Carbon dioxide capture process

Abstract

TITLE: Carbon Dioxide Capture Process The invention relates to a carbon dioxide capture process comprising the following steps, at the outlet of a carbon dioxide absorber: a) supplying a major portion of a solvent stream to a first desorber operating at a first temperature and pressure; b) supplying the remainder of the solvent stream to a second desorber operating at a second temperature and pressure, the second temperature and pressure being lower than the first temperature and pressure, respectively; c) recovering from each desorber a gas comprising carbon dioxide and water vapor; d) condensing the water vapor exiting the first desorber, the latent heat of condensation of the water being used to heat a boiler supplying the second desorber. Figure for abstract: Figure 1

Description

Title of the invention: Carbon dioxide capture process Technical field of the invention

[0001] The invention relates to the capture of carbon dioxide, in particular emitted by heavy industry such as steelmaking, cement works or refineries, or during the production of ammonia, or ethylene oxide or present in large quantities in a synthesis gas. Technical background

[0002] A widely used method for this purpose is described in US patent 3,823,222, hereinafter referred to as the Benfield method.

[0003] A diagram of the installation to implement this process is provided in [Fig.1].

[0004] The process consists first of all in supplying an absorber with 10 of carbon dioxide, On one hand, there is a gas G containing carbon dioxide, and on the other hand, an aqueous solvent containing a component (calcium carbonate, K₂CO₃) dissolved in the solvent. This component allows the carbon dioxide gas to dissolve in the solvent. The source of the gas containing the carbon dioxide introduced into the absorber is, for example, an exhaust from a steel mill, cement plant, or refinery. For example, the fumes from a blast furnace (steel industry) typically contain 10 to 25% carbon dioxide, with the remainder consisting of hydrogen, carbon monoxide, water vapor, and other gases as present.

[0005] At the outlet of the absorber 10, a solvent enriched in carbon dioxide is recovered, as well as the undissolved gases GND in the solvent (e.g., CO, N2, H2 and others as appropriate in a steelmaking application).

[0006] The carbon dioxide-enriched solvent is then advantageously preheated in a heat exchanger 20 before being introduced into a desorber 30. The purpose of the desorber 30 is to desorb the carbon dioxide dissolved in the aqueous solvent. To this end, a boiler 31 is added to the desorber 30 to raise the temperature of the solvent present in the desorber and thus desorb the carbon dioxide. The advantageous contribution of the heat exchanger 20 is clear here, as it will limit the energy required by the boiler 31 to ensure desorption.

[0007] At the outlet of the desorber 30, at the top of the column, carbon dioxide (CO2) is recovered in gaseous form, but also water vapor (H2O) and at the bottom of the column, the solvent depleted in carbon dioxide, which is sent to the exchanger 20 (hot source).

[0008] A reservoir 40, into which the component useful for dissolving gaseous carbon dioxide in the solvent can be introduced, as well as an optional supply of solvent. aqueous (water on the [Fig.l]), is provided on the path of the solvent exiting the regenerator 30. After the heat exchanger 20, the solvent depleted in carbon dioxide, is reinjected into the absorber 10.

[0009] The carbon dioxide recovered at the outlet of the desorber 30 can then be used in various ways. For example, it can be used for storage, transport, or sequestration. It can also be used as a reagent to produce methane (methanation) with the addition of dihydrogen, or to produce synthetic fuels.

[0010] In the Benfield process, the desorber 30 operates at a temperature between 80 and 120°C and at a pressure between 1 and 2 bar. Calcium carbonate is stable at these temperatures and remains in the solvent.

[0011] Energy must therefore be supplied to the boiler 31, which is the main cost center of this process (approximately 80%), even though heat recovery in the exchanger 20 reduces this energy input. The remaining 20% ​​of the cost center is related to the fact that the pressure remains low at the outlet of the desorber, and that for most uses, the carbon dioxide must therefore be compressed (for example, carbon dioxide is typically transported at 80 bar).

