a gas containing carbon dioxide is at a non-zero, non-straight angle with respect to the flow 211 of a liquid heat transfer medium.

[0134] The hollow fiber reactor 1301 further comprises at least one lumen side outlet 1307, and at least one shell side outlet 1308.

[0135] It is to be understood that the flow 212 of a gas containing carbon dioxide between the hollow fibers of each hollow fiber bundle 201 , 201 B may be controlled by one or more flow control arrangements. The flow 212 of a gas containing carbon dioxide to the hollow fiber bundles 201 , 201 B within the hollow fiber reactor 1301 may be active, with movement of the gas containing carbon dioxide into contact with the hollow fibers being facilitated by use of a flow P12679

[0136] 20 drive arrangement (not shown), for example comprising one or more fans, so that travel of the gas containing carbon dioxide through each hollow fiber bundle is assisted, or may be passive, with gas containing carbon dioxide being allowed to move freely into contact with the hollow fibers, open sides of the hollow fiber bundles 201 , 201 B being exposed to ambient gas containing carbon dioxide, so that travel of the gas containing carbon dioxide through each hollow fiber bundle 201 , 201 B is in the manner of natural ventilation.

[0137] In an example, the hollow fiber reactor 1301 is provided with a flow drive arrangement comprising one or more fans (not shown) for encouraging the flow of gas containing carbon dioxide through the shell side inlet 1306 into contact with the hollow fiber bundles 201 , 201 B and / or is provided with a flow regulator arrangement, for example comprising a movable closure element such as a door or shutter (not shown), for controlling an extent of flow of gas containing carbon dioxide through the shell side inlet 906 into contact with the hollow fiber bundles 201 , 201 B.

[0138] In a specific example, the hollow fiber reactor 1301 is provided with a flow regulator arrangement (not shown) that allows at least the shell side inlet 1306 of the shell side inlet 1306 and the shell side outlet 907 to be selectively fully shut, to prevent a flow 212 of gas containing carbon dioxide into / through the interior chamber 1303.

[0139] This allows, for example, the interior chamber 103 to be opened to an inflow of air (or other gas containing carbon dioxide) through the shell side inlet 1306 of the hollow fiber reactor 1301 , for adsorption, and then to be sealed, for desorption.

[0140] The or each lumen side inlet, the or each lumen side outlet, the or each shell side inlet and the or each shell side outlet may, individually, have any suitable form and be provided by any suitable arrangement.

[0141] For example, one or more of at least one lumen side inlet, at least one lumen side outlet, at least one shell side inlet and at least one shell side outlet may comprise an aperture defined in a surface of the hollow fiber reactor or may be provided by an opening or a space, the extent of which can be adjusted, to decrease / increase the area through fluid can flow, by a flow control arrangement, of any suitable type, for example comprising a door or a shutter. One or more of at least one lumen side inlet, at least one lumen side outlet, at least one shell side inlet and at least one shell side outlet may be in communication with at least one conduit, of any suitable type, and may be associated with one or more valves, of any suitable type. P12679

[0142] 21

[0143] The interior chamber 1303 of the hollow fiber reactor 1301 may provide a vacuum chamber in which the hollow fiber module 1304 is hermetically sealable, during a desorption phase.

[0144] Figures 14, 15 and 16 illustrate an adsorption phase, a desorption phase and a cooling phase respectively of an example carbon capture process.

[0145] In Figure 14, the shell side 105 of hollow fiber 101 is shown exposed to a flow 1401 of a gas comprising carbon dioxide, in this specific example, air. The air comprising carbon dioxide contacts the hollow fiber 102, thus adsorbing the carbon dioxide to the hollow fiber and depleting the air surrounding the hollow fiber 101 of carbon dioxide. Thus, the hollow fiber 102 acts as a solid sorbent for capturing carbon dioxide from the gas. In this Figure, the gas comprising carbon dioxide is shown flowing, on the shell side 104 of the hollow fiber 101 , in the direction indicated by arrow 1402, towards a first side 1403 of the hollow fiber 101 (as carbon dioxide laden gas) and flowing from a second, opposite side 1404 of the hollow fiber 101 (as carbon dioxide depleted gas); however, it is to be appreciated that the gas comprising carbon dioxide may flow across, along or around the shell side 104 of the hollow fiber 101 in any direction or directions.

