Method and system for separating CO2 from additional constituents of a gas mixture containing at least 70% to 90% CO2

Abstract

The present invention relates to a method and a system for separating carbon dioxide (CO2) from a CO2-containing gas mixture containing from at least 70% to 90% by volume of CO2, such as a gas stream from a direct air capture system. The CO2 gas is separated from the remaining gases contained in the CO2-containing gas mixture by pressurizing the gas stream and feeding it to an absorption column, where the CO2 is brought into contact with a water stream and preferentially dissolved, resulting in a water stream enriched in CO2. The CO2-containing water stream can then be reinjected into a geological storage formation or sent to a system that releases the CO2 from the water by releasing the pressure, thus generating a CO2 stream suitable for use. The water stream can then be reused in the absorption column.

Description

Technical Field

[0001] The present invention relates to a method and a system for separating substantially all of the carbon dioxide (CO2) from additional constituents of a gas mixture containing from at least 70% to 90% by volume of CO2. The gas mixture preferably results from a system for, for example, so-called direct air capture (DAC) of CO2, or from a unit designed to capture and / or concentrate a CO2-containing gas mixture, such as, for example, from an industrial or power plant. As long as the CO2-containing gas mixture results from a system for direct air capture (DAC) of CO2, the CO2-containing gas mixture preferably contains from at least 80% to 90% by volume of CO2 and can have a water content exceeding 500 ppm and / or a relative humidity of 20 - 100% (i.e., can be saturated with H2O at a given temperature and pressure).

[0002] The method and system of the present invention rely on contacting a stream of a first gas mixture (G1) containing from at least 70% to 90% by volume of CO2 with a stream of a first water (W2), thereby producing a second water stream (W4) enriched in dissolved CO2 compared to the first water stream (W2) and a pressurized gas mixture (G3) substantially depleted of CO2 compared to the first gas mixture (G1). Preferably, the first gas mixture (G1) contains from at least 80% to 90% by volume of CO2 and can have a water content exceeding 500 ppm and / or a relative humidity of 20 - 100% (i.e., can be saturated with H2O at a given temperature and pressure).

[0003] In one embodiment of the present invention, the produced water stream (W4) can be transferred, for example, to an injection system for injection into a geological reservoir and subsequent storage of the contained CO2 in the geological reservoir if the first water stream (W2) is in the form of groundwater from a geological reservoir.

[0004] Alternatively, in another embodiment of the present invention, the generated water stream (W4) is such that the gas mixture (G1) contains less than 10% by volume, for example less than 8% by volume, less than 6% by volume or less than 4% by volume of any one or more gases and has a solubility in water equal to or higher than the solubility of carbon dioxide (CO2) at the applied pressure and temperature, or has a solubility in water of 0.5 to 2.5 g per kg of water at a pressure of 1 atm and a temperature between 10°C and 70°C. In order to desorb the CO2 dissolved in the water stream (W4), or to transfer it to a system for CO2 desorption, a concentrated and purified CO2 stream and a third water stream (W5) can be generated. The third water stream (W5) may be recycled into the flow of the first water stream (W2) at a point before the first water stream (W2) contacts the gas mixture (G1).

[0005] Further alternatively, in yet another embodiment of the present invention where the first water stream (W2) is in the form of seawater, the water stream (W4) can be recovered and stored for subsequent use, for example, for the transport of captured CO2 for utilization, or for the transfer of captured CO2 to permanent or intermediate storage.

[0006] The gas mixture from which substantially all of the carbon dioxide (CO2) can be separated from additional components in the method and system of the present invention can be derived from any source. However, gas mixtures resulting from systems for direct air capture (DAC), for example, or units designed to capture or concentrate CO2 in CO2-containing gas mixtures emitted from industrial plants or power plants, for example, are particularly well-suited for the methods and systems according to the present invention. The CO2-containing gas mixture captured by a DAC system generally contains a significant amount of other gases of atmospheric origin, such as nitrogen (N2), oxygen (O2) and argon (Ar), which need to be separated from the captured CO2 if the CO2 is to be utilized or stored for subsequent use.

[0007] Most processes for further purification of the CO₂-containing gas stream obtained by today's DAC rely on subsequent liquefaction and transportation of CO₂ by compression at high pressure and low temperature, which is a relatively energy-intensive process with currently available technologies. Furthermore, the gas stream obtained by DAC generally contains a relatively large amount of moisture, especially when based on normal atmosphere, and in currently available technologies, it tends to be a problem in scenarios involving further treatment to a more concentrated CO₂ stream, such as by liquefaction of CO₂. Thus, compressing CO₂ with the presence of a significant amount of water produces a fluid that causes significant corrosion of pipeline and wellbore materials. Most of the water in a typical gas mixture obtained by DAC can be separated from CO₂ by cooling and condensation, but usually additional drying is required to reduce the water content from about 2 - 4% to less than 500 ppm.

[0008] In contrast, the method and system of the present invention rely on pressurized water scrubbing to separate substantially all of the CO₂ from additional components of a gas mixture (G1) containing from at least 70 volume % to 90 volume % of CO₂, such as additional gas that is part of the gas mixture normally obtained from a DAC system. Thus, unlike the processes for further purification of the CO₂-containing gas stream obtained by DAC known today, the method and system of the present invention avoid the need for additional drying to reduce the water content from 2 - 4% to less than 500 ppm. Thus, as long as the gas mixture results from a direct air capture (DAC) system, the first gas mixture (G1) preferably contains from at least 80 volume % to 90 volume % of CO₂ and can have a relative humidity from 20% to 100% (i.e., can be saturated with H₂O at a given temperature and pressure), and there is no problem in handling a gas mixture (G1) having a water content exceeding 500 ppm. The resulting CO₂-saturated water (W4) can then be directed, for example, towards an injection well for permanent removal from the atmosphere and can be permanently isolated through mineral storage via solubility trapping by aqueous chemical reactions and subsequent mineral trapping.

[0009] Alternatively, the stream of water (W4) enriched with dissolved CO2 can be transferred, for example by reducing the pressure, to a system for desorbing the CO2 dissolved in the second stream of water (W4), whereby at least a portion of the CO2 dissolved in the water is desorbed, generating a concentrated and purified CO2 stream, which can be used for other purposes, such as fuel production or surface carbonation.

[0010] As a further alternative, when the first stream of water (W2) is based on seawater, the stream of CO2-enriched water (W4) is recovered and can be stored for subsequent use, for example for the transport of the captured CO2 for utilization, or for the transfer of the captured CO2 to permanent or intermediate storage.

[0011] To optimize the use of water resources, the source of water in the method and system according to the invention can be condensate from the air generated by the DAC system when the CO2-containing gas stream (G1) is obtained by DAC.

[0012] For geological storage, the method and system according to the invention can rely on contacting the gas mixture (G1) with a stream of water (W2) in the form of groundwater from a geological reservoir, and then transferring the resulting stream of water (W4) enriched with dissolved CO2 to an injection system for injecting the second stream of water (W4) into the same geological reservoir for mineral storage of CO2.

[0013] When the CO2-containing gas stream (G1) is obtained by DAC, any water used as the first stream of water (W2) in the method and system of the invention can be used in the DAC system, for example as an energy source, before being directed towards the method and system of the invention.

[0014] The methods and systems according to the present invention generally reduce the power required overall by the process for separating CO2 from a CO2-containing gas mixture as compared to methods and systems that rely on water removal by drying (or cooling and condensation) and subsequent liquefaction of CO2 by compression. The methods and systems of the present invention are relevant to all applications that require either CO2 dissolved in water or purified gaseous CO2 and alleviate the steps of drying, liquefying, and CO2 vaporization / regasification for handling a CO2-containing gas mixture, such as those derived from a DAC system, which are characteristic of otherwise known processes. This simplification results in a reduction in equipment requirements for known processes for separating CO2 from a CO2-containing gas mixture and generally reduces energy consumption, thereby lowering both the required capital costs and operating expenses of the methods and systems according to the present invention as compared to those of the prior art.

Background Art

[0015] CO2 is a gas that has been historically emitted in large quantities in relation to a wide range of industrial processes such as the combustion of fossil fuels, the production of cement, aluminum, and steel. As a greenhouse gas, CO2 in the atmosphere is a major factor in climate change.

[0016] To mitigate climate change, it is essential to reach net-zero CO2 emissions. In addition to significant emission reductions, the development of CO2 removal technologies is also necessary to address emissions that are difficult to mitigate, such as those from aviation, and to remove CO2 that has already been emitted. To limit global warming to 1.5°C or less, a net negative emission pathway is required by the second half of the 21st century.