[0012] The energy supply to the boiler 31 can be carried out in different ways, depending on the industrial site on which the installation implementing the Benfield process is planned.

[0013] In all cases however, it would be advantageous to reduce the energy requirement at the boiler 31 to ensure the carbon dioxide desorption step in the desorber.

[0014] One objective of the invention is therefore to improve the energy efficiency of such a process. Summary of the invention

[0015] To achieve the aforementioned objective, the invention proposes a carbon dioxide capture process comprising the following steps: - to supply, to a carbon dioxide absorber, on the one hand a gas containing carbon dioxide and on the other hand an aqueous solvent containing dissolved calcium carbonate; - to recover at the outlet of the absorber a solvent stream, called the initial solvent stream, enriched in carbon dioxide; said process being characterized in that it comprises the following additional steps: a) supply a major part of the initial solvent flow to a first desorber operating at a first temperature and pressure; b) supply the remainder of the initial solvent flow, corresponding to a minority portion of said flow, to at least a second desorber operating at a second temperature and pressure, the second temperature and pressure being respectively lower than the first temperature and pressure; then: c) recover at the outlet of each desorber a gas comprising carbon dioxide and water vapor; d) condense the water vapor exiting the first desorber, the latent heat of condensation of the water being used to supply heat to a boiler supplying the second desorber.

[0016] The process according to the invention may include at least one of the following additional steps, taken alone or in combination: - the minority part of the solvent flow corresponds to 25 to 40% of the initial solvent flow and consequently the majority flow corresponds to 60 to 75% of the initial solvent flow; - the first temperature is between 180°C and 250°C and the first pressure is greater than 8 bar, for example between 10 and 50 bar; the second temperature is between 120°C and 160°C and the second pressure is between 1.3 and 7 bar; - step b) consists of supplying a major part of the remainder of the initial solvent flow to a second desorber and a minor part of the remainder of the initial solvent flow to a third desorber operating at a third pressure and a third temperature, the third pressure and the third temperature being respectively lower than the second pressure and the second temperature and wherein said process then comprises an additional step e) of condensing the water vapor exiting the second desorber, the latent heat of condensation of the water being used to supply heat to another boiler supplying the third desorber; - the majority part of the remaining initial solvent flow is between 60% and 80% of the remaining initial solvent flow and the minority part of the remaining initial solvent flow is between 40% and 20% of the remaining initial solvent flow; - the first temperature is above 240°C and the first pressure is above 30 bar; the second temperature is between 140°C and 220°C and the second pressure is between 2.5 and 20 bar; and the third temperature is between 80°C and 120°C and the third pressure is between 1 and 1.4 bar; - a major part of the water vapor recovered in step c) is condensed in step d); - not all of the water vapor recovered in step c) is condensed in step d); - in step d), between 60% and 90% of the water vapor recovered in step c) is condensed; - dissolved calcium carbonate has a mass concentration of between 18% and 50% in the aqueous solvent, in particular between 25% and 35%; - the process includes a step consisting of supplying energy to another boiler associated with the first desorber by an energy source using the carbon dioxide recovered in step c) at the outlet of each desorber; - before implementing step a), a step is planned consisting of preheating the initial solvent stream in a heat exchanger supplied with heat by a carbon dioxide-depleted solvent stream recovered from the outlet of each desorber; - after the heat exchanger, a step is planned consisting of introducing the carbon dioxide-depleted solvent stream into the carbon dioxide absorber. Brief description of the figures

[0017] Other objects and features of the invention will become clearer in the following description, made with reference to the accompanying figures, in which:

[0018] The [Fig. 1] is a representative diagram of an installation enabling the implementation of a prior art process, known as the "Benfield process";

[0019] Figure [Fig. 2] schematically represents the different main steps of the process according to the invention;

