Capturing carbon dioxide

Abstract

A direct air capture (DAC) system for capturing carbon dioxide (CO2) from a dilute gas source includes a gas-liquid contactor subsystem and a wash water regeneration subsystem. The gas-liquid contactor subsystem includes a capture section, a wash section, and at least one fan to produce a CO2-rich capture solution in the capture section and a used wash water stream in the wash section. The wash water regeneration subsystem is in fluid communication with the at least one gas-liquid contactor subsystem. The wash water regeneration subsystem receives at least a portion of the used wash water stream, regenerates the wash water stream, and flows the regenerated wash water stream to the wash section. The DAC system can include a capture solution regeneration subsystem receiving at least a portion of the CO2-rich capture solution, regenerate the CO2-rich capture solution, and flow the regenerated CO2 capture solution to the capture section.

Description

Attorney Docket No.: 30285-0051WO1 CAPTURING CARBON DIOXIDE TECHNICAL FIELD

[0001] This disclosure describes systems and methods for capturing carbon dioxide (CO2). BACKGROUND

[0002] Capturing carbon dioxide (CO2) from the atmosphere is one approach to mitigating greenhouse gas emissions and slowing climate change. However, many technologies designed for CO2capture from point sources, such as flue gas of industrial facilities, are generally ineffective in capturing CO2 from the atmosphere due to the significantly lower CO2 concentrations and large volumes of air required to process CO2 from the atmosphere. In recent years, progress has been made in finding technologies better suited to capture CO2directly from the atmosphere. Some of these direct air capture (DAC) facilities use a solid sorbent where an active agent is attached to a substrate. These DAC facilities typically employ a cyclic adsorption-desorption process where, after the solid sorbent is saturated with CO2, it releases the CO2using a humidity or thermal swing and is regenerated. Other solid sorbent DAC systems may employ flowable particles or moving blocks that may require notable operational costs in piping, fluidization energy, footprint, and number of reactors amongst other factors.

[0003] Other DAC facilities use a liquid sorbent (sometimes referred to as a solvent) to capture CO2 from the atmosphere. An example of such a gas-liquid contact system would be one where a fan is used to draw air across a high surface area packing that is wetted with a solution comprising the liquid sorbent. CO2in the air reacts with the liquid sorbent. The rich solution is further processed downstream to regenerate a lean solution and to release a concentrated CO2 stream. SUMMARY

[0004] In an example implementation, a Direct Air Capture (DAC) system for capturing carbon dioxide (CO2) from a dilute gas source, the system including: at least one gas-liquid contactor subsystem including: a capture section configured to receive the dilute gas source and to contact the CO2in the dilute gas source with a CO2capture solution to form a CO2-rich capture solution and a CO2-lean gas stream, the CO2-lean gas stream including at least one of aerosolizedAttorney Docket No.: 30285-0051WO1 particles of the CO2capture solution or volatilized components of the CO2capture solution; a wash section positioned adjacent the capture section and configured to contact the CO2-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CO2-lean gas stream flowable from the wash section and a used wash water stream; at least one fan configured to flow 1) the dilute gas source through the capture section, 2) the CO2-lean gas stream through the wash section, and 3) the washed CO2-lean gas stream from the wash section; and a wash water regeneration subsystem in fluid communication with at least one gas-liquid contactor subsystem, the wash water regeneration subsystem configured to: receive a liquid stream including at least the used wash water stream; regenerate the wash water stream; and flow the regenerated wash water stream to the wash section.

[0005] In an aspect combinable with the example implementation, the at least one gas- liquid contactor subsystem includes a liquid collection device in fluid communication with at least one of the wash section and the capture section to produce the liquid stream.

[0006] In another aspect combinable with one, some, or all of the previous aspects, the liquid collection device is in fluid communication with the wash section and the capture section to receive the CO2-rich capture solution from the capture section and to receive the used wash water stream from the wash section.

[0007] In another aspect combinable with one, some, or all of the previous aspects, the liquid collection device includes at least one bottom basin.

[0008] In another aspect combinable with one, some, or all of the previous aspects, the at least one bottom basin includes a common bottom basin for the capture section and the wash section; the capture section and the wash section are each positioned above the common bottom basin relative to gravity; the common bottom basin is configured to hold the CO2-rich capture solution and the used wash water; and the liquid stream includes both the used wash water stream and the CO2-rich capture solution.

[0009] In another aspect combinable with one, some, or all of the previous aspects, the capture section is in fluid communication with the common bottom basin, and the common bottom basin is configured to flow at least some of the liquid stream to the capture section.

[0010] In another aspect combinable with one, some, or all of the previous aspects, the wash water regeneration subsystem includes: a filtration unit configured to receive the liquid stream from the liquid collection device and to form a retentate stream including solid particlesAttorney Docket No.: 30285-0051WO1 and a permeate stream; a reverse osmosis (RO) unit or osmosis assisted water recovery unit configured to receive the permeate stream from the filtration unit and form an RO retentate stream including the CO2-rich capture solution and an RO permeate stream including the wash water stream; and a pump configured to flow the liquid stream from the liquid collection device to the filtration unit and to flow the RO permeate stream to the wash section.

[0011] In another aspect combinable with one, some, or all of the previous aspects, the liquid collection device is in fluid communication with the RO unit, and the pump is configured to flow the RO retentate stream including the CO2-rich capture solution to the liquid collection device.

[0012] In another aspect combinable with one, some, or all of the previous aspects, the RO unit is in fluid communication with the capture section, and the pump is configured to flow the RO retentate stream including the CO2-rich capture solution to the capture section.

[0013] In another aspect combinable with one, some, or all of the previous aspects, the at least one bottom basin includes a capture section bottom basin and a wash section bottom basin; the capture section is positioned above the capture section bottom basin relative to gravity; the capture section bottom basin is configured to hold the CO2-rich capture solution; the wash section is positioned above the wash section bottom basin relative to gravity; the wash section bottom basin is configured to hold the used wash water stream; and the wash water regeneration subsystem is in fluid communication with the wash section bottom basin and is configured to receive the liquid stream including the used wash water stream.

[0014] In another aspect combinable with one, some, or all of the previous aspects, the capture section is in fluid communication with the wash section bottom basin, and the wash water regeneration subsystem is configured to flow at least some of the used wash water stream to the capture section.

[0015] In another aspect combinable with one, some, or all of the previous aspects, the capture section is in fluid communication with the capture section bottom basin, and a pump is configured to flow at least some of the CO2-rich capture solution from the capture section bottom basin to the capture section.

[0016] In another aspect combinable with one, some, or all of the previous aspects, the wash water regeneration subsystem includes: a filtration unit configured to receive the liquid stream from the wash section bottom basin and to form a retentate stream including solid particlesAttorney Docket No.: 30285-0051WO1 and a permeate stream; a reverse osmosis (RO) unit configured to receive the permeate stream from the filtration unit and form an RO retentate stream including the CO2-rich capture solution and an RO permeate stream including the wash water stream; and a pump configured to flow the liquid stream from the wash section bottom basin to the filtration unit and to flow the RO permeate stream to the wash section.

[0017] In another aspect combinable with one, some, or all of the previous aspects, the capture section bottom basin is in fluid communication with the RO unit and configured to receive the RO retentate stream including the CO2-rich capture solution.

[0018] In another aspect combinable with one, some, or all of the previous aspects, the RO unit is in fluid communication with the capture section, and the pump is configured to flow the RO retentate stream including the CO2-rich capture solution to the capture section.

[0019] In another aspect combinable with one, some, or all of the previous aspects, the CO2 capture solution includes an amine, and the solid particles include at least one of carbamic acid solids or carbon containing solids.

[0020] Another aspect combinable with one, some, or all of the previous aspects further includes a capture solution regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem for regenerating the CO2-rich capture solution, the capture solution regeneration subsystem configured to: receive the CO2-rich capture solution from the at least one gas-liquid contactor subsystem; separate CO2 from the CO2-rich capture solution to form a regenerated CO2capture solution and a CO2product stream; and flow the regenerated CO2capture solution to the at least one gas-liquid contactor subsystem.

[0021] Another aspect combinable with one, some, or all of the previous aspects further includes: a solids sensor configured to detect an amount of solid particles in the CO2-rich capture solution; and a capture solution control valve upstream of the capture section, wherein the capture solution control valve is configured to open to allow at least some of the CO2-rich capture solution to flow to the capture solution regeneration subsystem in response to the solids sensor detecting the amount of solid particles is above a threshold.

[0022] In another aspect combinable with one, some, or all of the previous aspects, the capture solution regeneration subsystem includes an electrochemical system for regenerating the CO2-rich capture solution, the electrochemical system including: a carbonate separation subsystem configured to receive the CO2-rich capture solution and separate at least a portion of carbonateAttorney Docket No.: 30285-0051WO1 from the CO2-rich capture solution; and an electrochemical cell fluidly coupled to the carbonate separation subsystem, the electrochemical cell configured to: receive a feed solution and a water stream; and yield at least two product streams including a first product stream that includes the regenerated CO2capture solution.

[0023] In another aspect combinable with one, some, or all of the previous aspects, the capture solution regeneration subsystem includes: a slaker configured to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH)2); and a reactor configured to react, via a causticization reaction, the Ca(OH)2 slurry and the CO2-rich capture solution to produce hydroxide and calcium carbonate (CaCO3) solids.

[0024] In another aspect combinable with one, some, or all of the previous aspects, the at least one gas-liquid contactor subsystem is a dual-cell, cross flow gas-liquid contactor.

[0025] In another aspect combinable with one, some, or all of the previous aspects: the capture section includes a first capture section and a second capture section, each of the first capture section and the second capture section including: a capture section inlet; and one or more sections of capture section packing positioned lower than the at least one fan relative to gravity, the one or more sections of capture section packing each having an air travel depth defined between the respective capture section packing inlet and a respective capture section packing outlet, the one or more sections of capture section packing configured to be wetted by the CO2 capture solution; the wash section includes a first wash section and a second wash section, the first wash section disposed downstream of the first capture section and configured to receive the CO2-lean gas stream from the first capture section, and the second wash section disposed downstream of the second capture section and configured to receive the CO2-lean gas stream from the second capture section, each of the first wash section and the section wash section including: one or more sections of wash section packing positioned lower than the at least one fan relative to gravity, the one or more sections of wash section packing each having an air travel depth defined between a respective wash section packing inlet and a respective wash section packing outlet, the one or more sections of wash section packing configured to be wetted by the wash water stream; and the at least one gas- liquid contactor subsystem further includes a plenum positioned between the respective wash section packing outlet of each of the first wash section and the second wash section and beneath the at least one fan.Attorney Docket No.: 30285-0051WO1

[0026] In another aspect combinable with one, some, or all of the previous aspects, the at least one gas-liquid contactor subsystem further includes a capture section drift eliminator located downstream of the capture section and upstream of the wash section, the capture section drift eliminator configured to reduce at least the aerosolized particles from the CO2-lean gas stream.

[0027] In another aspect combinable with one, some, or all of the previous aspects, the at least one gas-liquid contactor subsystem further includes a wash section drift eliminator located downstream of the wash section, the wash section drift eliminator configured to reduce aerosolized particles of the used wash water from the washed CO2-lean gas stream.

[0028] Another aspect combinable with one, some, or all of the previous aspects further includes: a liquid level sensor configured to detect a liquid level in the at least one bottom basin; and a make-up water control valve in fluid communication with the at least one bottom basin, the make-up water control valve configured to open to enable water to flow into the at least one bottom basin in response to the liquid level sensor detecting the liquid level is below a threshold.

[0029] Another aspect combinable with one, some, or all of the previous aspects further includes: a concentration sensor upstream of the capture section configured to detect a concentration of a CO2 capture species in the CO2 capture solution flowing to the capture section; and a make-up CO2capture solution control valve in fluid communication with the capture section and communicatively coupled to the concentration sensor, the make-up CO2 capture solution control valve configured to open to enable additional CO2 capture solution to flow into the capture section in response the concentration sensor detecting the concentration of the CO2capture species in the CO2capture solution is below a threshold.

[0030] Another aspect combinable with one, some, or all of the previous aspects further includes: an emissions sensor positioned upstream of the wash section and downstream of the capture section, the emissions sensor configured to detect a concentration of a CO2capture species in the CO2-lean gas stream; and a make-up wash water control valve in fluid communication with the wash section and communicatively coupled to the emissions sensor, the make-up wash water control valve configured to open to enable additional wash water for flow to the wash section in response to the emissions sensor detecting the concentration of the CO2 capture species in the CO2- lean gas stream exceeds a threshold.Attorney Docket No.: 30285-0051WO1

[0031] In another aspect combinable with one, some, or all of the previous aspects, at least a portion of the CO2-rich capture solution in the liquid collection device is recirculated to the capture section.

[0032] In another aspect combinable with one, some, or all of the previous aspects: the CO2 capture solution includes an amine; the capture section is configured to contact the CO2 in the dilute gas source with the amine to form the CO2-lean gas stream containing the volatilized components of the CO2capture solution; and the wash section is configured to remove the volatilized components of the CO2 capture solution from the CO2-lean gas stream.

[0033] In another aspect combinable with one, some, or all of the previous aspects: the CO2capture solution includes a hydroxide; the capture section is configured to contact the CO2in the dilute gas source with the hydroxide to form the CO2-lean gas stream containing the aerosolized particles of the CO2 capture solution; and the wash section is configured to remove the aerosolized particles of the CO2 capture solution from the CO2-lean gas stream.

[0034] In another aspect combinable with one, some, or all of the previous aspects, the wash section includes: a wash water distributor configured to receive the wash water stream from the wash water regeneration subsystem; and a wash section packing disposed beneath the wash water distributor and configured to contact the CO2-lean gas stream with the wash water stream.

[0035] In another aspect combinable with one, some, or all of the previous aspects: the capture section includes a capture section housing defining a capture section interior sealed from an exterior of the capture section, the capture section housing defining a capture section liquid inlet to receive the CO2capture solution in the interior, a capture section gas inlet to receive the dilute gas source in the interior, a capture section gas outlet to flow the CO2-lean gas stream from the interior, and a capture section liquid outlet to flow the CO2-rich capture solution from the interior; and the wash section is positioned spaced apart from the capture section and downstream therefrom, the wash section in fluid communication with the capture section gas outlet to receive the CO2-lean gas stream therefrom.

[0036] In another aspect combinable with one, some, or all of the previous aspects, a filtration unit in fluid communication with the capture section liquid outlet to receive the CO2-rich capture solution, the filtration unit configured to form a retentate stream including a slurry, and a permeate stream flowable to the capture section liquid inlet.Attorney Docket No.: 30285-0051WO1

[0037] Another aspect combinable with one, some, or all of the previous aspects further includes: a capture solution reverse osmosis (RO) unit in fluid communication with the filtration unit to receive at least some of the permeate stream and form a capture solution retentate stream, and a wash water permeate stream including water; and at least one pump configured to flow the capture solution retentate stream to the capture section liquid inlet, and to flow the wash water permeate stream to the wash section.

[0038] In another aspect combinable with one, some, or all of the previous aspects, the CO2 capture solution includes an amine, and the slurry includes at least one of carbamic acid solids or carbon-containing solids.

[0039] Another aspect combinable with one, some, or all of the previous aspects further includes a capture solution regeneration subsystem fluidly coupled to the filtration unit for regenerating the CO2-rich capture solution, the capture solution regeneration subsystem configured to: receive the retentate stream from the filtration unit; separate CO2 from the slurry to form a regenerated CO2capture solution and a CO2product stream; and flow the regenerated CO2capture solution to the at least one gas-liquid contactor subsystem.

[0040] In another aspect combinable with one, some, or all of the previous aspects, the capture solution regeneration subsystem includes a regeneration reactor configured to heat the slurry to form the regenerated CO2 capture solution and the CO2 product stream.

[0041] Another aspect combinable with one, some, or all of the previous aspects further includes a reclamation unit in fluid communication with at least one of the gas-liquid contactor subsystem and the capture solution regeneration subsystem, the reclamation unit being configured to receive at least a portion of at least one of the permeate stream and the regenerated CO2 capture solution for reclamation of amine degradation products present in the permeate stream and / or the regenerated CO2capture solution.

[0042] Another aspect combinable with one, some, or all of the previous aspects further includes a degassing unit being located upstream of the capture solution regeneration subsystem, the degassing unit being configured to receive at least a portion of the CO2-rich capture solution for removing oxygen therefrom.

[0043] In another aspect combinable with one, some, or all of the previous aspects, the wash water regeneration subsystem includes: a reverse osmosis (RO) unit in fluid communication with the wash section to receive the used wash water stream and form an RO retentate stream andAttorney Docket No.: 30285-0051WO1 an RO permeate stream including the wash water stream; and at least one pump configured to flow the RO retentate stream to the capture section liquid inlet, and to flow the RO permeate stream to the wash section.

[0044] In another aspect combinable with one, some, or all of the previous aspects, the at least one gas-liquid contactor subsystem includes a housing defining an interior, the capture section positioned adjacent the wash section in the interior of the housing.

[0045] In an example implementation, a method for capturing CO2from a dilute gas source, the method including: contacting CO2 in the dilute gas source with a CO2 capture solution to form (1) a CO2-rich capture solution and (2) a CO2-lean gas stream including at least one of aerosolized particles of the CO2capture solution or volatilized components of the CO2capture solution; contacting the CO2-lean gas stream with a wash water stream to remove at least some of the at least one of the aerosolized particles or the volatilized components and to form a washed CO2-lean gas stream and a used wash water stream; regenerating the wash water stream from at least the used wash water stream; and flowing the wash water stream for use in the contacting the CO2-lean gas stream with the wash water stream.

[0046] In an aspect combinable with the example implementation, the method includes collecting at least one of the CO2-rich capture solution and the used wash water stream in a liquid collection device to produce a liquid stream including at least a portion of the at least one of the CO2-rich capture solution and the used wash water stream.

[0047] In another aspect combinable with one, some, or all of the previous aspects, the liquid stream includes at least some of the CO2-rich capture solution and at least some of the used wash water stream, and wherein regenerating the wash water stream includes: flowing the liquid stream from the liquid collection device, separating solid particles from the liquid stream to form a filtered stream; and flowing the filtered stream to a reverse osmosis (RO) unit to form an RO retentate stream and an RO permeate stream, the RO retentate stream including the CO2-rich capture solution and the RO permeate stream including the wash water stream.

[0048] In another aspect combinable with one, some, or all of the previous aspects, the method further includes: flowing the RO retentate stream to at least one of the liquid collection device or to a capture section for use in the contacting the CO2 in the dilute gas source with the CO2capture solution; and flowing the RO permeate stream to a wash section for use in the contacting the CO2-lean gas stream with the wash water.Attorney Docket No.: 30285-0051WO1

[0049] In another aspect combinable with one, some, or all of the previous aspects, collecting the at least one of the CO2-rich capture solution and the used wash water stream in the liquid collection device includes: collecting the CO2-rich capture solution in a capture section bottom basin of the liquid collection device; and collecting the used wash water stream in a wash section bottom basin of the liquid collection device; and wherein regenerating the wash water stream includes: flowing the used wash water stream from the wash section bottom basin to a filtration unit; separating solid particles from the used wash water stream with the filtration unit to form a filtered stream; and flowing the filtered stream to a reverse osmosis (RO) unit to form an RO retentate stream and an RO permeate stream, the RO retentate stream including the CO2-rich capture solution and the RO permeate stream including the wash water stream.

[0050] Another aspect combinable with one, some, or all of the previous aspects further includes: flowing the RO retentate stream to at least one of the capture section bottom basin or a capture section for use in the contacting the CO2 in the dilute gas source with the CO2 capture solution; and flowing the RO permeate stream to a wash section for use in the contacting the CO2- lean gas stream with the wash water stream.

[0051] Another aspect combinable with one, some, or all of the previous aspects further includes: detecting a liquid level in the liquid collection device; and in response to detecting the liquid level is below a threshold, flowing water to at least one of the liquid collection device or a wash section for use in the contacting the CO2-lean gas stream with the wash water stream.

[0052] Another aspect combinable with one, some, or all of the previous aspects further includes: detecting a concentration of a CO2capture species in the CO2capture solution; and in response to detecting the concentration of the CO2 capture species in the CO2 capture solution is below a threshold, flowing additional CO2 capture solution to a capture section for use in the contacting CO2in the dilute gas source with the CO2capture solution.

[0053] Another aspect combinable with one, some, or all of the previous aspects further includes: detecting a concentration of a CO2 capture species in the CO2-lean gas stream; and in response to detecting the concentration of the CO2capture species in the CO2-lean gas stream exceeds a threshold, flowing additional wash water to a wash section for use in the contacting the CO2-lean gas stream with the wash water stream.

[0054] In another aspect combinable with one, some, or all of the previous aspects, the liquid stream includes at least the CO2-rich capture solution and the method includes flowing theAttorney Docket No.: 30285-0051WO1 liquid stream from the liquid collection device to a capture section for use in the contacting CO2in the dilute gas source with the CO2 capture solution.

[0055] In another aspect combinable with one, some, or all of the previous aspects, contacting the CO2in the dilute gas source with the CO2capture solution includes contacting the CO2 in the dilute gas source with an amine solution.

[0056] Another aspect combinable with one, some, or all of the previous aspects further includes reducing at least the aerosolized particles of the CO2capture solution from the CO2-lean gas stream.

[0057] Another aspect combinable with one, some, or all of the previous aspects further includes reducing aerosolized particles of the used wash water from the washed CO2-lean gas stream.

[0058] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the CO2 capture solution includes contacting CO2 in the dilute gas source with the CO2capture solution in a first reactor to form the CO2-rich capture solution and the CO2-lean gas stream, the method including: flowing the CO2-lean gas stream away from the first reactor to a second reactor to contact the CO2-lean gas stream with the wash water stream.

[0059] In another aspect combinable with one, some, or all of the previous aspects, the method includes filtering the CO2-rich capture solution to form a retentate stream including a CO2- rich slurry, and a permeate stream.

[0060] Another aspect combinable with one, some, or all of the previous aspects further includes: flowing at least some of the permeate stream to a reverse osmosis (RO) unit to form a capture solution retentate stream, and a wash water permeate stream including water; flowing the capture solution retentate stream for use in the contacting CO2in the dilute gas source with the CO2 capture solution; and flowing the wash water permeate stream for use in the contacting the CO2-lean gas stream with the wash water stream.

[0061] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the CO2 capture solution includes contacting CO2 in the dilute gas source with an amine solution, the CO2-rich slurry including at least one of carbon containing solids and carbamic acid solids.Attorney Docket No.: 30285-0051WO1

[0062] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the amine solution includes contacting CO2 in the dilute gas source with 3-(aminomethyl)-3,5,5-trimethylcyclohexylamine (IPDA).

[0063] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the amine solution includes contacting CO2 in the dilute gas source with a diamine with an aminocyclic compound group.

[0064] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the diamine includes contacting CO2 in the dilute gas source with a cyclohexane-1,3-diamine-5 R X, wherein: R is a hydrocarbon chain and X is an amino group, and X functionalizes the cyclohexane or the R hydrocarbon chain.

[0065] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the diamine includes contacting CO2 in the dilute gas source with a cyclohexane-1,3-diamine-5 R, where R is a hydrocarbon chain.

[0066] In another aspect combinable with one, some, or all of the previous aspects, R is butane, pentane, hexane, or cycloalkane.

[0067] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2in the dilute gas source with the CO2capture solution includes contacting CO2in the dilute gas source with a guanidine-based solution, the CO2-rich slurry including carbonate solids.

[0068] In another aspect combinable with one, some, or all of the previous aspects, the guanidine-based solution includes a bis-iminoguanidine.

[0069] In another aspect combinable with one, some, or all of the previous aspects, the bis- imino(guanidine) is 2,5-furan-bis-(iminoguanidine) (FuBIG).

[0070] In another aspect combinable with one, some, or all of the previous aspects, contacting CO2 in the dilute gas source with the CO2 capture solution includes contacting CO2 in the dilute gas source with the CO2 capture solution including an alkali metal sorbent to form the CO2-rich capture solution, the method including: promoting precipitation of solids in suspension in the CO2-rich capture solution with an amine species being present in the CO2-capture solution in addition to the alkali metal sorbent.

[0071] Another aspect combinable with one, some, or all of the previous aspects further includes: separating CO2from the CO2-rich slurry to form a regenerated CO2capture solution andAttorney Docket No.: 30285-0051WO1 a CO2product stream; and flowing the regenerated CO2capture solution for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

[0072] In another aspect combinable with one, some, or all of the previous aspects, separating CO2from the CO2-rich slurry to form the regenerated CO2capture solution includes heating the CO2-rich slurry to form the regenerated CO2 capture solution and the CO2 product stream.

[0073] In another aspect combinable with one, some, or all of the previous aspects, the method includes removing oxygen from at least a portion of the CO2-rich capture solution prior to separating CO2 from the CO2-rich capture solution.

[0074] Another aspect combinable with one, some, or all of the previous aspects further includes flowing at least a portion of at least one of the permeate stream and the regenerated CO2capture solution to a reclamation unit to remove degradation products present in the permeate stream.

[0075] In another aspect combinable with one, some, or all of the previous aspects, regenerating the wash water stream includes: flowing the used wash water stream to a reverse osmosis (RO) unit to form an RO retentate stream, and an RO permeate stream including the wash water stream; flowing the RO retentate stream for use in the contacting CO2in the dilute gas source with the CO2 capture solution; and flowing the RO permeate stream for use in the contacting the CO2-lean gas stream with the wash water stream.

[0076] Another aspect combinable with one, some, or all of the previous aspects further includes: regenerating the CO2-rich capture solution to form the CO2capture solution and a CO2product stream; and flowing the CO2 capture solution for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

[0077] Another aspect combinable with one, some, or all of the previous aspects further includes: detecting an amount of solid particles in the CO2-rich capture solution; and in response detecting the amount of solid particles is above a threshold, flowing at least some of the CO2-rich capture solution to a capture solution regeneration subsystem to regenerate the CO2-rich capture solution.