[0146] Optionally, a liquid heat transfer medium (not shown) may be passed through the lumen to adjust the temperature of the hollow fiber as appropriate during the adsorption phase. Typically, adsorption occurs under ambient conditions. However, as exposure of the hollow fiber to elevated temperatures may be detrimental to the performance of the hollow fiber, the temperature of the hollow fiber may be reduced from ambient conditions during adsorption using a cold or cool water as the liquid heat flow transfer medium, such as water. For example, for particularly hot ambient conditions (e.g., temperatures above 40 degrees Celsius, etc.), it may be beneficial to reduce the temperature of the hollow fiber during adsorption so as to reduce oxidative degradation of the hollow fiber due to exposure to oxygen in the air at elevated temperatures.

[0147] In Figure 15, a flow 1501 of a liquid heat transfer medium, in this example comprising water, at a first, hot temperature is shown being fed into the lumen 103 of the hollow fiber 101. In some instances, the liquid heat transfer medium, such as water, may be fed into the lumen in absence of a vapor form of the heat transfer medium (i.e. water vapor). The thermal energy of the liquid heat transfer medium results in a temperature increase of the hollow fiber 101 and desorption of carbon dioxide and water from the hollow fiber 101. Single water molecules P12679

[0148] 22 diffuse through the semi-permeable layer, leaving it as steam thereby reducing the concentration of carbon dioxide within the polymer matrix and allowing for improved desorption kinetics. This form of steam formation is called pervaporation. The desorption phase is typically carried out under vacuum. Beneficially, mixing water with water miscible liquids with liquid heat transfer mediums having high boiling points, such as polyethylene glycol, may reduce the water permeation tendency. In this Figure, the liquid heat transfer medium is shown flowing, in the direction indicated by arrow 1502, along the lumen side 104 of the hollow fiber 101.

[0149] In Figure 16, a flow 1601 of a liquid heat transfer medium, in this example comprising water, at a second, cooler temperature is shown being fed into the lumen 103 of the hollow fiber 101 , so as to cool the hollow fiber 101 in preparation for another adsorption phase. In this Figure, the liquid heat transfer medium is shown flowing, in the direction indicated by arrow 1602, along the lumen side 104 of the hollow fiber 101.

[0150] A method of operating the hollow fiber reactor 1301 , comprises the steps of: exposing the hollow fiber module 1304 to ambient air for adsorption of carbon dioxide from the ambient air into a least one of the plurality of hollow fibers, subsequently reducing exposure of the hollow fiber module 1304 to the ambient air; introducing a first flow of a liquid heat transfer medium, at a first temperature, to the lumen of at least one of the plurality of hollow fibers, in which the liquid heat transfer medium is prevented from flowing from the lumen through the semi- permeable layer and wherein the vapor state of the heat transfer medium is allowed to pass from the lumen through the semi-permeable layer, the first temperature sufficient to elevate the temperature of the hollow fiber for desorbing adsorbed carbon dioxide therefrom; and subsequently introducing a second flow of a liquid heat transfer medium, at a second temperature that is lower than said first temperature, to the lumen of said at least one of the plurality of hollow fibers, the second temperature sufficient to cool the hollow fiber.

[0151] In an example, the liquid heat transfer medium is water, and a vapor state of the heat transfer medium is water vapor. In an example, the flow of water vapor lowers a carbon dioxide concentration in the hollow fiber.

[0152] In an example, the step of reducing exposure of the hollow fiber module 1304 to the ambient air comprises closing the shell side inlet 1306 of the hollow fiber reactor 1301. P12679

[0153] 23

[0154] In an example, the method comprises hermetically sealing the hollow fiber reactor 1301 and reducing a pressure within the hollow fiber reactor 1301 prior to introducing the first flow of a liquid heat transfer medium, at the first temperature, to the lumen of the least one of the plurality of hollow fibers.

