Direct air capture system and method

Abstract

A direct air capture (DAC) system (100) includes an absorber (106) configured to receive an air flow (102) and to absorb at least a portion of carbon dioxide present in the air flow (102). The DAC system (100) further includes a demister (134, 434, 534, 634, 734) configured to receive at least a portion of the air flow (102) from the absorber (106). The DAC system (100) further includes a cooling device (136, 436, 536, 636, 736) disposed in a heat exchange relationship with the demister (134, 434, 534, 634, 734) and configured to cool a portion of the airflow (102).

Description

Technical Field

[0001] The present disclosure relates to a direct air capture system and a method of operating a direct air capture system. Background Art

[0002] Direct air capture (DAC) of atmospheric carbon dioxide generally involves forcing an incoming stream of ambient air to interact with, for example, an adsorbent capture medium under certain thermodynamic conditions. The adsorbent capture medium may comprise a liquid medium or a solid medium. The adsorbent capture medium absorbs some portion of the carbon dioxide from the air stream. Furthermore, during a desorption process, the carbon dioxide can be separated from the adsorbent capture medium, allowing for the capture and storage of the carbon dioxide.

[0003] A DAC system typically includes an absorber. The absorption process occurs within the absorber of a DAC system. The absorber is an open system that allows a large air flow to pass through it while simultaneously extracting carbon dioxide from the air flow. Consequently, carbon dioxide-depleted air can exit the absorber. This carbon dioxide-depleted air can have a different temperature and humidity than the incoming ambient air flow. In particular, the temperature and humidity of the carbon dioxide-depleted air can be elevated compared to the incoming ambient air flow.

[0004] In instances where the sorbent capture medium is a liquid medium, conditions such as high temperatures within the absorber, high ambient temperatures, and reduced ambient humidity can lead to increased drift / droplet release, increased evaporation rates of the sorbent capture medium present in the airstream, and increased water loss within the absorber. Since the sorbent capture medium directly impacts the operating costs associated with the DAC system, increased drift / droplet release and higher evaporation rates of the sorbent capture medium can increase the operating costs of the DAC system. Summary of the Invention

[0005] In a first aspect, a direct air capture (DAC) system is provided. The DAC system includes an absorber configured to receive an air stream and absorb at least a portion of carbon dioxide present in the air stream. The DAC system further includes a demister configured to receive at least a portion of the air stream from the absorber. The DAC system further includes a cooling device arranged in heat exchange relationship with the demister and configured to cool a portion of the air stream.

[0006] The mist eliminator of the present disclosure can function as a droplet capture structure that captures droplets from the airstream before the airstream exits into the surrounding environment. Furthermore, the cooling device can reduce the temperature of the airstream, which in turn can reduce the evaporation rate of the adsorbent capture medium present in the airstream before the airstream exits into the surrounding environment. This phenomenon can also reduce water losses in the DAC system. Furthermore, the capture of droplets and the reduced evaporation rate of the adsorbent capture medium can reduce the operating costs of the DAC system. In an embodiment, the mist eliminator and the cooling device form a single, integral structure that can reduce droplets and lower the temperature of the airstream.

[0007] In some embodiments, a cooling device is configured to cool the demister to induce condensation on a surface of the demister. The cooling device may define one or more flow paths that receive a refrigerant for reducing the temperature of the airflow passing through the demister. In one example, the cooling device may be integral with the demister. In another example, the cooling device may be separate from the demister and may be positioned downstream of the demister in the direction of airflow.

[0008] In some embodiments, the demister includes a packing structure. The cooling device includes one or more tubes arranged in heat exchange relationship with the packing structure. In such an embodiment, the cooling device and the packing structure can be embodied as a single, integral structure. Furthermore, the tubes allow refrigerant to pass therethrough for reducing the temperature of the air flow passing through the demister.

[0009] In some embodiments, the cooling device comprises a thermally conductive material. In such embodiments, the cooling device comprising the thermally conductive material may form fins of the cooling device that conduct heat away from the air flow, thereby creating an effective cooling surface.

[0010] In some embodiments, the DAC system further includes a refrigeration circuit arranged in fluid communication with the cooling device and configured to extract heat from the cooling device. The refrigeration circuit includes a refrigerant flowing through one or more flow paths of the cooling device to reduce the temperature of the air flow flowing through the demister.

[0011] In some embodiments, the DAC system further includes a controller configured to control the refrigeration cycle of the refrigeration circuit based on at least one of an environmental parameter, a pressure within the absorber, and a temperature within the absorber. In some examples, the environmental parameter may include the temperature, pressure, or humidity of the environment surrounding the DAC system. Because the refrigeration cycle is dynamically controlled based on current conditions inside and outside the absorber, the DAC system described herein can eliminate unnecessary power consumption.

[0012] The controller may be configured to control the refrigeration circuit based on the humidity of the ambient air and the humidity of the air leaving the absorber so that condensation on the surface of the demister provides condensate to replace a portion of the water lost in the absorber, for example, at least 20% of the water lost, or preferably more, such as 30%, 50%, 70% or 100% of the water lost.