[0017] Direct air capture (DAC) technology extracts CO2 directly from the atmosphere. The separated CO2 can then be safely and permanently stored deep underground or converted into products by utilization processes.

[0018] The most established forms of DAC rely primarily on two different approaches to capture CO₂ from the air, namely liquid DAC and solid DAC.

[0019] On the one hand, liquid DAC systems pass air through a chemical solution (e.g., a hydroxide solution) that removes CO₂.

[0020] On the other hand, solid DAC technology utilizes solid sorbent filters that chemically bind to CO₂.

[0021] Regardless of the specific technology used, capturing CO₂ from the atmosphere via direct air capture is currently expensive for subsequent storage or use. The CO₂ concentration in the atmosphere is much more dilute than, for example, flue gas from a power plant or cement plant. This requires relatively more energy compared to other CO₂ capture technologies and applications. The specific costs and energy requirements vary depending on the type of technology used. However, in most current scenarios, the captured CO₂ (whether by solid DAC or liquid DAC) needs to be released from the material it is captured in, and none of the currently known DAC technologies yield 100% pure CO₂, so the resulting gas mixture also needs to be further purified by both water removal and compression under high pressure. These processes increase both the capital costs (due to the need for additional equipment such as compressors) and the operating costs (for operating the compressors) of most current DAC plants.

[0022] In the net-zero emissions by 2050 scenario, which is envisioned as part of the Paris Agreement, DAC will have to scale up to capture more than 85 MtCO2 / year by 2030 and approximately 980 MtCO2 / year by 2050. This level of deployment requires several larger-scale demonstrations to improve the technology and reduce the capture costs. Therefore, DAC is a growth technology and is considered necessary to manage climate change. However, as mentioned above, the main limitation to large-scale implementation of DAC technology in its current state of development is the energy required by the system. DAC technology is very energy-intensive and relies on carbon-neutral energy resources. Therefore, strategies to minimize energy consumption are an important step in scaling up DAC technology to the required Gt scale.

[0023] A substantial part of the energy requirements of most known DAC systems is the process of preparing the CO2-enriched gas stream resulting from the initial DAC process for geological storage or utilization after the capture process, for example, in the form of energy required for liquefaction by compression.

[0024] Even though DAC technology has become very diverse, most of the earliest and more established DAC technologies are based on adsorption / desorption processes, as described above. In these processes, CO2 adsorption is carried out without pre-treating the incoming air stream, and CO2 desorption is carried out by a temperature-vacuum swing (TVS) process. During this process, the pressure within the system is decreased and the temperature is increased, thereby releasing the captured CO2. After the cooling phase, the entire process is repeated. The resulting gas stream from such a process is inevitably a gas stream with a variable chemical composition, and the exact concentration of CO2 in the resulting CO2 / air gas mixture depends on the operating parameters of the system. However, in most cases, the resulting gas mixture will have to be subjected to additional processing steps, even if it is CO2-enriched, before injection or utilization for geological storage, for example.

[0025] One way to separate CO2 from other gases in the gas mixture exiting the DAC system is by liquefaction. In such a process, the gas mixture is cooled and compressed, and any N2, O2, and Ar having a lower boiling point than CO2 are discharged from the system, producing pure liquid CO2, which can be transferred for geological storage or supplied to a utilization process. By pressurizing pure CO2 gas to the liquefaction pressure, the energy required to form liquid CO2 is large. In the case of a gas mixture containing gases other than CO2, the required energy is even greater. If the final desired product of a given process is gaseous CO2, additional energy in the form of heat is required to convert the liquid CO2 to its gaseous counterpart. One use of this is when the CO2 captured by the DAC process is dissolved in water and injected underground for immediate solubility capture and subsequent mineral storage. Further, the gas mixture from the DAC typically contains air and moisture, which must be separated from the CO2 before compression and subsequent storage / utilization. Therefore, if the purification and compression steps of the conventional DAC process can be avoided, the overall energy consumption of the CO2 capture post-treatment, and thus the overall energy consumption per ton of CO2 actually captured, for example, for geological storage, can be significantly reduced.

[0026] In addition to the conventional DAC process described above, it has also been proposed to capture carbon dioxide from the atmosphere through multiple stages of aeration (dissolving the gas in water) followed by deaeration (stripping the gas from the water) until a high concentration of carbon dioxide of sufficient quality for subsequent geological storage remains. However, these methods rely on the ability to treat both the associated gas mixture and water at very low temperatures, i.e., in order to be effective, the water must be carried out at the coldest possible temperature, and they also have the drawback that the overall energy consumption per ton of CO2 actually captured for possible geological storage is relatively large.

[0027] The method and system of the present invention provide a solution to this problem by avoiding the purification and compression steps of conventional DAC processes, as well as any need for cooling of the associated gas mixtures and water. This is achieved by absorbing substantially all of the relatively soluble CO2 gas from the relatively impure gas mixtures typically obtained in conventional DAC processes at a temperature near ambient temperature, i.e., between about 10°C and about 50°C, and under a moderately elevated pressure, into a water stream. Thus, the inventors of the present invention have described for the first time a system and method that meet the need for less energy consumption and being structurally and operationally simpler, wherein the method is for separating substantially all of the CO2 from, for example, a first gas mixture (G1) obtained from a conventional DAC system, by contacting the gas mixture (G1) with a first water stream (W2), thereby producing a second water stream (W4) that is enriched in dissolved CO2 compared to the first water stream (W2), and a pressurized gas stream (G3) that is substantially depleted of all of the CO2 compared to the flow of the first gas mixture (G1).

[0028] The produced water stream (W4) can be transferred, for example, to an injection system for injection into the geological reservoir and subsequent storage of the contained CO2 therein, if the first water stream (W2) is in the form of groundwater from a geological reservoir.

[0029] Alternatively, the generated water stream (W4) is such that the gas mixture (G1) contains less than 10% by volume, for example less than 8, 6 or 4% by volume of any one or more gases and has a solubility in water equal to or higher than the solubility of carbon dioxide (CO2) at the applied pressure and temperature, or has a solubility in water of 0.5 to 2.5 g per kg of water at a pressure of 1 atm and a temperature between 10°C and 70°C. In order to desorb the CO2 dissolved in the water stream (W4), or for transfer to a system for CO2 desorption, a concentrated and purified CO2 stream and a third water stream (W5) can be generated, and the third water stream (W5) may be recycled to the flow of the first water stream (W2) at a point before the first water stream (W2) contacts the gas mixture (G1).

[0030] Further alternatively, if the first water stream (W2) is in the form of seawater, the water stream (W4) can be recovered and stored for subsequent use, for example for the transport of captured CO2 for utilization, or for transfer to permanent or intermediate storage of captured CO2.

[0031] If the water stream (W2) used in the method or system according to the invention is obtained, for example, from a geological storage formation, it can further be used as a heat energy source for powering a first part of the DAC process before being directed to the method and system of the invention. In such an embodiment, the overall need for external energy input for the DAC process in combination with the method of the invention is lower than the sum of the external energy inputs required for DAC and the method of the invention when each is considered alone.

[0032] Also, the method and system of the invention do not rely, for example, on the addition of chemicals as compared to conventional processes that rely on DAC, and leave only relatively poorly soluble O2, N2 and Ar gases in the pressurized gas (G3) in which substantially all of the CO2 has been depleted as compared to the flow of the first gas mixture (G1), which can then be discharged from the system.

[0033] CO2 is captured by contacting the entire gas stream (G1) with a stream of water (W2). However, since the solubility of different gases in the gas stream (G1) varies considerably, this requires large amounts of water in many situations. For example, at 293 K (about 20 °C) and 1 atmosphere (about 1 bar), the solubility of relatively soluble CO2 is 0.169 g per 100 g of water, while the solubilities of relatively poorly soluble N2, O2, and Ar are only 0.0019, 0.0043, and 0.0062 g per 100 g of water, respectively. Therefore, in the method and system of the present invention, the flow of water (W2) when measured in kg / s is typically at least 10 to 135 times the flow of the pressurized first gas mixture (G1) when measured in kg / s.

[0034] Taking into account the variability of gas solubility, the method and system of the present invention can separate substantially all of the CO2 from other gases in the first gas stream (G1) by absorbing the CO2 into a first stream of water (W2), thereby producing a second stream of water (W4) enriched in dissolved CO2 compared to the first stream of water (W2), and a pressurized second gas stream (G3) that is substantially depleted of CO2 compared to the flow of the first gas mixture (G1).