[0155] An example method of maintaining hollow fiber bundles of a hollow fiber reactor will now be described. An indicator that indicates that at least one hollow fiber bundle of the hollow fiber reactor is operationally subpar is detected. A hollow fiber bundle is removed from the hollow fiber reactor, and the hollow fiber bundle removed from the hollow fiber reactor is replaced.

[0156] An indicator that indicates that at least one hollow fiber bundle of the hollow fiber reactor is operationally subpar may be an indicator that a particular one or more of hollow fiber bundles is underperforming or an indicator that operation of a hollow fiber module is not meeting an expected standard. The performance of a hollow fiber bundle may be impaired for a variety of reasons, for example, but not limited to, an initial defect in, or damage to, that hollow fiber bundle, typical deterioration through use, a problem relating to one or more other hollow fiber bundles or the structure of the hollow fiber reactor, or due to an issue with fluid flow or temperature control during operation of the hollow fiber reactor.

[0157] An indicator that indicates that at least one hollow fiber bundle of the hollow fiber reactor is operationally subpar may be based on a single ground or condition, or a combination of grounds, conditions or grounds and conditions, for example, but in no way limited to, one or more of: a number of adsorption / desorption cycles, a period of use, a deviation from an anticipated level of performance, which may be determined by reference to an absolute or a relative value, a fixed or percentage value of difference from a predetermined value or range of values.

[0158] In an example, a hollow fiber bundle is removed and a different hollow fiber bundle is installed in the hollow fiber reactor to replace the removed hollow fiber bundle. The substitute hollow fiber bundle may be new. The substitute hollow fiber bundle may have been used previously, in the same or a different hollow fiber reactor, and may have been reconditioned.

[0159] The at least one maintenance action may comprise a cleaning process for removing foreign matter from the hollow fibers, such as solid particles or contaminants that may impair performance. The at least one maintenance action may comprise a protecting process for protecting against an accumulation of material or organisms. The at least one maintenance P12679

[0160] 24 action may comprise an amine removal process for removing amines from the hollow fibers, which may involve subjecting the one or more hollow fiber bundles to an elevated temperature under vacuum. The at least one maintenance action may comprise a regeneration process, which may involve exposing the hollow fiber bundle to at least one of an amine solution for replenishing amine sites of the hollow fibers, a biocidal solution, and an anti-scaling solution. The at least one maintenance action may comprise a lumen coating process, which may involve flowing a lumen coating through a lumen of each of the plurality of hollow fibers / the hollow fiber module.

[0161] Other different maintenance actions, which may be the purpose of treating and / or reconditioning, may be performed on a hollow fiber bundle after removal from a hollow fiber reactor. It is to be understood that one or more actions may be performed on a hollow fiber bundle while installed within a hollow fiber reactor.

[0162] Detailed Examples

[0163] Carbon dioxide capture-active hollow fiber sorbents are constructed into hollow fiber bundles, which are then stacked or otherwise arranged to form a hollow fiber module with a specific geometry utilising a V-shaped configuration (specific examples of which are shown in Figure 4 (“cuboid”) and in Figure 6 (“tubular”) to construct the reactor.

[0164] The reactor incorporates a crossflow design in which fluids introduced from the lumen side and the shell side circulate substantially perpendicularly (or at another suitable relative angle), which offers advantages in respect of a higher mass transfer coefficient, lower pressure drop, channelling on the shell side and improved efficiency.

[0165] The V-shaped configuration of the hollow fiber bundles, especially when used in a series as described herein, beneficially achieves a lower pressure drop and a higher H hollow fiber F packing density within the available volume of the reactor.