[0078] In an example implementation, a direct air capture (DAC) system for capturing carbon dioxide (CO2) from atmospheric air, the DAC system including: at least one gas-liquid contactor subsystem including: a capture section configured to receive the atmospheric air andAttorney Docket No.: 30285-0051WO1 contact the CO2in the atmospheric air with a CO2capture solution to form a CO2-rich capture solution and a CO2-lean gas stream, the CO2-lean gas stream including at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; a wash section positioned adjacent the capture section and configured to receive the CO2-lean gas stream from the capture section and contact the CO2-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CO2-lean gas stream flowable from the wash section and a used wash water stream; and at least one fan configured to flow 1) the atmospheric air through the capture section, 2) the CO2-lean gas stream through the wash section, and 3) the washed CO2-lean gas stream from the wash section; a wash water regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem, the wash water regeneration subsystem configured to: receive a liquid stream including at least the used wash water stream; regenerate the wash water stream; and flow the regenerated wash water stream to the wash section; and a capture solution regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem for regenerating the CO2-rich capture solution, the capture solution regeneration subsystem configured to: receive the CO2-rich capture solution; separate CO2 from the CO2-rich capture solution to form a regenerated CO2 capture solution; and flow the regenerated CO2capture solution to the capture section.

[0079] In an example implementation, a gas-liquid contactor subsystem for capturing carbon dioxide (CO2) from a dilute gas source, the gas-liquid contactor subsystem including: a capture section configured to receive the dilute gas source and to contact the CO2in the dilute gas source with a CO2capture solution to form a CO2-rich capture solution and a CO2-lean gas stream, the CO2-lean gas stream including at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; a wash section positioned adjacent the capture section and configured to contact the CO2-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CO2-lean gas stream flowable from the wash section and a used wash water stream; and at least one fan configured to flow 1) the dilute gas source through the capture section, 2) the CO2- lean gas stream through the wash section, and 3) the washed CO2-lean gas stream from the wash section.

[0080] In an aspect combinable with the example implementation, the gas-liquid contactor subsystem includes at least one feature as defined in one, some, or all of the previous aspects.Attorney Docket No.: 30285-0051WO1

[0081]

[0082] The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] FIG. 1A is a simplified process flow diagram of an example Direct Air Capture (DAC) system for capturing carbon dioxide (CO2) from a dilute gas source according to the present disclosure.

[0084] FIG. 1B shows an example gas-liquid contactor subsystem.

[0085] FIG. 1C shows another example gas-liquid contactor subsystem.

[0086] FIG. 1D shows another example gas-liquid contactor subsystem.

[0087] FIG. 1E shows another example gas-liquid contactor subsystem.

[0088] FIG. 2 is a simplified process flow diagram of an example DAC system for capturing CO2 from a dilute gas source including an example gas-liquid contactor subsystem according to the present disclosure.

[0089] FIG. 3 is a simplified process flow diagram of another example DAC system for capturing CO2from a dilute gas source including an example gas-liquid contactor subsystem according to the present disclosure.

[0090] FIG. 4 is a simplified process flow diagram of another example DAC system for capturing CO2from a dilute gas source including an example gas-liquid contactor subsystem according to the present disclosure.

[0091] FIG. 5A is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0092] FIG. 5B is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.Attorney Docket No.: 30285-0051WO1

[0093] FIG.6 is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0094] FIG.7 is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0095] FIG.8 is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0096] FIG.9 is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0097] FIG. 10 is a simplified process flow diagram of another example DAC system of the present disclosure including an example capture solution regeneration subsystem of the present disclosure.

[0098] FIG.11A is a side elevational view of an example contactor wall of a DAC system of the present disclosure.

[0099] FIG.11B is a top-down view of a DAC system of the present disclosure comprising multiple contactor walls.

[0100] FIG. 12 is a block flow diagram of a method for capturing CO2from a dilute gas source according to the present disclosure.

[0101] FIG. 13 is a schematic block flow diagram of a control system (or controller) for units, components and subsystems according to the present disclosure. DETAILED DESCRIPTION

[0102] FIG.1A is a schematic illustration of an example Direct Air Capture (DAC) system 100 for capturing carbon dioxide (CO2) from a dilute gas source according to an aspect of the present disclosure. In the configuration illustrated in FIG. 1A, a gas-liquid contactor subsystem 101 is purposed as a dual-cell cross flow gas-liquid contactor. In the dual-cell configuration of FIG. 1A, the gas-liquid contactor subsystem 101 includes capture sections 102A, 102B for capturing CO2 from a dilute gas source which includes the atmosphere (e.g., ambient orAttorney Docket No.: 30285-0051WO1 atmospheric air) or another fluid source that contains dilute concentrations of CO2. Concentrations of CO2 in the dilute gas source are dilute, in that they are presently in the range of 400-420 parts per million (“ppm”) or approximately 0.04-0.042% v / v. Such dilute concentrations of CO2 can vary depending on anthropogenic emissions of CO2, and are typically less than 1% v / v. These dilute concentrations of CO2 in the atmosphere are at least one order of magnitude lower than the concentration of CO2 in point-source emissions, such as flue gases, where point-source emissions can have concentrations of CO2ranging from 1.5-15% v / v, or from 5-15% v / v, or greater than 15% v / v, depending on the source of emissions.

[0103] For example, in the configuration illustrated in FIG.1A, the capture sections 102A, 102B are operated to capture the dilute CO2present in ambient air by ingesting the ambient air as a flow of CO2-laden air 104, and by treating the CO2-laden air 104 so as to transfer CO2present therein to a CO2 capture solution 106, which includes at least one CO2 sorbent (also referred to as at least one CO2 capture species), via absorption. Some or all of the CO2 in the CO2-laden air 104 is removed, and the treated CO2-laden air 104 is then discharged by the capture sections 102A, 102B as a CO2-lean gas stream 105 (or, CO2-low air). In operating to treat atmospheric air in this manner, the gas-liquid contactor subsystem 101 including the capture sections 102A, 102B can sometimes be referred to herein as an “air contactor” or “AC” because it facilitates absorption of CO2 from the atmospheric air into the CO2 capture solution 106. In contrast to water cooling towers which function primarily to transfer heat between water and atmospheric air, the capture sections 102A, 102B functions primarily to achieve mass transfer of CO2from the atmospheric air to the CO2capture solution 106. In operating in this manner, the gas-liquid contactor subsystem 101 can be used as part of a DAC system 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 being described in greater detail below in reference to FIGS. 2 to 10.

[0104] In example implementations, and referring to FIG. 1A, the CO2capture solution 106 is a caustic solution. In example implementations, the CO2 capture solution 106 has a pH of 10 or higher. In example implementations, the CO2 capture solution 106 has a pH of approximately 14. Non-limiting examples of the CO2capture solution 106 include aqueous solutions of an alkali metal sorbent, such as an alkali metal hydroxide (e.g., including KOH, NaOH, LiOH or a combination thereof as the at least one CO2 capture species), aqueous amine solutions, aqueous amino acid salt solutions, non-aqueous amine solutions, non-aqueous organic liquids / solutions (e.g., dimethyl sulfoxide or DMSO), aqueous guanidinium solutions, aqueous aminosiliconeAttorney Docket No.: 30285-0051WO1 solutions, aqueous amidine solutions, non-aqueous phosphazene solutions, aqueous amines slurries with MOF, aqueous slurries with amine polymers, aqueous carbonate and / or bicarbonate solutions, aqueous phenoxide / phenoxide salt solutions, ionic liquids, non-aqueous solvents, or any combinations thereof. In some implementations, the solvent of the CO2capture solution 106 has a higher vapour pressure than that of the CO2 capture species to facilitate regeneration of the CO2 capture solution 106. In example implementations, the CO2 capture solution 106 can include a guanidine-based capture species as the at least one CO2capture species, for example an aminoguanidine or an iminoguanidine. Non-limiting examples of the guanidine-based capture species of the CO2-capture solution 106 include bis-iminoguanidines. Examples of bis- iminoguanidines include 2,5-furan-bis(iminoguanidine) (FuBIG) whose chemical structure is as follows:

[0105] capture solution 106 include an imine, an amidine, an amine, a hindered or non-hindered amine group having alkanolamine and alcoholic hydroxyl, carbonyl or carboxyl groups, or a combination thereof. Non- limiting examples of amines have at least one amino group (monoamine), at least two amino groups (diamine), at least three amino groups (triamine) or more amino groups (multiamine).

[0106] In example implementations, the CO2 capture solution 106 can include a diamine as the at least one CO2capture species, for example a diamine with an aminocyclic compound group. For example, the at least one CO2capture species includes cyclopentane-1,3-diamine (being functionalized or not). For example, the aminocyclic compound group can be an aminocyclohexyl group. For example, the at least one CO2capture species includes a diamine including a cyclic compound being functionalized by a hydrocarbon chain (R). For example, the at least one CO2 capture species includes a diamine including a cyclic compound being functionalized by a functional group (X). For example, the at least one CO2capture species includes a diamineAttorney Docket No.: 30285-0051WO1 including a cyclic compound being functionalized by two amino groups in a first and third position of the cyclic compound, and by a hydrocarbon chain (R) and / or a functional group (X) at another position of the cyclic compound (e.g., cyclohexane-1,3-diamine-5 R X). The hydrocarbon chain R can be straight or branched, with or without rings, and can vary in length. The functional group X can functionalize the cyclic compound and / or the hydrocarbon chain R. The functional group X can be, without being limited to, alcohol, amine, amide, carboxylic acid, ester, ether, halogen, metal, or any combinations thereof. The hydrocarbon chain R can be, without being limited to, butane, pentane, hexane, or cycloalkane. Both the hydrocarbon chain R and the functional group X can exist independently or together at a same position of the cyclic compound (e.g., fifth position of a cyclohexane ring), or at other positions of the cyclic compound. For example, the at least one CO2capture species includes cyclohexane-1,3-diamine. For example, the at least one CO2capture species includes a cyclohexane-1,3-diamine-5 R X, where R is butane and X is an amino group, such as cyclohexane-1,3-diamine-5-normal-butane-amine. For example, the at least one CO2capture species includes a cyclohexane-1,3-diamine-5 R X, where R is hexane and X is absent, such as cyclohexane-1,3-diamine-5-normal-hexane. For example, the at least one CO2 capture species includes 3-(aminomethyl)-3,5,5-trimethylcyclohexylamine, also referred to as isophorone diamine or IPDA whose chemical structure is as follows:

[0107] Examples of the(MEA), diethanolamine, triethanolamine, methyldiethanolamine, diisopropanolamine, and diglycolamine. Examples of the hindered amine having alcoholic hydroxyl include 2-amino-2-methyl-1-propanol (AMP) whose chemical structure is as follows:Attorney Docket No.: 30285-0051WO1 ,

[0108] 2-(ethylamino)- structure is as follows:, and

[0109] 2-structure is as follows.

[0110] The captureCO2-laden air 104 to form carbonate can be improved by the introduction of an additive such as a promoter species in the CO2capture solution 106. In some implementations, the resulting carbonate-rich capture solution 107 produced by the capture sections 102A, 102B includes carbonates and bicarbonates and includes the promoter as well. An example composition of such a carbonate-rich capture solution 107 can include K2CO3 / KHCO3 and a promoter. Non-limiting examples of promoters include carbonic anhydrase, amines (primary, secondary, tertiary), zwitterionic amino acids, and boric acid. Non- limiting examples of additives include chlorides, sulfates, acetates, phosphates, surfactants, oxides and metal oxides. The carbonate-rich capture solution 107 (sometimes referred to herein as a “CO2-rich capture solution 107”) resulting from such a CO2 capture solution 106 can have a pH in the range of 11-13 and can have little residual hydroxide from the CO2capture solution 106. In example implementations, additives that are not considered promoters can be used to improve the uptake of CO2 in the CO2 capture solution 106. For example, a surfactant can be added to the CO2 capture solution 106 to lower the surface tension of the CO2 capture solution 106 to improve the ability of the CO2capture solution 106 to wet the material of a gas-liquid interface. Non-limiting examples of rate-enhancing additives include carbonic anhydrase, piperazine, monoethanolamine (MEA), diethanolamine (DEA), zinc triazacycles, zinc tetraazacycles, copper glycinates, hydroxopentaaminecobalt perchlorate, formaldehyde hydrate, saccharose, fructose, glucose,Attorney Docket No.: 30285-0051WO1 phenols, phenolates, glycerin, arsenite, vanadium pentoxide, hypochlorite, hypobromite, or other oxyanionic species.

[0111] In example implementations, at a given reference temperature, the density of the CO2capture solution 106 is greater than the density of water at the same reference temperature. At comparable reference temperatures, in example implementations, the density of the CO2 capture solution 106 is at least 10% greater than the density of water. In example implementations, at comparable reference temperatures, the density of the CO2capture solution 106 is approximately 10% greater than the density of water. The density and the viscosity of the CO2 capture solution 106 can vary depending on the composition of the CO2 capture solution 106 and the temperature. For example, at temperatures of 0°C to 20°C, a CO2capture solution 106 comprising 1 M KOH and 0.5 M K2CO3can have a density ranging from 1115-1119 kg / m3and a viscosity ranging from 1.3-2.3 mPa-s. In some examples, at temperatures of 20°C to 0°C, a CO2 capture solution 106 comprising 2 M KOH and 1 M K2CO3 can have a density ranging from 1260-1266 kg / m3and a viscosity ranging from 1.8-3.1 mPa-s. In comparison, water has a density of 998 kg / m3and viscosity of 1 mPa-s at 20°C.

[0112] In example implementations, and referring to FIG.1A, CO2 from the CO2-laden air 104 is captured by contacting the CO2-laden air 104 with the CO2capture solution 106 in the capture sections 102A, 102B. Reacting the absorbed CO2 from the CO2-laden air 104 with one or more CO2 capture species from the CO2 capture solution 106 can form the CO2-rich capture solution 107 including captured CO2, for example as carbonate, carbamate and / or carbamic acid species. The CO2-rich capture solution 107 can thus also be referred to as, for example, a the “carbonate-rich capture solution 107”. The composition of the CO2-rich capture solution 107 can vary in accordance with several factors including the nature of the CO2 capture solution 106 and the operational absorption conditions.

[0113] For example, in implementations of the present disclosure where the at least one CO2 capture species comprises an amine, CO2 is absorbed in the CO2 capture solution 106 and reacted with the amine to form the CO2-rich capture solution 107 which includes solids. Solids including carbamate solids, carbonate solids and carbamic acid solids can be referred to as carbon containing solids. In one example of such an implementation, the at least one CO2 capture species of the CO2capture solution 106 includes isophorone diamine (IPDA), and CO2is reacted with the amine to form the CO2-rich capture solution 107 which includes at least one of carbamic acidAttorney Docket No.: 30285-0051WO1 species, carbamate species and carbonate species (e.g., including carbamic acid solids). Depending on the solvent (aqueous and non-aqueous) of the CO2 capture solution 106, carbamic acid solids can be insoluble, such that the CO2-rich capture solution 107 forms a pumpable slurry.

[0114] For example, in implementations of the present disclosure where at least one CO2capture species of the CO2 capture solution 106 includes one or more alkali hydroxides, CO2 is absorbed and reacted with the alkali hydroxide(s) of the CO2 capture solution 106 to form the CO2- rich capture solution 107 which includes carbonates. The carbonates can be carbonate solids such that the that the CO2-rich capture solution 107 forms a pumpable slurry.

[0115] For example, in implementations of the present disclosure where at least one CO2 capture species of the CO2capture solution 106 is an alkali hydroxide (e.g., KOH), the carbonates (e.g., K2CO3,KHCO3,etc.) formed within the CO2-rich capture solution 107 can be reacted with another species such as an amine species. In example implementations, the amine species is IPDA. A solid precipitate resulting from the reaction, including solids such as carbamic acid solids, may be used to recover at least some of the CO2captured from the dilute gas source. In such implementations of using two or more CO2 capture species, the CO2 capture process can benefit from the comparatively favourable capture kinetics associated with inorganic capture species such as alkali hydroxides, while also benefiting from the favorable regeneration kinetics associated with organic capture species, for example. The additional chemical compounds may promote the precipitation of solids associated with the alkali hydroxide (e.g., KOH). Additional CO2-capture species that can be used, in combination with a first CO2-capture species, to precipitate solids from dissolved species include, but are not limited to at least one of a cyclic diamine or a bis- iminoguanidine. The additional chemical compounds may promote the precipitation of solids associated with the alkali hydroxide (ex: KOH) or hindered amine.

[0116] Reacting the CO2from the CO2-laden air 104 with the CO2capture solution 106 forms the CO2-lean gas stream 105 and the CO2-rich capture solution 107. The CO2-rich capture solution 107 can be processed to recover the captured CO2 for use and to regenerate the capture species to be reused in the CO2capture solution 106. The CO2-lean gas stream 105 can contain compounds of CO2 capture solution 106, and possibly also compounds of the CO2-rich capture solution 107. The compounds of the CO2 capture solution 106 and possibly also of the CO2-rich capture solution 107 can be in liquid and / or vapor phase, and are present in the flow of the CO2- lean gas stream 105, such that they can flow with the CO2-lean gas stream 105 to other componentsAttorney Docket No.: 30285-0051WO1 of the gas-liquid contactor subsystem 101 that are downstream of the capture sections 102A, 102B, relative to the flow direction of gases through the capture sections 102A, 102B.The terms“downstream” and “upstream” are used herein as positional descriptors, to describe the relative position of two or more components as a function of the flow direction of a corresponding liquid or gas. For example, if a first component is described as being downstream of a second component relative to a direction of gas flow, the first component receives the gas flow after the second component. Similarly, if a first component is described as being upstream of a second component relative to a direction of liquid flow, the first component receives the liquid flow before the second component.

[0117] In the configuration where the CO2capture solution 106 comprises an alkali hydroxide, CO2is absorbed by reacting with the alkali hydroxide to form the CO2-rich capture solution 107 which is carbonate-rich capture solution (e.g., K2CO3, Na2CO3, or a combination thereof). The term “rich,” in some aspects, can mean that a stream contains more CO2 than the associated CO2-lean stream (in this case, the CO2capture solution 106). The CO2-rich capture solution 107 can be processed to recover the captured CO2 for use and to regenerate the alkali hydroxide for use in the CO2 capture solution 106. In example implementations, recovered CO2 can be delivered downhole and sequestered in a geological formation, subsurface reservoir, carbon sink, or the like. In example implementations, the recovered CO2can be used for enhanced oil recovery by injecting the recovered CO2 into one or more wellbores to enhance production of hydrocarbons from a reservoir. In example implementations, recovered CO2can be fed to a fuel synthesis system, which can include a syngas generation reactor. In example implementations, the recovered CO2 can be a feedstock for making any suitable carbon-based or carbon-including product, non-limiting examples of which include cement, plastics, and polymers.

[0118] The CO2-rich capture solution 107 can also include other components in smaller amounts, such as hydroxide ions, alkali metal hydroxide (e.g., KOH, NaOH), water, and impurities. For example, the carbonate-rich capture solution 107 can comprise between 0.4 M to 6 M K2CO3and between 1 M to 10 M KOH. In example implementations, the carbonate-rich capture solution 107 can comprise an aqueous Na2CO3-NaOH mixture. In example implementations, the carbonate-rich capture solution 107 can comprise a mixture of K2CO3 and Na2CO3.Attorney Docket No.: 30285-0051WO1

[0119] Still referring to FIG. 1A, the gas-liquid contactor subsystem 101 includes a housing 120 which defines part of the corpus of the gas-liquid contactor subsystem 101 and provides structure thereto. The housing 120 includes exterior structure or walls that partially enclose any combination of interconnected structural members. The structural members provide structural support and stability to the gas-liquid contactor subsystem 101 and provide a body for supporting components of the gas-liquid contactor subsystem 101 within the housing 120. The structural members can include, but are not limited to, walls, panels, beams, frames, etc. The housing 120 can include other components as well, such as cladding, panels, etc. which help to close off parts of the housing 120 and define the enclosure of the housing 120. The housing 120 at least partially encloses and defines an interior of the housing. The interior of the housing 120 is an inner volume or inner space in which components of the gas-liquid contactor subsystem 101 are positioned. The housing 120 can also includes openings that allow for movement of gases into and out of the gas-liquid contactor subsystem 101. For example, and referring to FIG. 1A, the housing 120 has one or more inlet(s) 115A, 115B. In the implementation of FIG. 1A, the one or more inlet(s) 115A, 115B are formed by the openings, such that the inlet(s) 115A, 115B can be referred to herein as one or more inlet opening(s) 115A, 115B through which the CO2-laden air 104 enters the interior 113 of the housing 120.

[0120] In the implementation of the gas-liquid contactor subsystem 101 of FIG. 1A, the gas-liquid contactor subsystem 101 includes a fan stack with an upright orientation. The fan stack extends upwardly from the housing 120 and helps to discharge the CO2-lean gas stream 105. In such an implementation, the CO2-laden air 104 enters the interior 113 of the housing 120 along a substantially horizontal direction through the one or more inlets 115A, 115B of the capture sections 102A, 102B, and the CO2-lean gas stream 105 exits the capture sections 102A, 102B along a substantially horizontally direction.

[0121] The gas-liquid contactor subsystem 101 includes a gas-circulating device which functions to move or circulate gas flows into and out of the gas-liquid contactor subsystem 101. In the implementation of the gas-liquid contactor subsystem 101 of FIG. 1, the gas-circulating device is a fan 123 within an outlet of the fan cowling 122. The fan 123 functions to circulate gases like ambient air, such that the CO2-laden air 104 is caused by the fan 123 to flow into the capture sections 102A, 102B of the gas-liquid contactor subsystem 101, and such that the CO2- lean gas stream 105 is caused by the fan 123 to be discharged from the capture sections 102A,Attorney Docket No.: 30285-0051WO1 102B. The fan 123 thus functions to circulate the CO2-laden air 104 and the CO2-lean gas stream 105 in the manner described herein. Referring to FIG. 1, the fan 123 is rotatable about a fan axis defined by a fan shaft. In the implementation of the fan 123 depicted in FIG. 1, the fan axis has an upright or vertical orientation. Other orientations for the shaft and for the fan axis are possible.

[0122] Referring to FIG.1A, the fan 123 is positioned upstream of the end of the fan stack and functions, relative to the flow direction of gases through the fan stack, to induce a flow of the CO2-lean gas stream 105 through an outlet of the capture sections 102A, 102B. In some configurations, the fan 123 is positioned elsewhere between the vertically opposite ends of the fan stack and upstream of the outlet of the capture sections 102A, 102B relative to the flow of gases through the capture sections 102A, 102B, such that the fan 123 flows the CO2-lean gas stream 105.

[0123] Rotation of the fan 123 about the fan axis causes gases to circulate into the inlets 115A, 115B and through the capture sections 102A, 102B. For example, in the implementation of the gas-liquid contactor subsystem 101 of FIG. 1A, rotation of the fan 123 causes the CO2-laden air 104 to be drawn into the capture sections 102A, 102B and causes the CO2-lean gas stream 105 to be discharged from the capture sections 102A, 102B. The capture sections 102A, 102B each have one or more sections of capture section packing 127 positioned lower than the fan 123. The one or more sections of capture section packing 127 have an air travel depth defined between a capture section packing inlet 115A, 115B and a capture section packing outlet 109A, 109B. The fan 123 can cause the CO2-laden air 104 to enter the one or more sections of capture section packing 127 at airspeeds below 5 m / s. The fan 123 can cause the CO2-laden air 104 to enter the one or more sections of capture section packing 127 at airspeeds between 0.1 m / s and 5 m / s.

[0124] As the CO2 capture solution 106 circulates through the capture section packing 127, the CO2-laden air 104 is flowing (e.g., by action of the fan 123) substantially horizontally through the one or more sections of the capture section packing 127 to thereby contact the CO2capture solution 106. Thus, the flow of the CO2 capture solution 106 through the one or more sections of the capture section packing 127 is substantially perpendicular to the flow of the CO2-laden air 104 through the one or more sections of the capture section packing 127. Such a configuration of the flows may be referred to as a “cross flow” configuration. The packing liquid travel dimension along which the CO2 capture solution 106 flows through the one or more sections of the capture section packing 127 is defined along the vertical direction and is perpendicular to the packing air travel depth along which the CO2-laden air 104 flows horizontally through the one or more sectionsAttorney Docket No.: 30285-0051WO1 of the capture section packing 127. Other configurations of the gas-liquid contactor subsystem 101 are possible, some of which are now described in greater detail. The gas-liquid contactor subsystem 101 can include cooling-tower style gas-liquid contactors, spray towers, liquid-gas scrubbers, venturi scrubbers, packed towers, and other units designed to remove at least a portion of a particular gas component from a larger gas stream using a liquid sorbent. The gas-liquid contactor subsystem 101 can include single or multi cell air contactors, dual flow air contactors, or a combination thereof. The gas-liquid contactor subsystem 101 can operate in crossflow, countercurrent flow, co-current flow, or a combination thereof.

[0125] In example implementations, the compounds in the CO2-lean gas stream 105 can also be exhausted from the gas-liquid contactor subsystem 101 and into the atmosphere, unless measures are taken to reduce or eliminate these components, as described in greater detail below. The entrained compounds in the CO2-lean gas stream 105 can originate from the CO2 capture solution 106 and / or the CO2-rich capture solution 107 and include, but are not limited to, alkali hydroxides, carbonic anhydrase, amines (primary, secondary, tertiary), guanidines, carbonates and bicarbonates. The nature, size and phase of the entrained compounds can vary based on numerous factors, non-limiting examples of which include the physical and / or chemical properties of the CO2capture solution 106, ambient and / or solution temperature, and the relative humidity of ambient and / or of the CO2-laden air 104.

[0126] In some instances, the CO2-lean gas stream 105 can contain or entrain a portion of the CO2capture solution 106 and / or the CO2-rich capture solution 107 as suspended liquid droplets. These liquid droplets may, in some instances, be entrained with the CO2-lean gas stream 105 as liquid aerosolized particles, such that the CO2-lean gas stream 105 forms an aerosol as it flows out of the gas-liquid contactor subsystem 101. For example, in implementations of the present disclosure where the at least one capture species of the CO2capture solution 106 includes one or more amine species, the entrained compounds can include volatilized amine components which are in vapor or gas phase and are in equilibrium with the CO2-lean gas stream 105, due to the volatility of the amine species resulting from its high vapor pressure at most ambient conditions. In some examples, in implementations of the present disclosure where the at least one capture species of the CO2 capture solution 106 includes one or more alkali hydroxides species, the compounds can be in liquid phase as liquid aerosolized particles and can be entrained by, or suspended in, the CO2-lean gas stream 105, due to the comparatively low volatility of the alkaliAttorney Docket No.: 30285-0051WO1 hydroxide species resulting from its relatively low vapor pressure at most ambient conditions. In some examples, in implementations of the present disclosure where the at least one capture species of the CO2 capture solution 106 includes bicarbonate species, the compounds can be in liquid phase as liquid aerosolized particles and can be entrained by, or suspended in, the CO2-lean gas stream 105, due to the comparatively low volatility of the bicarbonate species resulting from its relatively low vapor pressure at most ambient conditions. In some examples, in implementations of the present disclosure where the at least one capture species of the CO2capture solution 106 includes two or more species which have both high and low volatilities, the compounds can be in both vapor phase, and liquid phase as liquid aerosolized particles. For example, the aerosolized particles can be liquid aerosolized particles of the CO2capture solution 106 and / or CO2-rich capture solution 107 that are suspended in the CO2-lean gas stream 105 and can range in size from less than 1 micron to over 70 microns. In such examples of liquid aerosolized particles, the liquid aerosolized particles of the CO2 capture solution 106 and / or CO2-rich capture solution 107 that are suspended in the CO2-lean gas stream 105 can have a size less than 2.5 microns. As the concentrations and nature of the chemical compounds in the CO2-capture solution 106 are evolving during CO2 absorption, when referring to liquid aerosolized particles, it should be understood that the liquid aerosolized particles can include any liquid (compound?) from the CO2-capture solution 106 and / or CO2-rich capture solution 107, that may or may not contain unreacted CO2 capture species.