[0035] In a preferred embodiment of the present invention, the first stream of water (W2) is in the form of groundwater from a geological reservoir, and the second stream of water (W4) enriched in dissolved CO2 compared to the first stream of water (W2) is transferred to an injection system for injecting the second stream of water (W4) into the same geological reservoir for mineral storage of CO2. In a particularly preferred embodiment of such methods and systems, they rely only on electricity and resources in the form of water supplied as condensate from the storage formation itself or from the air resulting from the DAC that produces the first gas stream (G1).

[0036] Therefore, by combining DAC technology with the above preferred embodiments and particularly preferred embodiments of the present invention, the overall resources required for the process to permanently remove CO2 from the atmosphere and convert it into solid carbonate minerals are reduced, and thus it becomes a more preferred solution to be applied in the fight against climate change.

[0037] In another embodiment of the method and system of the present invention, the generated water stream (W4) is such that the gas mixture (G1) contains less than 10% by volume, for example less than 8% by volume, less than 6% by volume or less than 4% by volume of any one or more gases and has a solubility in water equal to or higher than the solubility of carbon dioxide (CO2) at the applied pressure and temperature, or has a solubility in water of 0.5 - 2.5 g per kg of water at a pressure of 1 atm and a temperature between 10°C and 70°C. In this case, the CO2 dissolved in the water stream (W4) can be desorbed or transferred to a system for CO2 desorption, thereby generating a concentrated and purified CO2 stream, as well as a third water stream (W5). The third water stream (W5) may be recycled into the flow of the first water stream (W2) at a point before the first water stream (W2) comes into contact with the gas mixture (G1).

[0038] In yet another embodiment of the method and system according to the present invention, where the first water stream (W2) is in the form of seawater, the water stream (W4) can be recovered and stored for subsequent use, for example, for the transportation of the captured CO2 for utilization, or for the transfer of the captured CO2 to permanent or intermediate storage.

Summary of the Invention

[0039] Liquid and supercritical CO2 can be stored and transported commercially in a modular fashion, and their compositional integrity can be ensured. The efficient transport of CO2 is possible considering its low viscosity, high density, as well as its low critical temperature (31 °C) and pressure (74 bar). However, the liquefaction of CO2 as a purification step is an energy-intensive process, along with the potential need to remove moisture from the CO2-enriched gas mixture produced by the DAC process prior to liquefaction, which can slow down the scaling up of such solutions as a way to mitigate climate change in addition to the energy requirements of the DAC process itself. In response to these challenges, the method and system of the present invention enable an efficient direct air capture and storage / utilization chain by avoiding all possibilities where a liquefaction step and moisture removal are required.

[0040] In addition, the simplicity of the method and system of the present invention compared to known processes for separating CO2 from a CO2-containing gas mixture, such as the gas mixture obtained by DAC, both results in a reduction in equipment requirements, thereby lowering both the required capital costs and operating expenses of the method and system according to the present invention compared to those of the prior art.

[0041] In a preferred embodiment of the present invention, the method and system can be optimized to provide a CO2 storage pathway focused on reactive rock formations, tailings, and highly alkaline industrial slag, respectively.

[0042] To address one or more of the above concerns, in a first aspect of the present invention, - a method for separating substantially all of the carbon dioxide (CO2) from additional constituents of a first gas mixture (G1) comprising from at least 70 vol% to 90 vol% carbon dioxide (CO2), comprising: - pressurizing the first gas mixture (G1) to a pressure between 10 bar and 50 bar; - A step of bringing the flow of the pressurized first gas mixture (G1) into contact with the flow of first water (W2), wherein the pressure of the flow of first water (W2) is between 10 bar and 50 bar, and the flow of the first water (W2) measured in kg / s is 10 to 135 times the flow of the pressurized first gas mixture (G1) measured in kg / s, - A step of absorbing substantially all of the CO2 from the flow of the pressurized first gas mixture (G1) into the flow of first water (W2), thereby - - A second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2), and - A pressurized second gas flow (G3) that is substantially depleted of CO2 compared to the flow of the first gas mixture (G1) are produced. A method is provided that includes

[0043] In a preferred embodiment, the first gas mixture (G1) contains at least 80% to 90% by volume of CO2 and has a water content exceeding 500 ppm and / or a relative humidity of 20 to 100% (i.e., can be saturated with H2O).

[0044] In a preferred embodiment of the method according to the above first aspect of the present invention, the first gas mixture (G1) is pressurized to a pressure between 20 bar and 40 bar, the first water flow (W2) is in the form of groundwater from a geological reservoir, and the method - further includes a step of transferring the second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2) to an injection system for injecting the second water flow (W4) into the geological reservoir for mineral storage of CO2.

[0045] In another preferred embodiment of the method according to the above-described first aspect of the present invention, the first gas mixture (G1) is pressurized to a pressure between 20 bar and 40 bar, and the first gas mixture (G1) contains less than 10% by volume in total, for example less than 8, 6 or 4% by volume of any gas or plurality of gases, and has a solubility in water equal to or higher than the solubility of carbon dioxide (CO2) at the applied pressure and temperature, or has a solubility in water of 0.5 to 2.5 g per kg of water at a pressure of 1 atm and a temperature between 10 °C and 70 °C. The method comprises - transferring the second water stream (W4) enriched in dissolved CO2 compared to the first water stream (W2) to a system for desorbing the CO2 dissolved in the second water stream (W4) or for desorption of CO2, whereby - - a stream of CO2, and - a third water stream (W5) depleted in dissolved CO2 compared to the second water stream (W4) are generated, - recycling the third water stream (W5) into the flow of the first water stream (W2) at a point before the first water stream (W2) contacts the flow of the pressurized first gas mixture (G1) is further included.

[0046] In another preferred embodiment of the method according to the above-described first aspect of the present invention, the first gas mixture (G1) is pressurized to a pressure between 10 bar and 20 bar, and the first water stream (W2) is in the form of seawater. The method comprises - collecting the second water stream (W4) enriched in dissolved CO2 compared to the first water stream (W2) for subsequent transport or transfer to permanent storage or intermediate storage is further included.

[0047] In a particularly preferred embodiment of the method according to the above-described first aspect of the present invention, the first gas mixture (G1) is received from a direct air capture unit (DAC) or from a unit designed to capture and / or concentrate a CO2-containing gas mixture discharged from an industrial plant or a power plant. The first gas mixture (G1), insofar as it results from a direct air capture (DAC) system, preferably contains at least 80 vol% to 90 vol% of CO2 and can have a water content exceeding 500 ppm and / or a relative humidity of 20 to 100% (i.e., can be saturated with H2O).

[0048] In the context of the present invention, the term separation should be understood as any means of distinguishing or separating the different components of a mixture, for example, any means of isolating or extracting one component of the mixture from the additional components of that mixture.

[0049] In the context of the present invention, the term separating substantially all of the CO2 from the additional components of the first gas mixture (G1) should be understood as isolating or extracting substantially all of the CO2 in the first gas mixture from the additional components of that gas mixture.

[0050] In the context of the present invention, separating substantially all of the CO2 from the additional components of the first gas mixture (G1) means separating at least 95%, for example at least 96%, for example at least 97%, i.e., for example preferably at least 98%, even more preferably at least 99% of the CO2 in the first gas mixture from the additional components of that gas mixture.

[0051] In the context of the present invention, the term transfer should be understood as any means of transferring a liquid, such as water or a gas (e.g., a gas mixture), from one location to another, for example by pumping.

[0052] In the context of the present invention, the terms "recycle", "recycle", and "recycle" refer to, for example, a liquid, such as water or a gas (e.g., a gas mixture), from a downstream position of a given forward flow of the liquid or gas to an upstream position of the same forward flow of the liquid or gas, e.g., by pumping, so that the flow of the liquid or gas in a given process flow is recycled again, or a flow of the liquid or gas is recycled again in a given process flow, and should be understood as any means of an act or process.

[0053] In the context of the present invention, the term "flow" should be understood as a substance, such as water or a gas, that moves in a given direction at a given velocity with a specific flow rate that can be provided as either a volumetric flow rate or a mass flow rate. The volumetric flow rate is the volume of fluid or gas passing through a given point per unit time and is usually represented by the symbol Q (sometimes V). The SI unit of volumetric flow rate is m 3 / s. Thus, the volumetric flow rate is equal to volume / time. On the other hand, the mass flow rate is the mass of fluid or gas passing through a given point per unit time. The SI unit of mass flow rate is kg / s.

[0054] In the context of the present invention, the term "water source" or "water" should be understood as any type of water, such as water condensed from air, groundwater, ocean / seawater, spring water, geothermal condensed water or brine (geothermal water), or surface water from rivers, water currents or lakes, etc.

