System for capturing carbon dioxide within gas loaded with carbon dioxide

Abstract

The present invention relates to a carbon dioxide capture system (1), comprising a first heat exchanger (4a) and a second heat exchanger (4b), each of the heat exchangers (4) comprising a chamber (14), a first pass (12a) and a second pass (12b), characterized in that the first heat exchanger (4a) and the second heat exchanger (4b) are configured to be operated according to a first operating mode (101) and according to a second operating mode (102), the capture system (1) comprising control means (5) configured to effect an alternation between the first operating mode (101) and the second operating mode (102).

Description

[0001] DESCRIPTION

[0002] Title of the invention: System for capturing carbon dioxide from gas loaded with carbon dioxide

[0003] The present invention relates to the field of treatment of gases loaded with carbon dioxide and more particularly concerns a system for capturing carbon dioxide within said gases loaded with carbon dioxide.

[0004] When a gas emission source, such as combustion gases, is in operation, for example a vehicle such as a floating structure, carbon dioxide-laden gases are generated. These carbon dioxide-laden gases are generally released into the atmosphere. However, carbon dioxide is known to cause environmental damage when released into the atmosphere.

[0005] In addition to the ecological issue, this release into the atmosphere is a waste of energy, because carbon dioxide has multiple functions in various technical fields and can, for example, be used as a cooling medium or for other third-party uses.

[0006] It may therefore be appropriate to process carbon dioxide-laden gases from an emission source in order to extract the carbon dioxide and store it for later use or marketing. However, a system for liquefying carbon dioxide is bulky and consumes a lot of energy because it requires cooling the carbon dioxide-laden gases emitted from an emission source to very low temperatures.

[0007] The present invention makes it possible to capture carbon dioxide within gas laden with carbon dioxide and as such provides a system for capturing carbon dioxide within gas laden with carbon dioxide, comprising at least a first heat exchanger and a second heat exchanger, each of the heat exchangers comprising at least one chamber, a first pass and a second pass which both extend into the chamber,characterized in that the first heat exchanger and the second heat exchanger are configured to be operated according to a first operating mode where the chamber is configured to be crossed by a flow of gas loaded with carbon dioxide and to capture by desublimation the carbon dioxide present in said flow of gas loaded with carbon dioxide in order to generate a flow of decarbonized gas and according to a second operating mode where the first pass and / or the second pass are crossed by a / the flow of gas loaded with carbon dioxide to merge the carbon dioxide captured in the chamber, the capture system comprising control means configured to operate an alternation between the first operating mode and the second operating mode.,

[0008] Thanks to the capture system according to the invention, the carbon dioxide present in the gases loaded with carbon dioxide is captured by desublimation, then is merged to be recovered in the liquid state. Desublimation is the change of state of a body from the gaseous state to the solid state, without passing through the liquid state. The carbon dioxide is thus recovered instead of being released into the atmosphere. The first heat exchanger and the second heat exchanger are specifically designed to ensure the desublimation of an element comprising, for example, a fluid. When one or other of the heat exchangers is operated according to the first operating mode, the cooling parameters linked to this heat exchanger allow the desublimation of the carbon dioxide. The desublimated carbon dioxide, i.e. in the solid state, is then deposited on the walls of the heat exchanger operated according to the first operating mode.In order to ensure desublimation when the flow of gas loaded with carbon dioxide passes through the chamber of one and / or the other of the heat exchangers, the first pass and / or the second pass of one and / or the other of the heat exchangers is crossed by one or more fluids at a sufficiently low temperature in order to cool the flow of gas loaded with carbon dioxide so as to pass the carbon dioxide which composes it directly from the vapor state to the solid state.

[0009] Following the capture of carbon dioxide, the carbon dioxide-laden gas stream that has passed through the chamber emerges decarbonized. As it passes through the heat exchanger chamber, the decarbonized gas stream exits at a very low temperature, for example -120°C. The decarbonized gas stream can then be circulated to participate in one or more subsequent thermal treatments, for example by heat exchange.

[0010] It is therefore understood that the decarbonized gas stream is a gas stream having a carbon dioxide content lower than that of the gas stream loaded with carbon dioxide due to the capture of carbon dioxide by desublimation in the exchanger, with an external cold supplement, provided by liquefied natural gas or a refrigerant produced by a refrigeration unit. As a non-limiting example, the gas stream loaded with carbon dioxide may have a carbon dioxide content of 3 to 4 mol%. The decarbonized gas stream from the capture system according to the invention no longer contains carbon dioxide, or may have a very low residual carbon dioxide content of the order of 0.2 to 0.3 mol%.

[0011] In the context of the invention, the chamber is to be understood as a heat transfer zone between a cold flow and a hot flow. This chamber may be materialized by walls physically delimiting the zone, as shown in the figures and detailed below. However, the chamber may also not include walls. In this case, the chamber is a heat transfer zone during the implementation of the first operating mode between, on the one hand, the flow of gas loaded with carbon dioxide and, on the other hand, the flow of decarbonized gas and / or a flow of any other refrigerant. The exchanger comprising such a chamber is called a multi-flow exchanger. Similarly, the scope of the invention does not depart from the case of a pass in which a refrigerant circulates around which there is an annular space having fins, the gas loaded with carbon dioxide being intended to circulate in this annular space.The person skilled in the art therefore understands that the entire pass and the annular space constitute the exchanger and the chamber is then the heat exchange zone around the perimeter of the pass.

[0012] During the second mode of operation of either heat exchanger, the carbon dioxide in the solid, or desublimated, state, which has previously been deposited on the walls of said heat exchanger is fused, that is to say it passes from the solid state to the liquid state.

[0013] To melt carbon dioxide, a carbon dioxide-laden gas stream passes through the first pass and / or the second pass to heat the heat exchanger chamber where the solid carbon dioxide is to be melted. In the case of an internal combustion engine, the carbon dioxide-laden gas stream passing through the first pass and / or the second pass may, for example, have an inlet temperature between the combustion temperature of the internal combustion engine and -33°C.