[0013] In some embodiments, the refrigeration circuit includes a heat pump and a heat exchanger arranged in heat exchange relationship with the heat pump. The heat pump can convert the waste heat from the cooling device into useful heat. The useful heat can be supplied to any heat exchanger / heating device associated with the DAC system.

[0014] In some embodiments, the heat exchanger comprises a heating device for the DAC system. In such instances, the useful heat generated by the heat pump can be used to increase the temperature of the lean adsorbent stream flowing through the heating device. The heated lean adsorbent stream can then be used in the desorber of the DAC system.

[0015] In some embodiments, the DAC system further includes a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is arranged downstream of the cooling device and is configured to heat a portion of the air flow received from the cooling device, and the second heat exchanger is arranged downstream of the first heat exchanger and is configured to cool a portion of the air flow received from the first heat exchanger. In such an embodiment, the mist eliminator and the cooling structure can respectively capture the drift / droplets and reduce the evaporation rate of the adsorbent capture medium. In addition, the drift / droplets escaping through the mist eliminator can be captured by the first heat exchanger. The first heat exchanger is embodied as a hot heat exchanger, which can increase the temperature of the air flow, thereby evaporating the remaining droplets. In addition, the second heat exchanger is embodied as a cold heat exchanger, which can cause the temperature of the air flow to be reduced and can condense the remaining adsorbent capture medium present in the air flow before the air flow exits into the surrounding environment.

[0016] In some embodiments, the DAC system further includes an additional refrigeration circuit arranged in fluid communication with the first heat exchanger and the second heat exchanger. The additional refrigeration circuit is configured to provide heat exchange between the first heat exchanger and the second heat exchanger. The additional refrigeration circuit can convert waste heat from cooling of the second heat exchanger into useful heat, which can be used to heat the first heat exchanger to increase the temperature of the air flow flowing through the first heat exchanger.

[0017] In some embodiments, the DAC system further includes an electrostatic precipitator disposed downstream of the second heat exchanger. The electrostatic precipitator facilitates an efficient impurity removal step. In particular, the electrostatic precipitator can provide an air purification function, allowing the DAC system to purify the air stream of any contaminants (such as pollutants).

[0018] In some embodiments, the absorber, demister, and cooling device are integrated into a single absorber unit.The single absorber unit may comprise a compact structure, which may be retrofitted to an existing DAC system by replacing the existing absorber.

[0019] In a second aspect, a method is provided. The method includes removing at least a portion of carbon dioxide from an air stream via an absorber of a DAC system. The method further includes receiving at least a portion of the air stream from the absorber at a demister. The method further includes cooling a portion of the air stream passing through the demister via a cooling device.

[0020] The methods described herein can allow for the capture of drift / droplets from an airstream before the airstream exits into the surrounding environment. Furthermore, the methods can allow for the reduction of the temperature of the airstream, which in turn can reduce the evaporation rate of an adsorbent capture medium present in the airstream before the airstream exits into the surrounding environment. The methods can also reduce water loss in a DAC system. Furthermore, the methods can reduce the operating costs of a DAC system by capturing drift / droplets and reducing the evaporation rate of the adsorbent capture medium.

[0021] In some embodiments, the method further comprises extracting heat from the cooling device via a heat pump. The heat pump can convert waste heat from the cooling device into useful heat. The useful heat can be used in any other heat exchangers associated with the DAC system.

[0022] In some embodiments, the method further comprises heating a heating device of the DAC system via a heat pump. In such an example, the useful heat generated by the heat pump can be used to increase the temperature of the lean adsorbent stream flowing through the heating device. The heated lean adsorbent stream can then be used in the desorber of the DAC system.

[0023] In some embodiments, the method further includes heating a portion of the air flow received from the cooling device via a first heat exchanger. The method further includes cooling a portion of the air flow received from the first heat exchanger via a second heat exchanger. The method further includes providing heat exchange between the first heat exchanger and the second heat exchanger via an additional refrigeration circuit. In such an embodiment, the demister and the cooling structure can capture the droplets / liquid droplets and can reduce the evaporation rate of the adsorbent capture medium, respectively. In addition, the droplets / liquid droplets escaping through the demister can be captured by the first heat exchanger. The first heat exchanger is embodied as a hot heat exchanger, which can increase the temperature of the air flow, thereby evaporating the remaining droplets. In addition, the second heat exchanger is embodied as a cold heat exchanger, which can cause the temperature of the air flow to be reduced and the remaining adsorbent capture medium present in the air flow can be condensed before the air flow exits into the surrounding environment.

[0024] The skilled person will understand that, unless mutually exclusive, features or parameters described with respect to any one of the above aspects may be applied to any other aspect. In addition, unless mutually exclusive, any features or parameters described herein may be applied to any aspect and / or combined with any other features or parameters described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic diagram of a direct air capture (DAC) system according to an embodiment of the present disclosure;

[0027] Figure 2 According to the embodiment of the present disclosure, Figure 1 A schematic perspective view of a demister and a cooling device used in conjunction with a DAC system;

[0028] Figure 3 According to the embodiment of the present disclosure Figure 1 Schematic block diagram of the DAC system;

[0029] Figure 4 According to another embodiment of the present disclosure, Figure 1 A schematic perspective view of a demister and a cooling device used in conjunction with a DAC system;

[0030] Figure 5 According to yet another embodiment of the present disclosure, Figure 1 A schematic perspective view of a demister and a cooling device used in conjunction with a DAC system;

[0031] Figure 6 According to yet another embodiment of the present disclosure, Figure 1 A schematic perspective view of a demister and a cooling device used in conjunction with a DAC system;

[0032] Figure 7 According to another embodiment of the present disclosure, Figure 1 Schematic diagram of a mist eliminator used with a DAC system and a cooling device separate from the mist eliminator;

[0033] Figure 8 is a schematic diagram of a DAC system including a first heat exchanger and a second heat exchanger according to another embodiment of the present disclosure; and

[0034] Figure 9 is a flow chart of a method of operating a DAC system according to an embodiment of the present disclosure.