[0127] Solid airborne particles can also be entrained in the CO2-lean gas stream 105. Depending on such non-limiting factors as the physical and / or chemical properties of the CO2capture solution 106, the reaction products of the at least one capture species from the CO2capture solution 106 with CO2, the solids present in liquid flows returning to the gas-liquid contactor subsystem 101, and the environment in which the gas-liquid contactor subsystem 101 is operating, solid airborne particles can be suspended in the CO2-lean gas stream 105 flowing from the capture sections 102A, 102B. Such solid airborne particles can be, or can include non-process elements (NPEs) which are desirable to remove from a gas flow 134 exiting the gas-liquid contactor subsystem 101.

[0128] In such instances, aerosolized particles refer in the present disclosure to any liquid aerosolized particles and solid airborne particles that may form a “drift” exiting the gas-liquid contactor subsystem 101. The present disclosure describes measures to reduce or eliminate the drift, as described in greater detail below.Attorney Docket No.: 30285-0051WO1

[0129] Still referring to FIG.1A, the dual-cell gas-liquid contactor subsystem 101 includes two wash sections 103A, 103B. In example implementations, the dual-cell gas-liquid contactor subsystem 101 includes more or fewer wash sections 103A, 103B (e.g., 1, 3, 4, 5, etc. wash sections). The wash sections 103A, 103B help to reduce or eliminate emissions (e.g., the drift described above) from the gas-liquid contactor subsystem 101. The emissions reduced or eliminated from the gas-liquid contactor subsystem 101 can include one or more of: volatilized components of the CO2capture solution 106, and aerosolized / airborne particles of the CO2capture solution 106, as described in greater detail below. The wash section 103A and the corresponding capture section 102A define one of the “cells” of the dual-cell gas-liquid contactor subsystem 101 and the other wash section 103B and corresponding capture section 102B define another “cell” of the dual-cell gas-liquid contactor subsystem 101.

[0130] The wash sections 103A, 103B are positioned adjacent to and in fluid communication with the capture sections 102A, 102B. For example, the wash section 103A is disposed immediately downstream of, and in fluid communication with, the first capture section 102A, relative to the flow direction of gases through the gas-liquid contactor subsystem 101. The second wash section 103B is disposed immediately downstream of, and in fluid communication with, the second capture section 102B, relative to the flow direction of gases through the gas-liquid contactor subsystem 101.

[0131] In example implementations, the wash sections 103A, 103B each include one or more sections of wash section packing 131. The one or more sections of wash section packing131 can bepositioned lower than the fan 123. In example implementations, the one or moresections of wash section packing 131 have the same height, measured from grade level, as thecapture section packing 127.The one or more sections of wash section packing 131 have an air travel depth defined between a wash section packing inlet 110A, 110B and a wash section packingoutlet111A, 111B. Each “cell” of thethe dual-cell gas-liquid contactor subsystem 101 defines a cell air travel depth measured from a respective capture section packing inlet 115A, 115B to the corresponding wash section packing outlet 111A, 111B of the cell.In example implementations,the amount and material of construction of the one or more sections of wash section packing 131 used in each of the wash sections 103A, 103B are different than the one or more sections of the capture section packing 127, based on the distinctive characteristics and functions required in eachAttorney Docket No.: 30285-0051WO1 of these systems. The one or more sections of the wash section packing 131 are wetted by a wash water stream 133.

[0132] In example implementations, the DAC system 100 includes a hydration subsystem coupled with the gas-liquid contactor subsystem 101. The hydration subsystem is located upstream of each of the capture sections 102A, 102B, relative to the flow direction of gases through the capture sections 102A, 102B. The hydration subsystem includes a gas inlet section, a hydration subsystem contact zone with packing, hydration subsystem drift elimination sections, a hydration solution distribution unit, a hydration solution collection basin, and pumps. The drift elimination sections can include, but is not limited to, an electrostatic drift eliminator or precipitator. The CO2- laden air 104 is humidified upon contacting a hydration solution in the hydration subsystem. In some aspects, this pre-conditioning helps to reduce evaporative losses from the CO2capture solution 106 when it comes in contact with the CO2-laden air 104. In some aspects, having the hydration subsystem upstream of the capture sections 102A, 102B provides a humidified gas stream to the capture sections 102A, 102B, such that water loss through evaporation is minimized from the CO2 capture solution 106 flowing through the capture sections 102A, 102B. In some aspects, this could reduce the amount of fresh CO2 capture solution 106 make-up required in the capture sections 102A, 102B. Additionally, in some aspects where the capture sections 102A, 102B are operating in hot, dry climates, and / or where it might be desirable to conserve potable or clean water, the hydration subsystem can be operated with alternate water sources, such as those used for the hydration solution stream, as a means of reducing a process solution(e.g., the CO2capture solution 106) from evaporating from the capture sections 102A, 102B, which allows for the use of alternate water sources without incurring the problems associated with using these sources directly in the CO2 capture solution 106.

[0133] The CO2-laden air 104 is passed through the hydration subsystem and into the hydration subsystem contact zone. In some aspects, the hydration subsystem contact zone includes one or more of a packing, splash bars, trays, or spray nozzles. In some aspects, the hydration subsystem includes an inlet louver that is used to keep the hydration solution that is moving through the hydration subsystem contact zone from splashing out of the hydration subsystem. In the contact zone, the CO2-laden air 104 is contacted with the hydration solution and then exits the hydration subsystem contact zone as a humidified gas stream, which is partially or fully saturated with at least a portion of evaporated hydration solution. In some implementations, the extent ofAttorney Docket No.: 30285-0051WO1 saturation of CO2-laden air 104 is a function of the ambient temperature, the temperature of hydration solution stream, the surface area of the hydration subsystem contact zone, and / or other thermodynamic factors. The partially or fully saturated CO2-laden air 104 can exit the hydration subsystem through the hydration subsystem drift elimination sections, which reduces any non- evaporated hydration solution (e.g., hydration solution droplets) from being carried out of the hydration subsystem by the CO2-laden air 104 into the capture sections 102A, 102B of the gas- liquid contactor subsystem 101. In some implementations, parts of the drift elimination sections are a component of the hydration subsystem contact zone or the hydration subsystem packing.

[0134] The hydration solution stream flowing down the hydration subsystem contact zone, as well as any non-evaporated hydration solution that has been collected by the gas inlet section, the hydration subsystem drift elimination sections, or a combination thereof, is discharged into a hydration solution collection basin of the hydration subsystem. In some implementations, over time, the hydration solution in the hydration subsystem can become concentrated as a result of the continual evaporation of pure water from the hydration solution. In some implementations, as a result of the evaporation process, the hydration solution can become concentrated with non-volatile components, including, for example, metals, minerals, ions, suspended solids, organics, dissolved solids and the like. This concentrated solution and the concentrated non-volatiles can be periodically or continually removed from the basin as a slip stream, before a pump recycles the hydration solution back to the hydration solution distribution unit.

[0135] The hydration solution collection basin can also be periodically or continually supplied with a makeup hydration solution stream. In some implementations, the source of the makeup hydration solution stream can include at least a portion of fresh water, non-potable water, wastewater, gray water, rain or storm water, brackish water, saline water, sea water or the like. In example implementations, the hydration solution distribution unit can include at least a portion of a pressurized header system with nozzles to spray the hydration solution onto the hydration subsystem contact zone, a non-pressurized or atmospheric basin that feeds nozzles which operate using hydrostatic pressure or head, or a combination thereof. After the non-evaporated hydration solution (e.g., hydration solution droplets) are removed by the hydration subsystem drift elimination sections, the humidified CO2-laden air 104 enters the capture sections 102A, 102B and flows through the one or more sections of the capture section packing 127 where the CO2-laden air 104 comes in contact with the CO2capture solution 106. Reference is made to patentAttorney Docket No.: 30285-0051WO1 application US 2021 / 0101107 A1 entitled “Hydration of Gas Streams,” the entire contents of which are incorporated by reference herein.

[0136] Referring to FIG. 1A, the fan 123 functions to flow the CO2-lean gas stream 105 from the outlet 109A, 109B of the capture sections 102A, 102B to an inlet 110A, 110B of the wash sections 103A, 103B and through the one or more sections of the wash section packing 131. In the wash sections 103A, 103B, the CO2-lean gas stream 105 with the volatilized components and / or airborne particles of the CO2capture solution 106 is contacted with the wash water stream 133. The wash water stream 133 flowing along or through the wash section packing 131 helps to scrub the volatilized components and / or the airborne particles from the CO2-lean gas stream 105 to form a washed CO2-lean gas stream 134 and a used wash water stream 135. The presence of the volatilized components and / or the airborne particles in the washed CO2-lean gas stream 134 is reduced as a result of washing the CO2-lean gas stream 105 with the wash water stream 133. In example implementations, the volatilized components and / or the airborne particles are eliminated from the the washed CO2-lean gas stream 134. In example implementations, the volatilized components and / or the airborne particles are reduced in the washed CO2-lean gas stream 134 to such an extent that their potential emission from thegas-liquid contactor subsystem 101complies with applicable air emission standards or regulations.

[0137] The flow rates of the wash water stream 133 provided to the wash section packing 131 can vary. For example, in some implementations, the flow rate of the wash water stream 133 provided to the wash section packing 131 is between 1% and 500% of the flow rate of the CO2capture solution 106 provided to the capture section packing 127. In some implementations, the flow rate of the wash water stream 133 provided to the wash section packing 131 is between 10% and 100% of the flow rate of the CO2 capture solution 106 provided to the capture section packing 127. In some implementations, the flow rate of the wash water stream 133 provided to the wash section packing 131 is between 10% and 50% of the flow rate of the CO2 capture solution 106 provided to the capture section packing 127. In some implementations where the CO2 capture solution 106 includes isophorone diamine (IPDA) as the at least one capture species, the flow rate of the wash water stream 133 provided to the wash section packing 131 is between 40% and 80% of the flow rate of the CO2 capture solution 106 provided to the capture section packing 127. The flow rate of the wash water stream 133 provided to the wash section packing 131 can be dependentAttorney Docket No.: 30285-0051WO1 on numerous factors, non-limiting examples of which include the volatility of the capture molecule in the solvent, and the concentration of the capture molecule in the solvent.

[0138] Referring to FIG. 1A, the gas-liquid contactor subsystem 101 further comprises a plenum 121 between the wash section packing outlet 111A, 111B of each of the first wash section 103A and the second wash section 103B and beneath the fan 123. In example implementations, referring to FIG. 1A, the plenum 121 of the gas-liquid contactor subsystem 101 is the space or volume defined between the one or more sections of wash section packing 131 of the wash sections 103A, 103B and the or one or more structural members of the housing 120. The plenum 121 is flanked by the one or more sections of wash section packing 131 of the wash sections 103A, 103B.The plenum 121 is a void or space within the housing 120 into which gases flow from the one or more sections of wash section packing 131 of the wash sections 103A, 103B. The plenum 121 is part of the interior of the housing 120. In example implementations, the plenum 121 has a vertical extent defined from a bottom basin 124 to the fan 123. The plenum 121 can include a plenum chamber between the wash sections 103A, 103B and the fan 123. In other implementations of the gas-liquid contactor subsystem 101, the plenum is absent.

[0139] The gas-liquid contactor subsystem 101 has, includes components of, or is functionally linked to, a liquid distribution system including a capture section liquid distribution system 153 and a wash section liquid distribution system 155. The capture section liquid distribution system 153 operates to move, collect and distribute the CO2 capture solution 106 and / or the CO2-rich capture solution 107. The wash section liquid distribution system 155 operates to move, collect and distribute the wash water stream 133. In example implementations, the wash section liquid distribution system 155 includes a wash water regeneration subsystem 140. In example implementations, the wash section liquid distribution system 155 is in fluid communication with the wash water regeneration subsystem 140.

[0140] At least some of the features of the capture section liquid distribution system 153 and the wash section liquid distribution system 155 are supported by the housing 120. In the example implementation of FIG. 1A, the support provided by the housing 120 includes structural support, in that components of the capture section liquid distribution system 153 and the wash section liquid distribution system 155 are structurally supported by the housing 120, such as by the structural members, so that loads generated by these components are supported by the housing 120. Some or all of the features described in related to the capture section liquid distributionAttorney Docket No.: 30285-0051WO1 system 153 and the wash section liquid distribution system 155 in FIG. 1A can be part of the gas- liquid contactor subsystem 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901, or part of a DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 (see FIGS. 1B-10).

[0141] The capture section liquid distribution system 153 and the wash section liquid distribution system 155 each includes one or more liquid collection devices. The liquid collection device of the capture section liquid distribution system 153 is configured to receive one or both of the CO2 capture solution 106 and the CO2-rich capture solution 107 and to hold a volume thereof temporarily or for a longer duration, thereby serving as a source of the CO2 capture solution 106 and / or of the CO2-rich capture solution 107. The liquid collection device of the wash section liquid distribution system 155 is configured to receive the wash water stream 133 and to hold a volume thereof temporarily or for a longer duration, thereby serving as a source of the wash water stream 133. Each liquid collection device can have any configuration or be made of any material suitable to achieve the function ascribed to it in the present description. For example, one or more of the liquid collection devices can be open-topped, or partially or fully covered. In FIG. 1A, one or more of the liquid collection devices include, or are in the form of, basins. Other configurations of the liquid collection device are possible, such as a reservoir, a bed, a sheet, a culvert, a container, a receptable, an open pipe, a network of pressurized pipes with openings or spray nozzles, or any other device capable of retaining liquid.

[0142] In example implementations, referring to FIG. 1A, the liquid collection devices of the liquid distribution system include one or more top basins and one or more bottom basins. The one or more top basins are supported by the housing 120. In example implementations, the top basins are formed from portions of the housing 120. In the configuration of FIG.1A, the top basins include a capture section top basin 129 and a wash section top basin 130.

[0143] The capture section top basin 129 is configured to at least store the CO2 capture solution 106. Referring to FIG. 1A, each capture section top basin 129 is positioned at least partially above the one or more sections of the capture section packing 127 of each capture sections 102A, 102B. Referring to FIG. 1A, the capture section top basin 129 is positioned above the capture section inlets 115A, 115B. When stored (at least transiently) within the capture section top basin 129, the CO2capture solution 106 is positioned to be circulated (e.g., through pumping,Attorney Docket No.: 30285-0051WO1 gravity flow or both) downwards, through the one or more sections of the capture section packing 127 and ultimately into a bottom basin 124 of the gas-liquid contactor subsystem 101.

[0144] In the implementation of the gas-liquid contactor subsystem 101 of FIG. 1A, the bottom basin is a common bottom basin 124 for the capture sections 102A, 102B and the wash sections 103A, 103B. Referring to FIG. 1A, the common bottom basin 124 is beneath both the capture sections 102A, 102B and the wash sections 103A, 103B. Referring to FIG. 1A, the common bottom basin 124 is positioned directly underneath the capture section packing 127 and the wash section packing 131. In other implementations, the capture sections 102A, 102B and the wash sections 103A, 103B can have separate bottom basins.

[0145] As the CO2capture solution 106 is circulated through the one or more sections of the capture section packing 127, the CO2-laden air 104 is circulated through the one or more sections of the capture section packing 127 to contact the CO2 capture solution 106 and generate the CO2-lean gas stream 105. A process stream is formed by contacting the CO2-laden air 104 and the liquid CO2capture solution 106, where the process stream is or includes the CO2-rich capture solution 107 having CO2 absorbed from the CO2-laden air 104 by the CO2 capture solution 106. The capture section top basin 129 can each have any suitable form or feature for distributing the CO2capture solution 106 over the one or more sections of the capture section packing 127. Other configurations for the distribution of the CO2capture solution 106 over the one or more sections of the capture section packing 127 is possible. In one such possible configuration, the capture section top basin 129 includes, or is in fluid communication with, a network of pressurized pipes with openings, or spray nozzles which distribute the CO2capture solution 106 over the uppermost portions of the one or more sections of the capture section packing 127.

[0146] Referring to FIG. 1A, the wash section top basin 130 is positioned at least partially above the one or more sections of the wash section packing 131 of the wash sections 103A, 103B. In example implementations, referring to FIG. 1A, the wash section top basin 130 is part of the wash section liquid distribution system 155. The wash section liquid distribution system 155 can also include one or more top nozzles that are configured to receive the wash water stream 133 from the wash water regeneration subsystem 140. The one or more sections of wash section packing 131 are disposed below the wash section top basin 130. The one or more sections of wash section packing 131 are configured to contact the CO2-lean gas stream 105 with the wash water stream 133. The wash section top basin 130 is configured to store the wash water stream 133, which isAttorney Docket No.: 30285-0051WO1 circulated (e.g., through pumping, gravity flow or both) downwards, through the one or more sections of the wash section packing 131. The wash water stream 133 that is spent or used, ultimately flows into and collects in the common bottom basin 124 as the used wash water stream 135.

[0147] Referring to FIG. 1A, the common bottom basin 124 is positioned at the bottom of the gas-liquid contactor subsystem 101 opposite the top basins 129, 130. As can be seen in FIG. 1, the common bottom basin 124 is positioned below the one or more sections of the capture section packing 127 and the one or more sections of the wash section packing 131. The common bottom basin 124 acts as a collection reservoir for the process stream exiting the capture sections 102A, 102B (e.g., the CO2-rich capture solution 107) and for the used wash water stream 135 exiting the wash sections 103A, 103B. The CO2-rich capture solution 107, including absorbed CO2, as well as unreacted CO2 capture solution 106, collects in the common bottom basin 124. The used wash water stream 135 from the wash sections 103A, 103B, including dissolved capture species from the CO2-lean gas stream 105, also collects in the common bottom basin 124.

[0148] The liquids in the common bottom basin 124 comingle and form a liquid stream 141 that can then be pumped or otherwise moved out of the common bottom basin 124 for further processing. For example, at least a portion of the liquid stream 141 in the common bottom basin 124 can be processed and then pumped for redistribution over the one or more sections of capture section packing 127 for use in CO2 capture. In example implementations, some or all of the liquid stream 141 in the common bottom basin 124 is pumped to the capture section top basin 129 without being processed, for recirculation over the one or more sections of capture section packing 127 for CO2 capture. In example implementations, some or all of the liquid stream 141 in the common bottom basin 124 is pumped to the wash water regeneration subsystem 140 for regenerating the wash water stream 133 which is then recirculated over the one or more sections of wash section packing 131 for scrubbing the CO2-lean gas stream 105 with the wash water stream 133. In example implementations, some of the liquid stream 141 in the common bottom basin 124 is pumped to the capture section top basin 129 without being processed, for recirculation over the one or more sections of capture section packing 127, while the remainder of the liquid stream 141 in the common bottom basin 124 is pumped to the wash water regeneration subsystem 140 for regenerating the wash water stream 133.Attorney Docket No.: 30285-0051WO1

[0149] In example implementations, the common bottom basin 124 can be compatible with a containment structure and prevent loss of various CO2 capture solutions 106, many of which have corrosive, caustic or high pH properties. In some aspects, the common bottom basin 124 can be lined or coated with one or more materials that are resistant to caustic induced corrosion or degradation. In example implementations of the gas-liquid contactor subsystem 101, components can be kept out of the common bottom basin 124. Additionally, the gas-liquid contactor subsystem 101 can be designed to keep most or all the structural components out of the wettable area of the capture sections 102A, 102B, e.g., any portion of the gas-liquid contactor subsystem 101 that is in contact with the CO2 capture solution 106. Examples of wettable areas of the gas-liquid contactor subsystem 101 includes components supporting the one or more sections of capture section packing 127. FIG. 1A depicts a single bottom basin 124. However, other configurations and numbers of bottom basins 124 are possible.

[0150] In example implementations, the capture sections 102A, 102B includes a capture section liquid redistribution system. The capture section packing 127 in such implementations is vertically sectioned with redistribution of the CO2 capture solution 106 provided between the vertically-spaced apart packing. In example implementations, the wash sections 103A, 103B includes a wash section liquid redistribution system, and the wash section packing 131 is vertically sectioned with redistribution of the wash water stream 133 provided between the vertically-spaced apart packing. The capture section liquid redistribution system and the wash section liquid redistribution system can include one or more redistribution basins. The one or more redistribution basins are each positioned in a redistribution spacing that is defined between the upper and lower arrangements of the one or more sections of the capture section packing 127 or the wash section packing 131. The redistribution spacing is a vertically extending gap defined between the upper and lower arrangements of the capture section packing 127 and / or the wash section packing 131. In example implementations, each section of the capture section packing 127 and the wash section packing 131 includes a redistribution basin, which is positioned in the redistribution spacing of that respective packing section 127, 131. Thus, each redistribution basin divides each respective packing section 127, 131 into at least a top section and a bottom section. Each redistribution basin is located vertically between the top basins 129, 130, and the common bottom basin 124.

[0151] During operation of the gas-liquid contactor subsystem 101, a process stream including the CO2-rich capture solution 107 including absorbed CO2as well as unreacted CO2Attorney Docket No.: 30285-0051WO1 capture solution 106 flows from each upper arrangement of structured packings and collects in each redistribution basin. When stored (at least transiently) within the redistribution basins, the process stream is positioned to be redistributed (e.g., through pumping, gravity flow or both) downwards, through the remaining structured packings of the lower arrangement and eventually into the common bottom basin 124. In example implementations, the process stream is pumped into the redistribution basins from the common bottom basin 124.

[0152] The redistribution basins can each have any suitable form or feature for redistributing the process stream over the structured packings. Non-limiting examples of features of the redistribution basins include basin walls, redistribution apertures, and redistribution nozzles.

[0153] Thus, in the gas-liquid contactor subsystem 101, there can be a collector / distributor system that is positioned between vertical sections of packing 127, 131 and that collects fluid flowing from above and redistributes it evenly to the packing 127, 131 below. The description and one, some, or all of the advantages, and functions of features of the top basins 129, 130 and of the common bottom basin 124 apply mutatis mutandis to the redistribution basins.

[0154] In example implementations, the packing sections themselves include redistribution features. For example, the redistribution features can be part of redistribution packing that is different from the structured packings 127, 131. The redistribution packing can have a vertical extent and be positioned between arrangements of structured packings 127, 131, for example mid-way up the packing 127, 131. Alternatively, the redistribution packing can include multiple redistribution packing portions alternating with arrangements of structured packings 127, 131. The redistribution features promote redistribution of the CO2capture solution 106 to lower portions of the packing sections 127, 131.

[0155] In example implementations of the gas-liquid contactor subsystem 101, the gas- liquid contactor subsystem 101 does not include vertically sectioned packing or redistribution. In example implementations, the presence of a wash section liquid redistribution system is dependent on the flow rates of the wash water stream 133 to the wash sections 103A, 103B.

[0156] In example implementations of the DAC system 100, and referring to FIG. 1A, some of the CO2-rich capture solution 107 is sent to a capture solution regeneration subsystem 180 that is downstream of the common bottom basin 124, relative to the flow direction of the liquid stream 141 from the common bottom basin 124. The liquid stream 141 is flowed to the capture solution regeneration subsystem 180 for use in regenerating the CO2capture solution 106. InAttorney Docket No.: 30285-0051WO1 example implementations, at least a portion of the liquid stream 141 from the common bottom basin 124 is recirculated to the capture sections 102A, 102B for use in capturing CO2 from the CO2-laden air 104. In example implementations, at least a portion of the liquid stream 141 from the common bottom basin 124 is flowed to the capture section top basin 129 and recirculated to the one or more sections of capture section packing 127 of the capture sections 102A, 102B while also sending a portion of the liquid stream 141 to the capture solution regeneration subsystem 180 for use in regenerating the CO2capture solution 106.

[0157] Referring to FIG. 1A, the CO2-lean gas stream 105 is passed through the one or more sections of wash section packing 131 and is contacted with the wash water stream 133 to remove or reduce the volatilized components and / or the airborne particles from the CO2-lean gas stream 105. For example, in implementations of the present disclosure where the capture species of the CO2 capture solution 106 includes one or more amine species, the wash water stream 133 helps to remove or reduce the volatilized amine components from the CO2-lean gas stream 105. In some examples, in implementations of the present disclosure where the capture species of the CO2 capture solution 106 includes one or more alkali hydroxides species, the wash water stream 133 helps to remove or reduce the liquid airborne particles from the CO2-lean gas stream 105. In some examples, in implementations of the present disclosure where the capture species of the CO2capture solution 106 includes both low volatility and high volatility species, the wash water stream 133 helps to remove or reduce both volatilized components and liquid airborne particles from the CO2-lean gas stream 105. In some examples, in implementations of the present disclosure where the CO2-lean gas stream 105 includes solid airborne particles, irrespective of the capture species of the CO2 capture solution 106, the wash water stream 133 helps to remove or reduce the solid airborne particles entrained the CO2-lean gas stream 105, as well as any components of the CO2 capture solution 106. The wash sections 103A, 103B can thus scrub the CO2-lean gas stream 105 in order to remove or reduce entrained airborne particles and volatilized components.

[0158] The gas stream that is scrubbed flows from the wash sections 103A, 103B and is referred to as the washed CO2-lean gas stream 134. The washed CO2-lean gas stream 134 can flow through the plenum 121 and / or through the fan cowling 122 to an ambient environment. The wash water stream 133 that is spent or used for the scrubbing is referred to as the used wash water stream 135. The used wash water stream 135 is collected in the common bottom basin 124 of FIG. 1A. In the configuration where the CO2capture solution 106 includes a hydroxide, the airborneAttorney Docket No.: 30285-0051WO1 particles in the CO2-lean gas stream 105 include liquid droplets (e.g., aerosolized droplets) of the CO2 capture solution 106. In this configuration, the CO2-lean gas stream 105 is passed through the one or more sections of wash section packing 131 and is contacted with the wash water stream 133 to remove the liquid airborne particles from the CO2-lean gas stream 105.