[0020] Fig. 3 is a partial diagram of an installation for implementing a first embodiment of the process according to the invention;

[0021] The [Fig.4] is a partial diagram of an installation for implementing a second embodiment of the process according to the invention. Detailed description of the invention

[0022] In general, the invention relates to a method 100 for capturing carbon dioxide comprising the following steps: - to supply, to an ABS carbon dioxide absorber, on the one hand a gas comprising carbon dioxide and on the other hand an aqueous solvent comprising dissolved calcium carbonate (K2CO3); - to recover at the outlet of the absorber a solvent stream, called the initial solvent stream, enriched in carbon dioxide.

[0023] These steps are also implemented in the prior art.

[0024] From this point on, the process differs from the prior art and proposes to implement the following additional steps: a) supply a major part of the initial solvent flow to a first desorber DSB1 operating at a first temperature and pressure; b) supply the remainder of the initial solvent flow, corresponding to a minority part of said flow, to at least a second desorber DSB2, DSB3 operating at a second temperature and a second pressure, the second temperature and the second pressure being respectively lower than the first temperature and the first pressure; then: c) recover at the outlet of each desorber DSB1, DSB2, DSB3 a gas comprising carbon dioxide and water vapor; d) condense the water vapor exiting the first desorber DSB1, the latent heat of condensation of the water being used to supply heat to a boiler BOIL2 supplying the second desorber DSB2.

[0025] It should be noted that the energy to be supplied to a boiler consists mainly of the energy required to extract carbon dioxide from the solvent within a desorber and the energy to vaporize the water together with the carbon dioxide in the same desorber.

[0026] Thus, the more a large proportion of carbon dioxide is separated from the solvent, the more water is vaporized, this ratio increasing with the amount of carbon dioxide vaporized.

[0027] It is therefore necessary to find a compromise between the quantity of carbon dioxide from the solvent to be vaporized (which must be significant so as not to have a high cost of the installation compared to the quantity of carbon dioxide captured) and the quantity of water vaporized (which must not be too high because this would increase the overall energy cost).

[0028] Thus, in step a), supplying a majority of the initial solvent flow to the first desorber operating at a higher temperature and pressure than the second desorber aims to achieve this compromise in step c). Incidentally, the same comment can be made for the minority of the initial solvent flow supplied to the second desorber in step b).

[0029] In the end, step d) then saves energy since the latent heat recovered from the condensation of water vapor from the first desorber DSB1 is less heat to be supplied to the boiler BOIL2 associated with the second desorber.

[0030] The different steps of this process 100 are shown schematically on [Fig.2].

[0031] In a first embodiment, only two desorbers DSB1, DSB2 are provided. The corresponding installation is shown in [Fig. 3] with two stages Desorption units ETG1 and ETG2, the COND condenser at the outlet of the first desorber DSB1, which supplies heat to the B0IL2 boiler associated with the second desorber DSB2. The condensed water vapor is returned to the first desorber DSB1.

[0032] Each desorption stage is associated with an exchanger ECH1, ECH2, which is also supplied by a common absorber 10. Point S corresponds to the point of separation of the initial solvent flow towards one or the other of the desorbers DSB1, DSB2.

[0033] Advantageously, the minority portion of the solvent flow (i.e., the remainder of the initial solvent flow) corresponds to 25 to 40% of the initial solvent flow, and consequently, the majority flow corresponds to 60 to 75% of the initial solvent flow. The distribution between the majority and minority flows is then further optimized in order to achieve the aforementioned compromise.

[0034] Advantageously, the first temperature is between 180°C and 250°C and the first pressure is greater than 8 bar, for example between 10 and 50 bar, and the second temperature is between 120°C and 160°C and the second pressure is between 1.3 and 7 bar. Calcium carbonate (K2CO3) remains stable in the aqueous solvent (no evaporation) under these conditions.

