Device and method for capturing and storing atmospheric carbon dioxide
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-19
- Publication Date
- 2026-04-08
Smart Images
Figure FR2024050218_29082024_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title of the invention: DEVICE AND METHOD FOR THE CAPTURE AND STORAGE OF ATMOSPHERIC CARBON DIOXIDE
[0003] The invention relates to a device and method for capturing and storing atmospheric carbon dioxide.
[0004] Human activity has increased the concentration of carbon dioxide (CO2) in the atmosphere. In particular, the use of fossil fuels such as oil, gas, and coal, as well as deforestation and cement production, are among the causes of this increase.
[0005] The accumulation of CO2 induced by human activities contributes to approximately two-thirds of the increase in the greenhouse effect in the atmosphere. This is why the effect of other greenhouse gases is traditionally measured in CO2 equivalent. It is thus assumed that the increase in CO2 concentration is equivalent to the increase in greenhouse gas concentrations in the atmosphere in general. This increase accentuates the warming of our planet.
[0006] Today, the measured concentration of carbon dioxide in the atmosphere in 2021 was 421 ppm. This concentration is drastic, especially considering that in the middle of the 18 ème In the 19th century, it was only around 280 ppm. Thus, the current CO2 concentration is causing concern among many scientists, who point out the negative impacts on the climate, but also on the environment.
[0007] Recently, new technologies have been explored to capture and store CO2 from the atmosphere to mitigate negative impacts on our planet. Introducing alkalinity into the oceans is a promising method for capturing and storing CO2.
[0008] EP2024062 discloses a method for capturing atmospheric carbon dioxide using alkaline NaOH solutions.
[0009] Other methods are being considered, such as mining Trona, also called tronite, or sodium sesquicarbonate dihydrate [Na3(CO3)(HCC>3)*2(H2O)]. However, state-of-the-art techniques are not satisfactory, particularly because the CO2 balance is not effective for considering an application for the mitigation of global warming on a large scale. In addition, the availability of alkaline solutions is generally difficult, and mining methods are limited in raw materials and generate pollutants (particularly due to the need for transport).
[0010] The present invention improves the situation.
[0011] Thus, the invention introduces a method for capturing atmospheric carbon dioxide [CO2]. The method of the invention comprises the following steps: i. Providing a saline stream (1) and calcium carbonate [CaCOs] (7); ii. Producing an alkaline stream (5) comprising sodium hydroxide [NaOH]; and iii. Producing an acidic stream (6) comprising hydrochloric acid [HCl];
[0012] In this method, at least one of said steps ii. of producing the alkaline flow (5) and iii. of producing the acid flow (6) comprises a step of electrochemical treatment of at least a part of said saline flow (1).
[0013] Furthermore, the method of the invention comprises the following steps: iv. Neutralizing the hydrochloric acid [HCl] obtained in step iii. of producing an acid stream (6) by bringing the calcium carbonate [CaCOs] (7) of step i. of providing into contact in an acid reactor (AR) with said hydrochloric acid [HCl] so as to obtain a liquid stream (8) of calcium chloride [CaCL] and a gaseous stream (9) of carbon dioxide [CO2]; v. Producing a sodium carbonate [Na2COs] stream (10) by bringing at least a portion of the carbon dioxide [CO2] obtained in step iv. of neutralization into contact in a basic reactor (BR) with the sodium hydroxide [NaOH] of step ii. of producing an alkaline stream; and vi. The discharge of the sodium carbonate stream [Na2COs] (10) produced in the previous step v.in saline water selected from sea water and ocean water, so as to increase its alkalinity and thus cause the capture of atmospheric carbon dioxide [CO2]. In one embodiment, the provision of the saline flow from step i. is carried out by drawing from water selected from sea water and ocean water.
[0014] In a preferred embodiment, the electrochemical treatment is chosen from the group consisting of electrodialysis and chlor-alkali electrolysis.
[0015] In another preferred embodiment, step iv. of neutralizing the hydrochloric acid [HCl] further comprises collecting the liquid stream (8) of calcium chloride [CaCl2].
[0016] In another preferred embodiment, the method further comprises, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream (6), the following steps:
[0017] 1.1. A reverse osmosis (RO) to desalinate said saline flow (1) and thus obtain a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and
[0018] 1.2. A purification (F), preferably chosen from filtration and precipitation, receiving at least a portion of said flow of water concentrated in salts (2) from reverse osmosis (RO), in which Mg ions are eliminated 2+ and that 2+ of the flow of water concentrated in salts (2) and thus obtain a flow of purified water essentially free of Mg ions 2+ and that 2+ (2').
[0019] In another preferred embodiment, the method further comprises, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream (6), the following steps:
[0020] 1.3. Provision of a flow of purified water essentially free of Mg ions 2+ and that 2+(2'), and
[0021] 1.4. An electrodialysis in which said flow of purified water essentially free of Mg ions 2+ and that 2+ (2') is subjected to at least one electric field so as to produce said alkaline stream (5) and said acid stream (6) of steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream (6). In this embodiment, the method may further comprise, upstream of step i.4. of electrodialysis: 1.5. Provision of a desalinated water stream (1', 11), preferably a filtered desalinated water stream (1”), also subjected to said electric field during the electrodialysis so as to contribute to the production of said alkaline stream (5) and said acid stream (6) of steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream (6).
[0022] Alternatively, the method of the invention may further comprise, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream:
[0023] 1.6. A purification (F), preferably chosen from filtration and precipitation, receiving said from a saline flow (1), in which Mg ions are eliminated 2+ and that 2+ said saline flow (1) and thus obtain a flow of purified water essentially free of Mg ions 2+ and that 2+ (2');
[0024] 1.7. An electrodialysis in which said flow of purified water essentially free of Mg ions 2+ and that 2+ (2'), and preferably a flow of desalinated water (11), is / are subjected to at least one electric field so as to produce said alkaline flow (5) and said acid flow (6) of steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow (6).