[0035] Figure 10There are two graphs showing the effect of the system's operation in response to environmental conditions. DETAILED DESCRIPTION

[0036] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying drawings. Additional aspects and embodiments will be apparent to those skilled in the art.

[0037] Figure 1 A schematic diagram of a direct air capture (DAC) system 100 is shown. The DAC system 100 is operated to capture carbon dioxide (CO2) from a CO2-containing gas stream. The DAC system 100 is embodied as a liquid absorbent DAC system herein. In addition, the CO2-containing gas stream includes an air stream 102. The DAC system 100 includes a single absorber unit 104. The DAC system 100 includes an absorber 106 configured to receive the air stream 102 and absorb at least a portion of the CO2 present in the air stream 102. The absorber 106 is disposed within the absorber unit 104. The absorber unit 104 also includes a fan 108 configured to generate the air stream 102. The fan 108 can be disposed upstream or downstream of the absorber 106. Figure 1 In the illustrated embodiment, the fan 108 is arranged downstream of the absorber 106. The air flow 102 entering the absorber 106 undergoes an absorption process within the absorber 106. In addition, after flowing through the absorber 106, a CO2-depleted air flow 110 leaves the absorber unit 104.

[0038] In addition, the adsorbent flows through the absorber 106 and interacts with the air stream 102 flowing through the absorber 106. The adsorbent that captures CO2 can have a varying equilibrium between the carbonate form and the solution with CO2, depending on the temperature. The adsorbent can be loaded in a solvent, such as water, which can contain additional additives that can act as catalysts, change the physical properties of the solution and / or reduce degradation or other desired properties. The adsorbent can include an alkaline adsorbent, such as a hydroxide or an organic adsorbent. The alkaline adsorbent can include, for example, potassium hydroxide or calcium hydroxide. The organic adsorbent can include, for example, an amine, an amino acid. The amine can include, for example, ethanolamine. Preferred adsorbents can include, for example, an amino acid or an alkaline salt solution of an amino acid. The amino acid can be derived from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, ornithine, phenylalanine, proline, sarcosine, selenocysteine, serine, taurine, threonine, tryptophan, tyrosine or valine. The amino acid can be an amino acid compound such as methylamine or diethylamine. The preferred alkaline component of the amino acid salt is potassium or sodium. Examples of amino acid salts can include, for example, sodium glycinate, potassium lysinate, and sodium taurate.

[0039] exist Figure 1 In the illustrated embodiment, a lean stream 114 of sorbent enters the absorber 106. The term "lean stream," as used throughout this disclosure, relates to a stream of sorbent having a low CO2 value. The lean stream 114 contacts the air stream 102 and absorbs CO2 from the air stream 102 to become a rich stream 116. The term "rich stream," as used throughout this disclosure, relates to a stream of sorbent having a high CO2 value. The lean stream 114 is converted to the rich stream 116 based on the absorption of CO2 from the air stream 102. Additionally, a recycle stream 118 of sorbent may be recirculated within the absorber 106. The recycle stream 118 may increase the effective residence time of portions of the lean stream 114 of sorbent in the absorber 106.

[0040] In addition, the DAC system 100 includes a heat exchange device 120. The heat exchange device 120 can include any conventional heat exchanger known in the art. The rich stream 116 is passed through the heat exchange device 120 to recover some heat from the lean stream 114 returned by the desorber 122 of the DAC system 100. Based on the heat exchange at the heat exchange device 120, the temperature of the rich stream 116 leaving the heat exchange device 120 is slightly increased. In addition, the desorber 122 receives the rich stream 116 from the heat exchange device 120 and heats it to a temperature that causes the release of CO2 from the rich stream 116.

[0041] The DAC system 100 further includes a heating device 124. The heating device 124 is embodied as a reboiler herein. The heating device 124 increases the temperature of the rich stream 116 by circulating a stream 126 of heated adsorbent through the desorber 122. The heating device 124 receives a portion of the lean stream 114 exiting the desorber 122. The heating device 124 heats the lean stream 114 to form a heated stream 126, which is introduced into the desorber 122. In addition, the heating device 124 can also generate steam to form vapor bubbles, into which the desorbed CO2 can diffuse, leaving the lean stream 114 of adsorbent to return to the absorber 106 to repeat the absorption process. In addition, a mixture 128 of steam and desorbed CO2 exits the desorber 122. The DAC system 100 further includes a condensing medium 130 in fluid communication with the desorber 122. The condensing medium 130 receives the mixture 128 of vapor and desorbed CO 2 from the desorber 122 and may cool the mixture 128 , causing the vapor to condense so that a CO 2 product stream 132 exits the condensing medium 130 .