[0035] We then operate at higher temperatures and pressures than in a conventional Benfield process, moreover for each of the two desorbers DSB1, DSB2. In particular, the operation in the first desorber DSB1, DSB2 makes it possible to obtain temperature and pressure levels at the outlet of the first desorber DSB1 compatible on the one hand with a subsequent condensation of water vapor and the obtaining of a temperature level in the second desorber which is still of interest for recovering carbon dioxide, in particular at a pressure which can still be relatively high - therefore for which less energy will be required to carry out its compression.

[0036] Advantageously, in step d), a major portion of the water vapor recovered in step c) is condensed. However, it is advantageous to avoid condensing all or almost all of the vapor recovered in step c) in step d). Indeed, in such a case, the condensation temperature would have to be too low to be recovered in the second reboiler BOIL2 feeding the second desorber DSB2. Thus, advantageously, between 60% and 90% of the water vapor recovered in step c) can be condensed in step d).

[0037] The water vapor that is not condensed will remain with the carbon dioxide, from which it can subsequently be separated. The residual quantity of water vapor depends on the initial concentration of potassium carbonate, the percentage of carbon dioxide desorbed, and the condensation temperature.

[0038] It is then possible to recover between 30 and 60% of the heat used in the BOIL1 boiler of the first desorber DSB1 (high temperature, high pressure) to operate the second desorber DSB2 (lower temperature, lower pressure) and thus increase the carbon dioxide captured by 30 to 60% for the same heat supplied.

[0039] In a second embodiment, three desorbers DSB1, DSB2, DSB3 are provided. The third desorber DSB3 operates at a third temperature and a third pressure lower than the second temperature and the second pressure prevailing within the second desorber DSB2. Reference may be made to [Fig.4].

[0040] In this embodiment, the objective is to provide a third desorption stage ETG3 to further improve the overall efficiency of the process. This may also make economic sense given the additional installation and maintenance costs associated with implementing an extra desorber. This third stage ETG3 comprises a third desorber DSB3, as well as a third reboiler BOIL3 and a third heat exchanger ECH3.

[0041] In this case, step b) consists of supplying a major part of the remaining initial solvent flow to the second desorber DSB2 and a minor part of the remaining initial solvent flow to the third desorber DSB3. The separation of the remaining initial solvent flow takes place at point S' of the diagram in [Fig.4].

[0042] Furthermore, the process then includes an additional step e) consisting of condensing the water vapor exiting the second desorber DSB2, the latent heat Q of condensation of the water being used to supply heat to another boiler BOIL3 which feeds the third desorber DSB3. This is carried out by means of another condenser COND' located at the outlet of the second desorber DSB2. The water vapor that has thus been condensed is returned to the second desorber.

[0043] We therefore have here a latent heat input Q, Q' on the one hand to the boiler BOIL2 of the second desorber DSB2 and on the other hand to the boiler BOIL3 of the third desorber DSB3.

[0044] Advantageously, the majority portion of the initial solvent flux residue is between 60% and 80% of the initial solvent flux residue, and consequently, the minority portion of the initial solvent flux residue is between 40% and 20% of the initial solvent flux residue. As mentioned previously, the initial solvent flux residue corresponds to a proportion between 25% and 40% of the initial solvent flux.

[0045] Advantageously, the first temperature is greater than 240°C and the first pressure is greater than 30 bar; and the second temperature is between 140°C and 220°C and the second pressure is between 2.5 and 20 bar; and finally; The third temperature is between 80°C and 120°C and the third pressure is between 1 and 1.4 bar. Calcium carbonate (K2CO3) remains stable in the aqueous solvent (no evaporation) under these conditions.

[0046] Advantageously, in step d), a major portion of the water vapor recovered in step c) is condensed, whether this concerns the outlet of the first desorber DSB1 or the second desorber DSB2. However, it is advantageous to avoid condensing all or almost all of the vapor recovered in step c) in step d). Indeed, in such a case, the condensation temperature would have to be too low to be recovered, as the case may be, in the second boiler BOIL2 feeding the second desorber DSB2 or in the third boiler BOIL3 feeding the third desorber DSB3. Advantageously, between 60% and 90% of the water vapor recovered in step c) can be condensed in step d).