[0025] In another variant of the process of the invention, the latter may further comprise, upstream of said steps ii. of production of an alkaline flow (5) and iii. of production of an acid flow:
[0026] 1.8. A reverse osmosis (RO) to desalinate said saline flow (1) and thus obtain a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and
[0027] 1.9. An electrodialysis in which said flow of desalinated water (1') and said flow of water concentrated in salts (2) are subjected to at least one electric field so as to produce said alkaline flow (5) and said acid flow (6) of steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow (6).
[0028] In embodiments, the electrodialysis further produces a partially desalinated stream (4) which is subjected to a second electrodialysis so as to contribute to the production of said alkaline stream (5) and said acidic stream (6) of steps ii. of producing an alkaline stream (5) and iii. of producing an acidic stream (6). In another variant, step ii. of producing an alkaline stream (5) of the method of the invention comprises:
[0029] - a chlor-alkali (CA) electrolysis so as to produce the alkaline stream comprising sodium hydroxide [NaOH] (5), a gaseous stream of dihydrogen [H2] (13), and a gaseous stream of chlorine [Cl2] (14); and wherein step iii. of producing an acidic stream (6) comprises
[0030] - an injection into a H2 / CI2 fuel cell (FC) of said gaseous flow of dihydrogen [H2] (13), and of said gaseous flow of chlorine [CI2] (14) so as to obtain a concentrated flow of acid (15) comprising hydrochloric acid [HCl], and electricity and / or heat; and
[0031] - a mixture in a dilution tank (D) of said concentrated acid flow (15) with a liquid, preferably a saline liquid (16), so as to obtain the acid flow (6) comprising hydrochloric acid [HCl].
[0032] The present invention further relates to a device for capturing atmospheric carbon dioxide [CO2] comprising a means for drawing a saline flow (1), preferably sea or ocean water, and a means for supplying calcium carbonate [CaCOs] (7). The device further comprises
[0033] - an electrochemical treatment unit (ED, U-CA) capable of producing from at least part of said saline flow (1): o an alkaline flow (5) comprising sodium hydroxide [NaOH]; and o an acid flow (6) comprising hydrochloric acid [HCl];
[0034] - an acid reactor (AR) in fluid communication with the electrochemical treatment unit (ED, U-CA) and connected to the calcium carbonate [CaCOs] supply means (7), to respectively receive the hydrochloric acid [HCl] and the calcium carbonate [CaCOs] (7) and bring them into contact so as to neutralize the hydrochloric acid [HCl] and thus produce a liquid flow (8) of calcium chloride [CaCL] and a gaseous flow (9) of carbon dioxide [CO2];
[0035] - a basic reactor (BR) in fluid communication with the electrochemical treatment unit (ED, U-CA) and with the acid reactor (AR), to respectively receive sodium hydroxide [NaOH] and carbon dioxide [CO2] and bring them into contact so as to produce a flow of sodium carbonate [Na2COs] (10); and
[0036] - a means for discharging said flow of sodium carbonate [Na2COs] (10) produced by the basic reactor (BR) into saline water chosen from sea water and ocean water, so as to increase its alkalinity and thus cause the capture of atmospheric carbon dioxide [CO2].
[0037] In one embodiment, the electrochemical treatment unit (ED, U-CA) is selected from the group consisting of an electrodialyzer and a chlor-alkali electrolysis installation.
[0038] The device of the invention may further comprise:
[0039] - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and
[0040] - a purification unit (F) in fluid communication with the reverse osmosis (RO) unit to receive at least a portion of said salt-concentrated water stream (2) and arranged to remove Mg2+ and Ca2+ ions from said salt-concentrated water stream (2) and thus obtain a purified water stream essentially free of Mg2+ and Ca2+ ions (2').
[0041] In another embodiment, the device further comprises:
[0042] - a means of supplying a flow of purified water essentially free of Mg2+ and Ca2+ ions (2'), and
[0043] - the electrochemical treatment unit is an electrodialyzer (ED) arranged in fluid communication with the means for supplying the flow of purified water essentially free of Mg2+ and Ca2+ ions (2') so as to subject this flow (2') to at least one electric field and thus produce said alkaline flow (5) and said acid flow (6).
[0044] In this embodiment, the device may comprise: a means for supplying a flow of desalinated water (1', 11), preferably a flow of filtered desalinated water (1”), and in which - the electrodialyzer (ED) is also arranged in fluid communication with the means for supplying a flow of desalinated water (1', 11, 1”) so as to subject this flow to said electric field to produce the alkaline flow (5) and the acid flow (6).
[0045] Alternatively, the device of the invention may further comprise:
[0046] - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and in which
[0047] - the electrochemical treatment unit is an electrodialyzer (ED) arranged in fluid communication with, on the one hand, at least a part of said desalinated water flow (1') and, on the other hand, at least a part of said salt-concentrated water flow (2), so as to subject them to at least one electric field to produce said alkaline flow (5) and said acid flow (6).