[0042] The DAC system 100 further includes a mist eliminator 134 configured to receive at least a portion of the air stream 102 from the absorber 106. The mist eliminator 134 can act as a droplet / liquid droplet capture structure that captures droplets / liquid droplets from the air stream 102 before the air stream 102 leaves the absorption unit 104. In addition, the DAC system 100 includes a cooling device 136 that is arranged in a heat exchange relationship with the mist eliminator 134 and is configured to cool a portion of the air stream 102 before the air stream 102 leaves the absorption unit 104. In addition, the cooling device 136 can reduce the temperature of the air stream 102, which in turn can reduce the evaporation rate of the adsorbent that absorbs CO2 from the air stream 102. This phenomenon can also reduce water losses in the DAC system 100. In addition, the capture of droplets / liquid droplets and the reduced evaporation rate of the adsorbent can reduce the operating costs of the DAC system 100. Figure 1 In the illustrated embodiment, the absorber 106, the demister 134, and the cooling device 136 are integrated into a single absorber unit 104. Thus, the single absorber unit 104 can operate to capture CO2, can reduce drift / droplets, and can reduce the temperature of the air stream 102. The single absorber unit 104 can include a compact structure, which can be retrofitted to an existing DAC system by replacing an existing absorber. Figure 1 In the illustrated embodiment, the demister 134 and the cooling device 136 are arranged upstream of the fan 108. However, the demister 134 and the cooling device 136 may be arranged downstream of the fan 108.

[0043] Figure 2 The embodiments of the present disclosure are described. Figure 1 Schematic perspective view of a demister 134 and a cooling device 136 used in conjunction with the DAC system 100. Figure 2 In the illustrated embodiment, the cooling device 136 is configured to cool the demister 134 so as to induce condensation on the surface 138 of the demister 134. Figure 2 In the illustrated embodiment, the mist eliminator 134 includes a packing structure 140. The mist eliminator 134 is embodied as a honeycomb-type mist eliminator herein.

[0044] like Figure 2 As shown, filler structure 140 includes a plurality of structures 142 spaced apart from one another. Each structure 142 extends along direction D1. In some examples, structure 142 can be made of an insulator, such as a polymer material, a metal material, or a combination thereof. In one example, the polymer material can include polyethylene or polyvinyl chloride. In another example, the metal material can include stainless steel or aluminum. It should be noted that structure 142 can include any shape or design that maximizes the efficiency of capturing droplets / liquid droplets.

[0045] In addition, Figure 2 In the illustrated embodiment, the cooling device 136 includes one or more tubes 144 arranged in heat exchange relationship with the filler structure 140. The cooling device 136 may include a thermally conductive material. Figure 2 As shown, the cooling device 136 includes a plurality of tubes 144. Each tube 144 defines a flow path F1 to receive a refrigerant for reducing the temperature of the air flow 102 flowing through the demister 134. Each tube 144 has a trapezoidal shape. In addition, each tube 144 extends in a direction D1 and is parallel to the structure 142 of the packing structure 140. Alternatively, each tube 144 can be arranged at a certain angle relative to the structure 142. In addition, since the demister 134 and the cooling device 136 form a single component herein, each tube 144 of the plurality of tubes 144 is integral with the corresponding structure 142. Therefore, the demister 134 and the cooling device 136 can together form a cooling type demister. Figure 2 In the illustrated embodiment, each structure 142 has a corresponding tube 144 integral therewith. Thus, the total number of tubes 144 corresponds to the total number of structures 142 of the packing structure 140. In alternative embodiments, each structure 142 may define more than one tube 144, without limitation. Furthermore, in some examples, the surface 138 of the demister 134 may be embodied as fins that can conduct heat away from the air flow 102, thereby creating an effective cooling surface. In other examples, the surface 138 may include multiple fins extending therefrom to create a cooling surface.

[0046] Now refer to Figure 1 and Figure 2 DAC system 100 includes a refrigeration circuit 146 arranged in fluid communication with cooling device 136 and configured to extract heat from cooling device 136. Refrigeration circuit 146 is configured to circulate a refrigerant for cooling cooling device 136. Refrigeration circuit 146 may include a refrigerant source (not shown) configured to direct refrigerant to cooling device 136. Furthermore, each tube 144 of cooling device 136 is configured to allow refrigerant to pass therethrough. The refrigerant flows through tubes 144 and exchanges heat with a portion of air stream 102 flowing through demister 134. Consequently, the temperature of air stream 102 decreases, causing condensation of the adsorbent. The temperature of the refrigerant is below the dew point of the air stream exiting the absorber. Furthermore, the condensed adsorbent may drip back into absorber unit 104 along with any drift / droplets captured by demister 134.

[0047] It will be appreciated that the thermophoretic effect additionally causes the cooled mist eliminator 134 to capture more droplets from the air stream 102 than conventional mist eliminators. This weakening effect provides advantageous additional benefits.

[0048] The primary function of the cooling device 126 is to condense evaporated water by cooling the structure of the mist eliminator 134 that handles the droplets. Thermophoresis provides a welcome additional micro-force to further improve the elimination of particles from the air stream 102.