[0047] Regardless of the embodiment envisaged, the calcium carbonate (K2CO3) dissolved in the aqueous solvent has a mass concentration of between 18% and 50% in the aqueous solvent, in particular between 25% and 35%.

[0048] Regardless of the embodiment envisaged, before implementing step a), a step is advantageously provided, as shown in Figures 3 and 4, consisting of preheating the initial solvent stream in a heat exchanger ECH1, ECH2, and, where applicable, ECH3, supplied with heat by a carbon dioxide-depleted solvent stream recovered from the outlet of each desorber DSB1, DSB2, and, where applicable, DSB3. Each desorber DSB1, DSB2, and, where applicable, DSB3, thus contributes to forming the heat source of the heat exchanger used to preheat the carbon dioxide-enriched solvent stream. This reduces the energy required at each boiler BOIL1, BOIL2, and BOIL3.

[0049] Advantageously, after the heat exchanger, a step is provided consisting of introducing the carbon dioxide-depleted solvent stream into the carbon dioxide absorber 10.

[0050] The source of gaseous carbon dioxide feeding the absorber can be diverse, by way of non-limiting examples, steelmaking, cement making or refining or a synthesis gas containing a significant proportion of CO2.

[0051] The energy required for the BOIL1 boiler, and where applicable for each other BOIL2 or BOIL3 boiler, can be supplied by a heat source from a nuclear power plant, or recovered from a synthetic fuel production reactor, a Fischer-Tropsch synthesis reactor, or a methanation reactor. These processes provide heat (related to the reaction) resulting in a high temperature, between 220°C and 340°C depending on the case.

[0052] By way of example, to carry out a methanation reaction, the carbon dioxide from the desorbers DSB2, DSB3 as appropriate, is compressed to obtain A pressure similar to that of the carbon dioxide recovered from the outlet of the first desorber DSB1 is used, and dihydrogen is also supplied. The heat released by the methanation reactor, thus generated, can then be used to power the B0IL1 boiler.

[0053] More generally, the process according to the invention may include a step consisting of supplying energy to the BOIL1 boiler associated with the first desorber DSB1 by a heat source released by an exothermic process of valorizing the carbon dioxide recovered in step c) at the outlet of each desorber DSB1, DSB2 and where applicable DSB3.

[0054] Example of implementation:

[0055] In this example, we consider the first embodiment where the desorption takes place on two desorption stages DSB1, DSB2 ([Fig.3]).

[0056] The carbon dioxide originates from a modern steelmaking unit (DRI for "Direct Reduction of Iron" according to Anglo-Saxon terminology) using natural gas. The flue gases exiting the natural gas reformer, like the flue gases exiting the blast furnace, contain a large quantity of carbon dioxide, typically between 12 and 25% (molar).

[0057] Carbon dioxide is introduced into the absorber 10 at a pressure of 8 bar. The temperature in the absorber is approximately 70°C.

[0058] The aqueous solvent is water containing dissolved calcium carbonate at a concentration (mass) of 32%. The carbon dioxide-enriched solvent exiting absorber 10 is charged with 8% (mass) of dissolved carbon dioxide, while the depleted solvent entering absorber 10 is charged with 3.5% (mass) of dissolved carbon dioxide.

[0059] In the fumes entering the absorber, there are other GND gases which are not dissolved in the solvent and which are therefore recovered in the upper part of the absorber, here and typically dihydrogen, dinitrogen and carbon monoxide.

[0060] At the outlet of the absorber 10, the so-called initial solvent flow is at a pressure of 7 bar and at a temperature of 52°C.