[0166] Illustrative example 1

[0167] Functionalized hollow fibers are constructed into generally rectangular bundles where the bundles have separate cross flow channels for air and water flow from the shell side and lumen side respectively. Each bundle has one inlet and one outlet channel. Hot and cold water used during the desorption and cooling phases respectively, are flowed alternatively to avoid scaling and fouling in the hollow fiber lumens. In each bundle there are approximately 5000 hollow fibers held tightly by an epoxy potting on both terminal ends. The spacing between the hollow P12679

[0168] 25 fibers and the staggering ratio are predetermined. A staggering ratio of 1 .25-2 and a container volume capacity of 33-45% is used. Approximately 10-30 rows of the hollow fibers are present in each bundle.

[0169] The bundles are then arranged according to the pattern of the V-shaped configuration series 400 illustrated in Figure 4, at an angle 9. A hollow fiber module dimension of approximately 1 .25 x 1 .50 x 1 .00 m3and a vacuum chamber of approximately 2.5-5 m3is used, along with a hollow fiber bundle arrangement, comprising 12 bundles, of approximately 1.23 x 1.0 x 0.06 m3.

[0170] Referring to Figure 5, water for adsorption, desorption, and / or cooling flows into the lumens of the hollow fibers, in the indicated direction of flow 211 , and airflows across the hollow fibers of the series of hollow fiber bundles of the cuboid hollow fiber module, in the indicated direction of flow 212 (with carbon dioxide laden air flowing into contact with the hollow fiber bundles and carbon dioxide depleted air flowing from the hollow fiber bundles).

[0171] Illustrative example 2

[0172] Hollow fiber bundles constructed as described above in illustrative example 1 are arranged according to the pattern of the V-shaped configuration series 600 illustrated in Figure 6.

[0173] A vacuum chamber having a volume of approximately 4.8 m3is used, along with a hollow fiber module having an outer diameter of approximately 1.1 m and a length of approximately 2.8 m, and comprising 16 bundles, of approximately 2.8 x 0.3 x 0.06 m3.

[0174] Referring to Figure 7, water for adsorption, desorption, and / or cooling flows into the lumens of the hollow fibers, in the indicated direction of flow 211 , and air flows about the pleated structure of the hollow fiber bundles of the tubular hollow fiber module in the indicated direction of flow 212 (with carbon dioxide laden air flowing into contact with the hollow fiber bundles and carbon dioxide depleted air flowing from the hollow fiber bundles).

[0175] The design of each of the illustrative examples offers easy and modular maintenance of the reactor, which enables a bundle to be removed from the hollow fiber module independently of the other bundles of that hollow fiber module, in turn, reducing downtime of the reactor while a bundle is being replaced or otherwise removed for routine inspection and / or maintenance. This modular approach enhances the robustness of the design, reduces build costs and maintenance downtime. 26

[0176] Experimental Data

[0177] The amine-functionalized hollow fibers act as sorbent for capturing carbon dioxide from ambient air. The hollow fiber module is exposed to the ambient air via crossflow through the shell side, for adsorption. During desorption, hot water is passed axially through the lumen of the hollow fibers while the hollow fiber module is under vacuum. Then, cold water is passed through the lumen of the hollow fibers to cool down the sorbent before the next adsorption cycle. Cold water may also be passed through the lumen of the hollow fibers during adsorption, depending on the specific properties of the hollow fibers. The adsorption and desorption conditions inside the reactor can be changed, as discussed below.

[0178] Since the hollow fibers have high gravimetric surface area and pore sizes in the range of approximately 5-60 nm, they are suitable for selective chemisorption of carbon dioxide molecules. The carbon dioxide capture performances of the hollow fibers were studied in a proprietary tubular reactor, designed to house a maximum of 20 hollow fibers for adsorption and desorption studies. The hollow fibers has a length of 20 cm and were potted with thermally cured epoxy prior to placement in the reactor. The resulting hollow fiber sorbent was pre-dried in the vacuum oven at 70 °C overnight to remove any pre-adsorbed carbon dioxide and moisture.

[0179] During adsorption, a feed stream was passed through the reactor column at a rate of 1 L / min and pressure 1 bar. The feed stream was either a mixture of CO2 / N2gases (with concentration ranging from 0-100% carbon dioxide in N2, usually 400 ppm) or an air stream generated by an air compressor.