[0049] In some embodiments, the refrigeration circuit 146 includes a heat pump 148 and a heat exchanger 150 arranged in heat exchange relationship with the heat pump 148. Furthermore, refrigerant exits the cooling device 136 and is introduced into the heat pump 148. The heat pump 148 extracts waste heat from the refrigerant to generate useful heat, which is then directed to the heat exchanger 150. The heat exchanger 150 is embodied herein as the heating device 124 of the DAC system 100. In such an example, the useful heat generated by the heat pump 148 can be used to increase the temperature of the lean stream 114 flowing through the heating device 124. Alternatively, the heat exchanger 150 can be associated with any other component of the DAC system 100, or the heat exchanger 150 can be external to the DAC system 100.

[0050] Now refer to Figure 3 In some embodiments, the DAC system 100 includes a controller 152 configured to generate a signal based on environmental parameters, the absorber 106 (see Figure 1 ) and at least one of the pressure within the absorber 106 and the temperature within the absorber 106 to control the refrigeration cycle of the refrigeration circuit 146. In some instances, the environmental parameter may include the temperature, pressure, or humidity of the surrounding environment of the DAC system 100. Additionally, in some instances, a first sensor system 154 may be associated with the DAC system 100. The first sensor system 154 may include, for example, a temperature sensor, a pressure sensor, and / or a humidity sensor. In some instances, the DAC system 100 may include a second sensor system 156 associated with the absorber 106. The second sensor system 156 may include, for example, a temperature sensor or a pressure sensor. Each of the first and second sensor systems 154, 156 may be in communication with the controller 152. Based on the values determined by the first and second sensor systems 154, 156, the controller 152 may determine whether it is necessary to initiate a refrigeration cycle to reduce the temperature of the air flow 102 leaving the absorber unit 104 (see Figure 1 For example, when the ambient parameters (i.e., temperature, pressure, and / or humidity) or the temperature within the absorber 106 indicate that the evaporation rate and / or water loss is high, the refrigeration loop 146 can be activated. Because the refrigeration cycle is dynamically controlled based on the current conditions inside and outside the absorber 106, the DAC system 100 can eliminate unnecessary power consumption.

[0051] The controller can be configured to control the refrigeration circuit based on the humidity of the ambient air and the humidity of the air leaving the absorber so that condensation on the surface of the demister provides condensate to replace a portion of the water lost in the absorber. The controller can calculate the absolute humidity based on the sensor readings of the relative humidity and temperature and calculate the cooling load required to condense the water on the demister at a rate sufficient to replace a portion of the required water losses.

[0052] For example, the controller can control the refrigeration cycle so that the net water loss from the absorber is close to zero. The net water loss may include evaporation and dripping losses from the absorber, as well as other incidental losses from the adsorbent circuit and desorber system. The net water loss can be reduced by more than 20% of the loss that would be expected without a cooling demister. In some climates, 100% of the loss may be recoverable. The amount of water that is economically recoverable will depend on the local cost of providing cooling, fan power, and water, so in some environments, it may be desirable to recover less than 100% of the water for economic reasons. Therefore, the controller can be configured to change the water recovery rate based on ambient temperature and humidity and parameters indicating the cost of water and power.

[0053] Figure 10 Shown are two graphs, have described along with the variation of environmental conditions, the effect of controlling demister cooling.Chart A shows the environmental conditions of sampling day, and the dashed line on the right axis represents relative humidity, and the dotted line on the left axis shows ambient temperature.Chart B shows the example of the energy use and the water of recovery when equipment is controlled in one day, and the dashed line on the right axis represents water recovery, and the dotted line on the left axis represents the required energy of cooler.Both are expressed as the CO 2 of capture per ton.As can be seen from chart B, when the relative humidity that afternoon was higher, the water loss from adsorbent in absorber was less, therefore can reduce the cooling of drift eliminator (drift eliminator), use less energy.

[0054] In most cases, the controller can adjust heat pump operation to ensure that water loss is reduced to near zero. However, sometimes this is not desirable for practical purposes. At 21:00 in the figure, the controller recognizes that maintaining the zero water loss target would risk ice accumulation in the chiller, so it limits chiller power at that time and allows a small amount of water loss. Previously, when the chiller was able to cool slightly more and effectively harvest some water from the more humid incoming air, additional water could be temporarily stored. One option is to use a feedforward controller that checks the expected local weather (temperature, pressure, and humidity). This can allow for the storage of relatively small amounts of water for hours or days. On very hot and dry days, the workload required of the heat pump can be high, and again the controller can change its control target from instantaneous zero water loss to limiting water loss to a low value. Makeup water can again be stored from other times when humidity levels are more favorable. The control objective is to limit water loss within a set time period, rather than always achieving zero water loss instantaneously. With the option of temporarily storing water, the control objective can be to maximize cost savings while taking into account the cost of purchasing the supplemental water and the knowledge of the cost of purchasing low-carbon energy. The heat pump system providing the cooling can deliver heat elsewhere in the system, for example to a desorber that requires heat to separate the CO2 from the adsorbent. This can be via a cascade heat pump system that also recovers heat from elsewhere in the DAC plant at a different temperature.

