Systems and methods for removing species from a gas stream - Patents.com

Abstract

Various embodiments address the removal of one or more species from a gas stream by exposing the gas stream to divided portions of a fluid, such as droplets of water or mist, where the fluid and / or the contents of the fluid can absorb or modify the species, thereby at least partially removing it from the gas stream. 2 is one embodiment. In one embodiment, the liquid mist comprises a plurality of droplets, each droplet of the plurality of droplets having a maximum characteristic dimension of 20 micrometers or less.

Description

[Technical field]

[0001] (Related Applications) This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63 / 273,782, filed October 29, 2021, the disclosure of which is incorporated by reference in its entirety herein.

[0002] (Technical field) Generally, systems and methods for reducing the amount of one or more species in a gas stream, including, for example, reducing the amount of carbon dioxide (CO2) in a combustion exhaust stream, are described. [Background technology]

[0003] Global CO2 emissions continue to rise, reaching 36 gigatonnes (Gt) in 2019, placing a great burden on the global climate. Therefore, it is generally desirable to remove CO2 from the atmosphere. Post-combustion carbon capture in power plants offers an efficient path to reducing anthropogenic emissions, since capturing the CO2 produced by a single 500 MW natural gas power plant for one year would be equivalent to eliminating the emissions from 200,000 cars over the same period. Post-combustion carbon capture technologies can be categorized into three main approaches: (i) chemical approaches, (ii) physical approaches, and (iii) biochemical approaches. Chemical approaches include absorption, direct or membrane-assisted absorption into liquids, and chemical looping combustion. Physical approaches include membrane separation, physical absorption, and cryogenic distillation. Various biochemical methods utilizing enzymatic and algae-based approaches have also been proposed. Of these methods, chemical absorption into liquid absorbents is widely considered the most promising technology due to the higher efficiency, lower cost, and techno-economic maturity it offers.

[0004] Conventional chemical absorption plants utilize an absorption tower equipped with a packed bed reactor, which is an elongated tower filled with several packed units. An absorbent solution is provided to the top of the absorption tower and flows down above the surface of the packed units, thereby forming a film of liquid that reacts with the rising flue gas stream. The packed units are designed to improve the interfacial area and contact time between the liquid absorbent and the flue gas stream. To capture >90% of the CO2 released from a power plant (flue gas flow rates can vary from 100 to 800 kg / sec), the packed bed reactor needs to be large enough to provide sufficient area and time for absorption to take place. As a result, absorption towers equipped with packed bed reactors are invariably more than 10 meters in diameter and more than 20 meters in height, accounting for approximately 30% of the overall capital requirements for such carbon capture systems. Prohibitive costs are the main reason why there are only 28 large-scale carbon capture facilities in the world, and reducing the size of these absorption towers would help improve the practicality of post-combustion carbon capture systems. Summary of the Invention [Means for solving the problem]

[0005] Generally described are systems and methods for reducing the amount of one or more species in a gas stream, including, for example, reducing the amount of CO2 in a flue gas stream. The invention is summarized in the subject matter of the independent claims and other claims identified below. The subject matter of the present disclosure in some cases involves interrelated products, alternative solutions to a particular problem, and / or a plurality of different uses of one or more systems and / or articles.

[0006] In some embodiments, a system for removing gaseous species from a gas stream is described, the system comprising: a gas flow path having an inlet for receiving a gas flow and an outlet for releasing the gas flow, the gas flow containing fewer gaseous species at the outlet than were contained in the gas stream at the inlet; a gaseous species absorption zone along the gas flow path; a source of liquid mist configured to introduce the liquid mist into the gaseous species absorption zone, the gaseous species absorption zone configured to expose the liquid mist to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the liquid mist; and an electrostatic separation zone along the gas flow path fluidly connected to the gaseous species absorption zone and configured to electrostatically separate at least a portion of the liquid mist from the gas stream.

[0007] In one embodiment, a system for removing gaseous species from a gas stream comprises: a gas flow path having an inlet for receiving a gas flow and an outlet for releasing the gas flow, the gas flow containing fewer gaseous species at the outlet than were contained in the gas stream at the inlet; a gaseous species absorption zone along the gas flow path; a source of liquid mist configured to introduce liquid mist into the gaseous species absorption zone, the gaseous species absorption zone configured to expose the liquid mist to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the liquid mist, the liquid mist comprising a plurality of droplets, each droplet of the plurality of droplets having a maximum characteristic dimension of 70 micrometers or less; and a separation zone along the gas flow path fluidly connected to the gaseous species absorption zone and configured to separate at least a portion of the liquid mist from the gas stream.

[0008] According to some embodiments, a system for removing gaseous species from a gas stream comprises a gas flow pathway having an inlet for receiving a gas stream and an outlet for releasing the gas stream, the gas stream containing fewer gaseous species at the outlet than were contained in the gas stream at the inlet, a gaseous species absorption zone along the gas flow pathway, and an absorbent associated with the gaseous species absorption zone, the gaseous species absorption zone configured to expose the absorbent to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the absorbent, wherein the interfacial area between the absorbent and the gas stream is at least 10 times greater than the interfacial area between a comparative absorbent and a comparative gas stream in an absorption tower comprising an otherwise essentially identical packed bed reactor.

[0009] According to an embodiment, a method for removing gaseous species from a gas stream is described, the method comprising: exposing a gas stream containing gaseous species to a liquid mist, the liquid mist comprising a reactant configured to react with the gaseous species; carrying out a reaction between the reactant and the gaseous species in a gaseous species absorption zone, the reaction resulting in absorption of at least 50% of CO2 from the gas stream by the liquid mist; and separating at least a portion of the liquid mist from the gas stream in a separation zone fluidly connected to the gaseous absorption zone.

[0010] In some embodiments, a method for removing gaseous species from a gas stream includes exposing a gas stream containing the gaseous species to a liquid mist, the liquid mist comprising a reactant configured to react with the gaseous species, and carrying out in a gaseous species absorption zone a reaction between the reactant and the gaseous species that results in absorption of at least 50% of the gaseous species from the gas stream by the liquid mist, wherein the ratio of molar amount of gaseous species absorbed per hour to the volume of the gaseous species absorption zone is at least 5 times greater than the same ratio in an absorption tower comprising an otherwise essentially identical packed bed reactor.

[0011] Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments thereof, when considered in conjunction with the accompanying drawings. In cases where the present specification and any documents incorporated by reference contain conflicting and / or inconsistent disclosure, the present specification shall control. [Brief description of the drawings]

[0012] Non-limiting embodiments of the present disclosure will now be described by way of example with reference to the accompanying drawings, which are schematic and, unless otherwise indicated, are not intended to be drawn to scale. In the figures, each identical or nearly identical component shown is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, or every component of each embodiment of the present disclosure is not shown if illustration is not necessary to enable a person skilled in the art to understand the disclosure.

[0013] [Figure 1] FIG. 1 shows a schematic diagram of a system for removing gaseous species from a gas stream according to some embodiments, the system including a gaseous species absorption zone and a separation zone. [Diagram 2] FIG. 2 shows a schematic diagram of a system for removing gaseous species from a gas stream according to some embodiments, the system including a fluid connection between a gaseous species absorption zone and a separation zone. [Diagram 3] FIG. 3 shows a schematic diagram of multiple droplets according to some embodiments. [Figure 4] FIG. 4 shows a schematic diagram of an electrostatic separation zone according to some embodiments. [Diagram 5] FIG. 5 shows a schematic diagram of a system for removing gaseous species from a gas stream according to some embodiments, the system including a gaseous species sensor. [Figure 6] FIG. 6 shows a schematic diagram of a system for removing gaseous species from a gas stream according to some embodiments, the system including a scrubber. [Figure 7]FIG. 7 shows a schematic diagram of a system for removing gaseous species from a gas stream according to some embodiments, the system including a stripper. [Figure 8A] FIG. 8A shows a schematic diagram of a conventional absorption system according to some embodiments. [Figure 8B] FIG. 8B shows a schematic diagram of a two-stage mist-based absorption system according to some embodiments. [Figure 8C] FIG. 8C shows the calculated CO 2 capture efficiency for mist-based CO 2 capture as a function of absorber length and droplet size according to some embodiments. [Figure 8D] FIG. 8D shows the calculated mist capture efficiency for an electrostatic demister unit as a function of length for different average mist droplet diameters according to some embodiments. [Figure 9A] FIG. 9A shows a schematic diagram of a scaled-down two-stage mist-based absorption system according to some embodiments. [Figure 9B] FIG. 9B shows a histogram of droplet parameters produced by a mist generation unit according to some embodiments. [Figure 10A] FIG. 10A shows CO2 capture efficiency plotted as a function of time according to some embodiments. [Figure 10B] FIG. 10B shows a comparison of normalized gas fluxes of an experimental setup and an industrial system according to some embodiments. [Figure 10C] FIG. 10C shows CO2 concentration as a function of time according to some embodiments. [Figure 10D] FIG. 10D shows the CO2 capture efficiency as a function of time for different concentrations of potassium hydroxide (KOH) according to some embodiments. [Figure 11A] FIG. 11A shows a schematic diagram of a mist capture unit without any corona discharge according to some embodiments. [Figure 11B] FIG. 11B shows a schematic diagram of a mist capture unit with corona discharge according to some embodiments. [Figure 11C]FIG. 11C shows a digital photograph of the exit port of a demistization unit not under corona discharge according to some embodiments. [Figure 11D] FIG. 11D shows a digital photograph of the exit port of a demistization unit under corona discharge according to some embodiments. [Figure 11E] FIG. 11E shows the mist capture efficiency as a function of gas flow rate and applied voltage according to some embodiments. [Figure 12] FIG. 12 illustrates the capital expenditure (CAPEX) split for a conventional CO2 capture system with an absorption cylinder as a function of CO2 concentration according to some embodiments. [Figure 13] FIG. 13 shows a schematic diagram of the flow streams in a conventional CO2 capture system according to some embodiments. [Figure 14] FIG. 14 shows a schematic diagram of the flow stream in a two-stage mist-based system according to some embodiments. [Figure 15] FIG. 15 shows the improved surface area to volume ratio for mist droplets compared to falling droplets from a spray tower or a thin film flowing across a packed bed in an absorber tower according to some embodiments. [Figure 16] FIG. 16 shows a microscope image of mist droplets entrained with a gas flow according to some embodiments. [Figure 17] FIG. 17 shows mist size droplet diameter distribution according to some embodiments. [Figure 18] FIG. 18 shows a schematic diagram of mist droplets surrounded by flue gas according to some embodiments. [Figure 19] FIG. 19 shows the change in pH of deionized (DI) water collected on a mesh according to some embodiments. [Figure 20] FIG. 20 shows a schematic diagram of space charge injection illustrating droplet charging and redirection towards a collector electrode according to some embodiments. [Figure 21A] FIG. 21A shows an image of mist droplets flowing with the gas flow before applying space charge injection according to some embodiments. [Figure 21B] FIG. 21B shows an image of mist droplets collected on a mesh collector electrode after applying space charge injection according to some embodiments. [Figure 22A] FIG. 22A shows an image of mist droplets exiting a cylindrical chamber with gas flow before applying an electric field according to some embodiments. [Figure 22B] FIG. 22B shows an image of mist droplets being trapped inside a cylindrical chamber after applying an electric field according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Systems and methods for reducing the amount of one or more species in a gas stream, including, for example, reducing the amount of CO2 in a combustion exhaust stream, are generally described. Any of a variety of species can be removed from the gas stream, including, for example, one or more gases and / or one or more particulates. In some embodiments, examples of gases to be removed from the gas stream include greenhouse gases such as CO2, methane (CH4), nitrous oxide (N2O), ozone (O3), fluorinated gases, and / or combinations thereof. In much of the disclosure below, CO2 removal from a combustion exhaust stream is discussed and illustrated, but it should be understood that the present disclosure generally enables one of ordinary skill in the art to not only remove CO2 from a combustion exhaust stream by following the teachings discussed herein, but also to remove other species from other gas streams using the same or similar techniques.