[0014] The capture system is configured such that the carbon dioxide-laden gas flow passing through the chamber during the first mode of operation is the same gas flow as the carbon dioxide-laden gas flow passing through the first pass and / or the second pass during the second mode of operation. In other words, the capture system is configured such that the carbon dioxide-laden gas flow initially circulates within the first pass and / or the second pass of at least one of the heat exchangers operated according to the second mode of operation in order to merge the carbon dioxide captured in the chamber, then this same carbon dioxide-laden gas flow continues its circulation until it passes through the chamber of at least one of the heat exchangers operated according to the first mode of operation.

[0015] As described, the first heat exchanger and the second heat exchanger can be operated in two different operating modes, namely a first mode allowing the capture of carbon dioxide by desublimation and a second mode allowing the fusion of the captured carbon dioxide and the recovery thereof. The control means allow the management of each of these two operating modes by applying one or the other of these to the heat exchangers, but also by switching from one of the operating modes to the other. According to a characteristic of the invention, the control means are configured to operate an alternation of one heat exchanger relative to the other between the first operating mode and the second operating mode.The alternation of the two heat exchangers and their respective operating modes is established so that each of the operating modes is always active over time, whether on one or the other of the heat exchangers. The carbon dioxide can thus be captured continuously, which makes it possible to avoid periods of time where the gas flow laden with carbon dioxide cannot be treated. The control means operate so that, when the capture system comprises only two heat exchangers, a change in the operating mode is carried out simultaneously on both heat exchangers. In other words, when the first heat exchanger ensures the capture of carbon dioxide, the second heat exchanger is operated so as to melt the previously captured carbon dioxide. Once this operation is completed, the control means reverse the operating mode of each of the heat exchangers.

[0016] According to a characteristic of the invention, the control means comprise at least one management member configured to regulate a circulation of a first cooling fluid which circulates within one or other of the passes of one or other of the heat exchangers. The management member authorizes or prohibits the circulation of the first cooling fluid within one of the passes. It is thus understood that the circulation is authorized by the management member when the heat exchanger in question is operated according to the first operating mode.

[0017] Advantageously, the capture system comprises a heat exchanger management unit.

[0018] According to a characteristic of the invention, the management member comprises at least one first valve arranged upstream of one or other of the passes of one or other of the heat exchangers and / or at least one second valve arranged downstream of one or other of the passes of one or other of the heat exchangers. In other words, the first valve and the second valve are arranged on either side of one of the passes of one or other of the heat exchangers, and can switch between an open position and a closed position in order to authorize or prohibit the circulation of the first cooling fluid within the pass in question, for example the first pass of one or other of the heat exchangers.

[0019] According to a characteristic of the invention, the control means comprise at least one management device configured to regulate a circulation of a second cooling fluid which circulates within one or other of the passes of one or other of the heat exchangers. Like the management member, the management device authorizes or prohibits the circulation of the second cooling fluid within one of the passes. The circulation is authorized by the management device when the heat exchanger in question is operated according to the first operating mode. The second cooling fluid may be a fluid identical to or different from the first cooling fluid mentioned above.

[0020] Advantageously, the capture system comprises a heat exchanger management device. Thus, preferably, the capture system comprises a management member and a heat exchanger management device, the management member and the management device each regulating a circulation of cooling fluid within one of the two passes of one of the heat exchangers.

[0021] According to a characteristic of the invention, the management device comprises at least one third valve arranged upstream of one or other of the passes of one or other of the heat exchangers and / or at least one fourth valve arranged downstream of one or other of the passes of one or other of the heat exchangers. The third valve and the fourth valve are arranged on either side of one of the passes of one or other of the heat exchangers, and can switch between an open position and a closed position in order to authorize or prohibit the circulation of the second cooling fluid within the pass in question, for example the second pass of one or other of the heat exchangers.

[0022] In the configuration where the capture system comprises a management member and a heat exchanger management device, the first valve, the second valve, the third valve and the fourth valve are preferably all open simultaneously when the heat exchanger in question is operated according to the first operation, so that cooling fluid circulates within each of the two passes of said heat exchanger.

[0023] According to a feature of the invention, the first cooling fluid and / or the second cooling fluid may be the decarbonized gas stream. Indeed, after passing through the chamber where the carbon dioxide has been captured, the decarbonized gas stream is at a very low temperature, due to the fact that it has been cooled in order to ensure the capture of the carbon dioxide. The decarbonized gas stream may thus be used as a cooling fluid by circulating to the inlet of at least one of the two passes of one of the heat exchangers operated according to the first operating mode. The decarbonized gas stream is for example at a temperature of -120°C between the outlet of the chamber and an inlet of the first pass and / or the second pass.

[0024] According to a feature of the invention, the first cooling fluid and / or the second cooling fluid may be a flow of liquefied natural gas or a refrigerant. In the case where the capture system is arranged within an installation producing combustion gases from the combustion of liquefied natural gas or any other entity capable of transporting and / or storing liquefied natural gas, said gas may be used as a means of desublimating carbon dioxide. The installation may comprise at least one tank for transporting and / or storing liquefied natural gas and a means for pumping the liquefied natural gas therein and circulating it to the first pass and / or the second pass of at least one of the heat exchangers in order to participate in the capture of carbon dioxide by desublimation. The liquefied natural gas is for example at a temperature of -161°C before passing through the first pass and / or the second pass.

[0025] In the case where the capture system is arranged within an installation not interacting with liquefied natural gas, said installation may be equipped with a refrigerant circuit within which another refrigerant circulates. The refrigerant is thus treated so as to circulate within the first pass and / or the second pass of the heat exchanger at a sufficiently low temperature, for example -125°C, to participate in the desublimation of carbon dioxide.