[0055] The controller can change the temperature of the droplet eliminator so that the absolute humidity of the air leaving the demister is equal to or lower than the absolute humidity of the ambient air entering the absorber, the difference being sufficient to compensate for the accidental loss and the droplet loss.

[0056] The controller can control the temperature of the refrigerant delivered to the cooling device attached to the demister in response to psychometric sensor readings taken around or within the absorber. These can include some or all of the temperature and humidity of the ambient air, the air leaving the absorber, or the air leaving the demister. The ambient air readings can be received from a local weather station.

[0057] The controller can obtain an estimate of occasional water losses elsewhere in the system by calculation or from a table of empirical water loss measurements. The controller can receive a measurement of the total water content of the system, such as the level of adsorbent in a storage vessel connected to the system, and iteratively control the drift eliminator based on an indication of rising or falling adsorbent levels.

[0058] A group of absorbers may have their outlets connected to a common plenum, and the demister may be incorporated into the plenum so that the dripping and evaporation from all absorbers are collected at a location within the plenum. This will reduce the number of cooling devices required.

[0059] Controller 152 can include one or more processors and one or more memories. It should be noted that one or more processors can embody a single microprocessor or multiple microprocessors for receiving various input signals. Many commercially available microprocessors can be configured to perform the functions of one or more processors. Each processor can further include a general-purpose processor, a central processing unit, an application-specific integrated circuit (ASIC), a digital signal processor, a field programmable gate array (FPGA), a digital circuit, an analog circuit, a microcontroller, any other type of processor or any combination thereof. Each processor can include one or more components that can be operable to execute computer-executable instructions or computer codes that can be stored in and retrieved from one or more memories.

[0060] Figure 4 Explains that Figure 1 Another embodiment of a demister 434 and a cooling device 436 associated with the DAC system 100 is shown. The demister 434 and the cooling device 436 form a single integral component herein. The demister 434 includes a packing structure 440. The demister 434 is embodied as a honeycomb-type demister herein. The packing structure 440 includes a plurality of structures 442 spaced apart from each other. The design and function of each structure 442 are similar to those described with respect to FIG. Figure 2 The structure 142 described is similar.

[0061] In addition, the cooling device 436 includes one or more tubes 444 arranged in heat exchange relationship with the fill structure 440. The design and function of the tubes 444 are similar to those described with respect to Figure 2 The tube 144 is similar to that described. However, in Figure 4 In the illustrated embodiment, the cooling device 436 includes two tubes 444. In particular, only two structures 442 define corresponding tubes 444. Although only two tubes 444 are described herein, it is contemplated that the cooling device 436 may include more than two tubes or a single tube without limitation. Thus, only some structures 442 are provided with tubes 444, while tubes 444 are not present in other structures 442. Furthermore, in some examples, the surface 438 of the demister 434 may be embodied as fins that can conduct heat away from the air flow 402, thereby creating an effective cooling surface. In other examples, the surface 438 may include a plurality of fins extending therefrom to create a cooling surface.

[0062] Figure 5 Explains that Figure 11. Yet another embodiment of a demister 534 and a cooling device 536 associated with the DAC system 100. The demister 534 and the cooling device 536 form a single integral component herein. The demister 534 includes a packing structure 540. The demister 534 is embodied as a honeycomb-type demister herein. The packing structure 540 includes a plurality of structures 542 spaced apart from one another. The design and function of each structure 542 are similar to those described with respect to FIG. Figure 2 The structures 142 are similarly described. Each structure 542 extends along direction D2.

[0063] In addition, the cooling device 536 includes one or more tubes 544 arranged in heat exchange relationship with the fill structure 540. The function of the tubes 544 is similar to that of the Figure 2 The tube 144 is similar to that described. However, in Figure 5 In the illustrated embodiment, the tubes 544 extend orthogonally with respect to the direction D2. In other words, each tube 544 is orthogonal to the structure 542 of the filler structure 540. Alternatively, each tube 544 can be arranged at a certain oblique angle relative to the structure 542. The tubes 544 include a circular cross-section herein. In addition, for exemplary purposes, only two tubes 544 are illustrated herein; however, the cooling device 536 may include more than two tubes 544. In addition, in some examples, the surface 538 of each tube 544 can be embodied as a fin that can conduct heat away from the air flow 502, thereby creating an effective cooling surface. In other examples, the surface 538 can include a plurality of fins extending therefrom to create a cooling surface.

[0064] Figure 6 Explains that Figure 1 DAC system 100 is associated with a mist eliminator 634 and a cooling device 636. The mist eliminator 634 and the cooling device 636 form a single integral component herein. The mist eliminator 634 is embodied as a mesh-type mist eliminator herein. The mist eliminator 634 includes a packing structure 640. The packing structure 640 includes a first mesh 658 and a second mesh 660 spaced apart from each other. Alternatively, the packing structure 640 may be based on the absorber 106 (see Figure 1 ) size includes three or more nets.