[0159] The common bottom basin 124 of FIG. 1A contains a comingled or mixed stream of some of the CO2-rich capture solution 107 and some of the used wash water stream 135 and contains dissolved capture species. This comingled stream is referred to as the liquid stream 141.

[0160] Referring to FIG.1A, at least some of the liquid stream 141 is flowable to the wash water regeneration subsystem 140, which is configured for regenerating the wash water stream 133. The wash water regeneration subsystem 140 is in fluid communication with the common bottom basin 124. The wash water regeneration subsystem 140 is downstream of the common bottom basin 124, relative to the flow direction of the liquid stream 141 from the common bottom basin 124. In example implementations described in greater detail below and referring to FIG.1A, the wash water regeneration subsystem 140 is separate from the gas-liquid contactor subsystem 101. The regenerated wash water stream 133 produced by the wash water regeneration subsystem 140 can be flowed to the wash sections 103A, 103B for use in removing the volatilized components and / or the airborne particles from the CO2-lean gas stream 105.

[0161] Referring to FIG. 1A, in example implementations, the wash water regeneration subsystem 140 includes a pump 176, a filtration unit 150 and a reverse osmosis (RO) unit 151. The pump 176 is configured to flow the liquid stream 141 from the common bottom basin 124 to the filtration unit 150. In example implementations, the pump 176 is configured to provide enough fluid pressure to flow liquids from the wash water regeneration subsystem 140 to the wash section top basins 130. In other implementations, the wash water regeneration subsystem 140 includes one or more pumps, in addition to the pump 176, to flow regenerated wash water 133 to the wash section top basins 130.

[0162] In the filtration unit 150, the liquid stream 141 is processed to filter or separate solid particles from the CO2-rich capture solution 107 and form a retentate stream 144 which includes the solid particles and a permeate stream 145 which includes the CO2-rich capture solution 107. The retentate stream 144 which includes the solid particles can be further processed. For example, the retentate stream 144 can include desirable solid particles such as carbamic acid solids, whichAttorney Docket No.: 30285-0051WO1 can be sent to the capture solution regeneration subsystem 180, while undesirable non-process elements in the retentate stream 144 are discarded from the DAC system 100.

[0163] Referring to FIG. 1A, the RO unit 151 is located downstream of the filtration unit 150, relative to the flow direction of liquids from the common bottom basin 124 to the the wash section top basins 130. The RO unit 151 is in fluid communication with the filtration unit 150 and is configured to receive at least some of the permeate stream 145 from the filtration unit 150. Referring to FIG.1A, in example implementations, the pump 176 is a high-pressure RO pump that flows the permeate stream 145 at a relatively high pressure through the RO unit 151. In the RO unit 151, the permeate stream 145 comprising the CO2-rich capture solution 107 is processed to separate water from the CO2capture species within the CO2-rich capture solution 107. This process results in the formation of an RO retentate stream 146 comprising the CO2-rich capture solution 107 and an RO permeate stream 147 comprising water. In example implementations, the reverse osmosis unit 151 includes a semi-permeable membrane that allows water to pass through as permeate, effectively concentrating the CO2capture species in the RO retentate stream 146. One or more membranes of the RO unit can select for and reject ions of the capture species, to produce the RO retentate stream 146 being rich in the capture species, and the RO permeate stream 147 comprising primarily water.

[0164] The water of the RO permeate stream 147 is flowed from the RO unit 151 as the regenerated wash water stream 133 to the wash sections 103A, 103B for reuse in removing the volatilized components and / or the airborne particles from the CO2-lean gas stream 105. The pump 176 is used to flow the regenerated wash water stream 133 to the wash sections 103A, 103B.

[0165] In example implementations, the RO retentate stream 146 is split into two slip streams 146a and 146b. The first slip stream 146a can be flowed to the common bottom basin 124 which is in fluid communication with the RO unit 151. The second slip stream 146b can flow, directly or indirectly, to the capture solution regeneration subsystem 180 and / or to the capture sections 102A, 102B. This can be achieved by flowing the slip stream 146b to comingle with the liquid stream 141 at a location upstream of the capture solution regeneration subsystem 180, relative to a flow direction of liquids from the common bottom basin 124 to the capture solution regeneration subsystem 180. In example implementations, some of the permeate stream 145 is flowed to the common bottom basin 124. In example implementations, a slipstream of the permeate stream 145 is flowed, directly or indirectly, to the capture solution regenerationAttorney Docket No.: 30285-0051WO1 subsystem 180 and / or to the capture sections 102A, 102B. This can be achieved by flowing the slip stream to comingle with the liquid stream 141 at a location upstream of the capture solution regeneration subsystem 180, relative to a flow direction of liquids from the common bottom basin 124 to the capture solution regeneration subsystem 180.

[0166] Referring to FIG. 1A, the capture solution regeneration subsystem 180 is in fluid communication with the gas-liquid contactor subsystem 101. The capture solution regeneration subsystem 180 is configured to regenerate the CO2capture solution 106. A pump 170 in fluid communication with the common bottom basin 124 is used to flow the liquid stream 141 comprising the dissolved capture species and any undissolved solids from the common bottom basin 124 to the capture solution regeneration subsystem 180. In the capture solution regeneration subsystem 180, CO2is separated from the CO2-rich capture solution 107 to form a regenerated CO2 capture solution 106, and a CO2 product stream 125. The regenerated CO2 capture solution 106 is flowed to one or more components of the gas-liquid contactor subsystem 101 for use in capturing CO2from the CO2-laden air 104. In example implementations, the regenerated CO2capture solution 106 is flowed to the capture sections 102A, 102B. In example implementations, the regenerated CO2 capture solution 106 is flowed to the capture section top basins 129. In example implementations, the regenerated CO2capture solution 106 is flowed to the common bottom basin 124, or to the capture section bottom basins 224A, 224B of FIG. 2. In example implementations, the regenerated CO2 capture solution 106 is flowed to one or more distribution points of the capture section packing 127. A rate at which the capture solution 106 is pumped from each of the capture section bottom basins 224A and 224B to the one or more distribution points of the capture section packing 127 can be identical in one implementation. In another implementation, the rate at which the capture solution 106 is pumped from the bottom basin 224A can be different from the rate at which the capture solution 106 is pumped from the bottom basin 224B. Different implementations of the capture solution regeneration subsystem 180 are further described in detail below.

[0167] In example implementations and referring to FIG. 1A, the DAC system 100 includes a solids sensor 160 and a capture solution control valve 182. The solids sensor 160 and the capture solution control valve 182 are located downstream of the common bottom basin 124, and upstream of the capture sections 102A, 102B, relative to the flow direction of liquid from the common bottom basin 124 back to the capture sections 102A, 102B. The term “downstream,” inAttorney Docket No.: 30285-0051WO1 this context, refers to the position of the solids sensor 160 and the capture solution control valve 182 relative to the flow of the CO2-rich capture solution 107, where the solids sensor 160 and the capture solution control valve 182 components are located after the common bottom basin 124 along the direction of the flow of CO2-rich capture solution 107 from the bottom basin 124.

[0168] The solids sensor 160 is configured to detect an amount of solid particles in the CO2-rich capture solution 107. For example, when an amine-based capture solution is used, the solids sensor 160 is configured to detect an amount of solids (e.g., carbamic acid solids) in the CO2-rich capture solution 107. Upon detecting that the amount of solid particles is above a threshold, the capture solution control valve 182 is activated to open and a CO2-rich capture solution pump 174 is controlled to flow at least some of the CO2-rich capture solution 107 from the common bottom basin 124 to the capture solution regeneration subsystem 180 for use in regenerating the CO2 capture solution 106. The presence of solid particles above the threshold amount can be an indication that the CO2-rich capture solution 107 is saturated with solid particles formed from reacting CO2with the capture species of the CO2capture solution 106. The presence of solid particles above the threshold amount can be an indication that the CO2-rich capture solution 107 includes a high solids content of solid particles formed from reacting CO2 with the capture species of the CO2capture solution 106.

[0169] When the solids sensor 160 detects that the amount of solid particles is below the threshold, the pump 170 flows the liquid stream 141 comprising the CO2-rich capture solution 107 from the common bottom basin 124 to the capture sections 102A, 102B. The presence of solid particles below the threshold amount can be an indication that the CO2-rich capture solution 107 is below the saturation point of solid particles formed from reacting CO2 with the capture species of the CO2 capture solution 106, such that the CO2-rich capture solution 107 can be recirculated to the capture sections 102A, 102B to continue capturing CO2from the CO2-laden air 104. In example implementations, the CO2-rich capture solution pump 174 is optional, and only the pump 170 can be used to flow at least some of the CO2-rich capture solution 107 from the common bottom basin 124 to either the capture solution regeneration subsystem 180 or to the capture sections 102A, 102B.

[0170] In example implementations and referring to FIG. 1A, the DAC system 100 includes a liquid level sensor 161 and a make-up water control valve 181 in fluid communication with the common bottom basin 124. The liquid level sensor 161 is configured to detect a liquidAttorney Docket No.: 30285-0051WO1 level in the common bottom basin 124. Upon detecting that the liquid level is below a threshold using the liquid level sensor 161, the make-up water control valve 181 is activated to open and a make-up water pump 172 is controlled to flow make-up water 162 into the common bottom basin 124. When the level of liquid in the common bottom basin 124 detected by the liquid level sensor 161 is below the threshold value, it can be an indication that there is insufficient water circulating or present in the gas-liquid contactor subsystem 101, such that the make-up water 162 needs to be added. In addition to, or separately from, flowing make-up water 162 to the common bottom basin 124, the make-up water pump 172 can flow the make-up water 162 directly to the wash sections 103A, 103B. In addition to, or separately from, flowing the make-up water 162 to the common bottom basin 124 and / or to the wash sections 103A, 103B, the make-up water pump 172 can flow the make-up water 162 to a location where the make-up water 162 comingles with the RO permeate stream 147 flowing to the wash sections 103A, 103B.

[0171] In example implementations and referring to FIG. 1A, the DAC system 100 includes a concentration sensor 163 and a make-up CO2capture solution control valve 186. The concentration sensor 163 and the make-up CO2 capture solution control valve 186 are located upstream of the capture sections 102A, 102B. The concentration sensor 163 is configured to detect a concentration of a CO2capture species in the CO2capture solution 106 flowing into the capture sections 102A, 102B. Upon detecting the concentration of the CO2 capture species in the CO2 capture solution 106 is below a threshold using the concentration sensor 163, the make-up CO2 capture solution control valve 186 is activated to open and a make-up CO2capture solution pump 178 is controlled to flow the CO2capture solution 106 into the capture sections 102A, 102B for use in capturing CO2 from the CO2-laden air 104. When the concentration of the CO2 capture species in the CO2 capture solution 106 is below the threshold, it can be an indication that the CO2 capture solution 106 will be less effective at absorbing CO2from the CO2-laden air 104, such that it needs to be replenished.

[0172] In example implementations and referring to FIG. 1A, the DAC system 100 includes an emissions sensor 164 and a make-up wash water control valve 184. The emissions sensor 164 functions to detect the concentration or presence of the capture species in a gas flow. For example, and in example implementations, the emissions sensor 164 is located downstream of the wash sections 103A, 103B, relative to the flow direction of gas from the wash sections 103A, 103B. In such a location, the emissions sensor 164 functions to detect the concentration orAttorney Docket No.: 30285-0051WO1 presence of the capture species in the washed CO2-lean gas stream 134. In example implementations, the emissions sensor 164 can be located downstream of the capture sections 102A, 102B and located upstream of the wash sections 103A, 103B, relative to the flow direction of gas from the capture sections 102A, 102B. In such a location, the emissions sensor 164 functions to detect the concentration or presence of the capture species in the CO2-lean gas stream 105. In yet another configuration, the emissions sensor 164 is located both upstream of the wash sections 103A, 103B, and downstream of the wash sections 103A, 103B.

[0173] The emissions sensor 164 is configured to detect a concentration of a CO2 capture species at its location. The emissions sensor 164 is communicatively coupled to the make-up wash water control valve 184. Upon detecting the concentration of the CO2capture species in the monitored gas flow exceeds a threshold, the make-up wash water control valve 184 is activated to open and the pump 176 is controlled to flow the wash water stream 133 to the wash sections 103A, 103B, so as to further reduce the volatilized components and / or the airborne particles in the CO2- lean gas stream 105. The presence of the CO2capture species in the gas flow above the threshold amount can be an indication that the wash sections 103A, 103B are not reducing or eliminating the volatilized components and / or the airborne particles sufficiently, such that additional wash water 133 may be needed to adequately scrub the CO2-lean gas stream 105.

[0174] Other techniques can be used to prevent or reduce the presence of the CO2 capture species in the gas flow exiting the gas-liquid contactor subsystem 101. For example, one or more of the following non-limiting examples of techniques can be used: the make-up wash water control valve 184 is opened to flow additional wash water 133, the pump 170 is stopped to prevent the creation of additional volatilized components and / or the airborne particles of the CO2 capture solution 106, the fan 123 can be slowed or stopped to prevent volatilized components and / or the airborne particles from leaving the gas-liquid contactor subsystem 101.

[0175] In example implementations, the gas-liquid contactor subsystem 101 further includes a capture section drift eliminator 128 located downstream of the capture sections 102A, 102B and upstream of the wash sections 103A, 103B, relative to the flow direction of gases through the capture sections 102A, 102B. The capture section drift eliminator 128 is configured to reduce or eliminate drift from the CO2-lean gas stream 105 downstream of the capture sections 102A, 102B. In example implementations, the drift of the CO2-lean gas stream 105 includes entrained aerosolized particles, such as liquid aerosolized particles of the CO2capture solution 106 and / orAttorney Docket No.: 30285-0051WO1 solid airborne particles. In such implementations, and for example, the capture section drift eliminator 128 can include a series of baffles or vanes for removing liquid aerosolized particles of the CO2 capture solution 106 and the solid airborne particles from the CO2-lean gas stream 105. The aerosolized particles in the CO2-lean gas stream 105 of the present disclosure include liquid aerosolized particles and airborne particles (e.g., solids). For example, the capture section drift eliminator 128 can include a packing material for removing aerosolized particles from the CO2- lean gas stream 105. For example, the capture section drift eliminator 128 can be a portion of the capture section packing 127 for removing the aerosolized particles from the CO2-lean gas stream 105. In another example configuration, the drift eliminator 128 can be, but is not limited to, an electrostatic drift eliminator. In addition to aerosolized particles, in example implementations, the drift includes volatilized components of the CO2capture solution 106. The capture section drift eliminator 128 can work in concert with the wash sections 103A, 103B, thereby helping to reduce water usage by the wash sections 103A, 103B.

[0176] In example implementations, the gas-liquid contactor subsystem 101 further includes a wash section drift eliminator 132 located downstream of the wash sections 103A, 103B, relative to the flow direction of gases through the wash sections 103A, 103B. The wash section drift eliminator 132 is configured to reduce drift of the used wash water stream 135 entrained in the washed CO2-lean gas stream 134 downstream of the wash sections 103A, 103B. The drift of the used wash water stream 135 can include liquid aerosolized particles of the used wash water stream 135. For example, the wash section drift eliminator 132 can include a series of baffles or vanes for removing liquid aerosolized particles of the used wash water stream 135 from the washed CO2-lean gas stream 134 exiting the wash section drift eliminator 132. For example, the wash section drift eliminator 132 can include a packing material for removing liquid aerosolized particles of the used wash water stream 135 from the washed CO2-lean gas stream 134. For example, the wash section drift eliminator 132 can be a portion of the wash section packing 131 for removing liquid aerosolized particles of the used wash water stream 135 from the washed CO2- lean gas stream 134.

[0177] In some implementations, the DAC system 100 includes a control system 999 communicably coupled to the components (illustrated or otherwise). The liquid process streams in the gas-liquid contactor subsystem 101, as well as process streams within any downstream processes with which the gas-liquid contactor subsystem 101 is fluidly coupled, can be flowedAttorney Docket No.: 30285-0051WO1 using one or more flow control systems (e.g., control system 999). A flow control system can include one or more flow pumps (including or in addition to the pumps 170, 172, 174, 176, 178), fans, blowers, or solids conveyors to move the process streams, one or more flow pipes through which the process streams are flowed and one or more valves to regulate the flow of streams through the pipes. Each of the configurations described herein can include at least one variable frequency drive (VFD) coupled to a respective pump that is capable of controlling at least one liquid flow rate. In example implementations, liquid flow rates are controlled by at least one flow control valve. Additionally, the control system 999 shown in FIG. 1A can be used to control the speed and / or blade pitch of the fan 123. The control system 999 of FIG. 1A can be communicatively coupled to one or more sensors of the DAC system 100 (such as any one of the solids sensor 160, the liquid level sensor 161, the concentration sensor 163, and the emissions sensor 164), to help process information received from such sensors, and to communicate commands to componentry whose functions are linked to the such sensors (such as any one of the capture solution control valve 182, the make-up water control valve 181, the make-up CO2capture solution control valve 186, and the make-up wash water control valve 184, and their respective pump(s) 170, 172, 174, 176, 178).

[0178] In some embodiments, a flow control system can be operated manually. For example, an operator can set a flow rate for each pump or transfer device and set valve open or closed positions to regulate the flow of the process streams through the pipes in the flow control system. Once the operator has set the flow rates and the valve open or closed positions for all flow control systems distributed across the DAC system, the flow control system can flow the streams under constant flow conditions, for example, constant volumetric rate or other flow conditions. To change the flow conditions, the operator can manually operate the flow control system, for example, by changing the pump flow rate or the valve open or closed position.

[0179] In some embodiments, a flow control system can be operated automatically. For example, the flow control system can be connected to a computer or control system (e.g., control system 999) to operate the flow control system. The control system can include a computer- readable medium storing instructions (such as flow control instructions and other instructions) executable by one or more processors to perform operations (such as flow control operations). An operator can set the flow rates and the valve open or closed positions for all flow control systems distributed across the facility using the control system. In such embodiments, the operator canAttorney Docket No.: 30285-0051WO1 manually change the flow conditions by providing inputs through the control system. Also, in such embodiments, the control system can automatically (that is, without manual intervention) control one or more of the flow control systems, for example, using feedback systems connected to the control system. For example, a sensor (such as a pressure sensor, temperature sensor or other sensor described herein) can be connected to a pipe through which a process stream flows. The sensor can monitor and provide a flow condition (such as a pressure, temperature, or other flow condition) of the process stream to the control system. In response to the flow condition exceeding a threshold (such as a threshold pressure value, a threshold temperature value, or other threshold value), the control system can automatically perform operations. For example, if the pressure or temperature in the pipe exceeds the threshold pressure value or the threshold temperature value, respectively, the control system can provide a signal to the pump to decrease a flow rate, a signal to open a valve to relieve the pressure, a signal to shut down process stream flow, or other signals.

[0180] Referring to FIG.1A, the wash sections 103A, 103B can help to reduce or eliminate the volatilized components and / or the aerosolized particles before gas streams are exhausted from the gas-liquid contactor subsystem 101. In so doing, the wash sections 103A, 103B help to ensure that thegas-liquid contactor subsystem 101complies with applicable air emission standards or regulations, particularly in implementations of the present disclosure where volatile or gaseous components of the CO2 capture solution 106 are present in gas flows. The wash sections 103A, 103B allow for the gas-liquid contactor subsystem 101 to be designed or optimised based on which CO2capture solution 106 is most efficient at capturing CO2from the CO2-laden air 104, and thus may not need to consider emissions control of the capture species in the design or operation of the gas-liquid contactor subsystem 101. The wash sections 103A, 103B allow for the gas-liquid contactor subsystem 101 to use a variety of CO2capture solutions 106, and help to broaden the choice of suitable CO2 capture solutions 106 beyond those whose air emissions can only be managed using conventional techniques. For example, the wash sections 103A, 103B allow for amine capture species to be used in the CO2capture solution 106 despite the potential volatility of amine capture species and associated health and environmental issues, because the wash sections 103A, 103B allow for reducing or eliminating the volatile amine to acceptable levels.

[0181] Referring to FIG.1B, the flow of the CO2capture solution 106 through the packing 206 is counter-current (or counterflow) to the flow of the CO2-laden air 104 through the packingAttorney Docket No.: 30285-0051WO1 206. The packing liquid travel dimension along which the CO2capture solution 106 flows through the packing 206 is defined along the vertical direction and is the same as the packing depth along which the CO2-laden air 104 flows upwardly through the packing 206. A portion of the CO2 within the CO2-laden air 104 is transferred to (e.g., absorbed by) the CO2capture solution 106, and the fan 221 moves the CO2 lean gas 134 out of the gas-liquid contactor subsystem 101B to an ambient environment through a wash section 203. The wash section is positioned downstream of the packing 206 and upstream of the fan 221.

[0182] In the configuration of FIG. 1C, the gas-liquid contactor subsystem 101C has only one section of packing 306 and may therefore be referred to as a “single cell” gas-liquid contactor subsystem 101C. The CO2capture solution 106 circulates downwards by, for example, gravity flow, uniform or laminar flow, etc., within the packing 306 and eventually flows into one or more bottom basins 310. As the CO2 capture solution 106 circulates through the packing 306, the CO2- laden air 104 is flowing (e.g., by action of the fan 321) substantially horizontally through the packing 306 to thereby contact the CO2capture solution 106. Thus, the flow of CO2capture solution 106 through the packing 306 in FIG. 1C is substantially perpendicular to the flow of the CO2-laden air 104 through the packing 306. Such a configuration of the flows may be referred to as a “cross flow” configuration. The packing liquid travel dimension along which the CO2capture solution 106 flows through the packing 306 is defined along the vertical direction, and is perpendicular to the packing depth along which the CO2-laden air 104 flows horizontally through the packing 306. A portion of the CO2within the CO2-laden air 104 is transferred to the CO2capture solution 106, and the fan 321 moves the CO2-lean gas 134 out of the gas-liquid contactor subsystem 101C to an ambient environment through the wash section 203. The wash section 203 is positioned downstream of the packing 306 and upstream of the fan 321. The CO2 rich solution flows into the at least one bottom basin 310.

[0183] Referring to FIG. 1D, another possible configuration of a gas-liquid contactor subsystem 101D has an upright body and an air inlet 405 along a top portion through which the CO2-laden air 104 is admitted into the gas-liquid contactor subsystem 101D. The fan 423 rotates to push the CO2-laden air 104 into the gas-liquid contactor subsystem 101D and contact the packing section 406. In the configuration of FIG.1D, the gas-liquid contactor subsystem 101D has only one packing section 406 and can therefore be referred to as a “single cell” gas-liquid contactor. The CO2capture solution 106 circulates downwards by, for example, gravity flow,Attorney Docket No.: 30285-0051WO1 uniform or laminar flow, etc., within the packing 406 and eventually flows into one or more bottom basins 410. As the CO2 capture solution 106 circulates downward through and over the packing 406, the CO2-laden air 104 (e.g., by action of the fan 423) also flows downward through the packing 406 to contact the CO2capture solution 106. Thus, the flow of the CO2capture solution 106 through the packing 406 in FIG.1D is co-current to the flow of the CO2-laden air 104 through the packing 406. The packing liquid travel dimension along which the CO2 capture solution 106 flows through the packing 406 is defined along the vertical direction, and is the same as the packing depth along which the CO2-laden air 104 flows downwardly through the packing 406. At least a portion of the CO2 within the CO2-laden air 104 is transferred to (e.g., absorbed by) the CO2 capture solution 106, and the fan pushes the CO2-lean gas 134 through the wash section 203 and out of the gas-liquid contactor subsystem 101C to an ambient environment. The wash section 203 is positioned downstream of the packing 406.

[0184] In implementations as illustrated in FIG. 1E, the wash section 203 is positioned adjacent an outlet 202 of the gas-liquid contactor subsystem 101E. Some non-limiting examples of possible configurations for the gas-liquid contactor subsystem 101E include being a modular unit, being rounded or circular, being a cell of an array or train of gas-liquid contactor subsystems 101E being a cell of a rounded or circular gas-liquid contactor subsystem 101E and being a component of a heating, ventilation, and air conditioning (HVAC) system. The gas-liquid contactor subsystem 101E may include, or be fluidly coupled to, devices for managing liquid levels in the gas-liquid contactor subsystem 101E. These devices may include, but are not limited to, evaporators to reduce liquid levels and / or maintain concentrations of the CO2capture solution 106. These devices may include, but are not limited to, water make-up tanks or sources to manage liquid levels and / or maintain concentrations of the CO2 capture solution 106. The description, units, componentry, features, streams, reference numbers and advantages of the gas-liquid contactor subsystem 101 provided in relation to FIG. 1A apply mutatis mutandis to the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E of FIGS. 1B to 1E. The positioning and the orientation of the wash section 103, 203 may vary. The wash section 103, 203 may have a horizontal orientation. In some implementations, and referring to FIG. 1A for example, the wash section 103, 203 may have a vertical orientation. In example implementations, and referring to FIG. 1A for example, the wash section 103, 203 is positioned upstream of the fan 123, 221, 321, 423.Attorney Docket No.: 30285-0051WO1

[0185] The DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 may include multiple gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. In some implementations, the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 includes multiple gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 arranged adjacent each other to form an array or a train of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. The DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 may include multiple arrays or trains of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901.

[0186] FIG. 2 depicts another example DAC system 200 for capturing CO2from a dilute gas source. Referring to FIG. 2, the DAC system 200 includes a gas-liquid contactor subsystem 201 for capturing CO2 from a dilute gas source such as the atmosphere (e.g., ambient or atmospheric air) or from another fluid source that contains dilute concentrations of CO2. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101 of FIGS. 1A-1E, apply mutatis mutandis to the gas-liquid contactor subsystem 201 of FIG. 2.

[0187] In the configuration illustrated in FIG. 2, the gas-liquid contactor subsystem 201 includes separate bottom basins for the capture sections 102A, 102B and for the wash sections 103A, 103B. For example, the gas-liquid contactor subsystem 201 includes a capture section bottom basin 224A, 224B for each of the capture sections 102A, 102B and a wash section bottom basin 226A, 226B for each of the wash sections 103A, 103B. Each of the capture section bottom basins 224A, 224B are each located beneath a respective section of the capture section packing 127. The wash section bottom basins 226A, 226B are each located beneath a respective section of the wash section packing 131. In example implementations, the capture section bottom basins 224A, 224B and the wash section bottom basins 226A, 226B are physically and fluidly separate basins. In other implementations, the capture section bottom basin 224A, 224B and the wash section bottom basin 226A, 226B for the same cell are the same basin fluidly separated by structures that can include, but are not limited to, weirs, dividers, and raised walls.