[0026] According to a characteristic of the invention, the control means comprise at least one control member configured to regulate the circulation of the flow of gas loaded with carbon dioxide within one and / or the other of the passes of one or the other of the heat exchangers.

[0027] The control body authorizes or prohibits the circulation of the flow of gas loaded with carbon dioxide within at least one of the passes of the heat exchanger. It is thus understood that the circulation is authorized by the control body when the heat exchanger in question is operated according to the second operating mode.

[0028] Advantageously, the capture system comprises a heat exchanger control member.

[0029] According to a characteristic of the invention, the control member comprises at least one fifth valve arranged upstream of one or other of the passes of one or other of the heat exchangers and / or at least one sixth valve arranged downstream of one or other of the passes of one or other of the heat exchangers. In other words, the fifth valve and the sixth valve are arranged on either side of one of the passes of one or other of the heat exchangers, and can switch between an open position and a closed position in order to authorize or prohibit the circulation of the flow of gas loaded with carbon dioxide within the pass in question, for example the first pass of one or other of the heat exchangers to which they are assigned.

[0030] Advantageously, the control member comprises four valves, two of which are upstream of each of the two passes of one or other of the heat exchangers and two of which are downstream of each of the two passes of one or other of the heat exchangers, so that the flow of gas loaded with carbon dioxide circulates in the two passes to improve the homogeneity of the fusion of the captured carbon dioxide. All of the aforementioned valves may be independent of each other or may optionally be combined, for example to form a three-way valve.

[0031] According to a characteristic of the invention, the control means comprise at least one control device configured to regulate the circulation of the flow of gas loaded with carbon dioxide which circulates through one or other of the heat exchangers around one or other of its passes. In other words, the control device regulates the circulation of the flow of gas loaded with carbon dioxide which passes through the chamber and which leaves it in the form of the flow of decarbonized gas. The control device therefore only authorizes the circulation of the flow of gas loaded with carbon dioxide when the heat exchanger in question is operated according to the first operating mode.

[0032] According to a characteristic of the invention, the control device comprises at least one seventh valve arranged upstream of the chamber of one or other of the heat exchangers and / or at least one eighth valve arranged downstream of the chamber of one or other of the heat exchangers. In other words, the seventh valve and the eighth valve are arranged on either side of the chamber of one or other of the heat exchangers, and can switch between an open position and a closed position in order to allow or prohibit the circulation of the flow of gas loaded with carbon dioxide through the chamber.

[0033] According to a characteristic of the invention, the capture system comprises a first heat exchanger configured to carry out a heat exchange between the flow of gas loaded with carbon dioxide and the flow of decarbonized gas, the first heat exchanger comprising a first pass traversed by the flow of gas loaded with carbon dioxide and a second pass traversed by the flow of decarbonized gas, said first pass being arranged upstream of the chamber of one or other of the heat exchangers and said second pass being arranged downstream of the chamber. The first heat exchanger makes it possible to cool the flow of gas loaded with carbon dioxide to a temperature close to the desublimation temperature threshold of the carbon dioxide but while keeping the flow of gas loaded with carbon dioxide in the gaseous state.Subsequently, when the flow of gas loaded with carbon dioxide passes through the chamber of one of the heat exchangers operated according to the first operating mode, the desublimation of the carbon dioxide is facilitated due to the very low temperature of the flow of gas loaded with carbon dioxide at the entrance to the chamber, thanks to the presence of the first heat exchanger.

[0034] The heat exchange carried out in the first heat exchanger is also carried out with the participation of the flow of decarbonized gas leaving the chamber of one of the heat exchangers operated according to the first operating mode. The crossing of said chamber having lowered the temperature of the flow of decarbonized gas, the latter can therefore be used to cool the flow of gas loaded with carbon dioxide.

[0035] According to a characteristic of the invention, the capture system comprises a device for regulating the temperature of the flow of gas loaded with carbon dioxide upstream of the first pass of the first heat exchanger, configured to regulate the temperature of the flow of gas loaded with carbon dioxide after its passage through the first pass and / or the second pass of one or other of the heat exchangers, the regulation device comprising a bypass line of the first pass and / or the second pass of one or other of the heat exchangers, a control valve configured to control the circulation of the flow of gas loaded with carbon dioxide within the bypass line, and a member for detecting the temperature of the flow of gas loaded with carbon dioxide upstream of the first pass of said heat exchanger.

[0036] The control device makes it possible to control the temperature of the gas flow loaded with carbon dioxide in order to prevent the captured carbon dioxide from being fused too quickly when the heat exchanger in question is operated according to the second operating mode. This parameter is verified by measuring the temperature of the gas flow loaded with carbon dioxide via the temperature detection member at the outlet of the first pass and / or the second pass of the heat exchanger operated according to the second operating mode. A measured temperature that is too low means that the carbon dioxide is being fused too quickly.If this is the case, the control device can then open the control valve so that the carbon dioxide laden gas stream flows into the bypass line and then bypasses the heat exchanger instead of flowing into the first pass and / or the second pass to merge the captured carbon dioxide within the chamber.

[0037] According to one feature of the invention, the capture system comprises a recovery branch connected to each of the heat exchangers and configured to collect the carbon dioxide in the liquid state from at least one of the heat exchangers, the recovery branch comprising a recovery valve. When the carbon dioxide captured in the chamber is melted, it circulates in the liquid state within the recovery branch to a storage member, for example a tank or a reservoir. The recovery branch comprises a recovery valve which is open only when the carbon dioxide must circulate in the liquid state in the recovery branch. The recovery valve is therefore open only when the heat exchanger in question is operated according to the second operating mode. The opening and / or closing of the recovery valve can be controlled by the control means.