[0048] In another variant of the invention, the device may further comprise:
[0049] - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and
[0050] - a purification unit (F) in fluid communication with the reverse osmosis (RO) unit to receive at least a portion of said salt-concentrated water stream (2) and arranged to remove Mg2+ and Ca2+ ions from said salt-concentrated water stream (2) and thus obtain a purified water stream essentially free of Mg2+ and Ca2+ ions (2'), and wherein the electrochemical treatment unit is a chlor-alkali electrolysis installation comprising:
[0051] - a chlor-alkali (CA) reactor in fluid communication, on the one hand, with the reverse osmosis (RO) unit to receive at least a portion of said desalinated water flow (1 '), and, on the other hand, with the purification unit (F) to receive at least a portion of said purified water flow essentially free of Mg2+ and Ca2+ ions (2') so as to subject these flows (1 ', 2') to at least one electric field and thus produce said alkaline flow (5) comprising sodium hydroxide [NaOH] (5), a gaseous flow of dihydrogen [H2] (13), and a gaseous flow of chlorine [Cl2] (14);
[0052] - an H2 / CI2 fuel cell (FC) in fluid communication with the chlor-alkali reactor (CA) for receiving said dihydrogen [H2] gas stream (13) and said chlorine [CI2] gas stream (14) and thereby producing a concentrated acid stream (15) comprising hydrochloric acid [HCl], and electricity and / or heat; and a dilution tank (D) arranged to receive a liquid stream (1, 16), preferably a saline stream, and in fluid communication with the H2 / CI2 fuel cell (FC) so as to mix said liquid stream (1, 16) with said concentrated acid stream (15) and thereby producing the acid stream (6) comprising hydrochloric acid [HCl].
[0053] Other advantages and characteristics of the invention will appear on reading the detailed description below and on the attached drawings in which:
[0054] [Fig. 1] shows a flowchart of the method of the invention according to a preferred embodiment;
[0055] [Fig. 2] shows a flowchart of a method according to a second embodiment of the invention;
[0056] [Fig. 3] shows a flowchart of a method according to a third embodiment of the invention;
[0057] [Fig. 4] shows a flowchart of a method according to a fourth embodiment of the invention;
[0058] [Fig. 5] shows a flowchart of a method according to a fifth embodiment of the invention;
[0059] [Fig. 6] shows a flowchart of a method according to a sixth embodiment of the invention;
[0060] [Fig. 7] shows a flowchart of a method according to a seventh embodiment of the invention;
[0061] [Fig. 8] shows a flowchart of a method according to one variant of the invention; and [Fig. 9] shows a flowchart of a method according to another variant of the invention.
[0062] The figures, tables and description below contain, for the most part, elements of a certain nature. The figures and tables are an integral part of the description, and may therefore not only serve to better understand the present invention, but also contribute to its definition, where appropriate.
[0063] In general, the invention makes it possible to increase the alkalinity of terrestrial sea and / or ocean waters. By increasing the alkalinity of the waters, they are able to better capture and permanently store atmospheric CO2.
[0064] Thus, the present invention relates to a device designed to increase the alkalinity of seas and oceans. More particularly, the invention involves the discharge of an alkaline flow into sea or ocean water, hereinafter sea water(s). This discharge helps to restore the chemistry of the sea water, and in particular its acidity (pH), to pre-industrial levels. This increases the capacity of seas and oceans to capture, store and sustainably conserve CO2.
[0065] The present invention further relates to a process using sea and / or ocean water, electricity and minerals (for example, calcium carbonate) to obtain a sodium carbonate solution of an alkaline nature, as well as a neutralized solution. These two solutions, alkaline and neutralized, can be poured into seas and / or oceans in order to increase their alkalinity and thus capture CO2. Although the process of the invention is accompanied by the intermediate formation of CO2, the process controls this formation and at least partially reuses this gas during the process. An advantage of the invention is thus that the overall equation of the process does not result in any production of CO2 harmful to the environment, nor polluting waste.
[0066] Another advantage is that the raw materials used in the process of the invention are naturally abundant. These are in particular seawater, or more generally brine, and CaCOs. Consequently, the logistics are facilitated for the implementation of the process of the invention.
[0067] The seawater particularly concerned by the invention is in particular that of the Baltic Sea, the Antarctic Ocean, the Indian Ocean, the Atlantic Ocean, the Pacific Ocean, the Mediterranean Sea and / or the Red Sea. As a rough guide, typically 1 kg of seawater contains approximately 964.8 g of water (H2O) and 35.2 g of ionic compounds (mainly salts). Among these 35.2 g of ionic compounds, we generally find approximately: 19.352 g of chloride ion (Cl'); 10.784 g of sodium ion (Na + ); 2.712 g of sulfate ion (SC 2 '); 1.284 g of magnesium ion (Mg 2+ ) ; 0.108 g of bicarbonate ion (HCO3); 0.412 g of calcium ion (Ca2+ ) ; 0.399 g of potassium ion (K + ) ; and the rest in other ions; cf. Zeebe and Wolf-Gladrow, 2001, CO2 in Seawater: Equilibrium, Kinetics, Isotopes, Gulf Professional Publishing.
[0068] Recently, the addition of sodium carbonate Na2COs has been considered to increase the alkalinity of seawater, cf. Hartmann et al., Stability of alkalinity in Ocean Alkalinity Enhancement (OAE) approaches - consequences for durability of CO2 storage, Biogeosciences Discuss., 2022 - DOI: 10.5194 / bg-2022-126. However, implementing a large-scale process with Na2COs presents many challenges to overcome. In particular, the synthesis of Na2COs remains difficult. Therefore, the state of the art is rather oriented towards processes using alkaline solutions, such as sodium hydroxide (NaOH) solutions.
[0069] Despite the known difficulties, the Applicant has moved towards research involving Na2COs. One reason is that Na2COs does not appear to present any safety risks since its use is common in industry for environmental remediation; cf. Brockmann and Janse, 2008, Calcium and carbonate in closed marine aquarium systems, Advances in coral husbandry in public aquariums, pages 133-142, chapter 14, Burgers' Zoo, Arnhem, The Netherlands.