[0188] The CO2-rich capture solution 107 accumulates in the capture section bottom basins 224A, 224B. Some of the CO2-rich capture solution 107 can be sent to the capture solution regeneration subsystem 180 for use in regenerating the CO2capture solution 106. In exampleAttorney Docket No.: 30285-0051WO1 implementations, at least a portion of the CO2-rich capture solution 107 from the capture section bottom basins 224A, 224B is recirculated to the capture sections 102A, 102B for use in capturing CO2 from the CO2-laden air 104. In example implementations, at least a portion of the CO2-rich capture solution 107 received from the capture section bottom basins 224A, 224B is collected in the capture section top basin 129 and recirculated to the one or more sections of capture section packing 127 before sending a portion of the CO2-rich capture solution 107 to the capture solution regeneration subsystem 180 for use in regenerating the CO2capture solution 106.

[0189] Referring to FIG.2, the used wash water stream 135 is collected in the wash section bottom basins 226A, 226B. The wash water regeneration subsystem 140 is in fluid communication with the wash section bottom basins 226A, 226B and is configured to receive the used wash water stream 135 from the wash section bottom basins 226A, 226B. The wash water regeneration subsystem 140 is configured to regenerate the used wash water stream 135 which is then pumped to the wash sections 103A, 103B as the wash water stream 133 for use in removing components from the CO2-lean gas stream 105, as described above. A rate at which the used wash water stream 135 is pumped from each of the wash section bottom basins 226A and 226B to the wash sections 103A and 103B, can be identical in one implementation. In another implementation, the rate can be different.

[0190] In example implementations, the RO retentate stream 146 is split into two slip streams 146a and 146b. The pump 176 is used to flow the slip stream 146a to the capture section bottom basins 224A, 224B which is in fluid communication with the RO unit 151.

[0191] The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the common bottom basin 124 of FIG. 1A apply mutatis mutandis to the capture section bottom basins 224A, 224B and to the wash section bottom basins 226A, 226B of FIG. 2. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with components of the DAC system 100 of FIG. 1A apply mutatis mutandis to the components of the DAC system 200 of FIG. 2.

[0192] Referring to FIG.3, there is shown an example DAC system 300 for capturing CO2from a dilute gas source according to an aspect of the present disclosure. In the configuration illustrated in FIG.3, there is shown a gas-liquid contactor subsystem 301 configured as a dual-cell cross flow gas-liquid contactor subsystem 301 including capture sections 302A, 302B and a wash section 303. The gas-liquid contactor subsystem 301 of FIG.3 has a single wash section 303. TheAttorney Docket No.: 30285-0051WO1 wash section 303 is located downstream of the capture sections 302A and 302B, relative to the flow direction of gas through the capture sections 302A, 302B. In example implementations and referring to FIG. 3, the wash section 303 is located above a lower area of the plenum 121 and is flush with the fan cowling 122. In example implementations and referring to FIG. 3, an inlet of the wash section 303 is located at a height greater than a height of an outlet of the capture sections 302A, 302B.

[0193] The wash section 303 of FIG. 3 has a counter-flow arrangement where the wash water stream 133 flows in a direction opposite to the direction along which the CO2-lean gas stream 105 flows through the wash section 303. In example implementations, and referring to FIG.3, the wash water stream 133 flows along a downward direction relative to gravity, and the CO2-lean gas stream 105 flows through the wash section 303 along an upward direction relative to gravity. The housing 120 of the gas-liquid contactor subsystem 301 can include any suitable flow-guidance device to guide the flow of the CO2-lean gas stream 105 from the capture sections 302A, 320B to the inlet of the wash section 303. Non-limiting examples of such flow-guidance devices include walls, panelling, vanes, and any combination of the preceding.

[0194] The CO2-lean gas stream 105 is scrubbed in the wash section 303. The CO2-lean gas stream 105 flows through the one or more sections of wash section packing 331 and is contacted with the wash water stream 133 to remove the volatilized components and / or the aerosolized particles from the CO2-lean gas stream 105. In example implementations, and referring to FIG. 3, the wash water stream 133 is temporarily stored in, and distributed from, a wash section top basin 330 of the wash section 303. The wash section top basin 330 is positioned above the wash section packing 331 relative to gravity. When stored (at least transiently) within the wash section top basin 330, the wash water stream 133 is positioned to be flowed (e.g., through pumping, gravity flow or both) downwards over the wash section packing 331. In example implementations, the wash section top basin 330 is absent, and the wash water stream 133 is distributed over the wash section packing 331 through any combination of piping and nozzles. The washed CO2-lean gas stream 134 exits the gas-liquid contactor subsystem 301 through the outlet of the fan cowling outlet 122, to an ambient environment. The used wash water stream 135 is collected in the common bottom basin 124. The used wash water stream 135 and the CO2-rich capture solution 107 comingle in the common bottom basin 124 to form a comingled liquid stream 141. The common bottom basin 124 contains the comingled liquid stream 141, which includesAttorney Docket No.: 30285-0051WO1 the dissolved capture species. The liquid stream 141 is flowable from the common bottom basin 124 to be processed or used, as described above.

[0195] In the configuration illustrated in FIG. 3, liquid flow from the capture sections 302A, 302B and the wash section 303 feeds the common bottom basin 124. In other implementations of the gas-liquid contactor subsystem 301 of FIG. 3, the liquid flow from the capture sections 302A, 302B and the wash section 303 feed separate bottom basins. In such implementations of separate bottom basins, the description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the capture section bottom basins 224A, 224B and with the wash section bottom basins 226A, 226B of FIG. 2 apply mutatis mutandis to the such separate bottom basins of the gas-liquid contactor subsystem 301 of FIG. 3.

[0196] The emissions sensor 164 of the gas-liquid contactor subsystem 301 of FIG. 3 is located downstream of the wash section 303, relative to the flow direction of gas through the wash section 303. In such a location, the emissions sensor 164 functions to detect the concentration or presence of the capture species in the washed CO2-lean gas stream 134. In example implementations and referring to FIG. 3, the emissions sensor 164 is located downstream of the fan 123 relative to the direction of gas flow generated by the fan 123. In example implementations, the emissions sensor 164 is located immediately upstream of the fan 123, relative to the direction of gas flow generated by the fan 123. In example implementations, the emissions sensor 164 is located downstream of the capture sections 302A, 302B and located upstream of the wash section 303, 103B, relative to the flow direction of gas from the capture sections 302A, 302B. In such a location, the emissions sensor 164 functions to detect the concentration or presence of the capture species in the CO2-lean gas stream 105. Upon detecting that the concentration of the CO2 capture species in the monitored gas flow exceeds a threshold, the make-up wash water control valve 184 is activated to open and the pump 176 is controlled to flow additional wash water 133 to the wash section 303, so as to further reduce the volatilized components and / or the aerosolized particles in the CO2-lean gas stream 105.

[0197] The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201 of FIGS. 1A-1E and 2 apply mutatis mutandis to the gas-liquid contactor subsystem 301 of FIG. 3. The description, features, chemical reactions, reference numbers, andAttorney Docket No.: 30285-0051WO1 advantages of the present disclosure that are associated with components of the DAC system 100, 200 of FIGS. 1A-1E and 2 apply mutatis mutandis to the components of the DAC system 300 of FIG. 3.

[0198] FIG. 4 depicts another example DAC system 400 for capturing CO2from ambient air according to an aspect of the present disclosure. In the configuration illustrated in FIG. 4, a gas-liquid contactor subsystem 401 is configured as a single cell gas-liquid contactor subsystem 401, where the single cell includes a capture section 402 and a wash section 403. The wash section 403 is located immediately downstream of the capture section 402, relative to the flow direction of gases through the capture section 402. In example implementations, the wash section 403 is located downstream of the capture section 402, relative to the flow direction of gases through the capture section 402 and spaced apart from the capture section 402.

[0199] The fan 123 drives the flow of gas (e.g., the CO2-laden air 104, the CO2-lean gas stream 105) along a substantially horizontal direction, and liquids (e.g., the CO2 capture solution 106, the wash water stream 133) flow along a substantially downward direction. Thus, the flow of gases through the capture section 402 and the wash section 403 is substantially perpendicular to the flow of liquids through these sections 402, 403, such that single cell has a “cross flow” configuration.

[0200] The wash section 403 partially delimits the plenum 421. The washed CO2-lean gas stream 134 exits the gas-liquid contactor subsystem 401 by flowing first through the plenum 121, and then through the fan cowling 122 to an ambient environment.

[0201] In the configuration illustrated in FIG. 4, liquid flow from the capture section 402 and from the wash section 403 is received by a common bottom basin 124. In example implementations of the gas-liquid contactor subsystem 401, the liquid flow from the capture section 402 and from the wash section 403 feed into separate bottom basins. In such implementations of separate bottom basins, the description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the capture section bottom basins 224A, 224B and with the wash section bottom basins 226A, 226B of FIG. 2 apply mutatis mutandis to the such separate bottom basins of the gas-liquid contactor subsystem 401 of FIG. 4.

[0202] The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101, 101B,Attorney Docket No.: 30285-0051WO1 101C, 101D, 101E, 201, 301 of FIGS. 1A-1E to 3 apply mutatis mutandis to the gas-liquid contactor subsystem 401 of FIG. 4. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with components of the DAC system 100, 200, 300 of FIGS. 1A-1E to 3 apply mutatis mutandis to the components of the DAC system 400 of FIG. 4.

[0203] The at least one gas-liquid contactor subsystem (e.g., the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 701) comprises at least one liquid collection device 124, 210, 310, 410, 710 in fluid communication with at least one of the wash section 203 and the capture sections 102A, 102B to produce a liquid stream. Referring to the example implementation of FIG. 1A, the at least one liquid collection device can be at least one bottom basin 210, the CO2-rich capture solution 107 and the CO2capture solution 106 flowing into the at least one bottom basin 210.

[0204] The liquid collection device 124, 210, 310, 410, 710 is configured to receive various streams including streams containing solids, such as slurries of the present disclosure, as solids may form in-situ in the at least one gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 701 which will be described further below. The liquid collection device 124, 210, 310, 410, 710 is configured to receive one or both of the CO2capture solution 106 and the CO2-rich capture solution 107 and to hold a volume thereof temporarily or for a longer duration, thereby serving as a source of the CO2 capture solution 106 and / or of the CO2-rich capture solution 107. The liquid collection device 210, 310, 410, 710 can have any configuration or be made of any material suitable to achieve the function ascribed to it in the present disclosure. For example, one or more of the liquid collection devices 124, 210, 310, 410, 710 can be open-topped, or partially or fully covered. In FIGS. 1B to 1D and 8, the at least one liquid collection device 210, 310, 410, 710 includes, or is in the form of, a basin. Other configurations of the liquid collection device are possible, such as a reservoir, a bed, a sheet, a pan, a culvert, a container, a receptacle, a network of pipes (e.g. pressurized pipes with openings or spray nozzles), or any other device capable of retaining liquid.

[0205] FIG.5A depicts an example DAC system 1400. The DAC system 1400 includes a gas-liquid contactor subsystem 501, a wash water regeneration subsystem 537, and a capture solution regeneration subsystem 1480. The capture solution regeneration subsystem 1480 is an example implementation of the capture solution regeneration subsystem 180 of FIGS. 1A to 4Attorney Docket No.: 30285-0051WO1 described herein. The capture solution regeneration subsystem 1480 of FIG. 5A is configured for regenerating a CO2 capture solution (e.g., the CO2 capture solution 106).

[0206] In implementations of the present disclosure, for example, in FIG. 1A, the gas- liquid contactor subsystem is, or includes, open reactor(s), in that the interior 113 is exposed to the environment surrounding the gas-liquid contactor subsystem 101 and freely exchanges gases therewith. Other configurations of the gas-liquid contactor system are possible, some of which are described below in greater detail.

[0207] For example, and referring to FIG. 5A, the gas-liquid contactor subsystem 501 is, or includes, closed reactors. One such reactor is, or includes, the capture section 502 of the gas- liquid contactor subsystem 501. The capture section 502 includes a capture section housing 520. The capture section housing 520 defines an interior 533 that is sealed from an exterior of the capture section 502. The interior 533 is fluidly separated from the external environment of the capture section housing 520 (e.g., fluidly separated from the atmosphere) such that fluid streams enter and exit the interior 533 only through specific access points in the capture section housing 520. The capture section housing 520 includes multiple inlets and outlets to allow of the ingress and egress of various gas, liquids, and other material into and out of the interior 533. For example, referring to FIG. 5A, the capture section housing 520 defines or includes one or more capture section liquid inlet(s) 520LI to receive the CO2 capture solution 106 in the interior 533. The capture section housing 520 defines or includes one or more capture section gas inlet(s) 520GI to receive the dilute gas source (e.g., the CO2-laden air 104) in the interior 533. The capture section housing 520 defines or includes one or more capture section gas outlet(s) 520GO to flow the CO2-lean gas stream 105 from the interior 533 to other components of the DAC system 1400 described below. The capture section housing 520 defines or includes one or more capture section liquid outlet(s) 520LO to flow the CO2-rich capture solution 107 from the interior 533 to other components of the DAC system 1400 described below.

[0208] Still referring to FIG. 5A, in implementations where the at least one CO2 capture species of the CO2capture solution 106 includes IPDA as the one or more capture species, the CO2capture solution 106 is flowed to the capture section liquid inlet(s) 520LI to contact the incoming CO2-laden air 104 flowing via the capture section gas inlet(s) 520GI into the capture section 502. CO2from the CO2-laden air 104 is absorbed by the CO2capture solution 106 and can react with IPDA to form carbamic acid species, e.g. being solids, according to the following reactions:Attorney Docket No.: 30285-0051WO1 (CH3)3C6H7(NH2)(CH2NH2) (aq) + H2O ↔ (CH3)3C6H7(NH3+)(CH2NH2)(aq)+ OH-(aq)CO2(g) ↔ CO2(aq) CO - - 2(aq) + OH(aq) ↔ HCO3 (aq) CO2(aq)+ (CH3)3C6H7(NH2)(CH2NH2) (aq) ↔ (CH3)3C6H7(NH2+COO-)(CH2NH2) (aq) (CH3)3C6H7(NH2+COO-)(CH2NH2) (aq) + (CH3)3C6H7(NH2)(CH2NH2) (aq) ↔ (CH3)3C6H7(NHCOO-)(CH2NH2) (aq) + (CH3)3C6H7(NH3+)(CH2NH2) (aq) (CH3)3C6H7(NHCOO-)(CH2NH2)(aq) + H2O ↔ (CH3)3C6H7(NHCOOH)(CH2NH2)(aq) + OH- (CH ) C H (NH+)(CH NH ) + HCO - 3 3 6 7 3 2 2 (aq) 3 (aq) ↔ (CH3)3C6H7(NHCOOH)(CH2 NH2) (s) + H2O

[0209] The overall reversible absorption-desorption reaction reads as follows:

[0210] Carbamate species may also be formed by reacting IPDA with CO2according to the following reactions: HCO - - 2- 3 (aq)+ OH(aq) ↔ CO3 (aq) 2 (CH3)3C6H7(NH3+)(CH2NH2)(aq)+ CO32-(aq)↔ (CH3)3C6H7(NHCOO-)(CH2NH2)(aq)+ (CH3)3C6H7(NH3+)(CH2NH2)(aq)+ H2O

[0211] In implementations where the at least one CO2 capture species of the CO2 capture solution 106 includes IPDA, the CO2-rich capture solution 107 can include solids resulting from in-situ solids formation in the gas-liquid contactor subsystem 501 and the CO2-lean gas stream 105 can entrain one or more o the following, in any combination: volatilized compounds of the CO2 capture solution 106 including IPDA, liquid aerosolized particles of the CO2 capture solution 106 including IPDA, and liquid aerosolized particles of the CO2-rich capture solution 107 including at least one of unreacted IPDA, carbamate species or carbamic acid species (the latter two being in solid or dissolved form). Referring to FIG. 5A, the gas-liquid contactor subsystem 501 includes the wash section 503 to reduce or remove the volatilized compounds and / or the aerosolizedAttorney Docket No.: 30285-0051WO1 particles in the CO2-lean gas stream 105. The wash section 503 is another closed reactor of the gas-liquid contactor subsystem 501. The interior of the wash section 503 is fluidly separated from its external environment (e.g., fluidly separated from the atmosphere) such that fluid streams enter and exit the interior only through specific access points in the wash section 503. In some implementations, the wash section 503 is a reactor that is separate from another reactor of the gas- liquid contactor subsystem 501, specifically, the capture section 502. In some implementations, the wash section 503 is spaced apart from the capture section 502. In some implementations, the wash section 503 is enclosed in a housing that is separate from the capture section housing 520. In some implementations, the wash section 503 is positioned in the environment that is external to the capture section housing 520. Referring to FIG. 5A, the wash section 503 is positioned downstream of the capture section 502, and in fluid communication with the capture section 502. This allows the CO2-lean gas stream 105 to flow from the capture section gas outlet(s) 520GO to the wash section 503. In implementations of the present disclosure, for example as shown in FIG. 5A, the gas-liquid contactor subsystem 501 includes separate gas-liquid reactors in fluid communication with each other. The capture section 502 and the wash section 503 of FIG. 5A function similar to the capture section 102A, 102B, 302A, 302B, 402 and the wash section 103A, 103B, 303, 403, respectively, described above. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the capture section 102A, 102B, 302A, 302B, 402 of FIGS. 1A to 4 apply mutatis mutandis to the capture section 502 of FIG. 5A. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the wash section 103A, 103B, 303, 403 of FIGS. 1A to 4 apply mutatis mutandis to the wash section 503 of FIG. 5A.

[0212] Referring to FIG. 5A, the wash water regeneration subsystem 537 includes a water separation unit 505 which functions to regenerate the used wash water stream 504 and return regenerated wash water to the wash section 503. The wash section 503 is fluidly coupled to the water separation unit 505 such that the used wash water stream 504 from the wash section 503 flows into the water separation unit 505. In implementations where the CO2capture solution 106 includes IPDA as at least one capture species for capturing CO2, the used wash water stream 504 flowing from the wash section 503 includes, among other compounds, at least one of unreacted IPDA, corresponding carbamate species and corresponding carbamic acid species in accordance with IPDA-related chemical reactions described above. The water separation unit 505 functions toAttorney Docket No.: 30285-0051WO1 produce a permeate water product stream 507 (i.e., regenerated wash water) that is returned to the wash section 503. The water separation unit 505 functions to produce a retentate stream 509 containing, for example, at least one of IPDA, corresponding carbamate species, corresponding carbamic acid species and possibly other compounds, which is flowed directly to the capture section 502 and / or to be combined with the liquid stream(s) comprising the CO2 capture solution 106 used in the capture section 502. The water separation unit 505 can have different configurations or implementations to achieve the functionality ascribed to it herein. In example implementations, the water separation unit 505 is, or includes, a reverse osmosis (RO) unit to form an RO retentate stream (e.g., the retentate stream 509) comprising the at least one CO2 capture species, dissolved or undissolved CO2reaction products, etc., and to form an RO permeate stream (e.g., the permeate water product stream 507) comprising the regenerated wash water. Referring to FIG.5A, the wash water regeneration subsystem 537 (and / or other subsystems 501, 1480 of the DAC system 1400) includes one or more pump(s) to flow the liquid streams to and from the water separation unit 505. Other configurations of the water separation unit 505 are possible. The water separation unit 505 may be, or include, any one of the following components, in any combination: a spiral wound membrane or a tubular membrane, a hydrocyclone unit, an ultrafiltration unit, a microfiltration unit, a nanofiltration unit, or other comparable unit to produce the permeate water product stream 507 and the retentate stream 509.

[0213] Referring to FIG. 5A, in example implementations where the at least one CO2 capture species of the CO2capture solution 106 includes IPDA, the CO2-rich capture solution 107 produced in the capture section 502 may contain undissolved solids produced by reacting CO2in the CO2-laden air 104 with IPDA according to chemical reactions including the ones described above. For example, such solids may include at least one of carbamate solids and carbamic acid solids. In such example implementations, the CO2-rich capture solution 107 may be a slurry, and it may be desirable to separate the solids therein from the remaining liquid. In example implementations, and referring to FIG. 5A, this can be achieved by flowing the CO2-rich capture solution 107 to a separation unit 513. At the separation unit 513, at least a portion of the liquid of the CO2-rich capture solution 107 is removed. In some implementations, depending on the nature of the dissolved compounds and / or undissolved compounds of the CO2-rich capture solution 107, the separation unit 513, can include a solid-liquid separation unit. In some implementations, the separation unit 513 includes, but is not limited to, a hydrocyclone unit, an ultrafiltration unit, aAttorney Docket No.: 30285-0051WO1 microfiltration unit, a settling bed, a flotation bed or other comparable unit that can separate the CO2 capture solution 106 from the CO2-rich capture solution 107. The CO2 capture solution 106 separated at the separation unit 513 is flowed to the gas-liquid contactor subsystem 501 to be used in the CO2capture process. The separation unit 513 also produces a product stream 515 that can be processed as described below.

[0214] In example implementations, the separation unit 513 is, or includes, a filtration unit that functions to produce a retentate stream comprising a slurry (e.g., the product stream 515). The filtration unit also functions to produce a permeate stream (e.g., a stream of the CO2 capture solution 106) that can be flowed to the capture section liquid inlet(s) 520LI directly, or indirectly via a buffer or storage vessel.

[0215] Other configurations or implementations of the separation unit 513 are possible. For example, and referring to FIG. 5B, the separation unit 513 includes, or is in fluid communication with, another reactor that processes at least a portion of the CO2 capture solution 106 flowing from the separation unit 513. Such a reactor in FIG. 5B is referred to as a capture solution reverse osmosis (RO) unit 506, which processes a slipstream 106S of the CO2 capture solution 106 before flowing liquid streams to both the capture section 502 and to the wash section 503. The capture solution reverse osmosis (RO) unit 506 can be, but is not limited to, a high- pressure reverse osmosis unit. The capture solution reverse osmosis (RO) unit 506 produces a capture solution retentate stream 535 comprising the at least one CO2 capture species and / or dissolved CO2reaction products. Referring to FIG. 5B, one or more pump(s) in the DAC system 1400 can flow the capture solution retentate stream 535 directly to the capture section liquid inlet 520LI, or indirectly via a buffer or storage vessel. The capture solution reverse osmosis (RO) unit 506 also produces a wash water permeate stream 539 comprising regenerated wash water. Referring to FIG. 5B, one or more pump(s) in the DAC system 1400 can flow the wash water permeate stream 539 directly to the wash section 503, or indirectly via a buffer or storage vessel of the wash water regeneration subsystem 537.

[0216] In some implementations, the capture solution reverse osmosis (RO) unit 151, 506 of the present disclosure can be substituted with any osmosis assisted water recovery unit, such as a forward osmosis unit.

[0217] In implementations where the CO2capture solution 106 includes IPDA as the at least one CO2capture species, the product stream 515 may be a slurry where at least one of aAttorney Docket No.: 30285-0051WO1 carbamate species and carbamic acid species is suspended, settled, or dissolved / dispersed in solvent (e.g., Water, DMSO, Methanol). The carbamate species and / or carbamic acid species may be, but is not limited to, the intermediate and product species formed from the chemical reactions between CO2and IPDA, including the chemical reactions described above. A transition from intermediate species to product species can be dependent on factors that can be, but are not limited to, a carbon loading value. In one example configuration, the carbon loading value of the CO2-rich capture solution 107 may be within a range of 0.1 to 1.0 mol of total inorganic carbon per mol of CO2 capture species (e.g., IPDA).

[0218] Referring to FIG. 5A, the product stream 515 generated by the separation unit 513 is flowed to the capture solution regeneration subsystem 1480, or to a unit thereof such as a regeneration reactor. In some implementations, referring to FIG. 5A, the regeneration reactor is a stripper 517. In example implementations, at the stripper 517, the product stream 515 is heated to liberate CO2 from the product stream 515, thereby forming a CO2-rich gas stream 590 and a CO2- depleted liquid stream 524. The CO2-rich gas stream 590 is subsequently flowed through a condenser 521 (e.g., a chiller) to produce a condensed stream 591 of high-concentration CO2 and a condensed water stream 522. The condensed water stream 522 can flow to the stripper 517. The condensed stream 591 is further flowed to a compressor 523 as illustrated, to form the CO2product stream 525. The CO2-depleted liquid stream 524 has a composition that is substantially similar to the CO2 capture solution 106 that results from removing the CO2 from the product stream 515. In example implementations where IPDA is used as the at least one CO2capture species, the CO2- depleted liquid stream 524 may include IPDA. In some implementations, the CO2-depleted liquid stream 524 is flowed through a reboiler 529 to remove any residual CO2 that is flowed back to the stripper 517 as stream 526 and to produce a stream of regenerated CO2 capture solution 106 that is flowed back to the capture section 502. In example implementations, referring to FIGS.5A and 5B, heat from the regenerated CO2 capture solution 106 can be recovered in a heat exchanger 519 as further detailed below. In example implementations, and referring to FIGS.5A and 5B, a make- up stream 531 may be configured to provide additional CO2capture solution and flow into the retentate stream 509 flowing into the capture section 502.

[0219] In example implementations, and referring to FIG. 5A, the product stream 515 entering the stripper 517 may be pre-heated to reduce the duty of the reboiler 529. The capture solution regeneration subsystem 1480 (and / or the gas-liquid contactor subsystem 501, or the DACAttorney Docket No.: 30285-0051WO1 system 1400) includes the heat exchanger 519. The heat exchanger 519 transfers heat from the regenerated CO2 capture solution 106 flowing from the reboiler 529 to the product stream 515 flowing from the separation unit 513.

[0220] By sending a slurry in the form of the product stream 515 to the regeneration reactor (e.g., the stripper 517), the slurry is heated to form the regenerated CO2 capture solution 106 and the CO2-rich gas stream 590 as described above. When compared to thermally regenerating solids with very little moisture content (if any), thermally regenerating the solids of the product stream 515 may allow for improved regeneration of the at least one CO2 capture species (e.g., IPDA), and / or formation of the CO2 product stream 525. In example implementations, the stripper 517 receives a pumpable slurry product stream 515 with higher liquid content than a dried filter cake, where solids may be settled or dispersed within the slurry product stream 515. The description, units, componentry, features, streams, reference numbers and advantages of a regeneration reactor 1507 and its variants, as described below in relation to FIG. 6, apply mutatis mutandis to relevant componentry of the capture solution regeneration subsystem 1480 including, but not limiting to, the stripper 517 of FIG. 5A.