[0038] According to a feature of the invention, the capture system is associated with a source of emission of the carbon dioxide-laden gas stream, said carbon dioxide-laden gas stream originating from said emission source. The emission source may be an internal combustion engine, for example an engine used for propulsion of a vehicle and / or for generating an electric current, or for any other function. The combustion engine operates using a fuel, and the resulting internal combustion generates the carbon dioxide-laden gas stream. The emission source may also, but is not limited to, a chimney, a boiler or any factory.

[0039] According to a feature of the invention, the capture system comprises a third heat exchanger configured to be operated according to the first operating mode and according to the second operating mode, the control means being configured to operate an alternation between the first operating mode and the second operating mode on the third heat exchanger. This is an alternative to what was described previously, where the capture system comprises three heat exchangers instead of two. Integrating a third heat exchanger makes it possible to limit the alternations between the first operating mode and the second operating mode for each of the heat exchangers over time. Furthermore, the addition of a third exchanger also makes it possible to increase the treatment capacity of the installation.

[0040] The invention also covers a method for capturing carbon dioxide within a flow of gas loaded with carbon dioxide implemented by a system for capturing carbon dioxide within gas loaded with carbon dioxide as described above, during which: at least one of the heat exchangers is operated according to the first operating mode in order to desublimate the carbon dioxide present within the flow of gas loaded with carbon dioxide and passing through the chamber of said heat exchanger; switching from the first operating mode to the second operating mode of said heat exchanger in order to merge the desublimated carbon dioxide in the chamber by circulating the flow of gas loaded with carbon dioxide within the first pass and / or the second pass of said heat exchanger.

[0041] Such a method therefore makes it possible to capture the carbon dioxide present in the gas loaded with carbon dioxide via the first operating mode. Each of the heat exchangers has a maximum capacity for capturing carbon dioxide in the solid or desublimated state. Thus, switching to the second operating mode allows the captured carbon dioxide to melt and therefore rids the chamber of the carbon dioxide that was previously captured. This having been done, the chamber is once again able to capture carbon dioxide, and the heat exchanger is then again operated according to the first operating mode to be able to once again capture the carbon dioxide present within the flow of gas loaded with carbon dioxide.

[0042] According to a feature of the method, at least one of the heat exchangers is operated according to the first operating mode when the other of the heat exchangers is operated according to the second operating mode. The capture method is implemented so that the carbon dioxide can be captured by continuous desublimation, so that the gas laden with carbon dioxide is never released into the atmosphere. When the capture system comprises two heat exchangers, the first heat exchanger is operated according to the first operating mode while the second heat exchanger is operated according to the second operating mode and the switching of the two heat exchangers to the other operating mode is advantageously done simultaneously. This makes it possible to systematically have at least one heat exchanger capable of capturing the carbon dioxide from the flow of gas laden with carbon dioxide.

[0043] According to a feature of the method, the first operating mode followed by the second operating mode is a carbon dioxide capture / fusion cycle, said capture / fusion cycle being repeated by iterations. The capture / fusion cycle ensures that the heat exchangers alternate between the first operating mode and the second operating mode, continuously and uninterruptedly. Thus, the carbon dioxide can be captured continuously, regardless of the operating time of the source emitting the flow of gas loaded with carbon dioxide.

[0044] According to a characteristic of the method, when it is implemented by a capture system comprising three heat exchangers, two heat exchangers are operated according to the first operating mode while the last heat exchanger is operated according to the second operating mode, the capture / fusion cycle comprising three periods of use, two of which correspond to the first operating mode and one corresponds to the second operating mode, the three periods of use being of equal, or substantially equal, duration, the capture / fusion cycle being operated so that each of the three heat exchangers is operated according to each of the three periods of use and so that a transition of the periods of use takes place simultaneously between the three heat exchangers.

[0045] In other words, in a three-heat exchanger capture system, the capture process is configured so that two heat exchangers are systematically operated in the first mode of operation, with the remaining heat exchanger being operated in the second mode of operation. Each heat exchanger has its own capture / merge cycle that repeats over time. This is the same capture / merge cycle for each of the three heat exchangers, namely two periods during which the first mode of operation is operated, followed by a period during which the second mode of operation is operated. However, the capture / merge cycles for each of the three heat exchangers are offset from each other. This cycle offset allows for a configuration in which two heat exchangers are systematically operated in the first mode of operation as long as the capture system is in operation.This configuration allows for the optimization of the amount of carbon dioxide captured. This is why the capture / fusion cycle is divided into three periods of use.

[0046] The capture system is configured so that the first operating mode is maintained twice as long as the second operating mode. Thus, the operation of the first operating mode lasts two usage periods, which can be defined as a first carbon dioxide capture period and a second carbon dioxide capture period, while the operation of the second operating mode lasts one usage period, corresponding to a fusion period of the captured carbon dioxide. In other words, the desublimated carbon dioxide takes half the time to be fused as it does to be captured.

[0047] The simultaneous transition between each period and the shift of the cycles of each heat exchanger is configured so that at each time period, one heat exchanger is in the first period of carbon dioxide capture, one heat exchanger is in the second period of carbon dioxide capture and one heat exchanger is in the period of melting the captured carbon dioxide. This configuration thus optimizes the capture system and maximizes the flow rate of captured carbon dioxide.

[0048] According to a feature of the method, a first cooling fluid and a second cooling fluid circulate respectively in the first pass and in the second pass of at least one of the heat exchangers when it is operated according to the first operating mode. The cooling fluids make it possible to cool the flow of gas loaded with carbon dioxide passing through the chamber in order to capture the carbon dioxide by desublimation. Said cooling fluids must therefore circulate within the first pass and / or the second pass at a temperature suitable for ensuring the desublimation of the carbon dioxide when the flow of gas loaded with carbon dioxide passes through the chamber, for example -120°C for the flow of decarbonized gas or -161°C for the flow of liquefied natural gas.