[0015] In some embodiments, an absorption system comprising one or more spray towers can be used or modified to provide a significant improvement over conventional absorption systems comprising spray towers. In conventional spray towers, droplets of an absorbent (e.g., absorbent liquid) are exposed to a gas stream (e.g., flue gas) such that the droplets absorb one or more species (e.g., CO2) from the gas stream. After absorbing the one or more species, the droplets are collected (e.g., via gravity) at the bottom of the spray tower.

[0016] In an absorption system, the interfacial area between the absorbent and the gas stream is generally defined as the surface area of ​​contact between the absorbent and the gas stream.

[0017] Equation 1 demonstrates the enhancement to interfacial area provided by droplets compared to a liquid film in an absorber tower equipped with a packed bed reactor utilized in conventional chemical absorption plants.

number

[0018] In formula 1, A p is the area of ​​the packed bed, V is the volume of the liquid absorbent, t is the thickness of the liquid film in the packed bed, and A d is the area of ​​a droplet that would constitute the same volume of absorbent, and R and D are the droplet radius and diameter, respectively. As can be seen from Equation 1, for the same characteristic length, droplets offer a much higher interfacial area than the liquid films used in packed bed reactors. However, despite this advantage, some conventional spray towers result in lower CO2 capture efficiency in practice compared to packed bed reactors. In some cases, for example, there may be droplet losses to the walls of the spray tower, which reduces the overall CO2 capture efficiency of the absorption system.

[0019] Conventional spray towers are countercurrent systems and therefore rely on gravity to collect the absorbent droplets. The droplets cannot be smaller than a few hundred micrometers because they can be entrained by the gas flow and escape through the exhaust outlet of the absorption system. Passive demisters can be employed in conventional spray towers, but they tend to introduce undesirable back pressure into the exhaust stream and fail consistently at high liquid loading rates. Furthermore, droplets that are too large have a slower reaction rate and fall faster through the spray tower. The benefits associated with the high interfacial area provided by the droplets therefore cannot be fully exploited in conventional spray towers.

[0020] The inventors have recognized and understood that two-stage mist-based absorption can efficiently remove one or more target gaseous species (e.g., CO2) from a gas stream (e.g., a flue gas stream). In certain embodiments, the configuration of the system advantageously increases the interfacial area between the absorbent and the gas stream, while reducing the overall size of the system without any penalty to absorption efficiency, as compared to conventional absorption systems, for example, those that include one or more packed bed reactors. According to some embodiments, during the first stage (e.g., absorption stage), the absorbent in the form of a liquid mist is exposed to a gas stream containing one or more target gaseous species, such that the liquid mist absorbs one or more target gaseous species. In certain embodiments, during the second stage (e.g., separation stage), an electrostatic arrangement is utilized to charge the liquid mist via an electrical force that drives the liquid mist to a collector, thereby separating the liquid mist and the absorbed target gaseous species from the gas stream.

[0021] In some embodiments, a liquid mist is described, where the liquid mist is configured to absorb gaseous species (e.g., CO2) from a gas stream (e.g., a flue gas stream) in a gaseous species absorption zone, thereby at least partially removing the gaseous species from the gas stream. In certain embodiments, the liquid mist comprises a reactant and / or catalyst (e.g., an absorbent) configured to absorb the gaseous species (e.g., via dissolution). In some embodiments, the reactant and / or catalyst (e.g., an absorbent) causes and / or promotes a reaction of the gaseous species, thereby altering (e.g., chemically altering) the gaseous species and / or at least partially removing the gaseous species from the gas stream.

[0022] According to some embodiments, the liquid mist comprises droplets with a size (e.g., maximum diameter) small enough to provide a high contact surface area (e.g., interfacial area) with the gas stream to facilitate more effective and efficient removal and / or reaction of one or more gaseous species from the gas stream, for example, as compared to conventional absorption towers and / or spray towers. In certain embodiments, due to the small average size of the droplets, the liquid mist may become entrained in the gas stream. In some such embodiments, the liquid mist may be separated from the gas stream, as described in more detail herein.

[0023] In certain embodiments, which may be used alone or in combination with other aspects of the present disclosure, the liquid mist may be electrostatically and / or physically separated from the gas stream. In some embodiments, for example, an electrostatic separation section is used to separate at least a portion of the liquid mist from the gas stream after the liquid mist has absorbed one or more species from the gas stream. According to some embodiments, the electrostatic separation section may comprise an electrostatic component configured to attract and / or direct at least a portion of the liquid mist to a collection section, where the liquid mist is collected and optionally recycled for further use, for example, in an absorption system. In some embodiments, the physical separation of the liquid mist from the gas stream generally involves allowing the gas stream comprising the liquid mist to encounter a surface (e.g., a mesh and / or a porous surface) on which the liquid mist is absorbed and / or absorbed.

[0024] According to some embodiments, a system (e.g., an absorption system) for removing gaseous species from a gas stream is described herein. Figure 1 shows a schematic diagram of a system 100a for removing gaseous species from a gas stream 104 according to some embodiments.

[0025] In some embodiments, the system includes a gas flow path. With reference to FIG. 1, for example, system 100a shows an example of an arrangement including a gas flow path 102, represented in the figure by a dotted arrow. In some embodiments, the gas flow path has an inlet for receiving a gas flow. As shown in the embodiment illustrated in FIG. 1, for example, gas flow path 102 has an inlet 106 for receiving gas flow 104a. In some embodiments, the gas flow path also has an outlet for releasing the gas flow. As shown in the embodiment illustrated in FIG. 1, for example, gas flow path 102 has an outlet 108 for releasing gas flow 104b. According to some embodiments, the inlet and / or outlet may be associated with one or more blowers and / or fans to facilitate the flow of the gas flow along the gas flow path.

[0026] Any of a variety of suitable arrangements for the gas flow paths can be provided. Those skilled in the art will recognize, based on the entirety of this disclosure, that the gas flow paths can be constructed in any manner that directs some or all of the gas flow introduced at the inlet toward and through the outlet. The gas flow paths can be constructed from any of a variety of suitable materials, including, for example, standard materials often used in similar gas processing processes and / or selected materials that are resistant to corrosion by the gases in the gas flow paths, if desired.

[0027] Gas flow can be expressed as various suitable flow velocities (measured in m / s) or gas fluxes per area (m 3 / sec) / (m 2In some embodiments, for example, the gas flow has a flow velocity of 0.1 m / s or more, 0.5 m / s or more, 1 m / s or more, 2 m / s or more, 3 m / s or more, 4 m / s or more, 5 m / s or more, 6 m / s or more, 7 m / s or more, 8 m / s or more, or 9 m / s or more. In some embodiments, the gas flow has a flow velocity of 10 m / s or less, 9 m / s or less, 8 m / s or less, 7 m / s or less, 6 m / s or less, 5 m / s or less, 4 m / s or less, 4 m / s or less, 3 m / s or less, 2 m / s or less, 1 m / s or less, or 0.5 m / s or less. Combinations of the ranges listed above are also possible (e.g., the gas flow has a flow velocity of 0.1 m / s or more and 10 m / s or less, and the gas flow has a flow velocity of 4 m / s or more and 5 m / s or less). Other ranges are also possible.

[0028] According to an embodiment, an overall gas flow pressure drop may occur between an inlet of a gas flow path and an outlet of the gas flow path. With reference to FIG. 1, for example, an overall gas flow pressure drop may occur between an inlet 106 of gas flow path 102 and an outlet 108 of gas flow path 102.

[0029] The overall gas flow pressure drop between the gas flow path inlet and the gas flow path outlet can be any of a variety of suitable values. In some embodiments, for example, the overall gas flow pressure drop between the gas flow path inlet and the gas flow path outlet is less than 1×10 -5 Pa or more, 1×10 -4 Pa or more, 1×10 -3 Pa or more, 1×10 -2 Pa or more, 1×10 -1 Pa or more, 1 Pa or more, 10 Pa or more, 100 Pa or more, or 1,000 Pa or more. In some embodiments, the overall gas flow pressure drop between the inlet of the gas flow path and the outlet of the gas flow path is 10,000 Pa or less, 1,000 Pa or less, 100 Pa or less, 10 Pa or less, 1 Pa or less, 1×10 -1 Pa or less, 1×10 -2 Pa or less, 1×10 -3 Pa or less, or 1×10 -4Combinations of the above listed ranges are also possible (e.g., the overall gas flow pressure drop between the gas flow path inlet and the gas flow path outlet is 1×10 -4 The gas flow path may have a total gas flow pressure drop of 1×10 to 10,000 Pa and may be less than or equal to 10,000 Pa, and the total gas flow pressure drop between the gas flow path inlet and the gas flow path outlet may be less than or equal to 1×10 -1 (It can be 1 Pa or more and 1 Pa or less). Other ranges are possible. In certain embodiments, the overall gas flow pressure drop between the gas flow path inlet and the gas flow path outlet can be determined by measuring (e.g., using a pressure sensor and / or a pressure gauge) the difference in pressure of the gas flow between the gas flow path inlet and the gas flow path outlet.

[0030] According to certain embodiments, the overall gas stream pressure drop is less than a comparable gas stream pressure drop in a conventional absorption tower comprising one or more packed bed reactors. In some embodiments, for example, there is less resistance to gas flow in the gas flow path compared to, for example, a conventional absorption tower comprising one or more packed bed reactors. The lower overall gas stream pressure drop may advantageously reduce costs associated with one or more pressure sources and / or pumps configured to facilitate the flow of the gas stream along the gas flow path.

[0031] According to an embodiment, the gas flow contains fewer gaseous species at the outlet of the gas flow path than were contained in the gas flow at the inlet of the gas flow path. With reference to FIG. 1, for example, gas flow 104b contains fewer gaseous species at the outlet 108 of the gas flow path 102 than were contained in gas flow 104a at the inlet 106 of the gas flow path 102.

[0032] In some embodiments, the gas stream contains 10% or more less, 20% or more less, 30% or more less, 40% or more less, 50% or more less, 60% or more less, 70% or more less, 80% or more less, or 90% or more less gaseous species at the outlet of the gas flow path than contained in the gas stream at the inlet of the gas flow path. In certain embodiments, the gas stream contains 100% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less gaseous species at the outlet of the gas flow path than contained in the gas stream at the inlet of the gas flow path. Combinations of the ranges recited above are also possible (e.g., the gas stream contains 10% or more less and 100% or less gaseous species at the outlet of the gas flow path than contained in the gas stream at the inlet of the gas flow path, the gas stream contains 60% or more less and 80% or less gaseous species at the outlet of the gas flow path than contained in the gas stream at the inlet of the gas flow path). Other ranges are also possible. In some embodiments, the amount of gaseous species in the gas stream (e.g., at the inlet, at the outlet) can be measured by gas chromatography and / or a gaseous species sensor (e.g., a CO2 sensor).