[0061] The initial solvent flow is then separated into two flows (at point S), a first solvent flow corresponding to 2 / 3 of the initial solvent flow towards the desorber DSB1 which operates at 200°C and under 15 bar and a second solvent flow corresponding to 1 / 3 of the initial solvent flow towards the desorber DSB2 which operates at a temperature of 130°C and under 2.5 bar.

[0062] The first solvent stream is then compressed to 15 bar and then heated in the heat exchanger ECH1 (it could be increased to 25 bar to maintain the solvent in liquid form within the exchanger ECH1). The inlet temperature of the exchanger is 52°C and the outlet temperature (before entering the desorber DSB1) is 191°C. For The CO2-depleted solvent exits the boiler BOIL 1 at a temperature of 202°C before being cooled in the heat exchanger ECH1, from which it emerges at a temperature close to 62°C. The condenser COND operates at a temperature of 157°C.

[0063] The second solvent stream is heated in the second heat exchanger ECH2. The inlet temperature of heat exchanger ECH2 is 52°C and the outlet temperature (before entering desorber DSB2) is 111°C. For the CO2-depleted solvent, the outlet temperature of boiler BOIL 2 is 130°C, before being cooled in heat exchanger ECH2, from which it exits at a temperature close to 62°C.

[0064] At the outlet of each desorber (at the bottom), the solvent depleted in carbon dioxide (3.5%) is recovered, which is reinjected at the inlet of the absorber via the heat exchanger (cold source) in which it gives up its heat to the CO2-enriched solvent to be brought to the desorption column.

[0065] At the outlet of each desorber (top), gaseous carbon dioxide and water vapor are also present. Most (but not all) of the water vapor is then condensed in a condenser operating at a temperature of 157°C for desorber DSB1 and 80°C for desorber DSB2. The heat of condensation of the water vapor condensed at the outlet of the first desorber DSB1 (at 157°C) is then used to heat the boiler BOIL2 (at 130°C) associated with the second desorber DSB2. The water thus formed by condensation is reintroduced into desorber DSB1. The residual carbon dioxide and water vapor are then directed to a condenser operating at 50°C to separate the residual water.

[0066] The heat from the DSB2 desorber can, for its part, be advantageously used in a local heat network.

[0067] The carbon dioxide thus recovered / captured is then put to use. Thus, at the outlet of the second desorber DSB2, the gas is cooled to 50°C to separate the remaining water in a condenser operating at 50°C (in this example, approximately 0.5 moles of H2O for 1 mole of CO2). The remaining carbon dioxide is compressed to a pressure of 15 bar and combined with the carbon dioxide from the first desorber at the same pressure. All the carbon dioxide is then mixed with dihydrogen to produce methane (methanation). Such a reaction is usually carried out with several successive exothermic reactors to improve efficiency and operating in a temperature range between 250 and 400°C.In particular, it should be noted that the first reactor alone already makes it possible to transform 80% of the carbon dioxide into methane and that the heat recovery from the reactor makes it possible to recover more than 2.3 GJ / tonne of CO2 having reacted at a temperature of 240°C.

[0068] Each of the two desorbers DSB1 and DSB2 in this example requires approximately 2.7 GJ / tonne of CO2. By recovering the heat of condensation from the steam exiting the first desorber DSB1 to supply heat to the boiler BOIL2 associated with the second desorber DSB2, the overall energy requirement is limited to that of the first desorber, i.e., 1.8 GJ / tonne of CO2 (= 2 / 3 * 2.7 GJ / tonne of CO2). It can be seen that this energy requirement is entirely met by the heat of reaction released by the first methanation reactor.