[0049] According to a feature of the method, the first valve, the second valve, the third valve, the fourth valve, the seventh valve and the eighth valve are open while the fifth valve, the sixth valve and the recovery valve are closed when the heat exchanger in question is operated according to the first operating mode. The first valve, the second valve, the third valve, the fourth valve must be open in order to allow the circulation of the cooling fluids in the first pass and in the second pass of the heat exchanger in question. The seventh valve and the eighth valve are also open in order to allow the flow of gas laden with carbon dioxide through the chamber. The recovery valve is closed in order to keep the chamber sealed during the operation of the first operating mode.

[0050] According to a feature of the method, the first valve, the second valve, the third valve, the fourth valve, the seventh valve and the eighth valve are closed while the fifth valve, the sixth valve and the recovery valve are open when the heat exchanger in question is operated according to the second operating mode. When the heat exchanger is operated according to the second operating mode, the first valve, the second valve, the third valve, the fourth valve, the seventh valve and the eighth valve are closed in order to prevent the circulation of the cooling fluids through the passes as well as the crossing of the chamber by the flow of gas loaded with carbon dioxide.

[0051] The fifth valve and the sixth valve are opened so that the decarbonized gas flow circulates in the first pass and / or in the second pass of the heat exchanger in question, with the aim of melting the carbon dioxide previously captured in the chamber. At this stage, the gas flow loaded with carbon dioxide is for example at a temperature between -25°C and -33°C. This temperature is sufficient to melt the carbon dioxide. Subsequently, after passing through the first pass and / or the second pass of the heat exchanger operated according to the second operating mode, the gas flow loaded with carbon dioxide circulates until it passes through the chamber of another of the heat exchangers, which is operated according to the first operating mode. The recovery valve is open so that the carbon dioxide in the liquid state can be collected by circulating within the recovery branch.

[0052] According to a characteristic of the method, the temperature regulation device controls an opening section of the control valve in order to determine a flow rate of gas flow loaded with carbon dioxide passing through the first pass and / or the second pass of the heat exchanger operated according to the second operating mode and a flow rate of gas flow loaded with carbon dioxide circulating in the bypass branch, the opening section of the control valve being dependent on at least one temperature of the gas flow loaded with carbon dioxide recorded by the temperature detection member.The temperature control device thus makes it possible to control the melting rate of the carbon dioxide captured in the chamber of the heat exchanger operated according to the second operating mode, and this as a function of the temperature measured by the member for detecting the temperature of the gas flow loaded with carbon dioxide at the outlet of the first pass and / or the second pass. The larger the opening section of the control valve, the higher the flow rate of the gas flow loaded with carbon dioxide circulating in the bypass branch. This makes it possible to limit the circulation of the gas flow loaded with carbon dioxide through the first pass and / or the second pass of the heat exchanger operated according to the second operating mode and therefore to slow down the melting rate of the carbon dioxide captured therein.If the control valve is completely closed, the flow of gas loaded with carbon dioxide circulates entirely within the first pass and / or the second pass of the heat exchanger operated according to the second operating mode.

[0053] According to a feature of the process, the fused carbon dioxide from the heat exchanger operated according to the second operating mode is stored. Once the fused carbon dioxide has been fused, it then circulates in the liquid state within the recovery branch mentioned above until it is stored within a storage device.

[0054] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0055] [fig 1] represents a first embodiment of a system for capturing carbon dioxide within gas loaded with carbon dioxide according to the invention,

[0056] [fig 2] illustrates a first example of circulation of the different fluids within the first embodiment of the capture system,

[0057] [fig 3] illustrates a second example of circulation of the different fluids within the first embodiment of the capture system,

[0058] [fig 4] represents a second embodiment of a capture system according to the invention and an illustration of a circulation of the different fluids within this second embodiment, [fig 5] represents a third embodiment of a capture system according to the invention and an illustration of a circulation of the different fluids within this third embodiment,

[0059] [fig 6] is a graph detailing the sequence of capture / fusion cycles implemented by a carbon dioxide capture process operated according to the second embodiment of the capture system.

[0060] This document uses the words upstream and downstream to define the relative arrangement of components. These words are assessed according to the direction of circulation of the fluid passing through said components or circulating within the circuit concerned.

[0061] Figure 1 illustrates a first embodiment of a system 1 for capturing carbon dioxide within gas loaded with carbon dioxide according to the invention. Such a capture system 1 may for example be integrated within a vehicle, a chimney, a factory, or any other entity comprising an emission source 6 of gas loaded with carbon dioxide. The emission source 6 may for example be a combustion engine such as an engine providing propulsion for a vehicle or the engine of an electric generator of said vehicle.

[0062] When the emission source 6 is in operation, the fuel is burned and the emission source 6 therefore naturally emits gases laden with carbon dioxide, for example combustion gases. The capture system 1 thus makes it possible to capture the carbon dioxide present within a flow of gas laden with carbon dioxide 2 instead of releasing said flow directly into the atmosphere.

[0063] In order to treat the carbon dioxide-laden gas flow, it circulates from the emission source 6 to the capture system 1 according to the invention via a pipe. Before reaching the capture system 1, the carbon dioxide-laden gas flow is compressed by a compression device, not shown in Figure 1, in order to reach a pressure of approximately 4.5 bars. The carbon dioxide-laden gas flow 2 can also circulate through a drying device, also not shown, which ensures the elimination of traces of water that may remain within the carbon dioxide-laden gas flow. The capture system 1 is illustrated in Figure 1 without showing the circulation of the different flows. This figure therefore illustrates the components of the system without any circulation of fluid.

[0064] In order to ensure the capture of the carbon dioxide contained in the flow of gas loaded with carbon dioxide 2, the capture system 1 comprises at least two heat exchangers 4, more particularly a first heat exchanger 4a and a second heat exchanger 4b.

[0065] Each heat exchanger 4 comprises a chamber 14 defined by an internal volume of each of the heat exchangers 4, as well as two passes 12 which extend into the chamber 14. More specifically, each heat exchanger 4 comprises a first pass 12a and a second pass 12b within which a fluid can circulate. The first pass 12a and the second pass 12b both pass through the chamber 14. A heat exchange can thus be implemented between the passes 12 and the chamber 14.