[0033] According to some embodiments, the system includes a gaseous species absorption zone. With reference to Figure 1, for example, system 100a includes a gaseous species absorption zone 110. In certain embodiments, as discussed in more detail below, the gaseous species absorption zone is configured to expose an absorbent to a gas stream such that the absorbent absorbs gaseous species from the gas stream.

[0034] The gaseous species absorption zone may be positioned along the gas flow path in some embodiments. For example, gaseous species absorption zone 110 is positioned along gas flow path 102 as shown in Figure 1. In some embodiments, the gaseous species absorption zone is fluidly connected to an inlet of the gas flow path. For example, as shown in Figure 1, gaseous species absorption zone 110 is fluidly connected to inlet 106 of gas flow path 102.

[0035] According to some embodiments, the gaseous species absorption zone may be configured as a tube, a cylinder, and / or a cylinder. Configuring the gaseous species absorption zone as a tube, a cylinder, and / or a cylinder may advantageously facilitate flow of the gas stream along the gas flow path through the gaseous species absorption zone. However, other configurations for the gaseous species absorption zone are possible, including, for example, cubic, prismatic, and / or conical configurations, as the present disclosure is not meant to be limiting in this respect.

[0036] The gaseous species absorption section may have any of a variety of suitable dimensions. In some embodiments, for example, the gaseous species absorption section has a length that is long enough to provide an advantageously high interfacial area between the absorbent and the gas stream. With reference to FIG. 1, for example, the gaseous species absorption section 110 has a length 124a.

[0037] The gaseous species absorption zone may have any of a variety of suitable lengths. In some embodiments, for example, the length of the gaseous species absorption zone is 10 centimeters or more, 50 centimeters or more, 1 meter or more, 2 meters or more, 3 meters or more, 4 meters or more, 5 meters or more, 10 meters or more, or 20 meters or more. In some embodiments, the length of the gaseous species absorption zone is 30 meters or less, 20 meters or less, 10 meters or less, 5 meters or less, 4 meters or less, 3 meters or less, 2 meters or less, 1 meter or less, or 50 centimeters or less. Combinations of the ranges listed above are also possible (e.g., the length of the gaseous species absorption zone is 10 centimeters or more and 30 centimeters or less, and the length of the gaseous species absorption zone is 3 meters or more and 4 meters or less). Other ranges are also possible.

[0038] In certain embodiments in which the gaseous absorption zone is configured as a tube, a cylinder, and / or a cylinder, the gaseous absorption zone may have any of a variety of suitable diameters. In certain embodiments, for example, the gaseous species absorption zone has a diameter that is 1 centimeter or more, 50 centimeters or more, 1 meter or more, 5 meters or more, or 10 meters or more. In some embodiments, the gaseous species absorption zone has a diameter that is 20 meters or less, 10 meters or less, 5 meters or less, 1 meter or less, or 50 centimeters or less. Combinations of the ranges listed above are also possible (e.g., the gaseous species absorption zone has a diameter that is 1 centimeter or more and 20 meters or less, and the gaseous species absorption zone has a diameter that is 1 meter or more and 5 meters or less). Other ranges are also possible.

[0039] The gaseous species absorption zone may comprise any of a variety of suitable materials. According to some embodiments, for example, the gaseous species absorption zone may comprise a metal, a metal alloy, a clad material, a ceramic, a plastic, a carbon-based material, and / or combinations thereof. Other materials are also possible. In certain embodiments, the gaseous species absorption zone material may be at least partially coated. For example, in some embodiments, the gaseous species absorption zone material may be coated with a corrosion-resistant material (e.g., a plastic coated with a corrosion-resistant metal or alloy).

[0040] In certain embodiments, the gaseous species absorption zone is a non-packed bed reactor. According to some embodiments, for example, the gaseous species absorption zone does not comprise a packed bed reactor.

[0041] According to some embodiments, the gaseous species absorption zone may comprise any of a variety of suitable fluid components to enhance interaction between the gas stream and the absorbent. In certain embodiments, for example, the gaseous species absorption zone may comprise one or more secondary circulation flow promoters, flow disturbance promoters, and / or turbulence promoters configured to maximize interaction between the gas stream and the absorbent.

[0042] The gaseous species absorption zone may have any of a variety of suitable temperatures and / or pressures to promote absorption of the gaseous species from the gas stream by the absorbent. In some embodiments, for example, an increased temperature (e.g., relative to room temperature) may improve dissolution of the gaseous species into the absorbent and / or reaction between the absorbent and the gaseous species, but may also contribute to a faster evaporation rate of the absorbent. In certain embodiments, an increased overall pressure of the gaseous species absorption zone may improve dissolution of the gaseous species into the absorbent and / or reaction between the absorbent and the gaseous species, but may also be impractical from an economic standpoint. Thus, in certain embodiments, the temperature and / or overall pressure of the gaseous species absorption zone may be adjusted and / or selected by the user depending on the absorbent, the target gaseous species, and / or the components of the gas stream to promote absorption of the gaseous species from the gas stream while avoiding evaporation and / or increased costs of the absorbent.

[0043] According to an embodiment, the system includes an absorbent. With reference to FIG. 1, for example, the system 100a includes an absorbent 116. The absorbent 116 may be associated with a gaseous species absorption zone 110 in some embodiments. In some embodiments, for example, the gaseous species absorption zone 110 is configured to expose the absorbent 116 to the gas stream 104 (e.g., along the gaseous flow path 102). According to some embodiments, the absorbent 116 is exposed to the gas stream 104 (e.g., within the gaseous species absorption zone 110) under conditions that promote the transfer of at least a portion of the gaseous species from the gas stream 104 to the absorbent 116. Suitable conditions that promote the transfer of at least a portion of the gaseous species from the gas stream to the absorbent, including, for example, the concentration and / or size of the absorbent, temperature, pressure, and / or fluid conditions, are discussed in further detail herein.

[0044] According to some embodiments, the absorbent (e.g., a liquid absorbent) may be configured such that the gaseous species dissolves therein. In some embodiments, the absorbent may be a reactant and / or catalyst that causes and / or promotes a reaction of the gaseous species, thereby altering (e.g., chemically altering) the gaseous species and / or at least partially removing the gaseous species from the gas stream. In some embodiments, for example, the absorbent may react (e.g., chemically react) with the gaseous species in the gas stream. In some such embodiments, the absorbent may interact with and remove the gaseous species from the gas stream. In certain embodiments, the interaction between the absorbent and the gaseous species is one or more bonding interactions (e.g., chemical bonding interactions). Any of a variety of suitable bonding interactions between the absorbent and the gaseous species (e.g., including covalent bonds, ionic bonds, dipole-dipole interactions, van der Waals interactions, London dispersion forces, and / or hydrogen bonds) are possible.

[0045] Any of a variety of suitable absorbents may be employed. According to certain embodiments, virtually any absorbent may be used in the systems described herein. In some embodiments, the absorbent comprises an amine-containing compound (e.g., monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP)), a hydroxide (e.g., potassium hydroxide (KOH)), ammonia, quinones, amino acids, ionic liquids, and / or combinations thereof. Other absorbents are also possible.

[0046] In certain embodiments, the absorbent may be in liquid form (e.g., the absorbent exists as a liquid at standard temperature and pressure). The absorbent may, in some embodiments, comprise a mixture (e.g., an absorbent mixture). In some embodiments, for example, the absorbent mixture comprises a reactant (e.g., any of the absorbents described above) dissolved and / or dispersed in a liquid (e.g., water).

[0047] The absorbent mixture may comprise reactants in any of a variety of suitable amounts. In certain embodiments, for example, the absorbent mixture comprises reactants in an amount of 5 weight percent (wt.%) or more, 10 wt.% or more, 20 wt.% or more, 30 wt.% or more, or 40 wt.% or more, based on the total weight of the absorbent mixture. In some embodiments, the absorbent mixture comprises reactants in an amount of 50 wt.% or less, 40 wt.% or less, 30 wt.% or less, 20 wt.% or less, or 10 wt.% or less, based on the total weight of the absorbent mixture. Combinations of the ranges recited above are also possible (e.g., the absorbent mixture comprises reactants in an amount of 5 wt.% or more and 50 wt.% or less, based on the total weight of the absorbent mixture, and the absorbent mixture comprises reactants in an amount of 20 wt.% or more and 30 wt.% or less, based on the total weight of the absorbent mixture). Other ranges are also possible.

[0048] In some embodiments, the sorbent mixture may include one or more additives. In some embodiments, for example, the sorbent mixture includes nanoparticles configured to absorb gaseous species, thereby improving the removal efficiency of the sorbent mixture with respect to gaseous species. The nanoparticles, in some embodiments, may optionally be functionalized with one or more functional groups configured to absorb gaseous species. Other additives are also possible, including, for example, surfactants.

[0049] According to certain embodiments, the system may include an absorbent (e.g., in addition to or instead of the absorbent). The absorbent may, in some embodiments, be configured to absorb gaseous species from the gas stream. Suitable absorbents include, for example, nanofluids. In some embodiments, the nanofluid comprises a fluid comprising nanoparticles. The nanoparticles, in some embodiments, may optionally be functionalized with one or more functional groups configured to absorb gaseous species.

[0050] In some embodiments, the absorbent is in the form of a liquid mist. With reference to FIG. 1, for example, the absorbent 116 may be in the form of a liquid mist. In an embodiment, the system may include a source of liquid mist configured to convert the absorbent (e.g., a liquid absorbent) and / or the absorbent mixture (e.g., reactants dissolved and / or dispersed in a liquid) into a liquid mist. As shown in FIG. 1, for example, the system 100a includes a source of liquid mist 112. According to an embodiment, the source of liquid mist 112 is configured to introduce liquid mist into the gaseous species absorption zone 110, whereby the liquid mist is exposed to the gas flow 104 (e.g., along the gas flow path 102) under conditions that promote the transfer of at least a portion of the gaseous species from the gas flow 104 to the liquid mist. In an embodiment, for example, the source of liquid mist 112 is fluidly connected to a dispenser 122, which is configured to dispense the liquid mist into the gaseous species absorption zone 110. In some non-limiting embodiments, for example, the dispenser can be a nozzle configured to spray a liquid mist into the gaseous species absorption zone, however, other dispensers are possible as the present disclosure is not meant to be limited in this respect.

[0051] The source of the liquid mist can be any of a variety of suitable liquid mist sources. In some embodiments, for example, the source of the liquid mist is an ultrasonic mist and / or fog unit, a mist and / or fog generator, a mist and / or fog fan, a mist and / or fog sprayer, and / or an atomizer. Other sources of liquid mist are possible.

[0052] In some embodiments, the liquid mist comprises a plurality of droplets (eg, liquid droplets). Figure 3 shows a schematic diagram of a plurality of droplets 300 according to some embodiments.

[0053] Each droplet of the plurality of droplets may have any of a variety of suitable shapes. In some embodiments, for example, as shown in FIG. 3, each droplet 301 of the plurality of droplets 300 is substantially spherical. In other embodiments, at least some of the plurality of droplets are substantially non-spherical, as the present disclosure is not meant to be limited in this respect.