[0070] Thus, the Applicant has developed a method for capturing atmospheric carbon dioxide [CO2], comprising several operations. The method of the invention begins in particular with first operations comprising the provision of products essential for the technical effect of the invention. Thus, an operation of providing a saline flow on the one hand, and the provision of calcium carbonate [CaCOs] on the other hand, is provided. The provision of the saline flow may comprise, for example, drawing salt water or manufacturing a saline solution by adding salts to water. Preferably, the drawing of salt water is provided directly from seawater, for example by means of a pump. The saline flow may also come from mine or factory brine (industrial brine flow), in particular in the context of co-location of the device of the invention in an already installed factory structure.The availability of CaCOs is facilitated by the fact that CaCOs is one of the most abundant minerals on our planet. In fact, it represents approximately 4% of the Earth's crust. In particular, CaCOs is found in rock, mainly in chalk, limestone, and marble.
[0071] The method also comprises an operation comprising the production of an alkaline flux. In this operation, the alkaline flux which is produced comprises sodium hydroxide [NaOH], And, the method also comprises an operation comprising the production of an acidic flux. In this operation, the acidic flux comprises hydrochloric acid [HCl]. According to the invention, these production steps can be carried out by an electrochemical treatment. For this, the electrochemical treatment is carried out of at least a part of the saline flux supplied previously in the operation of making it available.
[0072] The process of the invention further comprises an operation of neutralizing the hydrochloric acid [HCl] produced during the operation comprising the production of the acid stream. The neutralization of the hydrochloric acid [HCl] is carried out by bringing it into contact in an acid reactor (AR) with the calcium carbonate [CaCOs] made available during the first operations of the process. In this way, in the process of the invention according to the present embodiment, on the one hand, a liquid stream of calcium chloride [CaCIs] and, on the other hand, a gaseous stream of carbon dioxide [CO2] are obtained.
[0073] In another embodiment, step iv. of neutralization of hydrochloric acid [HCl] provides for not giving priority to the formation of CO2 over the simple dilution in an acid medium of calcium carbonate [CaCOs] into Ca ions. 2+ and CO3-.
[0074] Then, the process comprises an operation comprising the production of a sodium carbonate stream [NasCOs]. For this, the process of the invention provides for bringing into contact in a basic reactor (BR) the carbon dioxide [CO2] obtained during the neutralization (or where appropriate another gas containing CO2 coming from elsewhere, see below) with the sodium hydroxide [NaOH] produced during the operation comprising the production of an alkaline stream. In this way, the sodium carbonate stream [Na2COs] is obtained.
[0075] Finally, the method of the invention involves discharging this sodium carbonate [Na2COs] stream into saline water. Saline water is seawater and ocean water. Thus, the alkalinity of the water is increased. This results in the increased capture of atmospheric carbon dioxide [CO2].
[0076] Discharge can be carried out directly or indirectly into seawater. Indirect discharge is, in particular, discharge into a factory stream which is then channelled into the sea for discharge.
[0077] Figure 1 shows a flowchart of a method according to one embodiment of the invention.
[0078] In this embodiment, the method begins when a stream of seawater, ocean water, or more generally a brine 1 enters a reverse osmosis RO device. This produces a stream of desalinated water 1' and a stream of salt-concentrated water 2. This salt-concentrated stream 2 is sometimes referred to as a "reject" stream comprising concentrated brines. A reverse osmosis device from the FilmTec product line available from DuPont may be used.
[0079] Part of the rejected flow 2 is sent to a filter F which eliminates most of the Ca ions 2+ and Mg 2+The filter can be, for example, a PRO-XS2 nanofiltration membrane filter available from Hydranautics or FilmTec NF270 available from Dupont. This produces a filtered flow 2' and a residual flow 3 comprising substantially the remainder of the Ca ions. 2+ and Mg 2+ . This residual flow 3 and rejected and thus the Ca ions 2+ and Mg 2+ are eliminated.
[0080] In another embodiment, the filter may be replaced by a precipitation device that removes most of the Ca ions 2+ and Mg 2+ .
[0081] The filtered stream 2' enters an electrodialysis equipment ED, as well as optionally a part of the desalinated water when required by the specifications of the electrodialysis equipment ED as in the case of the present embodiment. In particular, a three-circuit electrodialysis equipment EDBM available from the company PCCell GmbH or Eurodia can be used. Three streams exit the electrodialysis equipment ED: (i) a partially desalinated stream 4, (ii) an alkaline stream 5 containing NaOH, and (iii) an acidic stream 6 containing HCl. The partially desalinated stream 4 can be eliminated or possibly recovered in various applications, for example in steam generation. If necessary, in one embodiment, a part of the partially desalinated stream 4 coming from the electrodialysis equipment ED can be partially or totally recirculated in the electrodialysis equipment ED.
[0082] Acid stream 6 enters a reactor AR referred to as an "acid reactor". CaCOs is added to the acid reactor via a feed line 7 to neutralize the HCl included in acid stream 6. Neutralization is carried out according to the following equation:
[0083] 2HCI + CaCOs — > CO2 + CaCL + H2O
[0084] In addition to this reaction, there can be a dissolution of calcium carbonate (and neutralization of acidity) without formation of CO2 or with consumption of CO2, according to the following equation:
[0085] CaCOs + CO2 + H2O(aq) — > Ca 2+ + 2HCO3-
[0086] The acid reactor and other equipment for neutralization are described in particular in the book Maree and Plessis, 1993 (Kinetics of Calcium Carbonate Neutralization First-Order Case of the Cube-Root Law).
[0087] This produces a liquid stream 8 of calcium chloride [CaCl] and a gaseous stream 9 of carbon dioxide [CO2]. The CO2 stream 9 is fed to a BR reactor, referred to as the "base reactor". The alkaline stream 5 from the electrodialysis equipment enters the BR base reactor and reacts with the CO2 stream 9. This produces a sodium carbonate stream 10 [NasCOs]. The main reaction occurring in the reactor is essentially represented by the following equation:
[0088] 2NaOH + CO2 — > NasCOs + H2O (partial neutralization of NaOH); and also the possible dilution.