[0180] The humidity of the gas stream was controlled by passing the feed stream through a water humidifier while the humidities varied between 0-85% RH. After a certain duration the hollow fiber reactor bed got saturated, i.e. breakthrough of the gas stream, and that denoted the completion of the adsorption cycle. The adsorption cycle was between 0.5-3.0 hours while the typical adsorption duration was approximately 2.5 hours.

[0181] The captured carbon dioxide molecules in the hollow fiber matrix were released during the desorption step, during which thermal energy was provided to facilitate desorption. Since exposure of the amine-functionalized sorbent to air at elevated temperatures is detrimental to the amines, the reactor was placed under vacuum swing conditions before heating the reactor. While the vacuum pressure inside the reactor varied between 20-200 mbar, typically 100 mbar 27 vacuum pressure was used. In one example, temperature vacuum swing assisted desorption was used to undertake desorption. Here, the hollow fiber module was heated using a heating and cooling jacket. The desorption temperature was chosen between 50 °C - 110 °C with an optimum temperature around 95 °C. A flush gas of N2stream was used to enhance the desorption kinetics. A N2flow rate of 0.1-0.2 L / min was used. The desorption was carried out for 1-12 hours but ideally for 2 hours.

[0182] In another example, the hollow fiber module was connected to distinct air and water flow channels and steam-assisted desorption was carried out. Adsorption was achieved via the crossflow of the carbon dioxide stream on the outer shell side and the desorption was carried out by passing hot water through the lumens of the hollow fibers. After the completion of adsorption, hot water (at a temperature of approximately 80 °C - 100 °C) was passed through connectors attached to the inner lumen side of the hollow fiber module while the hollow fiber module was placed under vacuum. As the hot water passed through the lumen of the hollow fibers, sorbent was heated up and this initiated carbon dioxide desorption. The use of a steam permeable lumen coating allowed selective permeation of the steam generated from the hot water stream to pass through the porous matrix of the hollow fibers and escape out. During this process, the injected steam resulted in a localized decrease of the carbon dioxide partial pressure in the porous network, which drove the desorption kinetics. The temperature of the hot water, flow rate, internal diameter of the hollow fibers, and lumen layer thickness were optimized to achieve a steam flow rate of up to 1 kg steam / kg sorbent during the desorption cycle. Following the desorption, the hollow fibers were cooled by passing cold water through the lumens. The hollow fiber module was cooled down to below 40 °C, in this example to 25 °C - 35 °C, before being exposed to iterative adsorption / desorption cycles.

[0183] In another example, a two-step desorption profile was adopted. Athermal heating ramp of two isothermal steps was chosen to selectively desorb water in the first step and carbon dioxide in the second step. A two-step desorption process results in obtaining a higher purity of the carbon dioxide gas stream as compared to the single-step desorption process. Typically, the carbon dioxide output stream is contaminated with water vapour during the desorption step in a single-step desorption process and required to be separated in the product or fluid separation tank. Therefore, a two-step desorption process would eliminate or minimize the carbon dioxide contamination with water as well as bypass the product tank.

[0184] The carbon dioxide working capacity (CO2_cap) i.e. the difference between amount of adsorbed carbon dioxide (CO2_ads) and the amount of desorbed CO2(CO2_des) was P12679

[0185] 28 calculated for the different variants of the aminated hollow fibers. The CO2_cap varied between 0.05-0.35 mol / kg. Unfunctionalized hollow fibers devoid of any amine functionalities demonstrated a CO2_cap approximately 0.005 mol / kg. Diligent amine functionalization by different types of amines, amine concentration, and reaction conditions resulted in drastically higher CO2_cap. An interdependence of the amine concentration, reaction temperature, type of amines, and reaction temperature on the CO2_cap was observed. The best optimized hollow fiber sorbent with highest CO2_cap of 0.35 mol / kg was obtained through the aminations. This demonstrates the successful synthesis of carbon dioxide capture active sorbents from the carrier material as compared to the untreated or unfunctionalized counterparts.