[0054] Each droplet of the plurality of droplets may have any of a variety of suitable sizes. In some embodiments, each droplet of the plurality of droplets has a maximum characteristic dimension (e.g., a maximum diameter). With reference to FIG. 3, for example, each droplet 301 of the plurality of droplets 300 has a maximum characteristic dimension 302 (e.g., a maximum diameter). In some embodiments, the maximum characteristic dimension of each droplet of the plurality of droplets may be sufficiently small to provide an increased interfacial surface area between the liquid mist and the gas stream, as compared to, for example, a conventional absorption tower comprising one or more packed bed reactors.

[0055] The maximum characteristic dimension of each droplet of the plurality of droplets may be any of a variety of suitable values. According to an embodiment, each droplet of the plurality of droplets may have a maximum characteristic dimension (e.g., maximum diameter) of 0.1 micrometers or more, 0.5 micrometers or more, 1 micrometer or more, 10 micrometers or more, 20 micrometers or more, 30 micrometers or more, 40 micrometers or more, 50 micrometers or more, 60 micrometers or more, 70 micrometers or more, 80 micrometers or more, or 90 micrometers or more. In an embodiment, each droplet of the plurality of droplets has a maximum characteristic dimension (e.g., maximum diameter) of 100 micrometers or less, 90 micrometers or less, 80 micrometers or less, 70 micrometers or less, 60 micrometers or less, 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, 20 micrometers or less, 10 micrometers or less, 1 micrometer or less, or 0.5 micrometers or less. Combinations of the ranges recited above are also possible (e.g., each droplet of the plurality of droplets has a maximum characteristic dimension of 0.1 micrometers or more and 100 micrometers or less, and each droplet of the plurality of droplets has a maximum characteristic dimension of 40 micrometers or more and 60 micrometers or less). Other ranges are also possible. In some embodiments, the maximum characteristic dimension (e.g., maximum diameter) of the droplets may be determined by scanning electron microscopy (SEM) and / or transmission electron microscopy (TEM).

[0056] According to some embodiments, as can be appreciated by one of ordinary skill in the art, the plurality of droplets may have a size distribution such that each droplet of the plurality of droplets has a maximum characteristic dimension between 0.1 micrometers or more and 100 micrometers or less. In some embodiments, at least some of the droplets of the plurality of droplets having a size distribution may have a maximum characteristic dimension (e.g., a maximum diameter) that is greater than and / or less than the maximum characteristic dimensions listed above.

[0057] According to certain embodiments, the average size (e.g., average diameter) of the plurality of droplets may be 0.1 micrometers or more, 0.5 micrometers or more, 1 micrometer or more, 10 micrometers or more, 20 micrometers or more, 30 micrometers or more, 40 micrometers or more, 50 micrometers or more, 60 micrometers or more, 70 micrometers or more, 80 micrometers or more, or 90 micrometers or more. In some embodiments, the average size (e.g., average diameter) of the plurality of droplets may be 100 micrometers or less, 90 micrometers or less, 80 micrometers or less, 70 micrometers or less, 60 micrometers or less, 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, 20 micrometers or less, 10 micrometers or less, 1 micrometer or less, or 0.5 micrometers or less. Combinations of the ranges listed above are also possible (e.g., the average size of the plurality of droplets is 0.1 micrometers or more and 100 micrometers or less, and the average size of the plurality of droplets is 40 micrometers or more and 60 micrometers or less). Other ranges are also possible. In certain embodiments, the average size of the droplets may be determined by SEM and / or TEM.

[0058] According to certain embodiments, due to the size (e.g., largest characteristic dimension, average dimension) of the droplets of the liquid mist, the droplets may be entrained in the gas stream during the absorption stage. In some embodiments, the droplets of the liquid mist may be separated from the gas stream during a separation stage, as described in more detail herein.

[0059] According to certain embodiments, the system may have a high interfacial area between the absorbent and the gas stream in the gaseous species absorption zone, as compared to a conventional absorption tower, for example, comprising one or more packed bed reactors. The high interfacial area between the absorbent and the gas stream advantageously provides a higher absorption efficiency of the target species in the gas stream due to the surface area contact between the absorbent and the gas stream.

[0060] In some embodiments, the interfacial area between the absorbent and the gas stream in the gaseous species absorption zone is at least 10 times, at least 50 times, at least 100 times, at least 200 times, at least 300 times, at least 400 times, at least 500 times, at least 600 times, at least 700 times, at least 800 times, or at least 900 times greater than the interfacial area between a comparative absorbent and a comparative gas stream in an otherwise essentially identical absorption tower comprising one or more packed bed reactors. In certain embodiments, the interfacial area between the absorbent and the gas stream in the gaseous species absorption zone is no more than 1,000 times, no more than 900 times, no more than 800 times, no more than 700 times, no more than 600 times, no more than 500 times, no more than 400 times, no more than 300 times, no more than 200 times, no more than 100 times, or no more than 50 times greater than the interfacial area between a comparative absorbent and a comparative gas stream in an otherwise essentially identical absorption tower comprising one or more packed bed reactors. Combinations of the ranges recited above are also possible (e.g., the interfacial area between the absorbent and the gas stream in the gaseous species absorption zone is at least 10 times greater, and no more than 1000 times greater, than the interfacial area between a comparative absorbent and a comparative gas stream in an absorption tower with one or more otherwise essentially the same packed bed reactors, and the interfacial area between the absorbent and the gas stream in the gaseous species absorption zone is at least 400 times greater, and no more than 500 times greater, than the interfacial area between a comparative absorbent and a comparative gas stream in an absorption tower with one or more otherwise essentially the same packed bed reactors). Other ranges are also possible.

[0061] According to certain embodiments, the increase in interfacial area compared to a comparative absorbent and comparative gas stream in an absorption tower comprising one or more otherwise essentially identical packed bed reactors is due to: (i) a sufficiently small size (e.g., maximum characteristic dimension, average dimension) of the droplets of the liquid mist; (ii) a sufficiently small size (e.g., length, diameter) of the gaseous species absorption zone; and / or (iii) a tighter packing of the droplets within the gaseous species absorption zone compared to one or more packed bed reactors in the absorption tower.

[0062] According to some embodiments, the system includes a separation section. With reference to Figure 1, for example, system 100a includes separation section 114. As discussed in more detail below, the separation section, in some embodiments, is configured to separate at least a portion of the absorbent (e.g., in the form of a liquid mist) from the gas stream.

[0063] The separation zone may be positioned along the gas flow path in some embodiments. As shown in Figure 1, for example, separation zone 114 is positioned along gas flow path 102 (e.g., upstream from gaseous species absorption zone 110). In certain embodiments, the separation zone is fluidly connected to the gaseous species absorption zone. With reference to Figure 1, for example, separation zone 114 is fluidly connected to gaseous species absorption zone 110.

[0064] In some embodiments, the separation zone is an electrostatic separation zone. With reference to FIG. 1, for example, separation zone 114 can be an electrostatic separation zone in some embodiments. In some embodiments, the electrostatic separation zone comprises an electrostatic component. As shown in FIG. 1, for example, separation zone 114 comprises electrostatic component 118. The electrostatic separation zone can be configured to electrostatically separate at least a portion of the liquid mist from the gas stream in some embodiments. In some embodiments, for example, the electrostatic separation zone is configured to subject the gas stream comprising the liquid mist to space charge injection (e.g., corona discharge) from the electrostatic component.

[0065] FIG. 4 shows a schematic diagram of an electrostatic separation zone according to some embodiments. The electrostatic separation zone may comprise an electrostatic component comprising at least one emitter electrode and at least one collector electrode in some embodiments. With reference to FIG. 4, for example, the electrostatic separation zone 114 comprises an electrostatic component 118 comprising an emitter electrode 402 and a collector electrode 404 (e.g., 404a and 404b). In some embodiments, one or more emitter electrodes may be associated with a gas flow path. As shown in FIG. 4, for example, the emitter electrode 402 is associated with the gas flow path 102 such that the gas flow flows along the gas flow path 102 in proximity to the emitter electrode 402. The one or more collector electrodes may be associated with one or more walls and / or enclosures of the electrostatic component in some embodiments. With reference to FIG. 4, for example, collector electrode 404a is associated with a wall and / or enclosure 406a of electrostatic component 118, and collector electrode 404b is associated with a wall and / or enclosure 406b of electrostatic component 118.

[0066] The at least one emitter electrode may comprise any of a variety of suitable materials. The at least one emitter electrode material may be capable of conducting electrons in some embodiments. According to some embodiments, the at least one emitter electrode may be a corrosion-resistant material. In certain embodiments, for example, the at least one emitter electrode comprises a metal (e.g., molybdenum, tungsten), a metal oxide, and / or an alloy. The at least one emitter electrode may comprise one or more composite materials and / or one or more coatings (e.g., on an exterior surface of the at least one emitter electrode) to improve the stability and / or life of the at least one emitter electrode in some embodiments. In certain non-limiting embodiments, the emitter electrode is a wire electrode.

[0067] The at least one collector electrode may comprise any of a variety of suitable materials. The at least one collector electrode material may be capable of conducting electrons in some embodiments. According to certain embodiments, the at least one collector electrode may be a corrosion-resistant material. In some embodiments, for example, the at least one collector electrode comprises a metal, a metal oxide, and / or an alloy. The at least one collector electrode may comprise one or more composite materials and / or one or more coatings (e.g., on an outer surface of the at least one emitter electrode) to improve the stability and / or life of the at least one collector electrode in some embodiments. In certain non-limiting embodiments, the collector electrode is an annular cylindrical electrode.

[0068] In some embodiments, at least one emitter electrode is configured to emit a space charge injection (e.g., corona discharge) into the gas stream with entrained liquid mist when the gas stream flows along the gas flow path. With reference to FIG. 4, for example, emitter electrode 402 is configured to provide an electric field by emitting a space charge injection (e.g., corona discharge) into the gas stream with entrained liquid mist when the gas stream flows along gas flow path 102. In some embodiments, when a droplet of a plurality of droplets of liquid mist is exposed to a space charge injection (e.g., corona discharge), the droplet becomes charged (e.g., positively charged, negatively charged). As shown in FIG. 4, for example, when droplet 301a (e.g., uncharged droplet) is exposed to a space charge injection (e.g., corona discharge) from emitter electrode 402, the droplet becomes a charged droplet 301b (e.g., positively charged droplet, negatively charged droplet). In certain embodiments, for example, the emitter electrode provides an electric field that ionizes the atmosphere surrounding the emitter electrode, which imparts a net electric charge to each droplet of a plurality of droplets entrained in a gas stream flowing along the gas flow path.

[0069] According to an embodiment, at least one collector electrode is configured to collect the charged droplets after the droplets are exposed to space charge injection (e.g., corona discharge) from at least one emitter electrode. As shown in FIG. 4, for example, collector electrodes 404a and 404b are configured to collect the charged droplets 301b after the droplets are exposed to space charge injection (e.g., corona discharge) from emitter electrode 402. In some embodiments, the charged droplets experience an electrostatic force in the direction of the electric field and are thus attracted to and collected by the at least one collector electrode.