[0221] In one example implementation, the concentration of the solids (e.g., carbamate species and / or carbamic acid species) may be within a range of 10-50% with respect to a total mass of the product stream 515. In another example implementation, the concentration of the solids (e.g., carbamate species and / or carbamic acid species) may be within a range of 15-25% with respect to a total mass of the product stream 515. In another example implementation, the concentration of the solids (e.g., carbamic acid species) may be greater than 30 wt% with respect to a total mass of the product stream 515. Vacuum stripping, steam stripping or other comparable gas evolution techniques may be used at the stripper 517 for CO2 recovery.

[0222] The description, functionality, reference numbers and advantages of the units, componentry, or features shown in FIG.5A apply mutatis mutandis to similar units, componentry, or features shown in FIG. 5B.

[0223] Different configurations of the capture solution regeneration subsystem 180are possible and within the scope of the present disclosure, and some of these are described in greater detail. In each configuration, the capture solution regeneration subsystem 180functions to process the CO2-rich capture solution 107 (e.g., spent capture solution) to form regenerated CO2capture solution 106 that is flowed back to the gas-liquid contactor subsystem 101, 101B, 101C, 101D,Attorney Docket No.: 30285-0051WO1 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 and also recover and / or concentrate the CO2content laden in the CO2-laden capture solution 107 to form a concentrated carbon stream, for example, CO, the CO2 product stream 125, 525, or other carbon products. The capture solution regeneration subsystem 180 can be in fluid communication with the liquid collection device 124, 210, 310, 410, 710 of the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 to receive the CO2-laden capture solution 107. Referring to FIG. 1A, the capture solution regeneration subsystem 180 can be in fluid communication for example, with a top basin 129 of the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 to flow thereto the regenerated CO2 capture solution 106.

[0224] FIG. 6 depicts an example DAC system 1500 including an example configuration of a capture solution regeneration subsystem 1580. The DAC system 1500 includes a gas-liquid contactor subsystem 1501 (having some or all of the components of the gas-liquid contactor subsystems 101, 101A, 101B, 101C, 101D, 201, 301, 401, 501 of FIGS. 1A-5B) and the capture solution regeneration subsystem 1580. The capture solution regeneration subsystem 1580 of FIG. 6 is configured for regenerating a CO2 capture solution (e.g., the CO2 capture solution 106). The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101, 101A, 101B, 101C, 101D, 201, 301, 401 of FIGS.1A to 4 apply mutatis mutandis to the gas-liquid contactor subsystem 1501 of FIG. 6.

[0225] The gas-liquid contactor subsystem 1501 generates the CO2-rich capture solution 107 and can flow the CO2-rich capture solution 107 to the capture solution regeneration subsystem 1580 based, for example, on the control logic of the solids sensor 160 and the function of the capture solution control valve 182 of the gas-liquid contactor subsystem 1501. In implementations where the CO2 capture solution 106 includes an amine-based capture species, the CO2 in the CO2- laden air 104 reacts with the amine-based capture species to form the CO2-rich capture solution 107, and in some examples, solid precipitates, an example of which is carbamate species and / or carbamic acid species. In one implementation, depending on the composition of the CO2-capture solution 106, solid precipitates may be formed within the gas-liquid contactor subsystem 1501. In another implementation, the solid precipitates may be formed independent of the gas-liquid contactor subsystem 1501. The capture solution regeneration subsystem 1580 can include at leastAttorney Docket No.: 30285-0051WO1 a concentrator 1505, a heat exchanger 1509, and a regeneration reactor 1507. The CO2-rich capture solution 107 can include solids (e.g., carbonate solids and / or carbamic acid solids) and be in the form of a slurry. The slurry is flowed to the concentrator 1505, which functions to increase the concentration of the solids by separating solids from liquids. A slurry stream 1521 is generated by the concentrator 1505. The slurry stream 1521 includes a higher concentration of solids than the concentration of solids in the CO2-rich capture solution 107. At least some of the liquid separated from the CO2-rich capture solution 107 by the concentrator 1505 forms a separated liquid stream 1523, which can include unreacted capture species from the CO2 capture solution 106. The separated liquid stream 1523 is flowed back to any suitable component or unit of the gas-liquid contactor subsystem 1501.

[0226] Referring to FIG.6, the slurry stream 1521 flows to the heat exchanger 1509, where thermal energy from a regenerated, CO2-lean capture solution 1511 is transferred to the slurry stream 1521, as described below. The heated slurry stream 1521 flows from the heat exchanger 1509 to the regeneration reactor 1507. The heat exchanger 1509 may be considered a preheat heat exchanger that heat integrates a concentrated slurry (e.g., the slurry stream 1521) with a higher temperature regenerated capture solution (e.g., the CO2-lean capture solution 1511). In example implementations, the solids in the heated solids slurry stream 1521 are at least partially regenerated in the heat exchanger 1509 or downstream thereof, releasing CO2, prior to entering the regeneration reactor 1507. In example implementations, the heat exchanger 1509 is upstream of the concentrator 1505, relative to a flow direction of the CO2-rich capture solution 107 from the gas- liquid contactor subsystem 1501 to the concentrator 1505. In such implementations, the heat exchanger 1509 functions to transfer thermal energy from the CO2-lean capture solution 1511 to the CO2-rich capture solution 107 before it undergoes solid-liquid separation in the concentrator 1505. In transferring thermal energy to streams entering the regeneration reactor 1507, the heat exchanger 1509 helps to reduce the duty of the regeneration reactor 1507 in implementations where the regeneration reactor 1507 uses heat to regenerate the CO2-rich capture solution 107. In other implementations, the capture solution regeneration subsystem 1580 does not have a heat exchanger.

[0227] In implementations where the regeneration reactor 1507 is, or includes, a packed column, the heated slurry stream 1521 flows through packing 1503 within the regeneration reactor 1507. A regeneration heater 1506 supplies a source of heat, such as a stream of heated gas 1517Attorney Docket No.: 30285-0051WO1 (e.g., steam), which contacts the heated slurry stream 1521 flowing along the packing 1503. In example implementations, the regeneration reactor 1507 includes one or more nozzles for flowing the heated slurry stream 1521 onto the packing 1503. In alternate example implementations, the regeneration reactor 1507 includes a column with trays instead of, or in addition to, the packing column. In example implementations, the packing 1503 is non-structured (e.g., random packing).

[0228] By contacting the heated slurry stream 1521 and its solids (e.g., carbonate solids and / or carbamic acid solids) with the stream of heated gas 1517, the CO2-lean capture solution 1511 (e.g., regenerated CO2 capture solution 106) is generated and a CO2 gas 1519 is desorbed. The CO2-lean capture solution 1511 collects at the bottom of the regeneration reactor 1507. Referring to FIG. 6, the CO2-lean capture solution 1511 is at a relatively high temperature and is flowed to the heat exchanger 1509 to transfer at least some of its thermal energy to the slurry stream 1521 flowing from the concentrator 1505, as described above. In implementations where the capture solution regeneration subsystem 1580 does not have a heat exchanger, the CO2-lean capture solution 1511 is flowed directly to one or more components of the gas-liquid contactor subsystem 1501 and reused in the gas-liquid contactor subsystem 1501 for CO2 capture.

[0229] The CO2 gas 1519 is released from the regeneration reactor 1507 along with water vapor 1518 via a gas discharging line. The mixed gas stream (CO2gas 1519 and water vapor 1518) flow from the regeneration reactor 1507 to a condenser 1508. Depending on the capture species of the CO2 capture solution 106, the mixed gas stream can also include volatile amines / organics. The condenser 1508 condenses the water vapor 1518 (and the volatile amines / organics), forms a water stream 1520 (which can have condensable amines / organics), and separates the CO2 gas 1519 from the water stream 1520. The CO2 gas 1519 is released from the condenser 1508 as the CO2 product stream 1525. The CO2 product stream 1525 can be treated or processed as desired, such as by being compressed. The compressed CO2product stream 1525, either directly or after processing, can be provided for use as desired, or for export. In example implementations, the condensed water stream 1520 flows from the condenser 1508 to the regeneration heater 1506 to be used to generate the stream of heated gas 1517 in the regeneration reactor 1507. In example implementations, the condensed water stream 1520 flows directly to the heat exchanger 1509.

[0230] Other configurations for the regeneration reactor 1507 are possible. For example, in some configurations, the regeneration reactor 1507 does not include a packed column and isAttorney Docket No.: 30285-0051WO1 thus free of packing. In such a configuration, the regeneration reactor 1507 can be, or can include, any one of the following non-limiting examples of reaction vessels: a tubular reactor, a continuous stirred tank reactor (CSTR) in which reagents, reactants, and solvents flow into the reactor while the products of the reaction concurrently exit the vessel, or a fluidized-bed reactor. In implementations where the regeneration reactor 1507 is, or includes, a tubular reactor, the tubular reactor can have an internal heating device (e.g., an electric heating element) and / or an external heating device (e.g., a heating jacket), inlet and outlet ports, and a phase separator or other suitable outlet to permit CO2 to degas from the tubular reactor. In implementations where the regeneration reactor 1507 is, or includes, a CSTR, the CSTR can have an internal heating device (e.g., an electric heating element) and / or an external heating device (e.g., a heating jacket), a mixing element (such as a rotor and / or baffles), inlet and outlet ports, and a phase separator or other suitable outlet to permit CO2 to degas from the CSTR. In implementations where the regeneration reactor 1507 is, or includes, a fluidized-bed reactor, the slurry stream 1521 can enter the fluidized-bed reactor from a top of the reactor, and a heating medium (e.g., steam) can be heated externally and flowed to the fluidized-bed reactor to fluidize the bed of solids and transfer heat thereto. The fluidized-bed reactor can have a distribution plate or mesh at a bottom thereof to support the solids being fluidized. The fluidized-bed reactor can also have inlet and outlet ports, and a phase separator or other suitable outlet to permit CO2 to degas from the fluidized-bed reactor.

[0231] Other configurations for the regeneration reactor 1507 are possible. For example, in some implementations, the regeneration reactor 1507 subjects the slurry stream 1521 to elevated pressure within the regeneration reactor 1507. This pressurized regeneration can liberate CO2gas from the solids in the slurry stream 1521 while reducing downstream compression for stream 591. The liberated CO2 gas can flow for subsequent clean-up, treatment and / or processing as described herein. For example, in implementations where the at least one CO2capture species of the CO2capture solution 106 includes IPDA, the CO2-rich capture solution 107 may contain undissolved solids produced by reacting CO2 in the CO2-laden air 104 with IPDA. Such solid precipitates may include carbamic acid species. It may be possible to regenerate these solids in the pressurized environment of this implementation of the regeneration reactor 1507.

[0232] FIG. 7 depicts another example DAC system 600 including another example configuration of a capture solution regeneration subsystem 680. Some or all of the CO2-rich capture solution 107 can flow to an electrochemical system that includes a cell stack, which canAttorney Docket No.: 30285-0051WO1 include a set of one or more membranes, and a set of electrodes. The electrochemical system can regenerate the CO2 capture solution 106 from the CO2-rich capture solution 107 by applying an electric potential to an electrolyte including carbon-containing species from the CO2-rich capture solution 107. The difference in electric potential causes ionic exchange, thereby forming the CO2product stream 625 and the regenerated CO2 capture solution 106. The capture solution regeneration subsystem 680 is an example implementation of the capture solution regeneration subsystem 180 of FIG. 1A, FIG. 2, FIG. 3 and FIG. 4 described herein. The capture solution regeneration subsystem 680 of FIG. 7 is configured to regenerate a CO2-rich sorbent (e.g., the CO2-rich capture solution 107) received from a CO2 capture subsystem 601 (having some or all of the components of the gas-liquid contactor subsystem 101, 101A, 101B, 101C, 101D, 201, 301, 401, 501). The gas-liquid contactor subsystem 601 is fluidly coupled to a products generation subsystem 606 via a carbonate separation subsystem 604. The gas-liquid contactor subsystem 601 provides the CO2-rich capture solution 107 to the carbonate separation subsystem 604. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501 of FIG. 1A, FIG. 2, FIG. 3, FIG. 4 and FIGS. 5A-5B apply mutatis mutandis to the gas-liquid contactor subsystem 601 of FIG. 7.

[0233] The CO2-rich capture solution 107 can be an aqueous mixture comprising primarily carbonate ions, alkaline metal carbonate (e.g., K2CO3, Na2CO3), or a combination thereof. The CO2-rich capture solution 107 can also include other compounds in smaller amounts, such as hydroxide ions, alkali metal hydroxide (e.g., KOH, NaOH), water, and impurities. For example, the CO2-rich capture solution 107 can comprise between 0.4 M to 6 M K2CO3 and between 1 M to 10 M KOH. In example implementations, the CO2-rich capture solution 107 can comprise an aqueous Na2CO3—NaOH mixture. In example implementations, the CO2-rich capture solution 107 can comprise a mixture of K2CO3 and Na2CO3.

[0234] In example implementations, the carbonate separation subsystem 604 can include a caustic evaporator or a crystallizer (or both). In example implementations, the carbonate separation subsystem 604 can include a nanofiltration unit or a crystallizer (or both). The carbonate separation subsystem 604 yields a crystalline carbonate hydrate 614. Crystalline carbonate hydrate 614 can include carbonate sesquihydrate (M2CO3·1.5 H2O) or an anhydrous carbonate. For example, crystalline carbonate hydrate 614 can include potassium carbonateAttorney Docket No.: 30285-0051WO1 sesquihydrate (K2CO3·1.5 H2O). In some examples, the crystalline carbonate hydrate 614 can include sodium carbonate decahydrate (Na2CO3·10 H2O). In some examples, the crystalline carbonate hydrate 614 can include potassium sodium carbonate hexahydrate (KNaCO3·6 H2O). In example implementations, the crystalline carbonate hydrate 614 can include a different stoichiometry of water molecules per unit carbonate in the crystalline carbonate (e.g., M2CO3·n H2O where M is an alkali metal and n is an integer or fractional value).

[0235] The products generation subsystem 606 receives the crystalline carbonate hydrate 614. In example implementations, the products generation subsystem 606 includes a dissolving tank 608 fluidly coupled to an electrochemical cell 610. In example implementations, the products generation subsystem 606 can include a caustic evaporator.

[0236] The dissolving tank 608 can receive crystalline carbonate hydrate 614 from the carbonate separation subsystem 604, a water stream 620 and a brine stream 622. In example implementations, a polished aqueous solution can be used instead of or in addition to the water stream 620. A polished aqueous solution can be substantially free of particulates and dissolved contaminants. The crystalline carbonate hydrate 614 dissolves in water and combines with bicarbonate HCO3−in brine stream 622 to form a feed solution 616. The feed solution 616 can include a bicarbonate HCO3−-rich solution with a mixture of other compounds such as carbonate and water.

[0237] The electrochemical cell 610 receives the feed solution 616 and a water stream 620. The electrochemical cell 610 yields at least two product streams including a first product stream 626 that comprises a hydroxide (regenerated CO2capture solution 106) and is returned to the gas- liquid contactor subsystem 601 for reuse. The second product stream 628 is sent to a flash tank 612 where the gaseous CO2 product stream 625 is partially or fully released from the flash tank 612 and sent to one or more downstream processing units (e.g., compression unit, electroreduction subsystem, carbon products manufacturing system, syngas generation reactor). For further details and alternate implementations, reference is made to the patent application entitled “Systems and methods for capturing carbon dioxide and regenerating a capture solution” and published as US 2022 / 0362707 A1, the entire contents of which are incorporated by reference herein.

[0238] FIG. 8 depicts another example DAC system 700 including another example configuration of a capture solution regeneration subsystem 780. The DAC system 700 includes a gas-liquid contactor subsystem 701 (having some or all of the components of the gas-liquidAttorney Docket No.: 30285-0051WO1 contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 601), and the capture solution regeneration subsystem 780. The capture solution regeneration subsystem 780 is an example implementation of the capture solution regeneration subsystem 180 of FIG. 1A, FIG. 2, FIG. 3 and FIG.4 described herein. The capture solution regeneration subsystem 780 of FIG. 8 is configured for regenerating a CO2 capture solution (e.g., the CO2 capture solution 106). The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 201, 301, 401, 501 of FIGS. 1A to 5B apply mutatis mutandis to the gas-liquid contactor subsystem 701 of FIG. 8.

[0239] The CO2-rich capture solution 107 flows from the gas-liquid contactor subsystem 701 to a pellet reactor 711 of the capture solution regeneration subsystem 780. A slurry of calcium hydroxide 724 is injected into the pellet reactor 711. A reaction between the CO2-rich capture solution 107 and the calcium hydroxide Ca(OH)2 occurs in the pellet reactor 711. Ca2+reacts with CO32-in the pellet reactor 711 to form calcium carbonate solids and an aqueous alkaline solution as the CO2 capture solution 106 (such as hydroxide), thereby regenerating the CO2 capture solution 106. For example, potassium carbonate in the CO2-rich capture solution 107 can react with calcium hydroxide to form calcium carbonate and potassium hydroxide, thereby regenerating the CO2 capture solution 106 that includes potassium hydroxide.

[0240] The reaction of the CO2-rich capture solution 107 with Ca(OH)2 causes precipitation of calcium carbonate (CaCO3) onto calcium carbonate particles in the pellet reactor 711. Further processing of the calcium carbonate solids, including but not limited to filtering, dewatering or drying, can occur prior to sending the calcium carbonate solids to downstream process units. A stream 714 of calcium carbonate solids is transported from the pellet reactor 711 to a calciner 716 of the capture solution regeneration subsystem 780. The calciner 716 calcines the calcium carbonate of the stream 714 from the pellet reactor 711 to produce a stream of gaseous CO2718 and a stream of calcium oxide (CaO) 720, possibly by oxy-combustion of a fuel source in the calciner 716. The stream of gaseous CO2718 is processed for sequestration or other uses, thereby removing some of the CO2 from the CO2-laden air 104 processed in the gas-liquid contactor subsystem 701. The stream of gaseous CO2718, either directly or after processing, can be provided as a CO2product stream for use as desired, or for export. The stream of calcium oxide (CaO) 720 is slaked with water in a slaker 722 of the DAC system 700 to produce the slurry ofAttorney Docket No.: 30285-0051WO1 calcium hydroxide 724 that is provided to the pellet reactor 711. In example implementations, the slaker 722 is configured to react quicklime (e.g., (CaO) 720) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH)2) 724. The low carbonate content fluid includes at least one of liquid water or steam. An amount of carbonate in the water includes less than 0.1 moles of carbonate for every 1 mole of CaO 720 delivered to the slaking process. A fluidized-bed reactive crystallizer (e.g., pellet reactor 711) is in fluid communication with the slaker 722 and is configured to react the Ca(OH)2724 with an alkaline carbonate solution and grow calcium carbonate (CaCO3) crystal aggregates of between 0.0005 mm3to 5 mm3volume.

[0241] In example implementations, the CO2 capture solution 106 can be regenerated using a different capture solution regeneration subsystem 780. The capture solution regeneration subsystem 780 can be part of the gas-liquid contactor subsystem 701 or separate therefrom.

[0242] The capture solution regeneration subsystem 780 can include liquid distribution pipes, solids conveying equipment, filtration systems, intermediate components like storage vessels, and / or an assembly of components which function cooperatively to regenerate the CO2capture solution 106. The capture solution regeneration subsystem 780 also includes pumps which flow liquids to and from the capture solution regeneration subsystem 780.

[0243] The stream 714 of calcium carbonate solids of the DAC system 700 that is calcined in the calciner 716 can be produced according to other techniques for capturing CO2 from the CO2- laden air 104. For example, in one implementation, the gas-liquid contactor subsystem 701 of the DAC system 700 uses a liquid sorbent, and a carbonate-forming reactor which receives the CO2- rich capture solution 107 and includes one or more reactors similar to those used in the Kraft pulping process to form calcium carbonate solids. In some examples, the DAC system 700 is free of a causticization process, and the gas-liquid contactor subsystem 701 of the DAC system 700 uses a liquid sorbent such as a calcium hydroxide slurry and contacts it with air to form the stream 714 of calcium carbonate solids which are then calcined.

[0244] FIGS. 9 and 10 depict another example DAC system 800, 900 including another example configuration of a capture solution regeneration subsystem 880, 908. In some implementations, referring to FIGS. 9 and 10, the capture solution regeneration subsystem 880, 980 relies on other regeneration pathways that can be used when solids formation occurs in-situ, i.e., at least in part in the gas-liquid contactor subsystem 801, 901. The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associatedAttorney Docket No.: 30285-0051WO1 with the gas-liquid contactor subsystems 101, 101A, 101B, 101C, 101D, 201, 301, 401, 501 of FIGS. 1A to 5B apply mutatis mutandis to the gas-liquid contactor subsystems 801, 901 of FIGS. 9 and 10.

[0245] In an example implementation of a DAC system 1800 including a regeneration subsystem 880, referring to FIG. 9, some or all of the CO2-rich capture solution 107 can flow to a thermal regeneration unit 894 that employs a heat source to desorb CO2 from the solids of the CO2- rich capture solution 107, thereby forming the CO2product stream 194 and regenerated CO2capture solution 106.

[0246] The DAC system 1800 includes the gas-liquid contactor subsystem 801 that is operated for contacting CO2from the dilute gas source (e.g., CO2-laden air 104) with the CO2capture solution 106 comprising at least one capture species being a guanidine, for example, 2,5- furan-bis-(iminoguanidine) (FuBIG), to form the CO2-rich capture solution 107 and the CO2-lean gas stream 105. Inside the gas-liquid contactor subsystem 801, the at least one capture species reacts with the absorbed CO2from the CO2-laden air 104 such that solid carbonate precipitates out of the CO2 capture solution, thereby forming the CO2-rich capture solution 107. For example, the CO2-rich capture solution 107 contains FuBIG carbonate solids as the reaction between CO2 and FuBIG results in the formation of a hydrated solid FuBIGH2(CO3)·(H2O)4(s). More particularly, absorption of CO2 and further reaction of absorbed CO2 with the at least one capture species being FuBIG is based on the following reaction scheme: FuBIG(s)↔ FuBIG(aq)FuBIG(aq)+ 2 H2O ↔ FuBIGH22+(aq)+ 2OH-(aq)CO2(g) ↔ CO2(aq) CO + OH- ↔ HC - 2(aq) (aq) O3 (aq) (s)reads as follows: FuBIG(s) + CO2(g)+ 5 H2O ↔ FuBIGH2(CO3)(H2O)4(s)

[0248] The CO2-rich capture solution 107 can be defined as a slurry that includes the FuBIG carbonate solids, unreacted FuBIG and excess water flowing through the gas-liquid contactor subsystem 801. In some implementations, the gas-liquid contactor subsystem operates at ambient temperature and atmospheric pressure. In some implementations, when guanidiniumAttorney Docket No.: 30285-0051WO1 ions are the at least one capture species, such as FuBIGH22+(aq), absorption is operated in the gas- liquid contactor subsystem 801 at a loading of CO2 of at most 0.40 moles of CO2 absorbed per liter of CO2 capture solution 106. In some implementations, when guanidinium ions are the at least one capture species, such as FuBIGH22+(aq), absorption is operated in the gas-liquid contactor subsystem 801 at a loading of CO2 of between 0.05 moles and 0.40 moles of CO2 absorbed per liter of CO2 capture solution 106. In some implementations, when guanidinium ions are the at least one capture species, such as FuBIGH22+(aq), absorption is operated in the gas-liquid contactor subsystem 801 at a loading of CO2 of between 0.20 moles and 0.35 moles of CO2 absorbed per liter of CO2 capture solution 106. Depending on the concentration of the at least one capture species in the CO2-capture solution 106, the conversion of the capture species into solid carbonates can be between 50% and 99%, for example between 70% and 97%, or for example between 75% and 95%. In an example implementation where an aqueous solution of FuBIG is used as the CO2- capture solution 106, a molar concentration of the CO2-capture solution 106 can be between 0.05 M and 1 M, for example between 0.25 M and 0.50 M.

[0249] If not processed, the produced CO2-lean gas stream 105 can contain volatilized compounds and / or aerosolized particles of at least the CO2 capture solution 106 / CO2-rich capture solution 107. In some implementations, makeup water can be supplied to the gas-liquid contactor subsystem 801 (such as in a wash section of the present disclosure) that would scrub entrained FuBIG from the produced CO2-lean gas stream 105 before exiting the gas-liquid contactor subsystem 801, thereby reducing a CO2-capture solution makeup rate and reducing capture species (e.g., FuBIG) makeup costs accordingly. Accordingly, the wash section 103A, 103B, 303, 403, 50X of the present disclosure apply mutatis mutandis to the gas-liquid contactor subsystem 801of FIG. 9.

[0250] Still referring to the example implementation of FIG. 9, the CO2-rich capture solution 107 (slurry) undergoes a separation or filtration step in a separation unit 890 that removes carbonate solids from the remaining water and unreacted capture species in solution, e.g., FuBIGH22+(aq)as part of a permeate stream 145. In some implementations, the separation unit 890 can be a horizontal belt vacuum filter. In some implementations, the separation unit 890 includes multiple filters being operated in parallel to accommodate a flowrate of the slurry exiting the gas- liquid contactor subsystem 801. In some implementations, the separation unit 890 is a filtration unit 890, and the CO2-rich capture solution 107 is pumped to the filtration unit 890 including atAttorney Docket No.: 30285-0051WO1 least one of a filter press, a centrifuge, a cyclone or other liquid-solid separation device. The carbonate solids are recovered as a retentate component or stream 144 that has a moisture content between 5 and 70 wt%, for example between 10 and 30 wt%.

[0251] In some implementations, the retentate component / stream 144 is flowed / conveyed to a dewatering unit 891 to reduce or remove moisture / water from the retentate component / stream 144 and produce a dewatered retentate 146. In some implementations, the dewatering unit 891 is, or includes, a dryer and the recovered water exits the dewatering unit 891 as a vapor stream 148 comprising vaporized CO2 capture solution 106 / CO2-rich capture solution 107, which upon being further condensed, for example by passing through a heat exchanger 892, can be flowed, directly or indirectly, as at least part of a liquid stream 152 to the gas-liquid contactor subsystem 801. In the example implementation, the dewatered retentate 146 includes the FuBIG carbonate solids.