[0089] Partial neutralization of NaOH can be carried out in a CO2 injector available from Air Liquide. Dilution can be carried out in a conventional holding tank. In this way, the basic BR reactor can dilute the alkaline stream 5, obtaining a stream 10 with a high concentration of NaOH rather than NaCOs. The next operation involves the discharge of this stream 10 of sodium carbonate [Na2COs] into seawater, or more generally the discharge is carried out into saline water, directly or indirectly.
[0090] This process can be carried out continuously or in batches, depending on what is most appropriate given the given resources (e.g., seawater or brine, electricity, CaCOs).
[0091] Furthermore, as a variant, it is possible to control the operating conditions to set a residence time in the acid reactor AR in order to regulate the production of CO2. The residence time is thus chosen according to the concentration of the acid stream 6 and the size of the calcium carbonate (CaCOs) particles 7.
[0092] The Applicant has considered several variants of the preferred embodiment described above. These are described below. The structural elements (equipment(s), device(s), etc.), as well as the flows and / or elements and / or chemical formulas and / or equations bearing the same numerical or alphabetical or alphanumeric reference identify identical or similar elements.
[0093] Figure 2 shows a flowchart of a method according to a second embodiment of the invention.
[0094] In this second embodiment of the method of the invention, it is provided not to carry out reverse osmosis. In this case, the electrodialysis equipment ED is arranged so as to carry out the electrodialysis with the initial NaCl concentration of the saline flow (1) made available at the start of the process. In this embodiment, the electrodialysis equipment ED does not require a flow of desalinated water (1'). Alternatively, an external flow of desalinated water (11) from another source can be made available. After the operation comprising the electrolysis, the method of this second embodiment is analogous to that described with reference to FIG. 1.
[0095] Figure 3 shows a flowchart of a method according to a third embodiment of the invention.
[0096] In this third embodiment of the method of the invention, it is provided not to carry out filtration. In this case, the rejected flow 2 concentrated in salts, or at least a part of it, is directly subjected to electrodialysis, that is to say that it enters directly into the electrodialysis equipment ED. This implies that the electrodialysis equipment ED is arranged to operate with concentrations of Ca salts 2+ and Mg 2+ increased. For the rest, the method of this third embodiment is similar to that described with reference to figure 1.
[0097] Figure 4 shows a flowchart of a method according to a fourth embodiment of the invention.
[0098] In this fourth embodiment of the method of the invention, it is provided to filter the desalinated water 1 ' leaving the reverse osmosis equipment RO by means of additional filtration equipment F'. This additional filtration equipment F' is arranged to eliminate all, or almost all, of the traces remaining after reverse osmosis of the Ca ions 2+ and Mg 2+. The desalinated water 1' after reverse osmosis is thus conducted into the additional filtration equipment F'. A filtered desalinated flow 1" is thus obtained, which is conducted to the electrodialysis equipment ED. The additional filtration equipment F' generates a rejected desalinated flow 12, which it is generally disposed of. Alternatively, the rejected desalinated flow 12 can be recirculated to the base reactor BR, as shown in FIG. 4, in order to dilute the base flow 10. For the rest, the method of this third embodiment is similar to that described with reference to FIG. 1.
[0099] Figure 5 shows a flowchart of a method according to a fifth embodiment of the invention.
[0100] In this fifth embodiment of the method of the invention, an electrochemical treatment operation is provided to carry out a chlor-alkali (CA) type treatment. For this, electrochemical equipment is used producing at the output an alkaline stream 5 containing NaOH, a first gaseous stream 13 of dihydrogen (H2), and a second gaseous stream 14 of chlorine (Cl2). The alkaline stream 5 is conveyed to the basic reactor BR in a manner analogous to the embodiment described with reference to FIG. 1. The first 13 and second 14 gaseous streams, respectively of H2 and of CI2, are injected into an H2 / CI2 fuel cell FC to obtain: a concentrated acid stream 15 comprising HCl and electricity and / or heat (optionally used for the method). Alternatively, the H2 / CI2 FC cell can be replaced by a reactor to produce HCl without producing electricity.In particular, for this embodiment it is possible to use electrochemical equipment of the Chlor-pack type available from the company 3V-tech; electrodes for Chlor-Alkali available from the company De Nora and Chlor-Alkali membranes available from the company Nation.
[0101] The concentrated HCl acid stream 15 is fed into a dilution tank D, where it is mixed with a liquid stream 16 (e.g., seawater or brine) to produce an acid stream 6 that can be diluted with seawater. The dilution tank is a conventional tank arranged to receive and dilute one or more liquids.
[0102] More generally, the dilution tank (D) is arranged to receive a liquid flow (1, 16), preferably a saline flow, and more preferably a seawater flow. In another embodiment, the liquid flow may comprise fresh water, for example from a canal, a river, or even a tap.
[0103] Figure 6 shows a flowchart of a method according to a sixth embodiment of the invention.
[0104] In this sixth embodiment of the method of the invention, electrodialysis is provided with a two-compartment bipolar membrane device. In particular, it is possible to use two-circuit EDBM devices available from MEGA or Eurodia. In addition, it is possible to use CPM-CEM cell pairs available from REDstack BV and spacers available from Aqua Battery BV.
[0105] The electrodialysis equipment produces an alkaline stream 5 containing NaOH, and an acidic stream 6 containing HCl.
[0106] Unlike other embodiments described above with other electrodialysis equipment, in the present embodiment no partially desalinated flow 4 is generated.
[0107] Figure 7 shows a flowchart of a method according to a seventh embodiment of the invention.