[0070] According to some embodiments, one or more collector electrodes of the electrostatic component may be configured with a mesh and / or a porous surface. The mesh and / or porous surface of the one or more collector electrodes may be configured to absorb and / or absorb one or more droplets of the liquid mist in some embodiments. In some embodiments, for example, one or more droplets of the liquid mist (e.g., charged droplets) may be absorbed and / or absorbed by the mesh and / or porous surface of the collector electrode after the droplets are exposed to space charge injection (e.g., corona discharge).

[0071] In an embodiment, the electrostatic components of the electrostatic separation area may be associated with a power supply. With reference to FIG. 3, for example, the electrostatic components 118 of the electrostatic separation area 114 are associated with a power supply 408 (e.g., a high voltage power supply). The power supply may be connected to at least one emitter electrode and at least one collector electrode. As shown in FIG. 3, for example, the power supply 408 is connected to the emitter electrode 402 via connection (e.g., electrical connection) 410c, to the collector electrode 404a via connection (e.g., electrical connection) 410a, and to the collector electrode 404b via connection (e.g., electrical connection) 410b.

[0072] In certain embodiments, the separation zone comprises one or more surfaces configured to absorb and / or absorb the liquid mist. In some embodiments, for example, the gas stream comprising the entrained liquid mist can be caused to flow directly through a surface (e.g., mesh and / or porous surface) in the separation zone (e.g., collector electrode, non-electrode surface, etc.) that captures at least a portion of the liquid mist. In other embodiments, the gas stream comprising the entrained liquid mist can be caused to flow adjacent to a surface (e.g., mesh and / or porous surface) in the separation zone (e.g., collector electrode, non-electrode surface, etc.), but need not pass through the surface. In certain embodiments, for example, the surface can be disposed as an enclosure and / or wall of the separation zone, and the gas stream comprising the entrained liquid mist can be directed tangentially to and / or against the enclosure and / or wall, whereby the entrained liquid mist diffuses adjacent to the enclosure and / or wall. In one set of embodiments, the gas stream with the entrained liquid mist is circulated and repeatedly flowed by one or more walls of the separation zone enclosure, e.g., a mesh surface defining the separation zone enclosure, which is configured to separate the liquid mist from the gas stream.

[0073] According to some embodiments, the separation zone may be configured as a tube, a cylinder, and / or a cylinder. Configuring the separation zone as a tube, a cylinder, and / or a cylinder may advantageously facilitate flow of the gas stream along the gas flow path through the separation zone. However, other configurations for the separation zone are possible, including, for example, cubic, prismatic, and / or conical configurations, as the present disclosure is not meant to be limiting in this respect.

[0074] The separation area can have any of a variety of suitable dimensions in some embodiments. With reference to Figure 1, for example, separation area 114 has a length 124b.

[0075] The separation area may have any of a variety of suitable lengths. In some embodiments, for example, the length of the separation area is 10 centimeters or more, 50 centimeters or more, 1 meter or more, 2 meters or more, 3 meters or more, or 4 meters or more. In some embodiments, the length of the separation area is 5 meters or less, 4 meters or less, 3 meters or less, 2 meters or less, 1 meter or less, or 50 centimeters or less. Combinations of the ranges listed above are also possible (e.g., the length of the separation area is 10 centimeters or more and 5 meters or less, and the length of the separation area is 1 meter or more and 2 meters or less). Other ranges are also possible.

[0076] In some embodiments where the separation area is configured as a tube, cylinder, and / or cylinder, the separation area may have any of a variety of suitable diameters. In some embodiments, for example, the separation area has a diameter that is 1 centimeter or more, 5 centimeters or more, 10 centimeters or more, 20 centimeters or more, or 50 centimeters or more. In some embodiments, the separation area has a diameter that is 1 meter or less, 50 centimeters or less, 20 centimeters or less, 10 centimeters or less, or 5 centimeters or less. Combinations of the ranges listed above are also possible (e.g., the separation area has a diameter that is 1 centimeter or more and 1 meter or less, and the separation area has a diameter that is 10 centimeters or more and 20 centimeters or less). Other ranges are also possible.

[0077] According to some embodiments, the separation zone may be configured as a honeycomb structure. In some embodiments, for example, the separation zone may comprise a plurality of tubes, cylinders, and / or cylinders. In some such embodiments, each tube, cylinder, and / or cylinder of the honeycomb separation zone may be fluidly connected to the gaseous species absorption zone such that each tube, cylinder, and / or cylinder is configured to receive the gas stream after the gas stream flows through the gaseous species absorption zone. In some embodiments, the separation zone is an electrostatic separation zone, and each tube, cylinder, and / or cylinder of the honeycomb separation zone may comprise at least one emitter electrode and at least one collector electrode as described herein. According to some embodiments, each tube, cylinder, and / or cylinder of the honeycomb separation zone may have a length as described herein (e.g., 10 centimeters or more and 5 meters or less) and / or a diameter as described herein (e.g., 1 centimeter or more and 1 meter or less). Each tube, cylinder, and / or cylinder of the honeycomb separation section may, in some embodiments, have a relatively smaller diameter than the tubes, cylinders, and / or cylinders of the gaseous separation section.

[0078] The separation zone may comprise any of a variety of suitable materials. According to some embodiments, for example, the separation zone may comprise a metal, a metal alloy, a clad material, a ceramic, a plastic, a carbon-based material, and / or a combination thereof. Other materials are also possible. In certain embodiments, the separation zone material may be at least partially coated. For example, in some embodiments, the separation zone material is coated with a corrosion-resistant material (e.g., a plastic coated with a corrosion-resistant metal or alloy).

[0079] According to certain embodiments, the gas flow pressure drop along the gas flow path upstream of the gaseous species absorption zone (e.g., in the separation zone) is less than the overall gas flow pressure drop between the inlet of the gas flow path and the outlet of the gas flow path. With reference to Figure 1, for example, the gas flow pressure drop along the gas flow path 102 upstream of the gaseous species absorption zone 110 (e.g., in the separation zone 114) is less than the overall gas flow pressure drop between the inlet 106 of the gas flow path 102 and the outlet 106 of the gas flow path 102.

[0080] In some embodiments, the gas flow pressure drop along the gas flow pathway upstream of the gaseous species absorption zone (e.g., in the separation zone) is 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less than the overall gas flow pressure drop between the gas flow pathway inlet and the gas flow pathway outlet. In certain embodiments, the gas flow pressure drop along the gas flow pathway upstream of the gaseous species absorption zone (e.g., in the separation zone) is 1% or more, 10% or more, 20% or more, 30% or more, or 40% or more less than the overall gas flow pressure drop between the gas flow pathway inlet and the gas flow pathway outlet. Combinations of the ranges listed above are also possible (e.g., the gas stream pressure drop along the gas flow path upstream of the gaseous species absorption zone is 50% or less, 1% or more less than the overall gas stream pressure drop between the gas flow path inlet and the gas flow path outlet, and the gas stream pressure drop along the gas flow path upstream of the gaseous species absorption zone is 30% or less, 20% or more less than the overall gas stream pressure drop between the gas flow path inlet and the gas flow path outlet). Other ranges are also possible. In certain embodiments, the gas stream pressure drop along the gas flow path upstream of the gaseous absorption zone may be determined by measuring the difference in gas stream pressure between the gaseous species absorption zone outlet and the gas flow path outlet.

[0081] According to some embodiments, a system for removing gaseous species from a gas stream may include any of a variety of additional components.

[0082] In some embodiments, the system may include a fluid connector positioned between the gaseous species absorption zone and the separation zone. Figure 2 shows a schematic diagram of a system 100b for removing gaseous species from a gas stream 104 according to some embodiments, the system 100b including a fluid connector 120a positioned along the gas flow path 102 between the gaseous species absorption zone 110 and the separation zone 114. In some embodiments, it may be advantageous to position a fluid connector between the gaseous species absorption zone and the separation zone to concentrate the gas stream (and in some embodiments, the liquid mist entrained therein) prior to flowing the gas stream to the separation zone. Concentrating the gas stream (and in some embodiments, the liquid mist entrained therein) may, in some embodiments, increase the interfacial surface area between the liquid mist and the gas stream and / or the time of exposure between the liquid mist and the gas stream.

[0083] The fluid connector may be configured as a tube, a cylinder, and / or a cylinder, according to certain embodiments. Configuring the fluid connector as a tube and / or a cylinder may advantageously facilitate flow of gas flow along a gas flow path through the fluid connector. However, other configurations for the fluid connector are possible, including, for example, cubic, prismatic, and / or conical configurations, as the present disclosure is not meant to be limiting in this respect.

[0084] 2 shows the fluid connectors configured in a straight direction, the fluid connectors may have other directional configurations as the disclosure is not meant to be limiting in this respect, in certain embodiments, for example, the fluid connectors may be configured with any of a variety of turns and / or curves.

[0085] The fluid connectors, in some embodiments, can have any of a variety of suitable dimensions. With reference to Figure 2, for example, fluid connector 120a has a length 124c.

[0086] The fluid connector may have any of a variety of suitable lengths. In some embodiments, for example, the length of the fluid connector is 1 centimeter or more, 5 centimeters or more, 10 centimeters or more, 50 centimeters or more, or 1 meter or more. In certain embodiments, the length of the fluid connector is 2 meters or less, 1 meter or less, 50 centimeters or less, 10 centimeters or less, or 5 centimeters or less. Combinations of the ranges recited above are also possible (e.g., the length of the fluid connector is 1 centimeter or more and 2 meters or less, the length of the fluid connector is 10 centimeters or more and 50 centimeters or less). Other ranges are also possible.

[0087] The fluid connector may comprise any of a variety of suitable materials. According to some embodiments, for example, the fluid connector may comprise a metal, a metal alloy, a clad material, a ceramic, a plastic, a carbon-based material, and / or combinations thereof. Other materials are possible. In certain embodiments, the fluid connector material may be at least partially coated. For example, in some embodiments, the fluid connector material is coated with a corrosion-resistant material (e.g., a plastic coated with a corrosion-resistant metal or alloy).

[0088] In some embodiments, the system may include a gaseous species sensor. FIG. 5 shows a schematic diagram of a system 100c for removing gaseous species from a gas stream according to some embodiments, the system including a gaseous species sensor 502. According to some embodiments, the gaseous species sensor 502 may be fluidly connected to (and upstream from) the separation zone 114. In some embodiments, as shown in FIG. 5, the gaseous species sensor 502 may be fluidly connected to the separation zone 114 via the fluid connector 120b. The gaseous species sensor 502 may be configured to detect, in some embodiments, an amount of gaseous species in the gas stream as the gas stream flows along the gas flow path 102 upstream from the separation zone 114. In some embodiments, the gaseous species sensor 502 is fluidly connected to (and downstream from) the outlet 108.

[0089] In one embodiment, the gaseous species sensor may be a spectroscopic sensor, such as, for example, an infrared sensor (e.g., an infrared CO sensor), however, other gaseous species sensors are possible as the present disclosure is not meant to be limited in this respect.

[0090] According to some embodiments, the system may include a scrubber. FIG. 6 shows a schematic diagram of a system 100d for removing gaseous species from a gas stream according to some embodiments, the system including a scrubber 504. According to some embodiments, the scrubber 504 may be fluidly connected to (and upstream from) the inlet 106 of the gas flow path 102. The scrubber 502 may be configured, in some embodiments, to scrub one or more non-target species (e.g., non-target gaseous species) in the gas stream prior to the gas stream entering the gaseous species separation zone 110. In some embodiments, the scrubber 504 may be fluidly connected to (and downstream from) the gaseous species separation zone 110. According to some embodiments, as shown in FIG. 6, the scrubber 504 is fluidly connected to the gaseous species separation zone 110 via a fluid connector 120c.