[0055] In the context of the present invention, the term "injection well" should be understood as any type of structure that enables the downward placement of a fluid or gas deep underground or just below the ground surface, e.g., a device for placing a fluid into a rock formation such as basalt or basaltic rock, and a porous rock formation such as sandstone or limestone, or into or below a shallow soil layer.

[0056] In the context of the present invention, a CO2-containing gas mixture should be understood as any gas mixture in which the relative content of CO2 is higher than the relative content of CO2 in the atmosphere. In a particularly preferred embodiment of the present invention, the CO2-containing gas mixture contains from at least 70% to 90% by volume of carbon dioxide (CO2), for example from at least 75% to 90% by volume of carbon dioxide (CO2), for example from at least 80% to 90% by volume of carbon dioxide (CO2), for example from at least 85% to 90% by volume of carbon dioxide (CO2). In a particularly preferred embodiment of the present invention, the CO2-containing gas mixture has a water content exceeding 500 ppm and / or a relative humidity of 20 - 100% (i.e., partially or completely saturated with H2O), for example at least 0.05% by volume of H2O, for example at least 0.1% by volume of H2O, for example at least 0.15% by volume of H2O, for example at least 0.20% by volume of H2O, for example at least 0.25% by volume of H2O, for example at least 0.5% by volume of H2O, for example at least 0.75% by volume of H2O, for example at least 1% by volume of H2O, for example at least 1.25% by volume of H2O. Preferably, the CO2-containing gas mixture according to the present invention contains from at least 80% to 90% by volume of CO2 and has a water content exceeding 500 ppm, i.e., at least 0.05% by volume of H2O.

[0057] In the context of the present invention, the term "hydraulic pressure" should be understood as the pressure of the hydraulic fluid exerted in all directions on a container, shaft, hose, or anything in which the hydraulic fluid is present. Hydraulic pressure can cause a flow within the hydraulic system when the fluid flows from high pressure to low pressure.

[0058] Pressure is measured in the SI unit Pascal (Pa), i.e., 1 Newton per square meter (1 N / m 2 ) or 1 kg / (m·s 2 ) or 1 J / m 3 . Other commonly used pressure units are pounds per square inch, or more precisely pounds-force per square inch (abbreviation: psi) and bar. In SI units, 1 psi is approximately equal to 6895 Pa and 1 bar is equal to 100,000 Pa.

[0059] In the context of the present invention, the term "partial pressure of a gas (CO2)" or simply "pressure" should be understood as the conceptual pressure of the given gas in a gas mixture, i.e., the pressure that this given gas would have if it alone occupied the entire initial volume of the mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the individual constituent gases in the mixture.

[0060] In the context of the present invention, the terms "pressurizing" and "pressurized" should be understood as processes that result in a pressure higher than the ambient pressure, for example, higher than atmospheric pressure, for example, between 15 bar and 45 bar, for example, between 16 bar and 44 bar, for example, between 17 bar and 43 bar, for example, between 18 bar and 42 bar, for example, between 19 bar and 41 bar, for example, a pressure between 20 and 40 bar, and processes for maintaining it. In particular, the terms "pressurizing" and "pressurized" should not be construed in the context of the present invention as meaning compressing a given gas or a given gas mixture into a liquid state. Compressing into a liquid state means subjecting a given gas or a given gas mixture to a pressure above a specific threshold at a given temperature.

[0061] In the context of the present invention, the term "bringing into contact", for example, bringing a gas stream into contact with a water stream, should be understood as bringing something into contact with something else, i.e., bringing two or more things into contact with each other, physically interacting with each other, or associating with each other.

[0062] In the context of the present invention, the term "absorption", for example the absorption of a gas into water, should be understood as a physical or chemical phenomenon or process in which atoms, molecules or ions enter a bulk phase, such as a liquid or solid material. An example of this is gas-liquid absorption (also known as scrubbing), which is an operation in which a gas mixture is brought into contact with a liquid for the purpose of preferentially dissolving one or more components of the gas mixture and providing a solution of these in that liquid. In principle, there are two types of absorption processes, physical absorption and chemical absorption, depending on whether or not there is some chemical reaction between the solute and the solvent (absorbent). In processes such as those of the present invention, where water is used as the absorbent, little chemical reaction occurs between the absorbent and the solute, and thus this process is generally referred to as physical absorption. However, in processes where the pH of the water absorbent is modified by the addition of a base or an acid, absorption into the water may involve a rapid and irreversible neutralization reaction in the liquid phase, depending on the chemical nature of the solute, and at this time this process may be referred to as chemical absorption or reactive absorption. Thus, for example, by using chemical reactions induced by pH modification, it is possible to increase the absorption rate, increase the absorption capacity of the solvent, increase the selectivity to preferentially dissolve only certain components of the gas mixture, and / or convert harmful components of the gas mixture into safe or safer compounds.

[0063] In the context of the present invention, the term "generate", for example to generate a flow of water or a flow of pressurized gas, should be understood as causing, inducing, generating, bringing about or producing something, such as a flow of water or a flow of pressurized gas.

[0064] In the context of the present invention, "injecting / re-injecting" or "injection / re-injection" should be understood as the forced introduction / re-introduction of something into another, for example to push a fluid into a subsurface formation.

[0065] In the context of the present invention, the term geological reservoir should be understood as a subsurface structure that expands in directions other than upward and downward, such as fractures in basaltic rock, which provides a flow path for water injected into an injection well according to the present invention and can include what is referred to as a geothermal reservoir. In this context, the term geothermal reservoir should be understood as fractures in hot rocks that expand in directions other than upward and downward and provide a flow path for water injected from a wellbore.

[0066] Accordingly, there is provided a method of separating substantially all of the CO2 from the remaining gas of the first gas mixture (G1) by contacting the first gas mixture (G1) with a first water stream (W2), thereby producing a water stream (W4) enriched in dissolved CO2, such that the gas is thus prepared for subsequent storage, disposal or use.

[0067] In one embodiment, the disposal may be based, for example, on injecting a water stream (W4) enriched in dissolved CO2 into a geological system or reservoir, where chemical bonds are formed via a water-rock reaction. Accordingly, the water-rock reaction already occurring in natural geological systems can be utilized by injecting a water stream (W4) enriched in dissolved CO2 into a geological system or reservoir. Separating CO2 by dissolving it in a water stream and injecting it underground is considered an ideal method for reducing the CO2 concentration in the atmosphere. In a particular preferred embodiment of such an embodiment including the disposal of CO2, the first water stream (W2) can be in the form of groundwater from the same geological system or reservoir.

[0068] In one embodiment, the CO2-containing gas mixture (G1) further comprises at least one of the following gases: O2, N2 and / or Ar, and the method of separating substantially all of the CO2 gas from the remaining gases contained in the CO2-containing gas mixture (G1) comprises passing the CO2-containing gas mixture (G1) containing at least one of the O2, N2 and / or Ar gases through an absorption column, where the CO2 is brought into contact with a stream of water (W2), and the dissolved CO2 is separated from the remaining poorly soluble O2, N2 and / or Ar gases. In this way, a simple method for separating CO2 from the remaining poorly soluble gases remaining in the pressurized second gas stream (G3) is provided, and the pressurized second gas stream (G3) is substantially depleted of all of the CO2 compared to the flow of the first gas mixture (G1).

[0069] In one embodiment, the remaining gas in the pressurized second gas stream (G3) exiting the absorption column is transferred to a system where energy is recovered by expanding the gas to convert kinetic energy into useful energy for the purpose of increasing the overall efficiency of the system.

[0070] In one embodiment, the remaining gas in the pressurized second gas stream (G3) exiting the absorption column is directed towards the inlet of the DAC after expansion to ambient pressure for the purpose of increasing the overall efficiency of the system. This solution is applied when the concentration of CO2 in the remaining gas mixture exiting the absorption column is significantly higher than the concentration of air.

[0071] In one embodiment, the water stream (W4) enriched in dissolved CO2 is directed towards an evaporator where the pressure is released, thereby releasing CO2 from the water, thereby producing a stream of CO2 suitable for use and a third water stream (W5) depleted in dissolved CO2 compared to (W4). The resulting water stream (W5) is then recycled to the flow of the first water stream (W2) at a point prior to bringing the first water stream (W2) into contact with the flow of the pressurized first gas mixture (G1) for reuse in the absorption column.