Claims

Demands

1. A process (100) for capturing carbon dioxide comprising the following steps: - supplying, to a carbon dioxide absorber (10), on the one hand a gas (G) comprising carbon dioxide and on the other hand an aqueous solvent comprising dissolved calcium carbonate; - recovering at the outlet of the absorber a solvent stream, called the initial solvent stream, enriched in carbon dioxide; said process being characterized in that it comprises the following additional steps: a) supplying a major part of the initial solvent stream to a first desorber (DSB1) operating at a first temperature and a first pressure;b) supply the remainder of the initial solvent flow, corresponding to a minority part of said flow, to at least a second desorber (DSB2, DSB3) operating at a second temperature and a second pressure, the second temperature and the second pressure being respectively lower than the first temperature and the first pressure; then: c) recover at the outlet of each desorber (DSB1, DSB2, DSB3) a gas comprising carbon dioxide and water vapor; d) condense the water vapor exiting the first desorber (DSB1), the latent heat (Q) of condensation of the water being used to supply heat to a boiler (BOIL2) supplying the second desorber (DSB2).

2. A carbon dioxide capture process according to claim 1, wherein the minority part of the solvent stream corresponds to 25 to 40% of the initial solvent stream and consequently the majority stream corresponds to 60 to 75% of the initial solvent stream.

3. A method for capturing carbon dioxide according to any one of the preceding claims, wherein: - the first temperature is between 180°C and 250°C and the first pressure is greater than 8 bar, for example between 10 and 50 bar; - the second temperature is between 120°C and 160°C and the second pressure is between 1.3 and 7 bar.

4. A carbon dioxide capture process according to claim 1, wherein step b) consists of supplying a major part of the remainder of the initial solvent stream to a second desorber (DSB2) and a minor part of the remainder of the initial solvent stream to a third desorber (DSB3) operating at a third pressure and a third temperature, the third pressure and the third temperature being respectively lower than the second pressure and the second temperature, and wherein said process then comprises a further step e) of condensing the water vapor exiting the second desorber (DSB2), the latent heat (Q') of condensation of the water being used to supply heat to another boiler (B0IL3) supplying the third desorber (DSB3).

5. A carbon dioxide capture process according to the preceding claim, wherein the major part of the initial solvent flux remainder is between 60% and 80% of the initial solvent flux remainder and the minor part of the initial solvent flux remainder is between 40% and 20% of the initial solvent flux remainder.

6. A method for capturing carbon dioxide according to any one of claims 4 or 5, wherein: - the first temperature is above 240°C and the first pressure is above 30 bar; - the second temperature is between 140°C and 220°C and the second pressure is between 2.5 and 20 bar; and - the third temperature is between 80°C and 120°C and the third pressure is between 1 and 1.4 bar.

7. A carbon dioxide capture process according to any one of the preceding claims, wherein a major part of the water vapor recovered in step c) is condensed in step d).

8. A carbon dioxide capture process according to any one of the preceding claims, wherein not all of the water vapor recovered in step c) is condensed in step d).

9. A process according to any one of the preceding claims, wherein, in step d), between 60% and 90% of the water vapor recovered in step c) is condensed.

10. A carbon dioxide capture process according to any one of the preceding claims, wherein the dissolved calcium carbonate has a mass concentration of between 18% and 50% in the aqueous solvent, in particular between 25% and 35%.

11. A method for capturing carbon dioxide according to any one of the preceding claims, comprising a step of supplying energy to another boiler (BOIL1) associated with the first desorber (DSB1) by an energy source using the carbon dioxide recovered in step c) at the outlet of each desorber (DSB1, DSB2).

12. A carbon dioxide capture process according to any one of the preceding claims, wherein, prior to implementing step a), a step is provided consisting of preheating the initial solvent stream in a heat exchanger (ECH1, ECH2, ECH3) supplied with heat by a carbon dioxide-depleted solvent stream recovered from the outlet of each desorber (DSB1, DSB2, DSB3).

13. A method for capturing carbon dioxide according to the preceding claim, wherein, after the heat exchanger (ECH1, ECH2, ECH3), a step is provided for introducing the carbon dioxide-depleted solvent stream into the carbon dioxide absorber (10).

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