[0091] Any of a variety of suitable non-target species may be removed from the gas stream by the scrubber. In some embodiments, for example, the scrubber removes CO, sulfur oxides (SO x ) species, nitrogen oxide species (NO x ), hydrogen sulfide (HS), and / or combinations thereof. Other gases to be removed from the gas stream by the scrubber are also possible.

[0092] In some embodiments, the system may include a stripper. FIG. 7 shows a schematic diagram of a system 100e for removing gaseous species from a gas stream according to some embodiments, the system including a stripper 506. According to an embodiment, the stripper 506 may be fluidly connected to (and upstream from) the separation zone 114. In some embodiments, as shown in FIG. 7, the stripper 506 is fluidly connected to the separation zone 114 via a fluid connector 120d. The stripper 506 may be configured to remove one or more absorbed gaseous species from the absorbent 116 (e.g., in the form of a liquid mist) after separating the absorbent from the gas stream in the separation zone 114 in some embodiments. The stripper 506 may be fluidly connected to (and downstream from) the source of liquid mist 112 in some embodiments. In some embodiments, as shown in FIG. 7, the stripper 506 is fluidly connected to the source of liquid mist via a fluid connector 120e. According to some embodiments, after removing one or more absorbed gaseous species from the absorbent 116, the stripper 506 is configured to flow the absorbent 116 to the source of liquid mist 112. Configuring the system in this manner advantageously allows the absorbent to be recycled and reused for additional absorption of gaseous species from the gas stream.

[0093] According to an embodiment, the stripper 506 may be associated with a stripper outlet 508 for releasing a gaseous species stream 510 after removing the gaseous species from the absorbent 116 .

[0094] The system may include additional components not shown in the figures according to some embodiments. As would be recognized by one of ordinary skill in the art, the system may include one or more flow meters and / or pressure sources configured to control the flow rate of the gas stream through the system and / or the overall pressure of one or more components of the system (e.g., the gaseous species absorption zone and / or separation zone). The system may include one or more pressure sensors and / or gauges configured to measure the pressure of the gas stream in the gas flow path in some embodiments. In certain embodiments, the system may include one or more fans and / or blowers configured to facilitate the flow of the gas stream through the system (e.g., along the gas flow path). According to some embodiments, the system may include one or more temperature controllers and associated connections to control the overall temperature of the system.

[0095] The system may have any of a variety of suitable overall lengths. With reference to FIG. 1, for example, the system 100a has a length 124d, which in some embodiments may be measured from the inlet 106 of the gas flow path 102 to the outlet 108 of the gas flow path 102. In some embodiments, the overall length of the system is 20 centimeters or more, 50 centimeters or more, 1 meter or more, 5 meters or more, 10 meters or more, 20 meters or more, or 30 meters or more. In some embodiments, the overall length of the system is 40 meters or less, 30 meters or less, 20 meters or less, 10 meters or less, 5 meters or less, 1 meter or less, or 50 centimeters or less. Combinations of the ranges listed above are also possible (e.g., the overall length of the system is 20 centimeters or more and 40 meters or less, and the overall length of the system is 1 meter or more and 5 meters or less). Other ranges are also possible.

[0096] The gas stream can be any of a variety of suitable gas streams. In some embodiments, for example, the gas stream is a combustion exhaust stream (e.g., flue gas, exhaust gas, flue gas), for example, from a combustion plant. In certain embodiments, the gas stream is an industrial exhaust stream (e.g., a cement production exhaust stream). In certain embodiments, the gas stream is air. Other gas streams are possible.

[0097] The gaseous species can be any of a variety of suitable gaseous species. In some embodiments, the gaseous species is a gaseous exhaust species. For example, in some embodiments, the gaseous species is a gaseous exhaust species present in a combustion exhaust stream and / or an industrial exhaust stream. In certain embodiments, the gaseous species is a greenhouse gas. Examples of greenhouse gases include, but are not limited to, CO2, CH4, N2O, O3, fluorinated gases, and / or combinations thereof. Other gaseous species are also possible.

[0098] According to certain embodiments, a method for removing gaseous species from a gas stream is described. In some embodiments, the method includes exposing the gas stream containing the gaseous species to an absorbent (e.g., in the form of a liquid mist), the absorbent comprising a reactant configured to dissolve and / or react with the gaseous species as described herein.

[0099] In certain embodiments, the method includes carrying out a reaction between a reactant and a gaseous species in a gaseous species absorption zone, the reaction resulting in absorption of the gaseous species from the gas stream by an absorbent (e.g., in the form of a liquid mist).

[0100] The absorbent (e.g., in the form of a liquid mist) can be configured to absorb any of a variety of suitable amounts of gaseous species from the gas stream. In certain embodiments, for example, the absorbent is configured to absorb at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the gaseous species from the gas stream. In some embodiments, the absorbent is configured to absorb no more than 100%, no more than 90%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 40%, no more than 30%, or no more than 20% of the gaseous species from the gas stream. Combinations of the ranges listed above are also possible (e.g., the absorbent is configured to absorb at least 10% and no more than 100% of the gaseous species from the gas stream, and the absorbent is configured to absorb at least 50% and no more than 60% of the gaseous species from the gas stream). Other ranges are also possible.

[0101] According to certain embodiments, the ratio of the molar amount of gaseous species absorbed by the absorbent per hour to the volume of the gaseous species absorption zone is at least 2 times, at least 5 times, at least 10 times, at least 25 times, at least 50 times, at least 75 times, at least 100 times, at least 125 times, at least 150 times, or at least 175 times greater than the comparable ratio in an otherwise essentially similar absorber tower equipped with one or more packed bed reactors. In some embodiments, the ratio of the molar amount of gaseous species absorbed by the absorbent per hour to the volume of the gaseous species absorption zone is no more than 200 times greater, no more than 175 times greater, no more than 150 times greater, no more than 125 times greater, no more than 100 times greater, no more than 75 times greater, no more than 50 times greater, no more than 25 times greater, no more than 10 times greater, or no more than 5 times greater than the comparable ratio in an otherwise essentially similar absorber tower equipped with one or more packed bed reactors. Combinations of the above-listed ranges are also possible (e.g., the ratio of the molar amount of gaseous species absorbed by the absorbent per hour to the volume of the gaseous species absorption section is at least 2 times, and no more than 200 times, greater than the comparable ratio in an otherwise essentially similar absorption tower equipped with one or more packed bed reactors, and the ratio of the molar amount of gaseous species absorbed by the absorbent per hour to the volume of the gaseous species absorption section is at least 75 times, and no more than 100 times, greater than the comparable ratio in an otherwise essentially similar absorption tower equipped with one or more packed bed reactors). Other ranges are also possible.

[0102] According to an embodiment, the method includes separating at least a portion of the liquid mist from the gas stream in a separation section fluidly connected to the gaseous absorption section.

[0103] These and other embodiments may be utilized alone or in combination with the benefit of additional factors, components and / or procedures, as would be understood by one of ordinary skill in the art. Example 1

[0104] The following example describes a first embodiment of a two-stage mist-based absorption system for removing gaseous species from a gas stream.

[0105] Conventional absorption systems use long, narrow towers (10-20 meters in height) and packed beds to improve the interfacial area and residence time of the scrubbing liquid with the flue gas during absorption (see, for example, FIG. 8A). Misting the scrubbing fluid would allow for a significantly shorter absorber due to the higher interfacial area provided by the small droplets, however, such mist is difficult to capture and reclaim using passive demisters. Active electrostatic demisters can capture these mist without exerting significant back pressure.

[0106] For this, a two-stage mist-based absorption system (shown in FIG. 8B) is described herein. In the first stage, the absorption stage, mist-scale droplets with diameters of 15-50 μm were used, which allowed the system to achieve up to a 280-fold increase in the available interfacial area between the absorbent and the gas compared to conventional packed-bed reactors. This allowed for a significantly shorter absorber unit than conventional systems, but droplets of this size were easily entrained by the gas flow. To capture this large liquid volume, the second stage, the electrostatic droplet capture stage, was utilized. Specifically, by employing corona discharge, the mist-scale droplets were charged and an electric force was introduced that drove the charged mist-scale droplets to a collector, where the liquid absorbent was collected, treated, and recirculated.

[0107] To better understand the system's ability to reduce the overall size of the absorber, the required lengths for both stages of the system were theoretically estimated. CO2 absorption into droplets of different radii was modeled using the empirical model shown in Equation 2.

number

[0108] In Equation 2,

number

[0109] For the second stage of the system, the maximum length required to capture >95% of the mist droplets was also estimated. Considering the cylindrical design of the electrostatic collector shown in Figure 8B, the electrostatic force that the charged droplets would experience was compared to the aerodynamic drag force. The characteristic radial velocity (U r ) was estimated as shown in Equation 3. Using the Deutsch-Anderson equation (Equation 4), the droplet collection efficiency (η) was then calculated as a function of the cylinder length (L c ), diameter (D c ), and was estimated as a function of gas flow rate (Q).

number

number

[0110] In the above equation, q represents the charge accumulated on a single droplet, E represents the electric field strength, μ is the viscosity of the flue gas, R is the droplet radius, ε0 is the dielectric constant of free space, and C DA is a correction factor to the Deutsch-Anderson formula used for practical systems.

[0111] From Figures 8C and 8D, it was observed that the overall length of the absorber unit can be reduced from around 20 meters in a conventional packed bed reactor for a 400 MW power plant to less than 4 meters in the two-stage system discussed herein. This would allow for a dramatic reduction in the capital required for the CO2 absorber unit. To validate these models, a scaled-down version of the two-stage system was developed and tested. For the first stage of the system, the gas flux of an industrial absorber unit was matched and the effect of input CO2 and catalyst concentration on the CO2 capture efficiency was studied. For the second stage, the droplet capture efficiency of the scaled-down electrostatic system was explored as a function of gas flow rate and electric field strength. An economic analysis is also presented to capture the reduction in plant capital expenditure that can be enabled by a two-stage mist-based absorption system.

[0112] Experimental Setup: Figure 9A presents an illustration of the experimental setup used in this example. Flow-controlled CO2 and air flows were mixed to achieve the desired concentration of CO2 at the inlet to the system. Gas was then introduced into the mistification unit where droplets were entrained in the gas flow. Potassium hydroxide was used as the absorbent due to the simplicity of the experiment. The gas and entrained mist were then flowed through a fixed length of tubing to allow time for absorption of CO2. The mist-laden gas mixture was then flowed into an electrostatic demister capture unit where all absorbent droplets were removed. An infrared CO2 sensor was used to quantify the CO2 captured in the system. Figure 9B shows a histogram of droplet diameters produced by the mistification unit, showing that the majority of the droplets fall within the 10-20 μm diameter range. This histogram was obtained by visually recording the mist droplets as they passed through a viewing window when the electrostatic droplet capture unit was turned off, which provided an accurate representation of the droplets that had been entrained by the gas flow.