[0186] Various heat sources that may be used to meet the heat demand for the desorption step were considered, including waste heat generated in various processes and industries, such as waste incinerators, carbon capture technologies such as amine scrubbing, the cement industry, or other manufacturing-based industries, and heat generated through solar thermal systems, or by cooling towers.

[0187] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments and examples shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

P1267929Claims1. A hollow fiber reactor, comprising:(a) a hollow fiber module including a plurality of hollow fiber bundles, each bundle including a plurality of hollow fibers that are capable of carbon dioxide sorption, wherein said plurality of hollow fiber bundles comprises at least two bundles arranged in a parallel configuration or in a V-shaped configuration in which first ends of the two bundles are adjacent with first sides of the two bundles forming an internal angle that ranges from zero to 180 degrees;(b) a lumen side inlet for introducing a flow of a liquid heat transfer medium to the lumens of the hollow fiber bundles; and(c) a shell side inlet for introducing a flow of a gas containing carbon dioxide to contact the hollow fiber bundles, whereby the flow of gas containing carbon dioxide gas is at a nonzero, non-straight angle with respect to the flow of a liquid heat transfer medium.

2. A hollow fiber reactor as claimed in claim 1 , wherein the hollow fibers are functionalized with nucleophilic groups.

3. A hollow fiber reactor as claimed in claim 2, wherein the nucleophilic groups are amine groups.

4. A hollow fiber reactor as claimed in claim 2, wherein the hollow fibers are functionalized with aminosilanes.

5. A hollow fiber reactor as claimed in any one of claims 1 to 4, wherein the plurality of hollow fibers comprises coated hollow fibers, in which the inner surface of the lumen of the hollow fiber has a semi-permeable layer that is impermeable to liquid water but permeable to water vapor.

6. A hollow fiber reactor as claimed in any one of claims 1 to 5, wherein the hollow fibers include at least one filler.

7. A hollow fiber reactor as claimed in claim 7, wherein said at least one filler includes at least one filler selected from: ion exchange resins, di- and multi-amines, polyethyleneimine, desiccants, carbon molecular sieves, carbon adsorbents, graphites, activated alumina, molecular sieves, aluminophosphates, silicoaluminophosphates, zeolite adsorbents, ionP1267930 exchanged zeolites, hydrophilic zeolites, hydrophobic zeolites, modified zeolites, natural zeolites, faujasites, mordenites, metal-exchanged silico-aluminophosphates, zeolites, activated carbon, alumina, y-alumina, uni-polar resins, bi-polar resins, aromatic cross-linked polystyrenic matrices, ion exchange resins, cation exchange resins, anion exchange resins, Lewatit, Purolite, brominated aromatic matrices, methacrylic ester copolymers, graphitic adsorbents, carbon fibers, carbon nanotubes, nano-materials, metal salt adsorbents, perchlorates, oxalates, alkaline earth metal particles, metal oxides, chemisorbents, amines, organo-metallic reactants, hydrotalcites, silicalites, zeolitic imidazolate frameworks, covalent organic frameworks (COFs) and metal organic frameworks (MOFs) adsorbent compounds, and combinations thereof.

8. A hollow fiber reactor as claimed in any one of claims 1 to 7, wherein the hollow fiber module has a shape that is generally rectangular cuboid.

9. A hollow fiber reactor as claimed in any one of claims 1 to 8, wherein the hollow fiber module has a shape that is generally tubular.

10. A hollow fiber reactor as claimed in any one of claims 1 to 9, wherein each of said plurality of hollow fiber bundles is independently removable from the hollow fiber module.

11. A hollow fiber reactor as claimed in any one of claims 1 to 10, further comprising a vacuum chamber in which the hollow fiber module is hermetically sealable during a desorption phase.

12. A hollow fiber reactor as claimed in any one of claims 1 to 11 , wherein at least one hollow fiber bundle comprises a screen.