[0072] In a second aspect of the present invention, - from additional components of a first gas mixture (G1) containing at least 70% to 90% by volume of carbon dioxide (CO2), a system for separating substantially all of the CO2, - means for pressurizing the first gas mixture (G1) to a pressure between 10 bar and 50 bar, - means for bringing the flow of the pressurized first gas mixture (G1) into contact with a first water flow (W2), wherein the pressure of the first water flow (W2) is between 10 bar and 50 bar and the flow of the first water flow (W2) measured in kg / s is 10 to 135 times the flow of the pressurized first gas mixture (G1) measured in kg / s, - absorbing substantially all of the CO2 from the flow of the pressurized first gas mixture (G1) into the first water flow (W2), - a second water flow (W4) enriched with dissolved CO2 comparable to the first water flow (W2), and - a pressurized second gas flow (G3) substantially depleted of CO2 compared to the flow of the first gas mixture (G1) means for generating is provided. In a preferred embodiment, the first gas mixture (G1) contains at least 80% by volume of CO2 and has a water content of more than 500 ppm, i.e., at least 0.05% by volume of H2O.

[0073] In a preferred embodiment of the system according to the above-mentioned second aspect of the present invention,

[0074] ​- Means for bringing the flow of the pressurized first gas mixture (G1) into contact with a flow of first water (W2), wherein the pressure of the flow of first water (W2) is between 10 bar and 50 bar and the flow of the first water (W2) measured in kg / s is 10 to 135 times the flow of the pressurized first gas mixture (G1) measured in kg / s, said means; - Absorbing substantially all of the CO2 from the flow of the pressurized first gas mixture (G1) into the flow of first water (W2); - A second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2), and - A pressurized second gas flow (G3) substantially depleted of CO2 compared to the flow of the first gas mixture (G1). The means for generating is an absorption column.

[0075] In another particularly preferred embodiment of the system according to the second aspect of the invention described above, the system - Means for procuring the flow of first water (W2) in the form of groundwater from a geological reservoir, and - Means for transferring the second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2) to an injection system for injecting the second water flow (W4) into the geological reservoir for mineral storage of CO2. further comprises.

[0076] In another particularly preferred embodiment of the system according to the second aspect of the invention described above, the system - Means for transferring the second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2) to a system for desorbing the CO2 dissolved in the second water flow (W4) or for desorbing CO2, thereby generating a flow of CO2 and a third water flow (W5) depleted in dissolved CO2 compared to the second water flow (W4); - means for recirculating said third water flow (W5) into the flow of said first water flow (W2) at a point before bringing said first water flow (W2) into contact with the flow of said pressurized first gas mixture (G1) further comprises.

[0077] It should be noted that the term water according to the present invention can mean condensate from air, fresh water, water from geothermal wells, salt water (geothermal water), seawater, etc. Thus, said water source can be any type of water. Similarly, a CO2-containing gas mixture (G1) containing at least 70% to 90% CO2 can be derived from any source such as a conventional power plant, a geothermal power plant, industrial production, a gas separation station, etc. However, preferably, a CO2-containing gas mixture (G1) containing at least 70% to 90% CO2 results from a DAC process. Said first gas mixture (G1), insofar as it results from a direct air capture (DAC) system, preferably contains at least 80% to 90% by volume of CO2 and has a water content exceeding 500 ppm, i.e., at least 0.05% by volume of H2O.

[0078] Generally, the various aspects of the present invention can be combined and joined in any way possible within the scope of the present invention. These and other aspects, features and / or advantages of the present invention will become apparent and be elucidated with reference to the embodiments described below.

[0079] Hereinafter, some embodiments of the present invention will be described by way of example only with reference to the drawings.

Brief Description of the Drawings

[0080]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0081] Figure 1 shows a flowchart of a method according to the present invention for separating substantially all of the carbon dioxide (CO2) from an additional component of a CO2-containing gas mixture (G1), such as a gas stream from DAC, which contains at least 70% to 90% by volume of CO2 and at least one of O2, N2, and Ar gases. As long as the gas mixture (G1) results from a direct air capture (DAC) system, the gas mixture (G1) contains at least 80% to 90% by volume of CO2 and has a water content exceeding 500 ppm, i.e., at least 0.05% by volume of H2O.

[0082] It should be noted that a CO₂-containing gas mixture (G1) containing at least 70% to 90% CO₂ should not be construed as being limited to the gas stream from DAC in the context of the present invention. However, for simplicity, hereinafter, embodiments where the CO₂-containing gas mixture (G1) results from DAC will be referred to, and thus, the gas stream may further contain one or more gases selected from O₂, N₂, and Ar, but is not limited thereto. However, those skilled in the art can easily modify the specific conditions described in the following embodiments to provide specific conditions applicable to other embodiments, for example, embodiments where the CO₂-containing gas mixture (G1) containing at least 70% to 90% CO₂ does not result from DAC. As long as the gas mixture (G1) results from a direct air capture (DAC) system, the gas mixture (G1) contains at least 80% to 90% by volume of CO₂ and has a water content exceeding 500 ppm, i.e., at least 0.05% by volume of H₂O.

[0083] As discussed in more detail in relation to Figure 2, for example, substantially all separation of CO₂ in the CO₂-containing gas mixture (G1) containing at least 70% to 90% CO₂ from any O₂, N₂, and Ar contained in the gas stream (G1) is preferably carried out by passing the gas stream through an absorption column, where substantially all of the CO₂ dissolves in a liquid, typically a water stream (W2), and is thus separated from the remaining more poorly soluble O₂, N₂, and Ar gases. Subsequently, the resulting water stream (W4) containing dissolved CO₂ can be directed, for example, to an injection well for disposal / storage or to another process for the utilization of CO₂. In certain embodiments, the water stream (W5) resulting from the disposal / storage or utilization of CO₂ in the water stream (W4) can be reused as the water stream (W2).

[0084] Referring to Figure 2, the present invention particularly relates to - at least 70% to 90% by volume of carbon dioxide (CO₂) A method and system for separating substantially all of the CO2 from additional components of a first gas mixture (G1) comprising: The method comprising: ○ Pressurizing the first gas mixture (G1) to a pressure between 10 bar and 50 bar; ○ Contacting a flow of the pressurized first gas mixture (G1) with a first water flow (W2), wherein the pressure of the first water flow (W2) is between 10 bar and 50 bar and the flow of the first water flow (W2) measured in kg / s is 10 to 135 times the flow of the pressurized first gas mixture (G1) measured in kg / s; ○ Absorbing substantially all of the CO2 from the flow of the pressurized first gas mixture (G1) into the first water flow (W2), thereby ○ · A second water flow (W4) enriched in dissolved CO2 compared to the first water flow (W2), and · A pressurized second gas flow (G3) that is substantially depleted of CO2 compared to the flow of the first gas mixture (G1) are produced; relates to a method and system.

[0085] As long as the gas mixture (G1) results from a direct air capture (DAC) system, the gas mixture (G1) contains at least 80 vol% to 90 vol% CO2 and has a water content exceeding 500 ppm, i.e., at least 0.05 vol% H2O.

[0086] As shown in FIG. 1 and as described above, the pressurized second gas stream (G3) exiting the absorption column may be transferred to a system where energy is recovered by expanding the gas and thereby converting kinetic energy into useful energy for the purpose of increasing the overall efficiency of the system. Similarly, for the purpose of increasing the overall efficiency of the system, if the concentration of CO2 in the remaining gas mixture (G3) exiting the absorption column is significantly higher than that of air, it may be directed towards the inlet of the DAC after expansion to ambient pressure.

[0087] transferring the water stream (W4) enriched in dissolved CO2 to an injection well for injecting the water stream (W4) into a geological storage formation, or The process of transferring it to a system for utilization purposes is not shown in FIG. 2.

[0088] The process of transferring the water stream (W4) enriched in dissolved CO2 to an injection well for injecting the water stream (W4) into a geological storage formation is shown in FIG. 3.

[0089] The use of the water stream (W4) for utilization purposes is shown in FIG. 5, where at least a portion of the water stream (W4) enriched in dissolved CO2 compared to the first water stream (W2) is transferred to a system for desorbing the CO2 dissolved in the second water stream (W4) or for desorbing CO2, thereby generating a CO2 stream and a third water stream (W5) depleted in dissolved CO2 compared to the second water stream (W4). In certain embodiments, the water stream (W5) resulting from the disposal / storage or utilization of CO2 in the water stream (W4) can be reused as the water stream (W2) that contacts the stream of the pressurized first gas mixture (G1).

[0090] In a particularly preferred embodiment of the method according to the invention, the pressure of the pressurized gas mixture (G1) containing at least one of H2, N2 and / or Ar, together with from at least 70% to 90% by volume of CO2, is between 15 bar and 45 bar, for example between 16 bar and 44 bar, for example between 17 bar and 43 bar, for example between 18 bar and 42 bar, for example between 19 bar and 41 bar, for example between 20 bar and 40 bar, or between 15 bar and 40 bar, for example between 16 bar and 40 bar, for example between 17 bar and 40 bar, for example between 18 bar and 40 bar, for example between 19 bar and 40 bar, or between 20 bar and 45 bar, for example between 20 bar and 44 bar, for example between 20 bar and 43 bar, for example between 20 bar and 42 bar, for example between 20 bar and 41 bar, that is to say, for example above 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 bar and below 40, 39, 38, 37, 36, 35, 34, 33, 32, 31 or 30 bar.