[0113] Gas mixing and mist generation: Brooks® mechanical flowmeters were used to control the flow rates of CO2 and air before the two gas streams were mixed using a T-junction. The mixed gas was introduced into the headspace of an airtight vessel containing an absorbent bath and an ultrasonic misting unit (Mxmoonant® 6-head ultrasonic mist / fog maker). The experiment was started with the misting unit and mist capture unit turned off. The initial concentration of CO2 was recorded after the gas flowed through the headspace of the airtight vessel so that any effect of the absorbent bath was taken into account in the control measurement. When the ultrasonic mister was turned on, mist scale droplets were ejected into the headspace of the airtight vessel and were then entrained by the gas flow.

[0114] CO2 Sensor: CO2 concentration was measured using a GC-0007 ExplorIR® sensor. The sensor was placed in line with the gas flow in the vented vessel.

[0115] Absorption stage: To properly scale down the experimental absorber, the inlet gas flow rate was varied from 1 to 5 lpm while keeping the CO2 concentration constant at 50%. Figure 10A shows the CO2 capture efficiency of the system for these experiments. It was observed that the capture efficiency reached about 74 ± 5% for flow rates of 1 and 3 lpm, but it dropped to about 64 ± 5% for the 5 lpm case, indicating that the liquid-to-gas ratio and residence time were too low for scrubbing to be maximally effective. To further characterize this reduction in performance, the gas flux through the experimental setup was normalized by the flux achieved in the industrial absorption system, since the industrial absorber system is designed to optimize the gas flux to achieve the maximum capture efficiency possible. In Figure 10B, the ratio of the experimental gas flux to the industrial gas flux (kg / m 2 The time (in seconds) was determined and the 5 lpm case was found to have an unfavorable flux ratio which may explain the performance degradation as the gas flow rate was too high to optimize CO2 capture.

[0116] With the flow rate set at 3 lpm to remain in a favorable flux regime for the remaining absorption experiments, the input CO2 concentration was varied from about 17% to 50%, as shown in Figure 10C. In these cases, capture efficiencies of about 70 ± 5% were observed, which is consistent with industrial KOH-based absorption units. The liquid-to-gas mass flow ratio (L / G) was measured to be about 21 ± 4 for a gas flow rate of 3 lpm, which is also comparable to industrial and other conventional systems. Capture efficiencies of >70% demonstrate that the capabilities of the technique are robust to input CO2 concentration and that in these conditions, capture efficiency is limited by the chemistry of the absorbent.

[0117] Equation 5 shows the stoichiometric reaction between KOH and CO2. In the experimental setup, at a gas flow rate of 3 lpm, the molar flow rates of KOH and CO2 are 1.7 and 1.1 mmol per second, respectively. Since 2 moles of KOH are required to react with every mole of CO2, the stoichiometric capture efficiency is 76%. To verify that the observed experimental capture efficiency of 74±5% is indeed limited by the chemical concentration of the absorbent, the KOH concentration was increased from 1 M to 2 M, and the CO2 capture efficiency was observed to increase to 95±5% for a gas flow rate of 3 lpm and an inlet CO2 concentration of 50% (FIG. 10D). These results illustrate the promise of mist-based absorption systems, especially in terms of enabling a wider range of absorbents that may have better environmental and safety profiles than the alcoholic amines currently preferred in conventional absorber units.

number

[0118] Mist droplet capture stage: After demonstrating the ability of mist-scale droplets to achieve >70% CO2 capture efficiency, the ability of a scaled-down electrostatic unit to capture mist droplets was explored. Figures 11A and 11B show conceptual schematics of the mist capture unit when there is no corona discharge and when there is a stronger discharge, respectively. Figures 11C and 11D show digital photographs of the exit of the demisting unit under corona-free and strong corona conditions, respectively, visually illustrating the ability of the scaled-down demister to completely capture mist for a gas flow rate of 3 lpm and a voltage of about 8 kV. When the voltage source is off, the mist exits the mist-forming unit as it is entrained by the gas flow, but when the emitter electrode creates a strong corona discharge, all the mist is captured. Figure 11E shows the mist capture efficiency as a function of gas flow rate and applied voltage. When the voltage was not high enough to generate a corona discharge, the droplets were not charged and therefore not collected. As the voltage was increased, the corona onset voltage was exceeded and droplets began to be collected. In this condition, the concentration of free ions in the gas stream was not high enough to charge all the entrained mist-scale droplets and therefore only partial capture was achieved. In the region of strong corona, 100% capture was achieved as nearly all droplets became charged and were transported to the grounded collector. The electric field strength applied in the scaled-down system was about 2 kV / cm, which is well within the field strengths used in scaled-up electrostatic precipitator systems, demonstrating the practical promise of a two-stage mist-based absorption system.

[0119] Economic analysis of a scaled-up absorber unit: When a two-stage mist-based absorber is appropriately scaled down, a CO2 capture efficiency of 70-95% is achieved and all mist droplets are effectively captured. To assess the economic viability of the two-stage mist-based approach, the required CAPEX to install the system was estimated and compared to the CAPEX required for a conventional vertical packed-bed absorber tower. For the conventional vertical packed-bed architecture, two absorber towers of 19.06 m height and 11.93 m diameter were selected from an optimized MEA CO2 capture system for a 400 MW gas-fired power plant with a flue gas rate of 622 kg / sec. Purchase costs for the absorber tower enclosure and internal components were estimated from average historical data and then adjusted to US$2,019 via the Chemical Engineering Plant Cost Index (CEPCI). A typical Lang factor of 4.74 was applied to yield the estimated installation costs of the system components tabulated in Table 1.

[0120] The estimated total CAPEX for the packed bed system is $149 million. As expected, the stainless steel clad carbon steel absorber tower is the major cost driver, accounting for over 50% of the cost. To estimate a similar CAPEX for the two-stage mist-based absorption system, the same flue gas flow rate and absorber unit housing diameter as in the previous case were used. By taking advantage of the improved absorption dynamics of the mist, the absorber housing unit length can be reduced by a factor of 5, as explained above. Also, it can be installed in a horizontal configuration since it no longer uses gravity-driven flow, thereby reducing the installation cost factor. The cost of the electrostatic mist capture unit is derived from the historical cost and installation factor, scaled for capacity, and adjusted with the CEPCI index. At a CAPEX of $57.3 million, the two-stage mist-based absorption system provides approximately a 2.6-fold reduction in capital costs compared to a conventional packed bed absorber tower. These savings are due to the elimination of the packed bed in addition to the reduced absorber unit housing cost associated with the smaller total dimensions. [Table 1] Table 1: CO2 Absorption CAPEX Estimates for a 400 MW Gas-fired Coal Plant for a Conventional Vertical Packed Bed Architecture Compared to a Two-Stage Mist-Based Absorption System

[0121] In conclusion, a simple and efficient proof-of-concept absorber system for capturing CO2 using mist-scale droplets has been demonstrated. Using a scaled-down experimental setup that matches the gas flux and L / G ratio of other industrial and experimental post-combustion carbon capture systems, CO2 capture efficiencies of up to 95% were achieved using potassium hydroxide as the absorbent. The ability of the electrostatic droplet capture unit to collect >95% of the entrained droplets at electric field strengths consistent with industrial systems was also demonstrated. In addition, a chemical engineering plant economic model was used to estimate that a scaled-up installation of a two-stage mist-based absorption system could reduce CO2 absorber costs by a factor of 2.6. Example 2

[0122] The following example describes a second embodiment of a two-stage mist-based absorption system for removing gaseous species from a gas stream.

[0123] In conventional absorption systems, one or more absorber towers allow for interaction between the CO2-containing flue gas and an absorbent liquid (typically 30% wt. MEA in water). At the exhaust of the absorber tower, over 90% of the CO2 is removed from the flue gas and the CO2-rich amine solution is delivered to a stripper column to separate the CO2 from the amine, as shown in FIG. 13. As described herein, the need for such absorber towers can be eliminated, thereby reducing much of the capital expenditure and associated operating costs, by introducing absorbent liquid in the form of fine mist droplets that are subsequently captured via electrostatic space charge injection.

[0124] In the two-stage mist-based absorption system described herein, the absorbent liquid is designed to absorb the flue gas into the SO x The amine solution is introduced as a mist into the flue gas upstream of where it exits the scrubber. This maximizes the interfacial area of ​​interaction between the amine solution and the flue gas due to the increased surface area for the same volumetric flow rate of liquid resulting from the tiny mist droplets. Compared to conventional packed bed absorbers or spray towers, the mist droplets dramatically increase the total surface area for CO2 absorption, as shown in Figure 15, which makes the reaction kinetics much faster and eliminates the need for such towers.

[0125] Efficiently capturing CO2 is difficult because the fine mist droplets can easily be entrained with the flue gas flow and escape at the flue gas outlet. Conventional mist collector systems are inefficient, and increasing the mist collection efficiency by tightly packed mechanical components also significantly increases the back pressure in the flue gas stream. The two-stage mist-based system utilizes space charge injection for efficient collection of mist. A relatively smaller electrostatically driven space charge injection unit for mist collection replaces the absorber tower in conventional systems, as shown in FIG. 14.

[0126] The interaction parameters governing the rate of CO2 absorption are dictated by the interfacial area and the time of interaction between the flue gas and the absorbent liquid. In the case of an absorber tower, for a given volumetric flow rate of liquid, the area is increased by using a packed bed. However, the film thickness of the liquid flowing over the packed bed is about several hundred micrometers. Therefore, to maximize the interaction parameters, the interaction time is increased by increasing the height of the tower. In contrast, a two-stage mist-based system utilizes liquid droplets in the form of mist with a size of about 10 micrometers. These liquids are so minute that they can be entrained in the flue gas. By reducing the size of the droplets, the surface area of ​​interaction is increased dramatically (for a given volume of liquid, FIG. 15), and thereby the time required for CO2 absorption is reduced. Therefore, instead of using a long and slender absorber tower, a two-stage mist-based system utilizes a horizontal pipe for flue gas management to entrain the mist and cause CO2 absorption.

[0127] Mist Production: Dense mist was generated through a variety of techniques. However, one of the most efficient ways to generate dense mist was to utilize a mechanical ultrasonic generator. The generated mist was entrained in the gas flow due to the small size of the mist droplets, as shown in Figures 16 and 17.

[0128] CO2 Absorption: The generated mist was entrained with a CO2 / air mixture. The mist droplets rapidly reacted with the surrounding gases, thereby capturing the CO2, as depicted in Figure 18.

[0129] DI water was used to test the efficacy of the system. The DI water was rapidly saturated with CO2. After collecting the mist droplets, the pH of the CO2 saturated DI water was measured and compared to the pH of neutral DI water, as shown in Figure 19. The pH was observed to drop due to the formation of carbonic acid resulting from the dissolution of CO2 in the water.

[0130] Mist capture: Mist droplets that reacted with CO2 in the flue gas were captured via a technique called space charge injection. Briefly, space charge can be created using a sharp emitter, such as an electrode that provides an electric field concentration, with another electrode acting as a droplet collector. By applying a voltage between the emitter and the collector electrode, the air surrounding the emitter is ionized, creating space charge injection. The charged molecules then find the mist droplets flowing through the space between the electrodes, imparting a net charge to the droplets. The charged droplets experience an electrostatic force in the direction of the electric field, as shown in Figure 20, and are therefore collected on the collector electrode.