[0252] In some implementations, the dewatered retentate 146 is further subjected to a thermal regeneration step that produces a stream of CO2 saturated with water vapor. In the example implementation of FIG. 9, depending on the water content of the dewatered retentate 146, it may be flowed or conveyed to a thermal regeneration unit 894, being for example a thermal stripping column, that employs steam or other sources of thermal heat such as glycol. Upon being heated, the FuBIG carbonate solids liberate CO2, thereby regenerating the FuBIG capture species as part of a regenerated capture species stream 196. Hydration water of the FuBIG carbonate solids is also liberated upon heating the solids and vaporized so as to form a stream of CO2 saturated with water vapor, being referred to as a CO2-containing product stream 190.

[0253] The CO2-rich gas stream 190 is supplied to a separation assembly 896 to recover the CO2 from the CO2-rich gas stream 190. In some implementations, the separation assembly 896 can include a cooling unit (e.g., heat exchanger) for condensing vapor (e.g., water) from the CO2- rich gas stream 190 and a gas / liquid separation unit (e.g, a knockout vessel) for separating recovered condensed water 192 and a CO2-containing product stream 194. The gas / liquid separation unit is sized to have adequate height for liquid disengagement of condensed water droplets from the bulk gaseous CO2. For example, a vertical vessel with hemispherical heads can be used. In some implementations, the gas / liquid separation unit can include one or more knockout vessels being operated in series or parallel.Attorney Docket No.: 30285-0051WO1

[0254] In some implementations, the separation assembly 896 includes a blower flowing the CO2-rich gas stream 190 from the thermal regeneration unit 894 to the cooling unit of the separation assembly 896.

[0255] In some implementations, the thermal regeneration unit 894 has dewatering functions such that the upstream dewatering unit 891 is not needed and the heat exchanger 892 is instead located downstream of the thermal regeneration unit 894 as part of the separation assembly 896 to condense water vapor (derived from remaining water from the CO2-rich capture solution 107 and released hydration water from the carbonate solids). In this implementation, the thermal regeneration unit 894 can, for example, be an indirect fired rotary dryer, electric heater, microwave heater.

[0256] For example, the thermal regeneration unit 894 is sized based on normalized regeneration energy requirements to reverse the reaction between FuBIG and CO2, including sensible heating of FuBIG carbonate solids, reversing of the chemical reaction between FuBIG and CO2, and release of the chemically bound water of hydration. For example, a heat pump can be used to supply thermal energy to the thermal regeneration unit 894, e.g. the indirect fired rotary dryer 894.

[0257] In some implementations, the thermal regeneration unit 894 is maintained at a temperature above 80°C, for example at a temperature of 100 °C.

[0258] In some implementations, the DAC system 1800 includes a feed tank 893 that collects makeup and recycled liquid streams for mixing thereof, before flowing streams to the gas- liquid contactor subsystem 801. In some implementations, the feed tank 893 can be an agitated tank configured to, at least periodically, mix streams that are supplied to the feed tank 893 including at least one of the liquid stream 152, the recovered condensed water 192 and the permeate stream 145. In some implementations, the feed tank 893 is further supplied with make up streams including at least one of a makeup water stream and a makeup capture species stream (e.g., comprising FuBIG). In some implementations, the feed tank 893 is sized to allow mixing of the streams for a residence time between 1 minutes and 10 minutes, for example between 3 minutes and 5 minutes. When the feed tank 893 is used for holding / storing the collected streams, storage / holding can be above the provided ranges.

[0259] In some implementations, the regenerated capture species stream 196, e.g. including regenerated FuBIG solids produced in the thermal regeneration unit 894, is conveyed toAttorney Docket No.: 30285-0051WO1 the feed tank 893 where the solids are dissolved in water and pumped back into the gas-liquid contactor subsystem 801 as part of the CO2-capture solution 106, completing the regeneration loop. In some implementations, FuBIG solids that exit the thermal regeneration unit 894 are returned to the gas-liquid contactor subsystem 801 without any additional cooling or drying.

[0260] In another example implementation of a DAC system 1900 including a capture solution regeneration subsystem 980, referring to FIG. 10, some or all of the CO2-rich capture solution 107 can flow to a solvent-based regeneration unit 994 that employs a solvent to desorb CO2 from the solids of the CO2- rich capture solution 107.

[0261] The DAC system 900 includes the gas-liquid contactor subsystem 901 that is operated for contacting CO2from the dilute gas source (e.g., CO2-laden air 104) with the CO2capture solution 106 comprising at least one capture species being a guanidine, for example, 2,5- furan-bis-(iminoguanidine) (FuBIG), to form the CO2-rich capture solution 107 and the CO2-lean gas stream 105. Inside the gas-liquid contactor subsystem 901, the at least one capture species reacts with the absorbed CO2from the CO2-laden air 104 such that solid carbonate precipitates out of the CO2 capture solution, thereby forming the CO2-rich capture solution 107. For example, the CO2-rich capture solution 107 contains FuBIG carbonate solids as the reaction between CO2 and FuBIG results in the formation of a hydrated solid FuBIGH2(CO3).(H2O)4(s)produced according to the reaction scheme including reactions (vii) to (xii). The produced slurry (e.g., the CO2-rich capture solution 107) includes the FuBIG carbonate solids, unreacted FuBIG and excess water flowing through the gas-liquid contactor subsystem 901. In some implementations, the gas-liquid contactor subsystem 901 operates at ambient temperature and atmospheric pressure.

[0262] If not processed, the produced CO2-lean gas stream 105 can contain volatilized compounds and / or aerosolized particles of at least the CO2 capture solution 106 / CO2-rich capture solution 107. In some implementations, makeup water can be flowed to the gas-liquid contactor subsystem 901 in a water wash section of the present disclosure that would scrub FuBIG from the produced CO2-lean gas stream 105 before exiting the gas-liquid contactor subsystem 901, thereby reducing a CO2-capture solution makeup rate and reducing capture species (e.g., FuBIG) makeup costs accordingly. Accordingly, the wash section 103A, 103B, 203, 303, 403, 503 of the present disclosure apply mutatis mutandis to the gas-liquid contactor subsystems 801, 901 of FIGS.9 and 10.Attorney Docket No.: 30285-0051WO1

[0263] Referring to FIG. 10, the CO2-rich capture solution 107 (slurry) undergoes a separation step in a separation unit 990 that removes the carbonate solids from the remaining water and unreacted capture species in solution, e.g., FuBIGH 2+ 2 (aq) as part of the permeate stream 145. In some implementations, the separation unit 990 is a horizontal belt vacuum filter. In some implementations, the separation unit 990 includes multiple filters being operated in parallel to accommodate a flowrate of the slurry exiting the gas-liquid contactor subsystem 901. In some implementations, the CO2-rich capture solution 107 is pumped to the filtration unit 990. The carbonate solids are recovered as the retentate component or stream 144 that has a moisture content between 5 and 70 wt%, for example between 10 and 30 wt%.

[0264] In some implementations, the retentate component / stream 144 is dewatered in a dewatering unit 991 to reduce or remove moisture / water from the retentate component / stream 144 and produce a dewatered retentate 146. In some implementations, the dewatering unit 991 is a dryer and the recovered water exits the dewatering unit 991 as a vapor stream 148 comprising vaporized CO2capture solution 106 / CO2-rich capture solution 107, which upon being further condensed, for example by passing through a heat exchanger 992, can be redirected as at least part of the liquid stream 152 to the gas-liquid contactor subsystem 901. In the example implementation, the dewatered retentate 146 includes the FuBIG carbonate solids.

[0265] In some implementations, the dewatered retentate 146 is further subjected to a solvent-based regeneration step that produces a stream of CO2 saturated with water vapor. Referring to FIG. 10, the dewatered retentate 146 is flowed / conveyed to the solvent-based regeneration unit 994, using for example dimethyl sulfoxide (DMSO) as the solvent to liberate CO2 that is chemically bound to FuBIG. Upon contacting with the DMSO solvent, the FuBIG carbonate solids liberate CO2 (and the hydration water) as a CO2-rich gas stream 194, and regenerate the FuBIG capture species as part of a regenerated capture species stream 196 (comprising FuBIG solids in a water / DMSO mixture).

[0266] In some implementations, a solvent stream 199 (e.g., DMSO) is contacted with the dewatered retentate 146 in the solvent-based regeneration unit 994 to trigger regeneration of the capture species by precipitation as a solid in a water / solvent mixture. The resultant regenerated capture species stream 196 (e.g., slurry containing FuBIG solids in a water / DMSO mixture) is at most 35 wt% solids, at most 30 wt% solids, at most 25 wt% solids, at most 20 wt% solids or at most 15 wt% solids. Controlling a solids concentration in the regenerated capture species streamAttorney Docket No.: 30285-0051WO1 196 may mitigate issues (such as plugging) that can be encountered when processing a slurry with a high solids content.

[0267] In some implementations, the regenerated capture species stream 196, e.g. including the capture species solids (e.g., FuBIG solids), is supplied to a liquid / solid separation unit 998 that is configured to filter the capture species solids 197 from the water / solvent mixture 198 (e.g., water / DMSO mixture) that is recovered separately. The water / solvent mixture 198 may also include dissolved / undissolved captures species. In some implementations, the capture species solids 197 are washed to remove any physically entrained solvent that is adhered to the solid particles. In some implementations, a slipstream of recycled water, such as the permeate stream 145 or the liquid stream 152, can be used to wash the capture species solids 197. The capture species solids 197 can be recovered as a filter cake being substantially free of solvent and having a moisture content below about 40 wt%, for example below about 30 wt%, or for example below 10 wt%.

[0268] In some implementations, the water / solvent mixture 198 is separated into a water vapor stream 195 and the solvent stream 199 in a liquid / liquid separation unit 995, being for example a vacuum distillation column. For example, DMSO and water are completely miscible, and separation can require vacuum distillation to suppress column bottoms temperature and minimize DMSO thermal degradation. The solvent stream 199 exits the bottom of the liquid / liquid separation unit 995, and the water vapor stream 195 exits the top of the liquid / liquid separation unit 995.

[0269] In some implementations, the solvent stream 199 is flowed to the solvent-based regeneration unit 994 as described above, while the water vapor stream 195 is condensed and flowed back to the feed tank 993. In some implementations, the solvent stream 199 is cooled before being flowed to the solvent-based regeneration unit 994. In some implementations, the heat exchanger 992 or another heat exchanger can be used to cool the water vapor stream 195. The amount of liquid from the condensed water vapor stream 195 that is redirected (alone, or as part of other streams) to the feed tank 993 may be minimized, so as to minimize DMSO that could be carried over to the gas-liquid contactor subsystem 901, as such carried-over DMSO may, in certain conditions, reduce the efficacy of CO2 capture.Attorney Docket No.: 30285-0051WO1

[0270] In some implementations, the capture species solids 197 are conveyed to the feed tank 993 where the solids are dissolved in water and pumped back into the gas-liquid contactor subsystem 901 as part of the CO2-capture solution 106, completing the regeneration loop.

[0271] Although specific CO2capture species (e.g., IPDA or FuBIG) have been exemplified upon describing the implementations of the DAC system 1400, 1800, 1900 of FIGS. 5A, 5B, 9 and 10 involving in-situ solid formation in the gas-liquid contactor subsystem 501, 801, 901, various CO2capture species as encompassed by the present disclosure can be used to form the CO2 capture solution 106 that flows to the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 801, 901.

[0272] Referring to FIG. 12, a method 8100 for capturing CO2from a dilute gas source is disclosed. At 8102, the method 8100 includes contacting CO2from the dilute gas source (e.g., CO2-laden air 104) with a CO2 capture solution (e.g., the CO2 capture solution 106) to form a CO2- rich capture solution (e.g., the CO2-rich capture solution 107) and to form a CO2-lean gas stream (e.g., the CO2-lean gas stream 105) containing the volatilized compounds and / or the aerosolized particles of at least the CO2 capture solution.

[0273] In some implementations, the method 8100 includes collecting the CO2-rich capture solution in a liquid collection device, such as at least one bottom basin (e.g., the common bottom basin 124 in FIGS. 1A, 3 and 4 or the capture section bottom basins 224A, 224B in FIG. 2).

[0274] At 8106, the method 8100 includes contacting the CO2-lean gas stream with a wash water stream (e.g., the wash water stream 133) to remove at least some of the volatilized compounds and / or the aerosolized particles from the CO2-lean gas stream to form a washed CO2- lean gas stream (e.g., the washed CO2-lean gas stream 134) and a used wash water stream (e.g., the used wash water stream 135).

[0275] In some implementations, the method 8100 includes collecting the used wash water stream in the liquid collection device, such as the at least one bottom basin (e.g., the common bottom basin 124 in FIGS.1A, 3 and 4, or the wash section bottom basins 226A, 226B in FIG. 2).

[0276] At 8110, the method 8100 includes regenerating the wash water stream from at least the used wash water stream, and flowing the wash water stream for use in contacting the CO2-lean gas stream with the wash water stream.Attorney Docket No.: 30285-0051WO1

[0277] Referring to FIG. 11A and 11B, each gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 can be grouped together with one or more other gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 to provide the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900, with one or more wall(s), array(s) or train(s), where each wall, array or train has multiple gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. For example, and referring to FIGS. 11A and 11B, multiple gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 are arranged next to one another to form a contactor wall 2502. The number of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 composing the contactor wall 2502 may vary (as represented by the ellipsis symbol “[…]” in FIG. 11A). The contactor wall 2502 may include a large number of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901, for example between 10 and 100 gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. In some implementations, the number of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 in the contactor wall 2502 is greater than 1,000. The number of gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 in the contactor wall 2502 may be determined based on a variety of factors, such as a plume of CO2-lean gas 134 generated by the contactor wall 2502 during operation of the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. The contactor wall 2502 extends along its own wall axis 2509. The wall axis 2509 extends along a direction that is perpendicular to the packing depth 106D of the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 and perpendicular to the packing LTD 106L of the gas- liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901.

[0278] In implementations where the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 are positioned (e.g., directly) adjacent each other, and referring to FIG. 11A, they may be abutted along a dividing wall 2525 which fluidly separates components of one gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 from an adjacent gas-liquid contactor subsystem 101,Attorney Docket No.: 30285-0051WO1 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. The dividing wall 2525 helps to ensure that the CO2-laden air 104 flowing through the air inlet 115A of a gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901flows through the packing section(s) 127 of that gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901, rather than into an adjacent gas- liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. The dividing walls 2525 extend in an upright or vertical direction, and along a direction parallel to the packing depth 106D. In example implementations, the vertical extent of one or more of the dividing walls 2525 begins at, or below, the liquid level in the bottom basin 124. This configuration of the dividing walls 2525 can help to minimise or eliminate air bypassing the dividing walls 2525. The plenum 121 of each gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 701, 801, 901 is separated from the plenum 121 of an adjacent gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 by one or more dividing walls 2525. At least some of the dividing walls 2525 are internal to the contactor wall 2502. Each dividing wall 2525 forms a barrier to airflow between the adjacent plenums 121 delimited by that dividing wall 2525, so as to prevent air from flowing between the plenums 121. The dividing walls 2525 may allow for multiple gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 of the contactor wall 2502 to remain operational if one of the gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 or its fan 123 is deactivated. The dividing walls 2525 of FIG. 11A are internal to the contactor wall 2502, and it will be appreciated that the contactor wall 2502 can have externally-applied dividing walls 2525 at opposite longitudinal ends of the contactor wall 2502. The plenums 121 are arranged adjacent each other along the length of the contactor wall 2502 defined along the wall axis 2509. In other implementations, the contactor wall 2502 includes a single plenum 121 that is continuous along its length defined parallel to the wall axis 2509, such that the contactor wall 2502 is free of internal dividing walls 2525. In other implementations, the contactor wall 2502 includes multiple plenums 121 delineated by the dividing walls 2525, where two or more gas-liquid contactor subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 of the contactor wall 2502 share a common plenum 121. In some implementations, the dividing walls 2525 include doors or closeable openings, to provide access to the interior 113 of adjacent gas-liquid contactorAttorney Docket No.: 30285-0051WO1 subsystems 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901. In example implementations, and referring to FIG. 11A, the contactor wall 2502 includes multiple plenums 121, where each gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 forming the contactor wall 2502 has one plenum 121. Each plenum 121 is separated from an adjacent plenum 121 by one or more dividing walls 2525. In the example implementation of FIG. 11A, each dividing wall 2525 shown is located between two fan stacks 122, and forms a barrier to airflow between two plenums 121 delimited by that dividing wall 2525, where each plenum 121 is in fluid communication with a respective one of the fan stacks 122.

[0279] The contactor wall 2502 can be part of the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900. Referring to FIG. 11B, each DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 can include multiple contactor walls 2502 arranged on a plot of land 2505. Each contactor wall 2502 is spaced apart from another contactor wall 2502. In this disclosure, the terms “train”, “array” and “wall” may be used interchangeably. The DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 of FIG.11B is shown with multiple contactor walls 2502 for the purposes of illustration. The DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 can alternatively have only one contactor wall 2502. Referring to FIG. 11B, the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 includes a capture solution regeneration subsystem 180, 680, 780, 880, 980, 1480, 1580 such as one or more of those described above, in fluid communication with the contactor walls 2502. The capture solution regeneration subsystem 180, 680, 780, 880, 980, 1480, 1580 functions to regenerate^the CO2-rich sorbent (e.g., the CO2-rich capture solution 107) received from the contactor walls 2502, or from other componentry that treats the CO2-rich capture solution 107 from the contactor walls 2502. The capture solution regeneration subsystem 180, 680, 780, 880, 980, 1480, 1580 forms a regenerated sorbent (e.g., the regenerated CO2 capture solution 106) that is conveyed back to the contactor walls 2502. The capture solution regeneration subsystem 180, 680, 780, 880, 980, 1480, 1580 can also function to release CO2from the CO2-rich sorbent, to produce the CO2^product stream. In example implementations, and referring to FIG. 11B, each contactor wall 2502 has a single or common bottom basin 124. In such implementations, the bottom basin 124 of each contactor wall 2502 is in fluid communication with the capture solution regeneration subsystem 180, 680, 780, 880, 980, 1480, 1580. In example implementations, the process streams from the bottom basin 124Attorney Docket No.: 30285-0051WO1 of a contactor wall 2502 flows, or is flowed, to the bottom basin 124 of another contactor wall 2502.

[0280] In implementations where the CO2 capture solution 106 includes an amine-based capture species (e.g., including amino acids and / or diamines), undesired reaction products may form in the DAC system 100, 200, 300, 400, 1400, 1500, 1800, 1900 as a result of oxidative degradation and / or thermal degradation of the amine capture species during production of the CO2- rich capture solution 107 and / or regeneration of the CO2-rich capture solution 107 into the CO2capture solution 106. For example, oxidative degradation of the amine can happen because of the presence of oxygen (O2) in the CO2-laden air 104 that is flowed to the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 801, 901 leading in certain conditions to degradation products including, but not being limited to, carboxylic acid (heat-stable acid) and its product of reaction with the amine being a heat stable salt. For example, thermal degradation of the amine can happen in the capture solution regeneration subsystem 180, 880, 980, 1480, 1580 (e.g., in the stripper 517 referring to example implementations of FIGS. 5A and 5B) when the CO2-rich capture solution 107 undergoes a rise in temperature to assist in the liberation of CO2 from the CO2-rich capture solution 107, leading to polymerization of carbamate species, for example. An amount of oxygen can also dissolve in the CO2capture solution 106 upon flowing through the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 801, 901 and can reach the capture solution regeneration subsystem 180, 880, 980, 1480, 1580 along with the flow of CO2-rich capture solution 107, which may lead to oxy-thermal degradation of the amines in the capture solution regeneration subsystem 180, 880, 980, 1480, 1580. In some implementations, referring to FIGS. 5A and 5B, the amount of amine capture species lost to degradation (but also volatilization and / or aerosolization) can be mitigated by supplying a makeup stream 106M (e.g., including IPDA) at various locations of the DAC system 1400, including upstream of the gas-liquid contactor subsystem 501. In some implementations, referring to FIG. 5A, at least a portion (e.g. a slipstream 108) of the CO2 capture solution 106 may be fed to a reclamation unit 530 that is configured to regenerate the degradation products to the amine capture species form that are returned as a reclaimed stream 112 to the main stream of the CO2 capture solution 106.

[0281] The reclamation unit (e.g., the reclamation unit 530) of the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 can be installed in fluid communication with the CO2Attorney Docket No.: 30285-0051WO1 capture solution 106 flowing to the gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 801, 901, or with the CO2 capture solution 524, 106 flowing from the capture solution regeneration subsystem 180, 880, 980, 1480, 1580, from the thermal regeneration unit 894, 1507 from the reboiler 529, or a combination thereof. In some implementations, the reclamation unit can include an electrodialysis unit, ion exchange unit, thermal regeneration unit. In some implementations, the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 includes a degassing unit that receives the CO2-rich capture solution 107 to perform at least one of a nitrogen purge, O2 scavenger (e.g., sulfur compound like sulfite, thiosulfate) addition to the CO2-rich capture solution 107 or electrochemical-based dearation. Referring to the example implementation of FIG. 5A, the slipstream 114 of the CO2-rich capture solution 107 is flowed to the degassing unit 532 to remove O2therefrom. An O2-containing gas stream 119 and a degassed stream 116 are produced, the degassed stream 116 being returned to the main stream of the CO2- rich capture solution 107.

[0282] FIG. 13 is a schematic diagram of a control system (or controller) 900, which may be used for example with the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900, gas-liquid contactor subsystem 101, 101B, 101C, 101D, 101E, 201, 301, 401, 501, 1501, 601, 701, 801, 901 and the capture solution regeneration subsystem 180, 1480, 1580, 680, 780, 880, 980. The control system 900 can be used for the operations described in association with any of the computer-implemented methods described previously, for example as or as part of the control system 999 or other controllers described herein.

[0283] The control system 900 is intended to include various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The control system 900 can also include mobile devices, such as personal digital assistants, cellular telephones, smartphones, and other similar computing devices. Additionally, the control system can include portable storage media, such as, Universal Serial Bus (USB) flash drives. For example, the USB flash drives may store operating systems and other applications. The USB flash drives can include input / output components, such as a wireless transmitter or USB connector that may be inserted into a USB port of another computing device.

[0284] The control system 900 includes a processor 910, a memory 920, a storage device 930, and an input / output device 940. Each of the components 910, 920, 930 and 940 areAttorney Docket No.: 30285-0051WO1 interconnected using a system bus 950. The processor 910 is capable of processing instructions for execution within the control system 900. The processor may be designed using any of a number of architectures. For example, the processor 910 may be a CISC (Complex Instruction Set Computers) processor, a RISC (Reduced Instruction Set Computer) processor, or a MISC (Minimal Instruction Set Computer) processor.

[0285] In one implementation, the processor 910 is a single-threaded processor. In example implementations, the processor 910 is a multi-threaded processor. The processor 910 is capable of processing instructions stored in the memory 920 or on the storage device 930 to display graphical information for a user interface on the input / output device 940.

[0286] The memory 920 stores information within the control system 900. In one implementation, the memory 920 is a computer-readable medium. In one implementation, the memory 920 is a volatile memory unit. In example implementations, the memory 920 is a non- volatile memory unit.

[0287] The storage device 930 is capable of providing mass storage for the control system 900. In one implementation, the storage device 930 is a computer-readable medium. In various different implementations, the storage device 930 may be a floppy disk device, a hard disk device, an optical disk device, or a tape device.

[0288] The input / output device 940 provides input / output operations for the control system 900. In one implementation, the input / output device 940 includes a keyboard and / or pointing device. In example implementations, the input / output device 940 includes a display unit for displaying graphical user interfaces.

[0289] In example implementations, the processor 910 is configured to execute a machine learning model (e.g., an artificial intelligence model) that employs multiple layers of models to generate an output for a received input. A deep neural network is a deep machine learning model that includes an output layer and one or more hidden layers that each apply a non-linear transformation to a received input to generate an output. In some cases, the neural network may be a recurrent neural network. A recurrent neural network is a neural network that receives an input sequence and generates an output sequence from the input sequence. In particular, a recurrent neural network uses some or all of the internal state of the network after processing a previous input in the input sequence to generate an output from the current input in the input sequence. The machine learning model executed by the processor 910 can be, for example, a deep-Attorney Docket No.: 30285-0051WO1 learning neural network or a "very" deep learning neural network. For example, the machine learning model executed by the processor 910 can be a convolutional neural network or a recurrent network. The machine learning model can have residual connections or dense connections.

[0290] In example implementations, the machine learning model executed by the processor 910 is an ensemble of models that may include all or a subset of the architectures described above.

[0291] In example implementations, the machine learning model executed by the processor 910 is a graph neural network (GNN). GNNs are a designed to process data that can be represented in a graph form and feature pairwise message passing to enable iterative updating of node representation of the graph data.

[0292] In example implementations, the machine learning model executed by the processor 910 can be a feedforward auto-encoder neural network. For example, the machine learning model executed by the processor 910 can be a three-layer auto-encoder neural network. The machine learning model executed by the processor 910 may include an input layer, a hidden layer, and an output layer. In example implementations, the neural network has no recurrent connections between layers. Each layer of the neural network may be fully connected to the next, e.g., there may be no pruning between the layers. The neural network may include an optimizer for training the network and computing updated layer weights. In example implementations, the neural network may apply a mathematical transformation, e.g., a convolutional transformation or factor analysis to input data prior to feeding the input data to the network.

[0293] In example implementations, the machine learning model executed by the processor 910 can be a supervised model. For example, for each input provided to the model during training, the machine learning model can be instructed as to what the correct output should be. The machine learning model executed by the processor 910 can use batch training, e.g., training on a subset of examples before each adjustment, instead of the entire available set of examples. This may improve the efficiency of training the model and may improve the generalizability of the model. In example implementations, the machine learning model executed by the processor 910 may be an unsupervised model. For example, the model may adjust itself based on mathematical distances between examples rather than based on feedback on its performance. In example implementations, the machine learning model executed by the processorAttorney Docket No.: 30285-0051WO1 910 can provide suggested additional data that could further improve the output of the machine learning model.

[0294] Certain features described can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The apparatus can be implemented in a computer program product tangibly embodied in an information carrier, e.g., in a machine-readable storage device for execution by a programmable processor; and method steps can be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. The described features can be implemented advantageously in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0295] Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random-access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. Generally, a computer will also include, or be operatively coupled to communicate with, one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, ASICs (application- specific integrated circuits).Attorney Docket No.: 30285-0051WO1

[0296] To provide for interaction with a user, the features can be implemented on a computer having a display device such as a CRT (cathode ray tube) or LCD (liquid crystal display) monitor for displaying information to the user and a keyboard and a pointing device such as a mouse or a trackball by which the user can provide input to the computer. Additionally, such activities can be implemented via touchscreen flat panel displays and other appropriate mechanisms.