[0091] In an even more particularly preferred embodiment of the method according to the invention, the temperature of the gas stream (G1) containing from at least 70% to 90% by volume of CO2 is close to ambient temperature, that is to say, for example between 10°C and 50°C, for example between 12°C and 48°C, for example between 14°C and 46°C, for example between 16°C and 44°C, for example between 18°C and 42°C, for example between 20°C and 40°C, or for example between 15°C and 50°C, for example between 16°C and 50°C, for example between 17°C and 50°C, for example between 18°C and 50°C, for example between 19°C and 50°C, for example between 20°C and 50°C, or for example between 10°C and 45°C, for example between 11°C and 45°C, for example between 12°C and 45°C, for example between 13°C and 45°C, for example between 14°C and 45°C, for example between 15°C and 45°C, or for example between 15°C and 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C.

[0092] In an even more particularly preferred embodiment of the method according to the invention, the temperature of the water flow (W2) is close to the ambient temperature, i.e., for example, between 10°C and 50°C, for example, between 12°C and 48°C, for example, between 14°C and 46°C, for example, between 16°C and 44°C, for example, between 18°C and 42°C, for example, between 20°C and 40°C, or for example, between 15°C and 50°C, for example, between 16°C and 50°C, for example, between 17°C and 50°C, for example, between 18°C and 50°C, for example, between 19°C and 50°C, for example, between 20°C and 50°C, or for example, between 10°C and 45°C, for example, between 11°C and 45°C, for example, between 12°C and 45°C, for example, between 13°C and 45°C, for example, between 14°C and 45°C, for example, between 15°C and 45°C, or for example, between 15°C and 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C.

[0093] In an even more particularly preferred embodiment of the method according to the invention, the pressure of the water stream (W2) is between 15 bar and 45 bar, for example between 16 bar and 44 bar, for example between 17 bar and 43 bar, for example between 18 bar and 42 bar, for example between 19 bar and 41 bar, for example between 20 bar and 40 bar, or between 15 bar and 40 bar, for example between 16 bar and 40 bar, for example between 17 bar and 40 bar, for example between 18 bar and 40 bar, for example between 19 bar and 40 bar, or between 20 bar and 45 bar, for example between 20 bar and 44 bar, for example between 20 bar and 43 bar, for example between 20 bar and 42 bar, for example between 20 bar and 41 bar, that is, for example, above 15 bar, 16 bar, 17 bar, 18 bar, 19 bar, 20 bar, 21 bar, 22 bar, 23 bar, 24 bar or 25 bar and below 40 bar, 39 bar, 38 bar, 37 bar, 36 bar, 35 bar, 34 bar, 33 bar, 32 bar, 31 bar or 30 bar. In a particularly preferred embodiment of the method according to the invention, the pressure of the water stream (W2) is about 2 to 7 bar, for example 3 to 6 bar, for example 4 to 5 bar higher than the pressure of the pressurized gas mixture (G1) containing at least one of O2, N2 and / or Ar together with at least 70% to 90% by volume of CO2. Thus, when the pressure of the pressurized gas mixture (G1) containing at least one of O2, N2 and / or Ar together with at least 70% to 90% by volume of CO2 is about 20 bar, the pressure of the water stream (W2) should preferably be about 22 to 27 bar. Nevertheless, those skilled in the art will recognize that the optimal pressure difference between the pressure of the pressurized gas mixture (G1) containing at least one of O2, N2 and / or Ar together with at least 70% to 90% by volume of CO2 and the water stream (W2) depends, for example, on the column height of the applicable absorption column and the pressure drop of the applicable water distribution system and only on where in a given system the pressure is measured.

[0094] In an even more particularly preferred embodiment of the method according to the invention, the flow of the gas mixture (G1) is between 0.05 kg / s and 0.5 kg / s, for example between 0.1 kg / s and 0.45 kg / s, for example between 0.15 kg / s and 0.4 kg / s, for example between 0.16 kg / s and 0.35 kg / s, for example between 0.17 and 0.3, for example between 0.18 kg / s and 0.25 kg / s, for example between 0.05 kg / s, 0.06 kg / s, 0.08 kg / s, 0.1 kg / s, 0.12 kg / s or 0.14 kg / s and 0.5 kg / s, 0.4 kg / s, 0.3 kg / s or 0.2 kg / s.

[0095] In an even more particularly preferred embodiment of the method according to the invention, the flow of the water flow (W2) is between 5 kg / s and 15 kg / s, for example between 6 kg / s and 14 kg / s, for example between 7 kg / s and 13 kg / s, for example between 8 kg / s and 12 kg / s, for example between 5 kg / s, 6 kg / s, 7 kg / s or 8 kg / s and 15 kg / s, 14 kg / s, 13 kg / s or 12 kg / s.

[0096] In an even more particularly preferred embodiment of the method according to the invention, the flow of the water flow (W2) measured in kg / s is at least 10 to 135 times, for example at least 15 times, for example at least 20 times, for example at least 25 times, for example at least 30 times, for example at least 35 times, for example at least 40 times, for example at least 45 times the flow of the pressurized first gas mixture (G1) measured in kg / s, that is, for example at least 11 times, for example at least 12 times, for example at least 13 times, for example at least 14 times, for example at least 16 times, for example at least 17 times, for example at least 18 times, for example at least 19 times, for example at least 46, for example at least 47, for example at least 48, for example at least 49, for example at least 50, for example at least 51 to 135 times the flow of the pressurized first gas mixture (G1) measured in kg / s.

[0097] In an even more particularly preferred embodiment of the method according to the invention, the flow of said water (W2), when measured in kg / s, is at least 10 to 135 times, for example at least 15 to 135 times, for example at least 20 to 135 times, for example at least 25 to 135 times, for example at least 30 to 135 times, for example at least 35 to 135 times, for example at least 40 to 135 times, for example at least 45 to 135 times the flow of said pressurized first gas mixture (G1), when measured in kg / s, i.e., for example at least 11 to 135 times, for example at least 12 to 134 times, for example at least 13 to 133 times, for example at least 14 to 132 times, for example at least 16 to 135 times, for example at least 17 to 134 times, for example at least 18 to 133 times, for example at least 19 to 132 times, for example at least 46 to 134, for example at least 47 to 133, for example at least 48 to 132, for example at least 49 to 131, for example at least 50 to 130 times the flow of said pressurized first gas mixture (G1), when measured in kg / s.

[0098] In an even more particularly preferred embodiment of the method according to the invention, said gas mixture (G1) containing at least 70 vol% to 90 vol% CO2 is a gas stream resulting from DAC. As long as the gas mixture (G1) results from a direct air capture (DAC) system, the gas mixture (G1) contains at least 80 vol% to 90 vol% CO2 and has a water content exceeding 500 ppm, i.e., at least 0.05 vol% H2O.

[0099] Also, apart from the method described above, the present invention also particularly - at least 70 vol% to 90 vol% carbon dioxide (CO2) A system for separating substantially all of the CO2 from additional components of a first gas mixture (G1) containing - means for pressurizing said first gas mixture (G1) to a pressure between 10 bar and 50 bar - Means for bringing the flow of the pressurized first gas mixture (G1) into contact with a flow of first water (W2), wherein the pressure of the flow of first water (W2) is between 10 bar and 50 bar, and the flow of the flow of first water (W2) measured in kg / s is 10 to 135 times, for example at least 15 times, for example at least 20 times, for example at least 25 times, for example at least 30 times, for example at least 35 times, for example at least 40 times, for example at least 45 times, i.e., the flow of the pressurized first gas mixture (G1) measured in kg / s, for example at least 11 times, for example at least 12 times, for example at least 13 times, for example at least 14 times, for example at least 16 times, for example at least 17 times, for example at least 18 times, for example at least 19 times, for example at least 46, for example at least 47, for example at least 48, for example at least 49, for example at least 50, for example at least 51 to 135 times, the flow of the pressurized first gas mixture (G1) measured in kg / s, for example at least 10 to 135 times, for example at least 15 to 135 times, for example at least 20 to 135 times, for example at least 25 to 135 times, for example at least 30 to 135 times, for example at least 35 to 135 times, for example at least 40 to 135 times, for example at least 45 to 135 times, i.e., the flow of the pressurized first gas mixture (G1) measured in kg / s, for example at least 11 to 135 times, for example at least 12 to 134 times, for example at least 13 to 133 times, for example at least 14 to 132 times, for example at least 16 to 135 times, for example at least 17 to 134 times, for example at least 18 to 133 times, for example at least 19 to 132 times, for example at least 46 to 134, for example at least 47 to 133, for example at least 48 to 132, for example at least 49 to 131, for example at least 50 to 130 times, means; - Absorbing substantially all of the CO2 from the flow of the pressurized first gas mixture (G1) into the flow of first water (W2); · A second water stream (W4) enriched in dissolved CO2 comparable to said first water stream (W2), and · A pressurized second gas stream (G3) substantially depleted of CO2 compared to the flow of said first gas mixture (G1) means for generating and also relates to a system comprising.