[0131] In one embodiment of mist capture, a mesh-like collector electrode was used. FIG. 21A shows entrained mist droplets escaping with the gas flow when the electric field was off. Entrainment is one of the most common solution loss modes in conventional CO2 capture systems. FIG. 21B shows the capture of mist on the collection mesh electrode when the electric field was on. Most of the mist droplets did not disappear with the gas flow. Instead, the droplets were charged by the injected space charge, and the charged droplets were collected on the mesh.

[0132] Another embodiment of the mist capture system was designed using a thin wire electrode as an emitter to charge the mist droplets and an annular cylindrical electrode as a collector. Efficient capture of the mist was demonstrated as shown in Figures 22A-22B.

[0133] Advantages and improvements over conventional methods, devices, and materials: The two-stage mist-based system described herein allows for the complete elimination of the CO2 absorber tower, which contributes up to 55% of the CAPEX (FIG. 12) of a CO2 capture unit. In many conventional absorption systems, operating costs (OPEX) are closely related to CAPEX, as the majority of OPEX comes from the absorber tower installation, which needs to be maintained. The two-stage mist-based system reduces material costs and associated maintenance costs.

[0134] Increasing the interaction parameters of CO2 means that the reliance on amines (considered highly toxic) can also be reduced. However, the reaction rate of amines with CO2 is relatively higher than other green chemicals. By increasing the CO2 interaction area with the absorption solution, the two-stage mist-based system paves the way for the efficient use of cheaper and more green chemicals for CO2 capture, such as 2-amino-2-methyl-1-propanol (AMP) or KOH.

[0135] Finally, by reducing carbon capture costs, the dependence of carbon capture on the price of fossil fuels is also reduced. Because enhanced oil recovery is one of the uses of captured and concentrated carbon, if the price of recovered oil falls, capturing CO2 becomes economically unfeasible. Thus, currently, CO2 capture systems are much more dependent on fossil fuel prices.

[0136] Commercial Applications: The market size for CO2 capture and storage systems is approximately US$2 billion. However, due to the prohibitive costs of installation and maintenance, there are only about 28 large-scale commercial CO2 capture facilities in the world. By eliminating the absorber tower, a two-stage mist-based system can reduce the capital expenditure of a CO2 capture system by 30-55% and reduce operational expenditures proportionately. Reducing the cost of CO2 capture would exponentially increase the market size, since more power plants would be willing to install CO2 capture units if CO2 could be obtained cheaply to produce other value-added products.

[0137] Although several embodiments of the invention have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for performing the functions and / or obtaining one or more of the results and / or advantages described herein, and each such variation and / or modification is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the specific application or applications for which the teachings of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Thus, it is to be understood that the foregoing embodiments are presented by way of example only, and that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the scope of the present invention, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0138] All definitions, as defined and used herein, should be understood to take precedence over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms. The indefinite articles "a" and "an," as used herein in the specification and the claims, unless clearly indicated to the contrary, should be understood to mean "at least one."

[0139] The phrase "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctive in some cases and disjunctive in other cases. Multiple elements listed with "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so conjoined. Other elements other than the elements specifically identified by the "and / or" clause may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B," when used in conjunction with open-ended language such as "comprising," may refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), in yet another embodiment to both A and B (optionally including other elements), etc.

[0140] As used herein in the specification and claims, "or" shall be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one of several elements or a list of elements, optionally including additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," shall refer to the inclusion of exactly one element of several elements or a list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e., "one or the other, but not both") when preceded by a term of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0141] As used herein in the specification and claims, the phrase "at least one" in reference to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently, "at least one of A and / or B") can refer in one embodiment to at least one A with no B present (optionally including elements other than B), optionally including two or more As; in another embodiment to at least one B with no A present (optionally including elements other than A), optionally including two or more Bs; in yet another embodiment to at least one A with optionally two or more As, and at least one B with optionally two or more Bs (optionally including other elements); etc.

[0142] It is also to be understood that, unless expressly stated to the contrary, in any method claimed herein that includes two or more steps or actions, the order of the method steps or actions is not necessarily limited to the order in which the method steps or actions are recited.

[0143] In the claims and the above specification, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like, are intended to be open-ended, i.e., to mean "including but not limited to." Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

1. 1. A system for removing gaseous species from a gas stream, the system comprising: a gas flow path having an inlet for receiving the gas stream and an outlet for releasing the gas stream, the gas stream containing fewer of the gaseous species at the outlet than contained in the gas stream at the inlet; a gaseous species absorption zone along the gas flow path; a source of liquid mist configured to introduce the liquid mist into the gaseous species absorption zone, the gaseous species absorption zone configured to expose the liquid mist to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the liquid mist; an electrostatic separation zone along the gas flow path, fluidly connected to the gaseous species absorption zone; Equipped with The system, wherein the electrostatic separation zone is configured to electrostatically separate at least a portion of the liquid mist from the gas stream.

2. The system of claim 1 , wherein the liquid mist comprises a plurality of droplets, each droplet of the plurality of droplets having a maximum characteristic dimension of 70 micrometers or less.

3. The system of any one of claims 1 to 2, wherein the liquid mist comprises a plurality of droplets, each droplet of the plurality of droplets having a maximum characteristic dimension of 20 micrometers or less.

4. The system of any one of claims 1 to 2, wherein the electrostatic separation zone is configured to subject the gas stream comprising the liquid mist to a corona discharge.

5. The system of any one of claims 1 to 2, wherein the electrostatic separation zone comprises a surface configured to absorb the liquid mist.

6. 1. A system for removing gaseous species from a gas stream, the system comprising: a gas flow path having an inlet for receiving the gas stream and an outlet for releasing the gas stream, the gas stream containing fewer of the gaseous species at the outlet than contained in the gas stream at the inlet; a gaseous species absorption zone along the gas flow path; a source of liquid mist configured to introduce the liquid mist into the gaseous species absorption zone, the gaseous species absorption zone configured to expose the liquid mist to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the liquid mist, the liquid mist comprising a plurality of droplets, each droplet of the plurality of droplets having a maximum characteristic dimension of 70 micrometers or less; a separation zone along the gas flow path, fluidly connected to the gas species absorption zone; Equipped with The separation zone is configured to separate at least a portion of the liquid mist from the gas stream.

7. The system of claim 6 , wherein each droplet of the plurality of droplets has a maximum characteristic dimension of 20 micrometers or less.

8. The system of any one of claims 6 to 7, wherein the separation zone is an electrostatic separation zone configured to electrostatically separate at least a portion of the liquid mist from the gas stream.

9. The system of claim 8 , wherein the electrostatic separation zone is configured to expose the gas stream comprising the liquid mist to a corona discharge.

10. The system of any one of claims 6 to 7, wherein the separation zone comprises a surface configured to absorb the liquid mist.

11. 1. A system for removing gaseous species from a gas stream, the system comprising: a gas flow path having an inlet for receiving the gas stream and an outlet for releasing the gas stream, the gas stream containing fewer of the gaseous species at the outlet than contained in the gas stream at the inlet; a gaseous species absorption zone along the gas flow path; an absorbent associated with said gaseous species absorption zone; Equipped with the gaseous species absorption zone is configured to expose the absorbent to the gas stream under conditions promoting transfer of at least a portion of the gaseous species from the gas stream to the absorbent; wherein the interfacial area between the absorbent and the gas stream is at least 10 times greater than the interfacial area between a comparison absorbent and a comparison gas stream in an absorption tower comprising an otherwise essentially identical packed bed reactor.

12. 12. The system of claim 11, wherein the interfacial area between the absorbent and the gas stream is at least 400 times greater than the interfacial area between the comparison absorbent and the comparison gas stream in an absorption tower comprising an otherwise essentially identical packed bed reactor.

13. 13. The system of claim 11, further comprising a separation zone along the gas flow path fluidly connected to the gaseous species absorption zone, the separation zone configured to separate at least a portion of the sorbent from the gas stream.

14. The system of any one of claims 11 to 12, wherein the absorbent is in the form of a liquid mist.

15. 15. The system of claim 14, wherein the liquid mist comprises a plurality of droplets, each droplet having a maximum characteristic dimension of 70 micrometers or less.

16. 13. The system of claim 1, 2, 6, 7, 11, or 12, wherein the gas stream is a combustion exhaust stream.

17. 13. The system of claim 1, 2, 6, 7, 11, or 12, wherein the gaseous species is a gaseous exhaust species.

18. 13. The system of claim 1, 2, 6, 7, 11, or 12, wherein the gaseous species is a greenhouse gas.

19. The gaseous species is CO ２ 13. The system of claim 1, 2, 6, 7, 11, or 12, wherein:

20. 13. The system of claim 1, wherein the gas stream contains at least 10% less of the gaseous species at the outlet than is contained in the gas stream at the inlet.

21. 13. The system of claim 1, wherein the gas stream contains up to 80% less of the gaseous species at the outlet than contained in the gas stream at the inlet.

22. 13. The system of claim 1, wherein an overall gas flow pressure drop occurs between the inlet and the outlet of the gas flow path, and wherein the gas flow pressure drop along the gas flow path upstream of the gaseous species absorption zone is less than 50% of the overall gas flow pressure drop.

23. 1. A method for removing gaseous species from a gas stream, the method comprising: exposing the gas stream containing the gaseous species to a liquid mist, the liquid mist comprising a reactant configured to react with the gaseous species; carrying out a reaction between the reactant and the gaseous species in a gaseous species absorption zone, the reaction comprising absorbing CO 2 from the gas stream with the liquid mist; ２ and separating at least a portion of the liquid mist from the gas stream in a separation zone fluidly connected to the gaseous absorption zone; A method comprising:

24. 24. The method of claim 23, wherein the separation zone is an electrostatic separation zone.

25. 1. A method for removing gaseous species from a gas stream, the method comprising: exposing the gas stream containing the gaseous species to a liquid mist, the liquid mist comprising a reactant configured to react with the gaseous species; carrying out a reaction between said reactant and said gaseous species in a gaseous species absorption zone; Including, the reaction results in absorption of at least 50% of the gaseous species from the gas stream by the liquid mist; wherein the ratio of the molar amount of said gaseous species absorbed per hour to the volume of said gaseous species absorption zone is at least five times greater than the comparable ratio in an absorption tower comprising an otherwise essentially identical packed bed reactor.

26. 26. The method of claim 25, wherein the gaseous species absorption zone is a non-packed bed reactor.

27. 27. The method of any one of claims 25 to 26, wherein the reactants are a mixture comprising less than 50 wt.% of an amine-containing species, based on the total weight of the mixture.

28. 27. The method of any one of claims 25 to 26, wherein the ratio of the molar amount of the gaseous species absorbed per hour to the volume of the gaseous species absorption zone is at least 200 times greater than the comparable ratio in an absorber tower comprising an otherwise essentially identical packed bed reactor.

29. 27. The method of any one of claims 25 to 26, further comprising separating at least a portion of the liquid mist from the gas stream in a separation zone fluidly connected to the gaseous absorption zone.

30. 30. The method of claim 29, wherein the separation zone is an electrostatic separation zone.

31. A method according to any one of claims 23 to 26, wherein the gas stream is a combustion exhaust stream.

32. A method according to any one of claims 23 to 26, wherein the gaseous species are gaseous exhaust species.

33. The method of any one of claims 23 to 26, wherein the gaseous species is a greenhouse gas.

34. The gaseous species is CO ２ The method according to any one of claims 23 to 26, wherein

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