[0066] The heat exchangers 4 have the particularity of being operated according to two operating modes. A first operating mode ensures capture of the carbon dioxide present within the flow of gas loaded with carbon dioxide by desublimation. The flow of gas loaded with carbon dioxide 2 passes through the chamber 14 of one or other of the heat exchangers 4 and the carbon dioxide composing the flow of gas loaded with carbon dioxide 2 is desublimated and is deposited in the solid state on the walls of the heat exchanger 4 in question.

[0067] In order to desublimate the carbon dioxide contained in the carbon dioxide-laden gas stream 2, the first pass 12a and / or the second pass 12b are traversed by cooling fluids. The latter ensure the cooling of the carbon dioxide-laden gas stream 2 passing through the chamber 14, so as to provide the temperature condition suitable for capturing the carbon dioxide by desublimation. This makes it possible to generate a decarbonized gas stream 3 at the outlet of the chamber 14 of the heat exchanger 4.

[0068] The heat exchangers 4 can also be operated according to a second operating mode ensuring fusion of the carbon dioxide previously captured within the chamber 14 of the heat exchanger 4 in question. Preferably, the second operating mode is operated on a heat exchanger 4 previously operated according to the first operating mode.

[0069] In order to melt the captured carbon dioxide by fusing it, the first pass 12a and / or the second pass 12b of the heat exchanger 4 are traversed by the flow of gas loaded with carbon dioxide 2. The latter being at a relatively high temperature, for example around -25°C to -33°C, the chamber 14 receives the heat that the charge gas gives up to it as it cools and the captured carbon dioxide passes into the liquid state.

[0070] The capture system 1 therefore comprises a recovery branch 31 connected to the chamber 14 of each of the heat exchangers 4 and ensuring the circulation of carbon dioxide in the liquid state to a storage member 53. Thus, in addition to avoiding the release of carbon dioxide into the atmosphere, the capture system 1 according to the invention makes it possible to store carbon dioxide in the liquid state, which can subsequently be used or marketed for multiple third-party activities. The recovery branch 31 comprises a recovery valve 19 which can be opened to allow the circulation of carbon dioxide in the liquid state in the recovery branch 31.

[0071] In order to operate the heat exchangers 4 according to one or other of the operating modes, but also to switch said heat exchangers 4 from one operating mode to the other, the capture system 1 comprises control means 5 allowing the management of the circulation of the different fluids circulating in the passes 12 and / or passing through the chamber 14 of each of the heat exchangers 4.

[0072] The control means 5 comprise in particular at least one management member 42, at least one management device 40, at least one control member 38 and at least one control device 44. Advantageously, each of these control means 5 is present in as many copies as there are heat exchangers 4, so that each of the latter can be operated according to one or other of the operating modes mentioned above. The management member 42 makes it possible to control the circulation of a first cooling fluid within one or other of the passes 12 of the heat exchangers 4. For example, in FIG. 1, there is a management member 42 for each heat exchanger 4, and each of the management members 42 controls the circulation of the first cooling fluid within the first pass 12a.Each management member 42 comprises a first valve 42a and a second valve 42b arranged on either side of the first pass 12a of each heat exchanger 4, that is to say upstream and downstream of the first pass 12a.

[0073] The management device 40 makes it possible to control the circulation of a second cooling fluid, which may be identical to or different from the first cooling fluid, within one or other of the passes 12 of the heat exchangers 4. For example, in FIG. 1, there is a management device 40 for each heat exchanger 4, and each of the management devices 40 controls the circulation of the second cooling fluid within the second pass 12b. Each management device 40 comprises a third valve 40a and a fourth valve 40b arranged on either side of the second pass 12b of each heat exchanger 4, i.e. upstream and downstream of the second pass 12b.

[0074] It is thus understood that the first valve 42a, the second valve 42b, the third valve 40a and the fourth valve 40b are open in order to allow the circulation of the cooling fluids when the heat exchanger 4 considered is operated according to the first operating mode, the passage of the cooling fluids within the passes 12 ensuring the capture of the carbon dioxide by desublimation.

[0075] The control member 38 makes it possible to control the circulation of the flow of gas loaded with carbon dioxide 2 within one and / or the other of the passes 12 of the heat exchangers 4. For example, in FIG. 1, there is a control member 38 for each heat exchanger 4, and each of the control members 38 controls the circulation of the flow of gas loaded with carbon dioxide 2 within the first pass 12a and / or the second pass 12b. Each control member 38 comprises at least a fifth valve 38a and a sixth valve 38b arranged on either side of one or the other of the passes 12 of each heat exchanger 4, that is to say upstream and downstream of one or the other of the passes 12.Advantageously, and as illustrated in FIG. 1, each control member 38 comprises two fifth valves 38a and two sixth valves 38b, at a rate of one fifth valve 38a and one sixth valve 38b upstream and downstream of each of the passes 12 of the heat exchanger 4 considered.

[0076] It is thus understood that the fifth valves 38a and the sixth valves 38b are open in order to allow the circulation of the flow of gas loaded with carbon dioxide 2 within the passes 12 when the heat exchanger 4 considered is operated according to the second operating mode, the passage of the flow of gas loaded with carbon dioxide 2 within the passes 12 ensuring the melting of the carbon dioxide captured in the chamber 14 of the heat exchanger 4 considered.

[0077] In Figures 1 to 5, all of the above-mentioned valves are independent valves, but it is possible to combine some of them, for example to form three-way valves.