[0100] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered as illustrative or exemplary and not restrictive, i.e., the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and achieved by those skilled in the art in practicing the claimed invention from a study of the drawings, the disclosure, and the appended claims. In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processing device or other unit may perform the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

[0101] Example Example 1: For a DAC plant connected to the Carbfix injection facility in Hellisheidi, southwestern Iceland, a demonstration capture plant and injection system were designed.

[0102] A gas stream from the DAC plant containing 80% CO2 and 20% air (including any H2O) was directed to an absorption column where CO2 was dissolved in water at a constant temperature (15 °C to 17 °C) under high pressure (20 bar).

[0103] The operating conditions for capturing water-soluble carbon dioxide (CO2) from the CO2-containing gas stream from the DAC are outlined below.

Table 1

[0104] More than 95% of the carbon dioxide dissolved in water and was injected deep into the rock formation of the plant site for mineralization.

[0105] A person skilled in the art will readily understand that the above temperatures, flows, and pressures are based on the specific conditions of the project at Hellisheidi in Iceland and that they may vary if other predetermined conditions are given with respect to the gas flow and temperature. Similarly, a person skilled in the art will readily understand that the relevant water flow should be a specific ratio of the actual gas flow that should vary depending on the applicable pressure and temperature. In this regard, a person skilled in the art will understand that, for example, from the recommended relationship between the water flow rate and the water temperature in the supply gas stream containing 80% CO2 in the method according to the present invention shown in FIG. 6, CO2 is more soluble at lower temperatures than at higher temperatures, so CO2 absorption in water is temperature-dependent. Similarly, a person skilled in the art can find the relationship between the water flow rate required for 98% absorption of CO2 (in the supply gas stream containing 80% CO2) in the method according to the present invention in FIG. 7 and the absorber column operating pressure.

[0106] Example 2: A demonstration system was designed to capture CO2 from a DAC plant and inject the dissolved CO2 for mineral storage.

[0107] The gas stream from the DAC plant contained 80% CO2 and 20% air and was led to the absorption column at 20 bar using a dry compressor with a capacity of 832 kg / h. There, the CO2 was dissolved in water at a constant temperature (15 °C to 17 °C) and high pressure (20 bar).

[0108] To compensate for the pressure losses encountered within the system and the elevation difference between the water pumps where water enters the columns, water was supplied to the absorption column at 22 bar by a submersible pump, followed by a booster pump. The same feed water was used to cool the gas compressor that supplies the absorption column. The used cooling water was directed towards the flow of CO₂-enriched water exiting the absorption column, and the temperature of the water outlet increased with respect to its inlet temperature.

[0109] In this system, in order to ensure stable injection conditions when the operating state of the absorption column is unstable, the absorption column can be ignored and water can be sent directly to the injection well. Maintaining high pressure within the injection system prevents any release of CO₂ downstream of the absorption column and prevents sudden pressure and flow changes in the injection well during unstable gas supply.

[0110] The parameters of the stainless-steel absorption column are shown below.

Table 2

[0111] Using the parameters of the capture plant, the operating conditions for capturing water-soluble carbon dioxide (CO₂) from the CO₂-containing gas stream from the DAC and achieving a CO₂ capture efficiency of over 98% are outlined below. This table shows that 51.3 kg of water is required to capture 1 kg of CO₂. This water transports the CO₂ to the storage formation. Subsequently, the water is retrieved from the storage formation and returned to the system for reuse.

Table 3

[0112] More than 98% of the carbon dioxide dissolved in water and was injected deep into the rock formation of the plant site for mineralization (Patent PCT / EP 2020 / 064306).

[0113] A person skilled in the art would understand that the above-mentioned temperature, flow rate, and pressure are based on the specific conditions of a specific DAC plant installed at a specific location where these utilized flows are available, and that they could be different when other predetermined conditions are given regarding the gas flow rate and temperature. Similarly, a person skilled in the art would easily understand that the relevant water flow rate should be a specific ratio of the actual gas flow rate, which should vary according to the applicable pressure and temperature. In this regard, a person skilled in the art would understand that, for example, from the recommended relationship between the water flow rate and the water temperature in the supply gas flow containing 80% CO2 in the method according to the present invention shown in FIG. 6, CO2 is more soluble at lower temperatures than at higher temperatures, so CO2 absorption in water is temperature-dependent. Similarly, a person skilled in the art can find the relationship between the water flow rate required for 98% absorption of CO2 (in the supply gas flow containing 80% CO2) in the method according to the present invention in FIG. 7 and the absorber column operating pressure.

[0114] Example 3: A demonstration system was designed to capture CO2 from a DAC plant using seawater and inject the dissolved CO2 into a shallow underground layer for immediate solubility storage.

[0115] The gas flow from the DAC plant contained 80% CO2 and 20% air and was directed to the absorption column at a pressure of 10 bar using a liquid-sealed compressor with a capacity of 832 kg / h. There, CO2 was dissolved in water at a constant temperature (15°C) and high pressure (10 bar).

[0116] To compensate for the pressure loss encountered in the system and the height difference between the pumps where water enters the column, water was supplied to the absorption column at 12 bar by a submersible pump followed by a booster pump. The same feed water was used to cool the gas compressor supplying the absorption column. The used cooling water was directed towards the flow of CO2-saturated water exiting the absorption column (a flow not shown in the schematic), and the temperature of the water outlet increased with respect to the inlet temperature.

[0117] The parameters of the same stainless-steel absorption column as in Example 2 were used for this system.

[0118] Using the parameters of the capture plant, the operating conditions for capturing water-soluble carbon dioxide (CO2) from the CO2-containing gas stream from the DAC and achieving a CO2 capture efficiency exceeding 98% are outlined below. This table shows that approximately 100 - 130 kg of water is required to capture 1 kg of CO2. This water transports the CO2 to the storage formation.

[0119] This system is designed to operate in coastal or offshore areas. Seawater for the process can be supplied from shallow depths, in which case only electricity is required to achieve the operating pressure of the absorption column and overcome the pressure loss of the system. Furthermore, the gas-filled water can be disposed of in shallow (deeper than 102 m) seabed wells where the hydrostatic pressure in the storage formation exceeds 10 bar to maintain the dissolution of CO2. The final placement of the injection well and the depth at which the CO2-filled fluid exits the casing must take into account the scale of the injection activity as well as the structure and conditions of the storage formation. The parameters of the absorption column are shown below.

Table 4

Table 5

[0120] As in the above example, a person skilled in the art would readily understand that the above-mentioned temperature, flow rate, and pressure are based on the specific conditions of this example and may be different when other predetermined conditions are given regarding the gas flow rate and temperature. Similarly, a person skilled in the art would readily understand that the relevant water flow rate should be a specific ratio of the actual gas flow rate, which should vary according to the applicable pressure and temperature. In this regard, a person skilled in the art would understand that, for example, from the recommended relationship between the water flow rate and the water temperature in the supply gas stream containing 80% CO2 in the method according to the present invention shown in FIG. 6, since CO2 is more soluble at a lower temperature than at a higher temperature, the CO2 absorption in water is temperature-dependent. Similarly, a person skilled in the art can find the relationship between the water flow rate required for 98% absorption of CO2 in the method according to the present invention (in the supply gas stream containing 80% CO2) and the absorber column operating pressure in FIG. 7.

[0121] Example 4: A demonstration system was designed to capture CO2 from a DAC plant and inject the dissolved CO2 for mineral storage.

[0122] The gas stream from the DAC plant contains 80% CO2 and 20% air at a flow rate of 4749 kg CO2 / hour (equivalent to approximately 1.32 kg / s) and is led to the absorption column. Then, approximately 99.85% of the CO2 is absorbed by a water stream having an initial temperature of 20°C - at variable water flow rates under a constant high pressure (20 bar) at absorber column internal temperatures within the range of 20°C to 1°C respectively, - or at variable high pressures at a constant water flow rate (equivalent to 254000 kg / hr, approximately 70.56 kg / s) at absorber column internal temperatures within the range of 20°C to 1°C respectively is absorbed.