[0065] The first and second nets 658, 660 can be made of a metal material. In addition, each of the first and second nets 658, 660 can be composed of one or more layers of net. In addition, the first and second nets 658, 660 can be aligned with each other, or the first and second nets 658, 660 can be arranged in an offset / staggered manner. In some examples, it is also contemplated that a honeycomb type mist eliminator (such as Figure 2 、 4 and 5) with mesh type mist eliminator (as Figure 6 shown) to improve the efficiency of drift / droplet capture.

[0066] In addition, the cooling device 636 includes a single tube 644 arranged in heat exchange relationship with the filler structure 640. In particular, the tube 644 is sandwiched between the first and second meshes 658, 660. The function of the tube 644 is similar to that of the first mesh 658, 660. Figure 2 Tube 644 is similar to tube 144 described above. Tube 644 includes a circular cross-section as described herein. Furthermore, in some examples, surface 638 of tube 644 can be embodied as fins that can conduct heat away from air flow 602, thereby creating an effective cooling surface. In other examples, surface 638 can include multiple fins extending therefrom to create a cooling surface.

[0067] Figure 7 Explains that Figure 1 Another embodiment of the DAC system 100 is associated with a mist eliminator 734 and a cooling device 736. Figure 7 In the illustrated embodiment, the demister 734 and the cooling device 736 are embodied as separate components arranged in the absorber unit 104. The cooling device 736 is arranged downstream of the demister 734 along the direction D3 of the air flow 702. The cooling device 736 can be embodied as a fin-and-tube heat exchanger, or the cooling device 736 can include any other design known in the art. In addition, the demister 734 can include a heat exchanger that can be used with respect to Figure 2 、 4 , 5 and 6 respectively explained in any of the packing structure 140, 440, 540, 640 packing structure. It should be noted that the mist eliminator 134, 434, 534, 634, 734 (see Figure 2 、 4 , 5, 6 and 7) and cooling devices 136, 436, 536, 636, 736 (see Figure 2 、 4 , 5, 6 and 7) may include any other designs and / or combinations of components other than those described herein to achieve the intended functions.

[0068] Figure 8 A DAC system 800 according to another embodiment of the present disclosure is described. Figures 1 to 3 The DAC system 800 is similar to the DAC system 100 explained above. In addition, the same parts are referred to by the same numbers in this document. It should be noted that the components with the same reference numerals in different figures have the same structural features and the same functions. The DAC system 800 includes a demister 134, a cooling device 136, an absorber 106 and a refrigeration circuit 146, as described above. Figures 1 to 3 described.

[0069] exist Figure 8In the illustrated embodiment, the DAC system 800 further includes a first heat exchanger 862 disposed downstream of the cooling device 136 and configured to heat a portion of the air flow 102 received from the cooling device 136. Figure 8 In the illustrated embodiment, the DAC system 800 further includes a second heat exchanger 864, which is disposed downstream of the first heat exchanger 862 and is configured to cool a portion of the air stream 102 received from the first heat exchanger 862. In such an embodiment, the mist eliminator 134 and the cooling device 136 can each capture drift / droplets and reduce the evaporation rate of the adsorbent present in the air stream 102. Furthermore, drift / droplets escaping through the mist eliminator 134 can be captured by the first heat exchanger 862. The first heat exchanger 862 is embodied as a hot heat exchanger, which can increase the temperature of the air stream 102 received from the cooling device 136, thereby evaporating any remaining drift / droplets. Furthermore, the second heat exchanger 864 is embodied as a cold heat exchanger, which can reduce the temperature of the air stream 102 received from the first heat exchanger 862, thereby condensing the adsorbent and water present in the air stream 102.

[0070] In addition, Figure 8 In the illustrated embodiment, the DAC system 800 further includes an additional refrigeration circuit 866 arranged in fluid communication with the first heat exchanger 862 and the second heat exchanger 864. The additional refrigeration circuit 866 is configured to provide heat exchange between the first heat exchanger 862 and the second heat exchanger 864. In some examples, the additional refrigeration circuit 866 includes a heat pump 868 that converts waste heat from cooling of the second heat exchanger 864 into useful heat. The useful heat can then be used to heat the first heat exchanger 862 to increase the temperature of the air flow 102 flowing through the first heat exchanger 862.

[0071] In some embodiments, DAC system 800 further includes an electrostatic precipitator 870 disposed downstream of second heat exchanger 864. Electrostatic precipitator 870 is embodied as a low-loss filter. Electrostatic precipitator 870 can facilitate an efficient impurity removal step. In particular, electrostatic precipitator 870 can provide an air purification function, allowing DAC system 800 to purify air stream 102 of any contaminants (such as pollutants). In other embodiments, DAC system 800 can omit electrostatic precipitator 870.

[0072] Figure 9 A method 900 according to an embodiment of the present disclosure is described. The method 900 relates to the operation of the DAC system 100, 800, as respectively related to Figures 1 to 3 and Figure 8 Explained. Reference Figures 1 to 3 and Figure 9In step 902, the absorber 106 of the DAC system 100 removes at least a portion of the CO2 from the air stream 102. In step 904, the demister 134 receives at least a portion of the air stream 102 from the absorber 106. In step 906, the cooling device 136 cools the portion of the air stream 102 that passes through the demister 134. In some embodiments, the heat pump 148 extracts heat from the cooling device 136. In some embodiments, the heat pump 148 heats the heating device 124 of the DAC system 100.