[0078] The control device 44 makes it possible to control the circulation of the flow of gas loaded with carbon dioxide 2 through the chamber 14 of the heat exchangers 4. More precisely, it is the flow of gas loaded with carbon dioxide 2 which passes through the chamber 14 around the passes 12 and which is cooled in order to capture the carbon dioxide by desublimation. For example, in FIG. 1, there is a control device 44 for each heat exchanger 4. Each control device 44 comprises at least a seventh valve 44a and an eighth valve 44b arranged on either side of the chamber 14 of each heat exchanger 4, that is to say upstream and downstream of the chamber 14 of each heat exchanger 4.

[0079] It is thus understood that the seventh valve 44a and the eighth valve 44b are open in order to allow the circulation of the flow of gas loaded with carbon dioxide 2 through the chamber 14 when the heat exchanger 4 considered is operated according to the first operating mode, the passage of the flow of gas loaded with carbon dioxide 2 through the chamber 14 making it possible to capture the carbon dioxide which it contains. It should be noted that the management member 42, the management device 40, the control member 38 and the control device 44 are not material objects but only names making it possible to designate all of the aforementioned valves. Furthermore, the recovery valve 19 mentioned above can also be controlled by the control means 5.

[0080] Whatever the embodiment of the invention or its variants, a regulating member 90 is provided whose role is to control the temperature which prevails within at least one of the two chambers 14a, 14b, and advantageously within a single chamber or all the chambers operated according to the first operating mode. By controlling the temperature within the chamber 14, it is possible to act on the desublimation which takes place in this chamber 14. To do this, the regulating member 90 comprises at least one channel 93 allowing a portion of the decarbonized gas flow 3 to bypass the pass(es) 12 of the heat exchanger(s) 4, depending on the embodiment envisaged. In doing so, the flow rate within the pass(es) 12 can be reduced and therefore the supply of cold within the chamber 14 can be adjusted.

[0081] The circulation of the decarbonized gas flow in this channel 93 is placed under the control of a measuring member 91 of the temperature within at least one of the two chambers 14, 14a, 14b. This measuring member 91 is for example a temperature sensor installed inside the chamber 14. This measuring member 91 acts on a regulating valve 92 placed on the channel 93 and which adjusts the flow rate of the decarbonized gas flow 3 which circulates in the channel 93.

[0082] The capture system 1 further comprises a first heat exchanger 16 and a second heat exchanger 10, each of them configured to carry out a heat exchange between the flow of gas loaded with carbon dioxide 2 and the flow of decarbonized gas 3, after the latter leaves the chamber 14 of at least one heat exchanger 4 operated according to the first operating mode.

[0083] The decarbonized gas flow 3 being at a very low temperature due to its passage through the chamber 14 of one of the heat exchangers 4 operated according to the first operating mode, the first heat exchanger 16 and the second heat exchanger 10 make it possible to exploit this temperature of the decarbonized gas flow 3 in order to pre-cool the gas flow loaded with carbon dioxide 2 before it passes through the chamber 14 of a heat exchanger 4 operated according to the first operating mode. Thus, the first heat exchanger 16 comprises a first pass 16a within which the flow of gas loaded with carbon dioxide 2 circulates and a second pass 16b within which the flow of decarbonized gas 3 circulates, and the second heat exchanger 10 comprises a first pass 10a within which the flow of gas loaded with carbon dioxide 2 circulates and a second pass 10b within which the flow of decarbonized gas 3 circulates.As will be detailed later, the second heat exchanger 10 is positioned upstream of the first heat exchanger 16 relative to the direction of circulation of the flow of gas loaded with carbon dioxide 2.

[0084] Figure 2 illustrates the same capture system 1 as that illustrated in Figure 1. Figure 2, however, illustrates a first example of the circulation of the different fluids within the capture system 1 when the latter is in operation.

[0085] In Figures 2 to 5, the thick solid lines are those within which the flow of gas loaded with carbon dioxide 2 circulates, the thin solid lines are those within which the flow of decarbonized gas 3 circulates, the dashed lines are those within which a flow of liquefied natural gas circulates, the long dotted lines correspond to a flow of carbon dioxide in the liquid state, and the short dotted lines correspond to lines where there is no circulation of any fluid in the operating mode considered.

[0086] In Figure 2, the second heat exchanger 4b is operated by the control means 5 according to the first operating mode. In other words, it is within the chamber 14b of the second heat exchanger 4b that the carbon dioxide contained in the gas flow loaded with carbon dioxide 2 is being captured. The first heat exchanger 4a is operated by the control means 5 according to the second operating mode. In other words, carbon dioxide has been previously captured within the chamber 14a of the first heat exchanger 4a, and said carbon dioxide is being melted.

[0087] When the gas flow loaded with carbon dioxide 2 is emitted by the emission source 6, it circulates to the capture system 1 after being previously compressed and dried as mentioned above. At the inlet of the capture system 1, the gas flow loaded with carbon dioxide 2 is at a temperature, for example, between +5°C and +15°C.

[0088] The flow of gas loaded with carbon dioxide 2 then circulates within the capture system 1, more precisely within a first supply circuit 8. The first supply circuit 8 is divided into a first path 8a and a second path 8b and makes it possible to fluidically connect the arrival of the flow of gas loaded with carbon dioxide 2 to the heat exchangers 4.

[0089] The flow of gas loaded with carbon dioxide 2 circulates within the first path 8a to the second heat exchanger 10 within which it is pre-cooled by the flow of decarbonized gas 3 to a temperature of approximately -33°C.

[0090] The flow of gas loaded with carbon dioxide 2 continues its circulation within the first path 8a to the first heat exchanger 4a. The control means 5, more particularly the control member 38 associated with the first heat exchanger 4a, is configured to keep open the fifth valves 38a and the sixth valves 38b arranged on either side of the passes 12 of the first heat exchanger 4a. This configuration allows the flow of gas loaded with carbon dioxide 2 to circulate within the first pass 12a and the second pass 12b of the first heat exchanger 4a.The flow of gas loaded with carbon dioxide 2 being at a temperature between -25°C and -33°C, a heat exchange is carried out, cooling the flow of gas loaded with carbon dioxide 2, for example to a temperature between -42°C and -49°C, and heating the chamber 14a of the first heat exchanger 4a, thus causing the fusion of the carbon dioxide present within said chamber 14a of the first heat exchanger 4a. The carbon dioxide in the liquid state thus formed can circulate within the recovery branch 31 to the storage member 53, the recovery valve 19 of the first heat exchanger 4a being open.