[0123] Figures 8 and 9 show the power / energy consumption (kWh) required to absorb 1 ton of CO2 under various different process conditions. Figure 8 relates to scenarios including a variable condensate / water flow rate (black circles) at a constant high pressure (20 bar). Figure 9 relates to scenarios including a variable high pressure (black circles) at a constant condensate / water flow rate (254000 kg / hr, equivalent to approximately 70.56 kg / s).

[0124] Both the individual energy consumption of each of all water cooling (chiller) (white squares), compressor (black triangles), condensate / water pump (crosses), and injection pump (white circles), and the total (black diamonds) power / energy consumption (kWh) are shown in Figures 8 and 9, and the actual values are presented in the table below.

Table 6

Table 7

[0125] As can be seen from the above tables and Figures 8 and 9, when the water / condensate stream (initially at ambient temperature) has to be cooled to a temperature of less than about 10°C, in any case, any water / condensate cooling (chiller, white squares), the required power / energy consumption (kWh) becomes significant (i.e., more than about 33% of the total energy consumption, black diamonds). Therefore, these results indicate that for any system based on the absorption of CO2 in a water / condensate stream close to ambient temperature (i.e., 20°C in this case), if the water / condensate temperature is significantly reduced below 10°C, the total power / energy consumption (kWh) increases significantly, and thus the efficiency of being able to absorb CO2 decreases significantly.

Claims

1. From the additional components of the first gas mixture (G1) received from the Direct Air Capture Unit (DAC), CO ２ A method for separating at least 98% of the first gas mixture (G1) at a temperature between about 10°C and about 50°C, -70% to 90% by volume of carbon dioxide (CO2) ２ ), - Contains a water content exceeding 500 ppm, i.e., at least 0.05 volume% H ２ Including O, The method described above is ○ A step of pressurizing the first gas mixture (G1) to a pressure between 15 bar and 45 bar, ○A step of bringing the flow of the pressurized first gas mixture (G1) into contact with a first water flow (W2) in the form of water condensed from air, groundwater, ocean / seawater, spring water, geothermal condensed water or brine (geothermal water), or surface water from a river, stream or lake, wherein the temperature of the first water flow (W2) is between approximately 10°C and approximately 50°C, the pressure of the first water flow (W2) is between 15 bar and 45 bar, and the flow rate of the first water flow (W2) when measured in kg / s is 10 to 135 times the flow rate of the pressurized first gas mixture (G1) when measured in kg / s. ○From the flow of the pressurized first gas mixture (G1), the CO ２ A step of absorbing at least 98% of it into the first water flow (W2), thereby, ○ Compared to the first water flow (W2), dissolved CO ２ The second water flow (W4) is enriched, and - Compared with the flow of the first gas mixture (G1), the CO ２ At least 98% of the pressurized second gas flow (G3) is depleted. The process of generating ○At least a portion of the second water flow (W4) is CO ２ For storage, the process involves transferring the water to an injection system for injecting the second water flow (W4) into a geological reservoir. ○The pressurized second gas flow (G3) - For emission into the atmosphere, - A system for expanding the gas flow, and / or - At the input of the DAC unit Transfer process Methods that include...

2. - The first gas mixture (G1) is pressurized to a pressure between 20 bar and 40 bar. - The first water flow (W2) is a form of groundwater from a geological system or reservoir, The above method causes the second water flow (W4) to be CO ２ The process further includes transferring the second water flow (W4) to an injection system for injecting it into the geological system or reservoir for storage. The method according to claim 1.

3. - The first gas mixture (G1) is pressurized to a pressure between 20 bar and 40 bar. - the first gas mixture (G1) contains any gas or plurality of gases in total of less than 10% by volume and has a solubility in water equal to or higher than the solubility of CO ２ at the applied pressure and temperature, The method described above is - At least a portion of the second water flow (W4) is CO2 dissolved in the second water flow (W4). ２ To attach or detach, or CO ２ The process of transferring to a system for attachment and detachment, and thereby, － -CO ２ The flow, and - Dissolved CO2 compared to the second water flow (W4) ２ The third water source (W5) is depleted. A process to generate - A step of recirculating the third water flow (W5) into the flow of the first water flow (W2) at a point before the first water flow (W2) comes into contact with the flow of the pressurized first gas mixture (G1). The method according to claim 1, further comprising:

4. The first water flow (W2) is in the form of seawater, The method described above is - A step of collecting at least a portion of the second water flow (W4) for subsequent transport or transfer to permanent storage or interim storage. The method according to claim 1, further comprising:

5. The method according to any one of claims 1 to 4, wherein the temperature of the first gas mixture (G1) is between 10°C and 50°C, for example between 12°C and 48°C, for example between 15°C and 35°C, for example between 20°C.

6. The method according to any one of claims 1 to 4, wherein the temperature of the first water flow (W2) is between 10°C and 50°C, for example between 10°C and 45°C, for example between 15°C and 40°C, for example between 16°C and 35°C, for example between 17°C and 30°C, for example between 18°C ​​and 25°C, for example between 20°C.

7. The method according to any one of claims 1 to 4, wherein the flow of the first gas mixture (G1) is between 0.05 kg / s and 0.5 kg / s, for example between 0.1 kg / s and 0.4 kg / s, for example between 0.15 kg / s and 0.3 kg / s, for example between 0.2 kg / s.

8. The method according to any one of claims 1 to 4, wherein the flow of the first water flow (W2) is between 1.5 kg / s and 15 kg / s, for example between 3 kg / s and 12 kg / s, for example between 5 kg / s and 11 kg / s, for example between 10 kg / s.

9. From the additional components of the first gas mixture (G1) received from the Direct Air Capture Unit (DAC), CO ２ A system for separating at least 98% of the first gas mixture (G1) at a temperature between about 10°C and about 50°C. -70% to 90% by volume of carbon dioxide (CO2) ２ ), - Contains a water content exceeding 500 ppm, i.e., at least 0.05 volume% H ２ Including O, The aforementioned system - Means for pressurizing the first gas mixture (G1) to a pressure between 15 bar and 45 bar, - A means for obtaining a first water flow (W2) in the form of water condensed from air, groundwater, ocean / seawater, spring water, geothermal condensed water or brine (geothermal water), or surface water from a river, stream or lake, wherein the temperature of the first water flow (W2) is between approximately 10°C and approximately 50°C. - A means for bringing the flow of the pressurized first gas mixture (G1) into contact with the flow of the first water (W2), wherein the pressure of the first water flow (W2) is between 15 bar and 45 bar, and the flow rate of the first water flow (W2), measured in kg / s, is 10 to 135 times the flow rate of the pressurized first gas mixture (G1), measured in kg / s. - From the flow of the pressurized first gas mixture (G1), the CO ２ At least 98% of it is absorbed by the first water flow (W2), Compared to the first water flow (W2), dissolved CO ２ The second water flow (W4) is enriched, and Compared with the flow of the first gas mixture (G1), CO ２ At least 98% of the pressurized second gas flow (G3) is depleted. Means for generating, - At least a portion of the second water flow (W4) is the CO ２ Means for transferring to an injection system for injecting the second water flow (W4) into a geological reservoir for storage, - The pressurized second gas flow (G3) - For emission into the atmosphere, - A system for expanding the gas flow, and / or - At the input of the DAC unit Means for transport and A system that includes this.

10. - The means for bringing the flow of the pressurized first gas mixture (G1) into contact with the flow of the first water (W2), - From the flow of the pressurized first gas mixture (G1), the CO ２ At least 98% of it is absorbed by the first water flow (W2), i. Dissolved CO2 compared to the first water flow (W2) ２ The second water flow (W4) is enriched, and ii. Compared with the flow of the first gas mixture (G1), CO ２ At least 98% of the pressurized second gas flow (G3) is depleted. The means for generating and The system according to claim 9, wherein the absorption column is.

11. - At least a portion of the second water flow (W4) is CO2 dissolved in the second water flow (W4). ２ To attach or detach, or CO ２ It is transferred to a system for attachment and detachment, thereby CO ２ Compared to the flow of the second water (W4), dissolved CO ２ A means to generate a third water flow (W5) that is depleted, - Means for recirculating the third water flow (W5) into the flow of the first water flow (W2) at a point before the first water flow (W2) comes into contact with the flow of the pressurized first gas mixture (G1) and The system according to claim 9 or 10, further comprising:

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