[0108] In this seventh embodiment of the method of the invention, an operation is provided comprising the introduction of a liquid flow 17 (for example, seawater, brine, partially desalinated) into the base reactor BR and the acid reactor AR. This provides additional control over these two reactors (BR and AR).
[0109] In the embodiment described above, each filter can be replaced by a precipitation device which removes most, if not all, of the target ions.
[0110] Furthermore, it will be noted that the calcium chloride [CaCl2] generated in the process of the invention (stream 8) can be recovered, particularly in the food industry.
[0111] It should also be noted that the neutralization of the acid stream (HCl) from the electrochemical treatment step allows the process to be scaled up. Indeed, without this neutralization of the acid according to the invention, there would be a generation of significant quantities of acid, which is not sustainable for implementing the process at high capacity and / or in many geographies neutralization. If the acid stream is not neutralized, it will be necessary to plan for its recovery or elimination, which limits the implementation of the process depending on the availability of HCl or the possibilities of its elimination. _ Note that the transport of HCl may require a prior concentration step to reduce transport costs. Such a concentration step, however, increases the energy requirements of the process, as well as CO2 emissions (particularly associated with the transport of HCl). The efficiency of the process is thus affected.Furthermore, transporting acids is a generally dangerous activity, and is restricted by safety standards.
[0112] An additional advantageous effect of the method and device of the invention is that they can be used in various industrial sectors (e.g., chemical, food, pharmaceutical) for the production of sodium carbonate, or even sodium bicarbonate.
[0113] In a particular embodiment, the Applicant has arranged the method and the device so as to recover, at least in part, the carbon dioxide from the acid reactor AR.
[0114] Figure 8 shows a flowchart of a method according to a variant of the invention. In this embodiment, the CO2 stream 9 is conveyed to its final destination for recovery. This embodiment is particularly interesting due to the purity of the CO2 generated by the acid reactor AR. Consequently, in this embodiment, the base reactor BR is supplied with CO2 via another gas stream 12. The gas stream 12 comprising the CO2 can be a pure stream comprising 100% CO2 or a less pure stream (air or industrial fumes, for example). The base reactor BR then generates the sodium carbonate stream 10 [Na2COs] which is accompanied in parallel by a stream 13 corresponding to the exhaust of the remaining elements of the gas stream 12.
[0115] Figure 9 shows a flowchart of a process according to another variant of the invention, in which the CO2 stream 9 from the acid reactor is divided so as to be conducted partly to the basic reactor (BR) and partly to its final destination for recovery. Optionally, the part of the stream 9 conducted to the basic reactor (BR) can join a gas stream 12 less pure in CO2 (air). The basic reactor BR then generates the stream 10 of sodium carbonate [Na2COs] which is accompanied in parallel by a stream 13 corresponding to the exhaust of the remaining elements of the gas stream 12.
[0116] Thus, this variant of the invention can be defined as follows:
[0117] A method for capturing atmospheric carbon dioxide [CO2], characterized in that it comprises the following steps: a) Providing a saline stream (1) and calcium carbonate [CaCOs] (7); b) Producing an alkaline stream (5) comprising sodium hydroxide [NaOH]; and c) Producing an acid stream (6) comprising hydrochloric acid [HCl];and wherein at least one of said steps b) of producing the alkaline stream (5) and c) of producing the acid stream (6) comprises a step of electrochemical treatment of at least a portion of said saline stream (1), and in that the method further comprises the following steps: d) Neutralizing the hydrochloric acid [HCl] obtained in step c) of producing an acid stream (6) by bringing the calcium carbonate [CaCOs] (7) from step a) of making available into contact in an acid reactor (AR) with said hydrochloric acid [HCl] so as to obtain a liquid stream (8) of calcium chloride [CaCl2] and a gaseous stream (9) of carbon dioxide [CO2]; e) The production of a sodium carbonate stream [NasCOs] (10) by bringing carbon dioxide [CO2], optionally obtained in step d) of neutralization, into contact in a basic reactor (BR) with sodium hydroxide [NaOH] from step b) of production of an alkaline stream;and f) Discharging the sodium carbonate [NasCOs] stream (10) produced in the previous step e) into saline water selected from sea water and ocean water, so as to increase its alkalinity and thus cause the capture of atmospheric carbon dioxide [CO2].;
[0118] In the present description, it is generally described that the discharge of the sodium carbonate [NasCOs] stream (10) can be carried out into saline water chosen from sea water and ocean water. Of course, in each embodiment described, the discharge of the sodium carbonate [NasCOs] stream (10) can be carried out directly or indirectly into saline water. The discharge can thus also be carried out into saline water contained in a tank provided for this purpose. Any saline water can in fact cause the capture of atmospheric carbon dioxide [CO2] when it is modified by means of a device and / or the method of the invention. The invention can be implemented on land or in territorial waters (in particular on a fixed or mobile platform).
[0119] The invention uses calcium carbonate [CaCOs]. More particularly, and within the scope of the invention, the CaCOs comes from a source, in itself, independent of the process for capturing atmospheric carbon dioxide [CO2]. This is a so-called "third-party source". The third-party source of CaCOs can be rock, chalk, limestone and marble as mentioned above. Since CaCOs is one of the most abundant minerals on Earth, its supply is facilitated. The external source of this component to the process is advantageous, particularly in terms of the energy balance. Indeed, the process of the invention harvests the CaCOs from a natural source. It is therefore not necessary to synthesize it by conversion or chemical synthesis, for example, which generally generates CO2, which further degrades the atmosphere and is harmful to the energy balance.The use of limestone is made possible in particular in the process of the present invention, without the need for a storage solution and / or use of CO2. In particular, the physical link existing between the acid (RA) and basic (RB) reactors makes it possible to convey the gaseous flow (9) of carbon dioxide and allows the direct use of limestone.