13. A method of operating a hollow fiber reactor, comprising:(a) exposing a hollow fiber module to ambient air, the hollow fiber module including a plurality of hollow fiber bundles, each bundle including a plurality of hollow fibers, wherein said plurality of hollow fiber bundles comprises at least two bundles arranged in a parallel configuration or in a V-shaped configuration in which first ends of the two bundles are adjacent with first sides of the two bundles forming an internal angle, for adsorption of carbon dioxide from the ambient air into at least one of the plurality of hollow fibers;(b) subsequently reducing exposure of the hollow fiber module to the ambient air;P1267931(c) introducing a first flow of a liquid heat transfer medium, at a first temperature, to the lumen of at least one of the plurality of hollow fibers, in which the liquid heat transfer medium is prevented from flowing from the lumen through the semi-permeable layer and wherein a vapor state of the heat transfer medium is allowed to pass from the lumen through the semi- permeable layer, the first temperature sufficient to elevate the temperature of the hollow fiber for desorbing adsorbed carbon dioxide therefrom; and(d) subsequently introducing a second flow of a liquid heat transfer medium, at a second temperature that is lower than said first temperature, to the lumen of said at least one of the plurality of hollow fibers, the second temperature sufficient to cool the hollow fiber.

14. The method of claim 13, wherein said second temperature is sufficient to cool the hollow fiber below 40 °C.

15. The method of claim 13 or claim 14, wherein the liquid heat transfer medium is liquid water, and the vapor state of the heat transfer medium is water vapor.

16. The method of claim 15, in which the flow of water vapor lowers a carbon dioxide concentration in the hollow fiber.

17. The method of claim 15 or claim 16, wherein the liquid heat transfer medium is mixed with at least one of demineralized water, water dosed with a conditioning agent, a corrosion inhibitor, an anti-frost additive, a biocide treatment, a boiling point adjuster, silicone oil, propylene glycol, ethyl glycol, polyethylene glycol, a salt, m-Xylene, ethyl benzoate, o-Xylene, decamethyltetrasiloxane (MD2M), and undecane methanol, ethanol, t-butanol, 2-propanol, 1- propanol, 2-butanol, t-amyl alcohol, i-butanol, 1 butanol, i-amyl alcohol, 2 ethylbutanol, 2- ethylhexanol, heptane, octane, cholorobenzene, p-cymene, and tetralin.

18. The method of any one of claims 13 to 17, wherein the reducing exposure of the hollow fiber module to the ambient air comprises closing a shell side inlet of the hollow fiber reactor.

19. The method of any one of claims 13 to 17, comprising hermetically sealing the hollow fiber reactor and reducing a pressure within the hollow fiber reactor prior to introducing the first flow of a liquid heat transfer medium, at the first temperature, to the lumen of the least one of the plurality of hollow fibers.

20. The method of any one of claims 13 to 19, further comprising:P1267932(i) removing a hollow fiber bundle from the hollow fiber module; and(ii) replacing the hollow fiber bundle removed from the hollow fiber module at (i).

21. The method of claim 20, wherein (ii) comprises substituting the hollow fiber bundle removed from the hollow fiber reactor at (i).

22. The method of claim 20 or claim 21 , further comprising performing at least one maintenance action on the hollow fiber bundle removed from the hollow fiber reactor at (i).

23. The method of claim 22, further comprising, after said at least one maintenance action has been performed on the hollow fiber bundle removed from the hollow fiber reactor at (i), returning the hollow fiber bundle removed from the hollow fiber reactor at (i) to the hollow fiber reactor.

24. The method of claim 22 or claim 23, wherein said at least one maintenance action comprises a regeneration process, the regeneration process involving exposing the hollow fiber bundle to at least one of: an amine solution to reactivate nucleophilic amine sites of the hollow fibers, reagents to re-activate oxidized nucleophilic amine sites, a biocidal solution, and an anti-scaling solution.

25. The method of claim 22 or claim 23, further comprising, after said at least one maintenance action has been performed on the hollow fiber bundle, exposing the hollow fiber bundle to a reducing agent treatment to re-activate the oxidized nucleophilic amine sites.

26. The method of claim 23, wherein the exposing the hollow fiber bundle to an amine solution involves flowing the amine solution through the hollow fiber module.

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