[0297] The features can be implemented in a control system (such as control system 999) that includes a back-end component, such as a data server, or that includes a middleware component, such as an application server or an Internet server, or that includes a front-end component, such as a client computer having a graphical user interface or an Internet browser, or any combination of them. The components of the control system can be connected by any form or medium of digital data communication such as a communication network. Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), peer-to-peer networks (having ad-hoc or static members), grid computing infrastructures, and the Internet.

[0298] The description, features, chemical reactions, reference numbers, and advantages of the present disclosure that are associated with the DAC system 100, 200, 300, 400, 600, 700, 1400, 1500, 1800, 1900 for capturing CO2 from a dilute gas source apply mutatis mutandis to systems for capturing CO2 from other dilute gas sources, such as point-source emissions having a CO2concentration of at least 1.5%v / v, for example from 1.5-15% v / v.

[0299] The term “couple” and variants of it such as “coupled,” “couples,” and “coupling” as used in this description is intended to include indirect and direct connections unless otherwise indicated. For example, if a first device is coupled to a second device, that coupling may be through a direct connection or through an indirect connection via other devices and connections. Similarly, if the first device is communicatively coupled to the second device, communication may be through a direct connection or through an indirect connection via other devices and connections. In particular, a fluid coupling means that a direct or indirect pathway is provided for a fluid to flow between two fluidly coupled devices. Also, a thermal coupling means that a direct or indirect pathway is provided for heat energy to flow between to thermally coupled devices.

[0300] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather asAttorney Docket No.: 30285-0051WO1 descriptions of features specific to particular implementations s. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0301] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0302] A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims. Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. It is to be understood that the forms shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described herein without departing from the spirit and scope as described in the following claims.

Claims

AMENDED CLAIMS received by the International Bureau on 30 December 2025 (30.12.2025)1. A direct air capture (DAC) system for capturing carbon dioxide (CO2) from a dilute gas source, the system comprising: at least one gas-liquid contactor subsystem comprising: a capture section configured to receive the dilute gas source and to contact the CO2 in the dilute gas source with a CO2 capture solution to form a CCh-rich capture solution and a CCh-lean gas stream, the CCh-lean gas stream comprising at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; a wash section positioned adjacent the capture section and configured to contact the CCh-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CCh-lean gas stream flowable from the wash section and a used wash water stream; at least one fan configured to flow 1) the dilute gas source through the capture section, 2) the CCh-lean gas stream through the wash section, and 3) the washed CCh- lean gas stream from the wash section; and a wash water regeneration subsystem in fluid communication with at least one gas-liquid contactor subsystem, the wash water regeneration subsystem configured to: receive a liquid stream comprising at least the used wash water stream; regenerate the wash water stream; and flow the regenerated wash water stream to the wash section.

2. The DAC system of claim 1, wherein the at least one gas-liquid contactor subsystem comprises a liquid collection device in fluid communication with at least one of the wash section and the capture section to produce the liquid stream.

3. The DAC system of claim 2, wherein the liquid collection device is in fluid communication with the wash section and the capture section to receive the CCh-rich capture solution from the capture section and to receive the used wash water stream from the wash section.

4. The DAC system of claim 2 or 3, wherein the liquid collection device comprises at least one bottom basin.

5. The DAC system of claim 4, wherein: the at least one bottom basin comprises a common bottom basin for the capture section and the wash section; the capture section and the wash section are each positioned above the common bottom basin relative to gravity; the common bottom basin is configured to hold the CCh-rich capture solution and the used wash water; and the liquid stream comprises both the used wash water stream and the CCh-rich capture solution.

6. The DAC system of claim 5, wherein the capture section is in fluid communication with the common bottom basin, and the common bottom basin is configured to flow at least some of the liquid stream to the capture section.

7. The DAC system of any one of claims 2 to 5, wherein the wash water regeneration subsystem comprises: a filtration unit configured to receive the liquid stream from the liquid collection device and to form a retentate stream comprising solid particles and a permeate stream; a reverse osmosis (RO) unit or osmosis assisted water recovery unit configured to receive the permeate stream from the filtration unit and form an RO retentate stream comprising the CO2-rich capture solution and an RO permeate stream comprising the wash water stream; and a pump configured to flow the liquid stream from the liquid collection device to the filtration unit and to flow the RO permeate stream to the wash section.

8. The DAC system of claim 7, wherein the liquid collection device is in fluid communication with the RO unit, and the pump is configured to flow the RO retentate stream comprising the CO2-rich capture solution to the liquid collection device.

9. The DAC system of claim 7 or 8, wherein the RO unit is in fluid communication with the capture section, and the pump is configured to flow the RO retentate stream comprising the CO2-rich capture solution to the capture section.

10. The DAC system of claim 4, wherein: the at least one bottom basin comprises a capture section bottom basin and a wash section bottom basin; the capture section is positioned above the capture section bottom basin relative to gravity; the capture section bottom basin is configured to hold the CCh-rich capture solution; the wash section is positioned above the wash section bottom basin relative to gravity; the wash section bottom basin is configured to hold the used wash water stream; and the wash water regeneration subsystem is in fluid communication with the wash section bottom basin and is configured to receive the liquid stream comprising the used wash water stream.

11. The DAC system of claim 10, wherein the capture section is in fluid communication with the wash section bottom basin, and the wash water regeneration subsystem is configured to flow at least some of the used wash water stream to the capture section.

12. The DAC system of claim 10 or 11, wherein the capture section is in fluid communication with the capture section bottom basin, and a pump is configured to flow at least some of the CCh-rich capture solution from the capture section bottom basin to the capture section.

13. The DAC system of any one of claims 10 to 12, wherein the wash water regeneration subsystem comprises: a filtration unit configured to receive the liquid stream from the wash section bottom basin and to form a retentate stream comprising solid particles and a permeate stream; a reverse osmosis (RO) unit configured to receive the permeate stream from the filtration unit and form an RO retentate stream comprising the CO2-rich capture solution and an RO permeate stream comprising the wash water stream; and a pump configured to flow the liquid stream from the wash section bottom basin to the filtration unit and to flow the RO permeate stream to the wash section.

14. The DAC system of claim 13, wherein the capture section bottom basin is in fluid communication with the RO unit and configured to receive the RO retentate stream comprising the CO2-rich capture solution.10815. The DAC system of claim 13 or 14, wherein the RO unit is in fluid communication with the capture section, and the pump is configured to flow the RO retentate stream comprising the CO2-rich capture solution to the capture section.

16. The DAC system of any one of claims 1 to 15, wherein the CO2 capture solution comprises an amine, and the solid particles comprise at least one of carbamic acid solids or carbon containing solids.

17. The DAC system of any one of claims 1 to 16, further comprising a capture solution regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem for regenerating the CCh-rich capture solution, the capture solution regeneration subsystem configured to: receive the CCh-rich capture solution from the at least one gas-liquid contactor subsystem ; separate CO2 from the CCh-rich capture solution to form a regenerated CO2 capture solution and a CO2 product stream; and flow the regenerated CO2 capture solution to the at least one gas-liquid contactor subsystem.

18. The DAC system of claim 17, further comprising: a solids sensor configured to detect an amount of solid particles in the CCh-rich capture solution; and a capture solution control valve upstream of the capture section, wherein the capture solution control valve is configured to open to allow at least some of the CCh-rich capture solution to flow to the capture solution regeneration subsystem in response to the solids sensor detecting the amount of solid particles is above a threshold.10919. The DAC system of claim 17 or 18, wherein the capture solution regeneration subsystem comprises an electrochemical system for regenerating the CCh-rich capture solution, the electrochemical system comprising: a carbonate separation subsystem configured to receive the CCh-rich capture solution and separate at least a portion of carbonate from the CCh-rich capture solution; and an electrochemical cell fluidly coupled to the carbonate separation subsystem, the electrochemical cell configured to: receive a feed solution and a water stream; and yield at least two product streams comprising a first product stream that comprises the regenerated CO2 capture solution.

20. The DAC system of claim 17 or 18, wherein the capture solution regeneration subsystem comprises: a slaker configured to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH)2); and a reactor configured to react, via a causticization reaction, the Ca(OH)2 slurry and the CCh-rich capture solution to produce hydroxide and calcium carbonate (CaCCh) solids.

21. The DAC system of any one of claims 1 to 20, wherein the at least one gas-liquid contactor subsystem is a dual-cell, cross flow gas-liquid contactor.11022. The DAC system of any one of claims 1 to 21, wherein: the capture section comprises a first capture section and a second capture section, each of the first capture section and the second capture section comprising: a capture section inlet; and one or more sections of capture section packing positioned lower than the at least one fan relative to gravity, the one or more sections of capture section packing each comprising an air travel depth defined between the respective capture section packing inlet and a respective capture section packing outlet, the one or more sections of capture section packing configured to be wetted by the CO2 capture solution; the wash section comprises a first wash section and a second wash section, the first wash section disposed downstream of the first capture section and configured to receive the CO2- lean gas stream from the first capture section, and the second wash section disposed downstream of the second capture section and configured to receive the CCh-lean gas stream from the second capture section, each of the first wash section and the section wash section comprising: one or more sections of wash section packing positioned lower than the at least one fan relative to gravity, the one or more sections of wash section packing each comprising an air travel depth defined between a respective wash section packing inlet and a respective wash section packing outlet, the one or more sections of wash section packing configured to be wetted by the wash water stream; and the at least one gas-liquid contactor subsystem further comprises a plenum positioned between the respective wash section packing outlet of each of the first wash section and the second wash section and beneath the at least one fan.

23. The DAC system of any one of claims 1 to 22, wherein the at least one gas-liquid contactor subsystem further comprises a capture section drift eliminator located downstream of the capture section and upstream of the wash section, the capture section drift eliminator configured to reduce at least the aerosolized particles from the CCh-lean gas stream.11124. The DAC system of any one of claims 1 to 23, wherein the at least one gas-liquid contactor subsystem further comprises a wash section drift eliminator located downstream of the wash section, the wash section drift eliminator configured to reduce aerosolized particles of the used wash water from the washed CCh-lean gas stream.

25. The DAC system of any one of claims 4 to 6, further comprising: a liquid level sensor configured to detect a liquid level in the at least one bottom basin; and a make-up water control valve in fluid communication with the at least one bottom basin, the make-up water control valve configured to open to enable water to flow into the at least one bottom basin in response to the liquid level sensor detecting the liquid level is below a threshold.

26. The DAC system of any one of claims 1 to 25, further comprising a concentration sensor upstream of the capture section configured to detect a concentration of a CO2 capture species in the CO2 capture solution flowing to the capture section; and a make-up CO2 capture solution control valve in fluid communication with the capture section and communicatively coupled to the concentration sensor, the make-up CO2 capture solution control valve configured to open to enable additional CO2 capture solution to flow into the capture section in response the concentration sensor detecting the concentration of the CO2 capture species in the CO2 capture solution is below a threshold.

27. The DAC system of any one of claims 1 to 26, further comprising: an emissions sensor positioned upstream of the wash section and downstream of the capture section, the emissions sensor configured to detect a concentration of a CO2 capture species in the CCh-lean gas stream; and a make-up wash water control valve in fluid communication with the wash section and communicatively coupled to the emissions sensor, the make-up wash water control valve configured to open to enable additional wash water for flow to the wash section in response to the emissions sensor detecting the concentration of the CO2 capture species in the CCh- lean gas stream exceeds a threshold.11228. The DAC system of claim 2, wherein at least a portion of the CCh-rich capture solution in the liquid collection device is recirculated to the capture section.

29. The DAC system of any one of claims 1 to 28, wherein: the CO2 capture solution comprises an amine; the capture section is configured to contact the CO2 in the dilute gas source with the amine to form the CCh-lean gas stream containing the volatilized components of the CO2 capture solution; and the wash section is configured to remove the volatilized components of the CO2 capture solution from the CCh-lean gas stream.

30. The DAC system of any one of claims 1 to 28, wherein: the CO2 capture solution comprises a hydroxide; the capture section is configured to contact the CO2 in the dilute gas source with the hydroxide to form the CCh-lean gas stream containing the aerosolized particles of the CO2 capture solution; and the wash section is configured to remove the aerosolized particles of the CO2 capture solution from the CCh-lean gas stream.

31. The DAC system of any one of claims 1 to 30, wherein the wash section comprises: a wash water distributor configured to receive the wash water stream from the wash water regeneration subsystem; and a wash section packing disposed beneath the wash water distributor and configured to contact the CCh-lean gas stream with the wash water stream.

32. The DAC system of any one of claims 1 to 31, wherein: the capture section comprises a capture section housing defining a capture section interior sealed from an exterior of the capture section, the capture section housing defining a capture section liquid inlet to receive the CO2 capture solution in the interior, a capture section gas inlet to receive the dilute gas source in the interior, a capture section gas outlet to flow the CCh-lean gas stream from the interior, and a capture section liquid outlet to flow the CCh-rich capture solution from the interior; and113the wash section is positioned spaced apart from the capture section and downstream therefrom, the wash section in fluid communication with the capture section gas outlet to receive the CCh-lean gas stream therefrom.

33. The DAC system of claim 32, comprising a filtration unit in fluid communication with the capture section liquid outlet to receive the CCh-rich capture solution, the filtration unit configured to form a retentate stream comprising a slurry, and a permeate stream flowable to the capture section liquid inlet.

34. The DAC system of claim 33, comprising: a capture solution reverse osmosis (RO) unit in fluid communication with the filtration unit to receive at least some of the permeate stream and form a capture solution retentate stream, and a wash water permeate stream comprising water; and at least one pump configured to flow the capture solution retentate stream to the capture section liquid inlet, and to flow the wash water permeate stream to the wash section.

35. The DAC system of claim 33 or 34, wherein the CO2 capture solution comprises an amine, and the slurry comprises at least one of carbamic acid solids or carbon- containing solids.

36. The DAC system of any one of claims 33 to 35, comprising a capture solution regeneration subsystem fluidly coupled to the filtration unit for regenerating the CCh-rich capture solution, the capture solution regeneration subsystem configured to: receive the retentate stream from the filtration unit; separate CO2 from the slurry to form a regenerated CO2 capture solution and a CO2 product stream; and flow the regenerated CO2 capture solution to the at least one gas-liquid contactor subsystem.

37. The DAC system of claim 36, wherein the capture solution regeneration subsystem comprises a regeneration reactor configured to heat the slurry to form the regenerated CO2 capture solution and the CO2 product stream.11438. The DAC system of claim 36 or 37, comprising a reclamation unit in fluid communication with at least one of the gas-liquid contactor subsystem and the capture solution regeneration subsystem, the reclamation unit being configured to receive at least a portion of at least one of the permeate stream and the regenerated CO2 capture solution for reclamation of amine degradation products present in the permeate stream and / or the regenerated CO2 capture solution.

39. The DAC system of any one of claims 36 to 38, comprising a degassing unit being located upstream of the capture solution regeneration subsystem, the degassing unit being configured to receive at least a portion of the CCh-rich capture solution for removing oxygen therefrom.

40. The DAC system of any one of claims 32 to 39, wherein the wash water regeneration subsystem comprises: a reverse osmosis (RO) unit in fluid communication with the wash section to receive the used wash water stream and form an RO retentate stream and an RO permeate stream comprising the wash water stream; and at least one pump configured to flow the RO retentate stream to the capture section liquid inlet, and to flow the RO permeate stream to the wash section.

41. The DAC system of any one of claims 1 to 40, wherein the at least one gas-liquid contactor subsystem comprises a housing defining an interior, the capture section positioned adjacent the wash section in the interior of the housing.

42. A method for capturing CO2 from a dilute gas source, the method comprising: contacting CO2 in the dilute gas source with a CO2 capture solution to form (1) a CCh- rich capture solution and (2) a CCh-lean gas stream comprising at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; contacting the CCh-lean gas stream with a wash water stream to remove at least some of the at least one of the aerosolized particles or the volatilized components and to form a washed CCh-lean gas stream and a used wash water stream; regenerating the wash water stream from at least the used wash water stream; and flowing the wash water stream for use in the contacting the CCh-lean gas stream with the wash water stream.11543. The method of claim 42, comprising collecting at least one of the CCh-rich capture solution and the used wash water stream in a liquid collection device to produce a liquid stream comprising at least a portion of the at least one of the CCh-rich capture solution and the used wash water stream.

44. The method of claim 43, wherein the liquid stream comprises at least some of the CCh-rich capture solution and at least some of the used wash water stream, and wherein regenerating the wash water stream comprises: flowing the liquid stream from the liquid collection device, separating solid particles from the liquid stream to form a filtered stream; and flowing the filtered stream to a reverse osmosis (RO) unit to form an RO retentate stream and an RO permeate stream, the RO retentate stream comprising the CO2-rich capture solution and the RO permeate stream comprising the wash water stream.

45. The method of claim 44, further comprising: flowing the RO retentate stream to at least one of the liquid collection device or to a capture section for use in the contacting the CO2 in the dilute gas source with the CO2 capture solution; and flowing the RO permeate stream to a wash section for use in the contacting the CO2-lean gas stream with the wash water.

46. The method of claim 43, wherein collecting the at least one of the CO2-rich capture solution and the used wash water stream in the liquid collection device comprises: collecting the CO2-rich capture solution in a capture section bottom basin of the liquid collection device; and collecting the used wash water stream in a wash section bottom basin of the liquid collection device; and wherein regenerating the wash water stream comprises: flowing the used wash water stream from the wash section bottom basin to a filtration unit; separating solid particles from the used wash water stream with the filtration unit to form a filtered stream; andflowing the filtered stream to a reverse osmosis (RO) unit to form an RO retentate stream and an RO permeate stream, the RO retentate stream comprising the CO2-rich capture solution and the RO permeate stream comprising the wash water stream.

47. The method of claim 46, further comprising: flowing the RO retentate stream to at least one of the capture section bottom basin or a capture section for use in the contacting the CO2 in the dilute gas source with the CO2 capture solution; and flowing the RO permeate stream to a wash section for use in the contacting the CO2-lean gas stream with the wash water stream.

48. The method of claim 43, further comprising: detecting a liquid level in the liquid collection device; and in response to detecting the liquid level is below a threshold, flowing water to at least one of the liquid collection device or a wash section for use in the contacting the CO2-lean gas stream with the wash water stream.

49. The method of any one of claims 42 to 48, further comprising: detecting a concentration of a CO2 capture species in the CO2 capture solution; and in response to detecting the concentration of the CO2 capture species in the CO2 capture solution is below a threshold, flowing additional CO2 capture solution to a capture section for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

50. The method of any one of claims 42 to 49, further comprising: detecting a concentration of a CO2 capture species in the CCh-lean gas stream; and in response to detecting the concentration of the CO2 capture species in the CCh-lean gas stream exceeds a threshold, flowing additional wash water to a wash section for use in the contacting the CCh-lean gas stream with the wash water stream.

51. The method of claim 43, wherein the liquid stream comprises at least the CCh-rich capture solution and the method comprises flowing the liquid stream from the liquid collection device to a capture section for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

52. The method of any one of claims 42 to 51, wherein contacting the CO2 in the dilute gas source with the CO2 capture solution comprises contacting the CO2 in the dilute gas source with an amine solution.

53. The method of any one of claims 42 to 52, further comprising reducing at least the aerosolized particles of the CO2 capture solution from the CCh-lean gas stream.

54. The method of any one of claims 42 to 53, further comprising reducing aerosolized particles of the used wash water from the washed CCh-lean gas stream.

55. The method of any one of claims 42 to 54, wherein contacting CO2 in the dilute gas source with the CO2 capture solution comprises contacting CO2 in the dilute gas source with the CO2 capture solution in a first reactor to form the CCh-rich capture solution and the CCh-lean gas stream, the method comprising: flowing the CCh-lean gas stream away from the first reactor to a second reactor to contact the CCh-lean gas stream with the wash water stream.

56. The method of claim 55, comprising filtering the CCh-rich capture solution to form a retentate stream comprising a CCh-rich slurry, and a permeate stream.

57. The method of claim 56, comprising: flowing at least some of the permeate stream to a reverse osmosis (RO) unit to form a capture solution retentate stream, and a wash water permeate stream comprising water; flowing the capture solution retentate stream for use in the contacting CO2 in the dilute gas source with the CO2 capture solution; and flowing the wash water permeate stream for use in the contacting the CO2-lean gas stream with the wash water stream.

58. The method of claim 56 or 57, wherein contacting CO2 in the dilute gas source with the CO2 capture solution comprises contacting CO2 in the dilute gas source with an amine solution, the CCh-rich slurry comprising at least one of carbon containing solids or carbamic acid solids.11859. The method of claim 58, wherein contacting CO2 in the dilute gas source with the amine solution comprises contacting CO2 in the dilute gas source with 3-(aminomethyl)-3,5,5- trimethylcyclohexylamine (IPDA).

60. The method of claim 58, wherein contacting CO2 in the dilute gas source with the amine solution comprises contacting CO2 in the dilute gas source with a diamine with an aminocyclic compound group.

61. The method of claim 60, wherein contacting CO2 in the dilute gas source with the diamine comprises contacting CO2 in the dilute gas source with a cyclohexane- 1,3 -diamine-5 R X, wherein:R is a hydrocarbon chain and X is an amino group, andX functionalizes the cyclohexane or the R hydrocarbon chain.

62. The method of claim 60, wherein contacting CO2 in the dilute gas source with the diamine comprises contacting CO2 in the dilute gas source with a cyclohexane- 1,3 -diamine-5 R, where R is a hydrocarbon chain.

63. The method of claim 61 or 62, wherein R is butane, pentane, hexane, or cycloalkane.

64. The method of claim 56 or 57, wherein contacting CO2 in the dilute gas source with the CO2 capture solution comprises contacting CO2 in the dilute gas source with a guanidine-based solution, the CCh-rich slurry comprising carbonate solids.

65. The method of claim 64, wherein the guanidine-based solution comprises a bis- iminoguanidine.

66. The method of claim 65, wherein the bis-imino(guanidine) is 2,5-furan-bis-(iminoguanidine) (FuBIG).

67. The method of claim 56 or 57, wherein contacting CO2 in the dilute gas source with the CO2 capture solution comprises contacting CO2 in the dilute gas source with the CO2 capture solution comprising an alkali metal sorbent to form the CCh-rich capture solution, the method comprising:119promoting precipitation of solids in suspension in the CCh-rich capture solution with an amine species being present in the CCh-rich capture solution in addition to the alkali metal sorbent.

68. The method of any one of claims 56 to 67, comprising: separating CO2 from the CCh-rich slurry to form a regenerated CO2 capture solution and a CO2 product stream; and flowing the regenerated CO2 capture solution for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

69. The method of claim 68, wherein separating CO2 from the CCh-rich slurry to form the regenerated CO2 capture solution comprises heating the CCh-rich slurry to form the regenerated CO2 capture solution and the CO2 product stream.

70. The method of claim 69, further comprising removing oxygen from at least a portion of the CCh-rich capture solution prior to separating CO2 from the CCh-rich capture solution.

71. The method of any one of claims 69 to 70, further comprising flowing at least a portion of at least one of the permeate stream and the regenerated CO2 capture solution to a reclamation unit to remove degradation products present in the permeate stream.

72. The method of any one of claims 42 to 71, wherein regenerating the wash water stream comprises: flowing the used wash water stream to a reverse osmosis (RO) unit to form an RO retentate stream, and an RO permeate stream comprising the wash water stream; flowing the RO retentate stream for use in the contacting CO2 in the dilute gas source with the CO2 capture solution; and flowing the RO permeate stream for use in the contacting the CO2-lean gas stream with the wash water stream.12073. The method of any one of claims 42 to 72, further comprising: regenerating the CCh-rich capture solution to form the CO2 capture solution and a CO2 product stream; and flowing the CO2 capture solution for use in the contacting CO2 in the dilute gas source with the CO2 capture solution.

74. The method of claim 73, further comprising: detecting an amount of solid particles in the CCh-rich capture solution; and in response detecting the amount of solid particles is above a threshold, flowing at least some of the CCh-rich capture solution to a capture solution regeneration subsystem to regenerate the CCh-rich capture solution.

75. A direct air capture (DAC) system for capturing carbon dioxide (CO2) from atmospheric air, the DAC system comprising: at least one gas-liquid contactor subsystem comprising: a capture section configured to receive the atmospheric air and contact the CO2 in the atmospheric air with a CO2 capture solution to form a CCh-rich capture solution and a CCh-lean gas stream, the CCh-lean gas stream comprising at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; a wash section positioned adjacent the capture section and configured to receive the CCh-lean gas stream from the capture section and contact the CCh-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CCh-lean gas stream flowable from the wash section and a used wash water stream; and at least one fan configured to flow 1) the atmospheric air through the capture section, 2) the CCh-lean gas stream through the wash section, and 3) the washed CCh-lean gas stream from the wash section; a wash water regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem, the wash water regeneration subsystem configured to: receive a liquid stream comprising at least the used wash water stream; regenerate the wash water stream; and flow the regenerated wash water stream to the wash section; and121a capture solution regeneration subsystem fluidly coupled to the at least one gas-liquid contactor subsystem for regenerating the CCh-rich capture solution, the capture solution regeneration subsystem configured to: receive the CCh-rich capture solution; separate CO2 from the CCh-rich capture solution to form a regenerated CO2 capture solution; and flow the regenerated CO2 capture solution to the capture section.

76. A gas-liquid contactor subsystem for capturing carbon dioxide (CO2) from a dilute gas source, the gas-liquid contactor subsystem comprising: a capture section configured to receive the dilute gas source and to contact the CO2 in the dilute gas source with a CO2 capture solution to form a CCh-rich capture solution and a CCh-lean gas stream, the CCh-lean gas stream comprising at least one of aerosolized particles of the CO2 capture solution or volatilized components of the CO2 capture solution; a wash section positioned adjacent the capture section and configured to contact the CCh-lean gas stream with a wash water stream to remove the at least one of the aerosolized particles or the volatilized components and to form a washed CCh-lean gas stream flowable from the wash section and a used wash water stream; and at least one fan configured to flow 1) the dilute gas source through the capture section, 2) the CCh-lean gas stream through the wash section, and 3) the washed CCh- lean gas stream from the wash section.

77. The gas-liquid contactor subsystem of claim 76, comprising at least one feature as defined in any one of claims 2 to 41.122

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