[0120] The use of limestone ores has an additional advantage. Limestone ores have a high level of purity. They are generally free of heavy metals - particularly nickel, which is typical of silicate minerals or rocks containing reduced iron (Fe, Fe + , Fe 2+ ) - which induce negative impacts on ecosystems.
[0121] Compared to existing approaches, the energy balance of the invention is, among other things, improved by the fact that the method increases the alkalinity of seawater (called "Ocean Alkalinity Enhancement"). In the art, we essentially find methods for direct capture of CO2 in seawater (called "Direct Ocean Capture"). Direct CO2 capture methods constitute a radically different approach from the present invention, in particular in that they release CO2 from seawater rather than treating the CO2 in situ directly in these waters. Direct capture methods thus pose problems of storage of the captured CO2 and / or the conversion treatment thereof. The invention avoids these problems.
Claims
Claims
1. A method for capturing atmospheric carbon dioxide [CO2], characterized in that it comprises the following steps: i. Providing a saline stream (1) and calcium carbonate [CaCOs] (7); ii. Producing an alkaline stream (5) comprising sodium hydroxide [NaOH]; and iii. Producing an acidic stream (6) comprising hydrochloric acid [HCl]; and wherein at least one of said steps ii. of producing the alkaline stream (5) and iii. of producing the acidic stream (6) comprises a step of electrochemical treatment of at least a portion of said saline stream (1), and in that the method further comprises the following steps: iv. Neutralizing the hydrochloric acid [HCl] obtained in step iii. of producing an acid stream (6) by bringing into contact in an acid reactor (AR) the calcium carbonate [CaCOs] (7) from step i.of making available with said hydrochloric acid [HCl] so as to obtain a liquid stream (8) of calcium chloride [CaCL] and a gaseous stream (9) of carbon dioxide [CO2]; v. The production of a stream of sodium carbonate [Na2COs] (10) by bringing into contact in a basic reactor (BR) at least a portion of the carbon dioxide [CO2] obtained in step iv. of neutralization with the sodium hydroxide [NaOH] of step ii. of production of an alkaline stream; and vi. The discharge of the stream of sodium carbonate [Na2COs] (10) produced in the preceding step v. into saline water chosen from sea water and ocean water, so as to increase its alkalinity and thus cause the capture of atmospheric carbon dioxide [CO2].
2. A method according to claim 1, wherein the provision of the saline flow of step i. is carried out by drawing in water chosen from sea water, ocean water and industrial brine.
3. A method according to one of the preceding claims, wherein the electrochemical treatment step is selected from the group consisting of electrodialysis and chlor-alkali electrolysis.
4. Method according to one of the preceding claims, in which step iv. of neutralizing the hydrochloric acid [HCl] further comprises collecting the liquid stream (8) of calcium chloride [CaCl2].
5. Method according to one of the preceding claims, further comprising, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream, the following steps: 1.
1. A reverse osmosis (RO) to desalinate said saline flow (1) and thus obtain a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and 1.
2. A purification (F), preferably chosen from filtration and precipitation, receiving at least a portion of said flow of water concentrated in salts (2) from reverse osmosis (RO), in which Mg ions are eliminated 2+ and that 2+ of the flow of water concentrated in salts (2) and thus obtain a flow of purified water essentially free of Mg ions 2+ and that 2+ (2').
6. Method according to one of the preceding claims, further comprising, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream, the following steps: 1.
3. Provision of a flow of purified water essentially free of Mg ions 2+ and that 2+ (2'), and 1.
4. An electrodialysis in which said flow of purified water essentially free of Mg ions 2+ and that 2+(2') is subjected to at least one electric field so as to produce said alkaline flow (5) and said acid flow (6) of steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow (6).
7. Method according to claim 6, further comprising, upstream of step i.
4. of electrodialysis: i.
5. Provision of a flow of desalinated water (1 ', 11 ), preferably a flow of filtered desalinated water (1 ”), also subjected to said electric field during of electrodialysis so as to contribute to the production of said alkaline stream (5) and said acid stream (6) of steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream (6).
8. Method according to one of claims 1 to 4, further comprising, upstream of said steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow: 1.
6. A purification (F), preferably chosen from filtration and precipitation, receiving said from a saline flow (1), in which Mg ions are eliminated 2+ and that 2+ said saline flow (1) and thus obtain a flow of purified water essentially free of Mg ions 2+ and that 2+ (2'); 1.
7. An electrodialysis in which said flow of purified water essentially free of Mg ions 2+ and that 2+ (2'), and optionally a flow of desalinated water (1 1 ), is / are subjected to at least one electric field so as to produce said alkaline flow (5) and said acid flow (6) of steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow (6).
9. Method according to one of claims 1 to 4, further comprising, upstream of said steps ii. of producing an alkaline stream (5) and iii. of producing an acid stream: 1.
8. A reverse osmosis (RO) to desalinate said saline flow (1) and thus obtain a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and 1.
9. An electrodialysis in which said flow of desalinated water (1') and said flow of water concentrated in salts (2) are subjected to at least one electric field so as to produce said alkaline flow (5) and said acid flow (6) of steps ii. of producing an alkaline flow (5) and iii. of producing an acid flow (6).