[0073] Now refer to Figure 8 and Figure 9 In some embodiments, a portion of the air stream 102 received from the cooling device 136 is heated via the first heat exchanger 862. In some embodiments, a portion of the air stream 102 received from the first heat exchanger 862 is cooled via the second heat exchanger 864. In some embodiments, heat exchange between the first heat exchanger 862 and the second heat exchanger 864 is provided via an additional refrigeration loop 866.

[0074] It should be understood that the present invention is not limited to the above-described embodiments and that various modifications and improvements may be made without departing from the concepts described herein. Unless mutually exclusive, any feature may be used alone or in combination with any other feature, and the present disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

Claims

1. A direct air capture (DAC) system (100, 800), comprising: an absorber (106) configured to receive the air stream (102) and absorb at least a portion of the carbon dioxide present in the air stream (102); a demister (134, 434, 534, 634, 734) configured to receive at least a portion of the air flow (102) from the absorber (106); and A cooling device (136, 436, 536, 636, 736) is arranged in heat exchange relationship with the demister (134, 434, 534, 634, 734) and is configured to cool the portion of the air flow (102).

2. The DAC system (100, 800) of claim 1, wherein: The cooling device (136, 436, 536, 636) is configured to cool the demister (134, 434, 534, 634) to induce condensation on a surface of the demister (134, 434, 534, 634).

3. The DAC system (100, 800) of claim 2, wherein: The demister (134, 434, 534, 634) includes a packing structure (140, 440, 540, 640), and wherein the cooling device (136, 436, 536, 636) includes one or more tubes (144, 444, 544, 644) arranged in heat exchange relationship with the packing structure (140, 440, 540, 640).

4. The DAC system (100, 800) of claim 3, wherein: The cooling device (136, 436, 536, 636) includes a thermally conductive material.

5. The DAC system (100, 800) according to any one of claims 2 to 4, further comprising a refrigeration circuit (146) arranged in fluid communication with the cooling device (136, 436, 536, 636) and configured to extract heat from the cooling device (136, 436, 536, 636).

6. The DAC system (100, 800) of claim 5, further comprising a controller (152) configured to control a refrigeration cycle of the refrigeration circuit (146) based on at least one of an environmental parameter, a pressure within the absorber (106), and a temperature within the absorber (106).

7. The DAC system according to claim 6, wherein: The controller is configured to control the refrigeration circuit based on the humidity of ambient air and the humidity of air exiting the absorber such that condensation on a surface of the demister provides condensate to replace a portion of water lost in the absorber.

8. The DAC system (100, 800) according to any one of claims 5 to 7, wherein: The refrigeration circuit (146) includes a heat pump (148) and a heat exchanger (150) arranged in heat exchange relationship with the heat pump (148).

9. The DAC system (100, 800) of claim 8, wherein: The heat exchanger (150) comprises a heating device (124) of the DAC system (100, 800).

10. The DAC system (800) according to any preceding claim, further comprising: a first heat exchanger (862) disposed downstream of the cooling device (136) and configured to heat the portion of the air flow (102) received from the cooling device (136); as well as A second heat exchanger (864) is disposed downstream of the first heat exchanger (862) and is configured to cool the portion of the air flow (102) received from the first heat exchanger (862).

11. The DAC system (800) of claim 10, further comprising an additional refrigeration circuit (866) arranged in fluid communication with the first heat exchanger (862) and the second heat exchanger (864), wherein The additional refrigeration circuit (866) is configured to provide heat exchange between the first heat exchanger (862) and the second heat exchanger (864).

12. The DAC system (800) according to claim 10 or claim 11, further comprising an electrostatic precipitator (870) arranged downstream of the second heat exchanger (864).

13. A DAC system (100, 800) according to any preceding claim, wherein The absorber (106), the demister (134, 434, 534, 634, 734) and the cooling device (136, 436, 536, 636, 736) are integrated into a single absorber unit (104).

14. A method (900) comprising: removing at least a portion of carbon dioxide from an air stream (102) via an absorber (106) of a direct air capture (DAC) system (100, 800); receiving at least a portion of the air flow (102) from the absorber (106) at a demister (134, 434, 534, 634, 734); as well as The portion of the air flow (102) flowing through the demister (134, 434, 534, 634, 734) is cooled via a cooling device (136, 436, 536, 636, 736).

15. The method of claim 14, further comprising controlling the cooling device based on the humidity of the ambient air and the humidity of the air exiting the absorber so that condensation on surfaces of the demister provides sufficient condensate to replace a portion of the water lost in the absorber.

16. The method (900) of claim 14 or claim 15, further comprising extracting heat from the cooling device (136, 436, 536, 636, 736) via a heat pump (148).

17. The method (900) of claim 16, further comprising heating a heating device (124) of the DAC system (100, 800) via the heat pump (148).

18. The method (900) according to any one of claims 14 to 17, further comprising: heating the portion of the air flow (102) received from the cooling device (136) via a first heat exchanger (862); cooling the portion of the air stream (102) received from the first heat exchanger (862) via a second heat exchanger (864); as well as Heat exchange is provided between the first heat exchanger (862) and the second heat exchanger (864) via an additional refrigeration circuit (866).

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