10. A method according to one of claims 5 to 9, wherein the electrodialysis further produces a partially desalinated stream (4) which is subjected to a second electrodialysis so as to contribute to the production of said alkaline stream (5) and said acidic stream (6) of steps ii. of producing an alkaline stream (5) and iii. of producing an acidic stream (6). [Claim 1 1] Method according to one of claims 1 to 4, in which step ii. of producing an alkaline flux (5) comprises: - a chlor-alkali (CA) electrolysis so as to produce the alkaline stream comprising sodium hydroxide [NaOH] (5), a gaseous stream of dihydrogen [H2] (13), and a gaseous stream of chlorine [Cl2] (14); and wherein step iii. of producing an acidic stream (6) comprises - an injection into a H2 / CI2 fuel cell (FC) of said gaseous flow of dihydrogen [H2] (13), and of said gaseous flow of chlorine [CI2] (14) so as to obtain a concentrated flow of acid (15) comprising hydrochloric acid [HCl], and electricity and / or heat; and - a mixture in a dilution tank (D) of said concentrated acid flow (15) with a liquid, preferably a saline liquid (16), so as to obtain the acid flow (6) comprising hydrochloric acid [HCl].
12. Device for capturing atmospheric carbon dioxide [CO2] comprising: - a means for drawing a saline flow (1), preferably sea or ocean water, and a means for supplying calcium carbonate [CaCOs] (7); characterized in that the device comprises - an electrochemical treatment unit (ED, U-CA) capable of producing from at least part of said saline flow (1): o an alkaline flow (5) comprising sodium hydroxide [NaOH]; and o an acid flow (6) comprising hydrochloric acid [HCl]; - an acid reactor (AR) in fluid communication with the electrochemical treatment unit (ED, U-CA) and connected to the calcium carbonate [CaCOs] supply means (7), to respectively receive the hydrochloric acid [HCl] and the calcium carbonate [CaCOs] (7) and bring them into contact so as to neutralize the hydrochloric acid [HCl] and thus produce a liquid flow (8) of calcium chloride [CaCI ] and a gaseous flow (9) of carbon dioxide [CO2]; - a basic reactor (BR) in fluid communication with the electrochemical treatment unit (ED, U-CA) and with the acid reactor (AR), to respectively receive sodium hydroxide [NaOH] and carbon dioxide [CO2] and bring them into contact so as to produce a flow of sodium carbonate [Na2COs] (10); and - a means for discharging said flow of sodium carbonate [Na2COs] (10) produced by the basic reactor (BR) into saline water chosen from sea water and ocean water, so as to increase its alkalinity and thus cause the capture of atmospheric carbon dioxide [CO2].
13. Device according to claim 12, in which the electrochemical treatment unit (ED, U-CA) is chosen from the group consisting of an electrodialyzer and a chlor-alkali electrolysis installation.
14. Device according to one of claims 12 and 13, further comprising: - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and - a purification unit (F) in fluid communication with the reverse osmosis (RO) unit to receive at least a portion of said salt-concentrated water stream (2) and arranged to remove Mg2+ and Ca2+ ions from said salt-concentrated water stream (2) and thus obtain a purified water stream essentially free of Mg2+ and Ca2+ ions (2').
15. Device according to one of claims 12 to 14, further comprising: - a means for supplying a flow of purified water essentially free of Mg2+ and Ca2+ ions (2'), and in which - the electrochemical treatment unit is an electrodialyzer (ED) arranged in fluid communication with the means for supplying the flow of purified water essentially free of Mg2+ and Ca2+ ions (2') so as to subject this flow (2') to at least one electric field and thus produce said alkaline flow (5) and said acid flow (6).
16. A device according to claim 15, further comprising: - a means for supplying a flow of desalinated water (1', 11), preferably a flow of filtered desalinated water (1"), and in which - the electrodialyzer (ED) is also arranged in fluid communication with the means for supplying a flow of desalinated water (1', 11', 1') so as to subject this flow to said electric field to produce the alkaline flow (5) and the acid flow (6).
17. A device according to claim 12, further comprising: - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and in which - the electrochemical treatment unit is an electrodialyzer (ED) arranged in fluid communication with, on the one hand, at least a part of said desalinated water flow (1') and, on the other hand, at least a part of said salt-concentrated water flow (2), so as to subject them to at least one electric field to produce said alkaline flow (5) and said acid flow (6).
18. A device according to claim 12, further comprising: - a reverse osmosis (RO) unit arranged to receive the saline flow (1) so as to desalinate it and thus produce a flow of desalinated water (1') on the one hand, and a flow of water concentrated in salts (2) on the other hand; and - a purification unit (F) in fluid communication with the reverse osmosis (RO) unit to receive at least a portion of said salt-concentrated water stream (2) and arranged to remove Mg2+ and Ca2+ ions from said salt-concentrated water stream (2) and thus obtain a purified water stream essentially free of Mg2+ and Ca2+ ions (2'), and wherein the electrochemical treatment unit is a chlor-alkali electrolysis installation comprising: - a chlor-alkali (CA) reactor in fluid communication, on the one hand, with the reverse osmosis (RO) unit to receive at least part of said flow of desalinated water (1 '), and, on the other hand, with the purification unit (F) to receive at least part of said flow of purified water essentially free of of Mg2+ and Ca2+ ions (2') so as to subject these flows (1', 2') to at least one electric field and thus produce said alkaline flow (5) comprising sodium hydroxide [NaOH] (5), a gaseous flow of dihydrogen [H2] (13), and a gaseous flow of chlorine [CI2] (14); - an H2 / CI2 fuel cell (FC) in fluid communication with the chlor-alkali reactor (CA) for receiving said dihydrogen [H2] gas stream (13) and said chlorine [CI2] gas stream (14) and thereby producing a concentrated acid stream (15) comprising hydrochloric acid [HCl], and electricity and / or heat; and - a dilution tank (D) arranged to receive a liquid stream (1, 16), preferably a saline stream, and in fluid communication with the H2 / CI2 fuel cell (FC) so as to mix said liquid stream (1, 16) with said concentrated acid stream (15) and thus produce the acid stream (6) comprising hydrochloric acid [HCl].