[0091] At the outlet of the passes 12 of the first heat exchanger 4a, the flow of gas loaded with carbon dioxide 2 continues its circulation to the first heat exchanger 16 within which it is again cooled by the flow of decarbonized gas 3. The flow of gas loaded with carbon dioxide 2 is cooled to a limit threshold of temperature for the change of state of the carbon dioxide, for example to a temperature of approximately - 99°C.

[0092] The flow of gas loaded with carbon dioxide 2 then circulates to the second heat exchanger 4b. The control means 5, more particularly the control device 44 associated with the second heat exchanger 4b, is configured to keep open the seventh valve 44a and the eighth valve 44b arranged on either side of the chamber 14b of the second heat exchanger 4b so that the flow of gas loaded with carbon dioxide 2 can pass through it.

[0093] When the gas flow loaded with carbon dioxide 2 passes through the chamber 14b of the second heat exchanger 4b, a heat exchange takes place because the passes 12 of the second heat exchanger 4b are traversed by the first cooling fluid and the second cooling fluid. The gas flow loaded with carbon dioxide 2 is then cooled to a temperature such that the carbon dioxide contained in the gas flow loaded with carbon dioxide 2 is desublimated, that is to say it passes from the vapor state to the solid state. The carbon dioxide is then deposited in the form of frost on the walls of the chamber 14b of the second heat exchanger 4b or around the passes 12 thereof. The details concerning the characteristics and the nature of the cooling fluids will be mentioned subsequently.

[0094] Crossing the chamber 14b of the second heat exchanger 4b results in the generation of the decarbonized gas flow 3 from the carbon dioxide-laden gas flow 2. The decarbonized gas flow 3 is then at a temperature of approximately -120°C. The capture system 1 comprises a second supply circuit 20 ensuring the circulation of the decarbonized gas flow 3 within the capture system 1. The second supply circuit 20 comprises in particular a line 22 which ensures the circulation of the decarbonized gas flow 3 from the chambers 14 of the heat exchangers 4 to the passes 12 of the heat exchangers.

[0095] Indeed, the decarbonized gas flow 3 being at approximately -120°C, it can be used as a cooling fluid for at least one of the heat exchangers 4 operated according to the first operating mode. In Figure 2, line 22 allows the circulation of the decarbonized gas flow 3 to the first pass 12a of the second heat exchanger 4b.

[0096] The control means 5, more particularly the management member 42 associated with the second heat exchanger 4b, is configured to keep open the first valve 42a and the second valve 42b arranged on either side of the first pass 12a of the second heat exchanger 4b so that the decarbonized gas flow 3 can circulate therein to be used as a first cooling fluid within the second heat exchanger 4b and thus participate in the desublimation of the carbon dioxide contained in the carbon dioxide-laden gas flow 2. At the outlet of the first pass 12a of the second heat exchanger 4b, the decarbonized gas flow 3 is at a temperature of approximately -102°C. In order to keep the chamber 14b airtight, the recovery valve 19 of the second heat exchanger 4b is closed.

[0097] The second supply circuit 20 also comprises a collector 24 for recovering the decarbonized gas flow 3 after it has been evacuated from one or other of the passes 12 of at least one of the heat exchangers 4 operated according to the first operating mode, here the first pass 12a of the second heat exchanger 4b. The collector 24 in particular makes it possible to circulate the decarbonized gas flow 3 to the first heat exchanger 16 in order to cool the carbon dioxide-laden gas flow 2.

[0098] At the outlet of the first heat exchanger 16, the decarbonized gas flow 3 is at a temperature between -52°C and -55°C. It then circulates to the second heat exchanger 10 to ensure the pre-cooling of the carbon dioxide-laden gas flow 2. At the outlet of the second heat exchanger 10, the decarbonized gas flow 3 is at a temperature between -19°C and -25°C. Such a succession of heat exchanges makes it possible to exploit to the maximum the cooling capacities of the decarbonized gas flow 3. The latter then circulates outside the capture system 1 and can, for example, if possible, contribute to the cooling of the carbon dioxide-laden gas flow 2 during its compression and drying prior to its arrival in the capture system 1.

[0099] The capture system 1 further comprises a third supply circuit 28, within which a flow of liquefied natural gas 30 or another refrigerant fluid can circulate. The capture system 1, as mentioned previously, can in fact be integrated within a vehicle, for example a floating structure. Such a floating structure can comprise a tank 34 for transporting and / or storing liquefied natural gas. The latter can also be used as fuel to supply the emission source 6. In all of FIGS. 2 to 5, it is therefore a flow of liquefied natural gas 30 which circulates in the third supply circuit 28. It is however possible that the third supply circuit 28 is a cooling circuit within which a refrigerant fluid circulates, ensuring a function identical to the flow of liquefied natural gas 30.

[0100] The tank 34 comprises a pump 32 ensuring the circulation of the flow of liquefied natural gas 30. This then circulates within the third supply circuit 28 to the heat exchangers 4. It is thus understood that the flow of liquefied natural gas can be used as a cooling fluid to participate in the capture of the carbon dioxide present in the flow of gas loaded with carbon dioxide 2.

[0101] In Figure 2, the flow of liquefied natural gas 30 circulates to the second pass 12b of the second heat exchanger 4b, the latter being operated according to the first operating mode. The control means 5, more particularly the management device 40 associated with the second heat exchanger 4b is configured to keep open the third valve 40a and the fourth valve 44b arranged on either side of the second pass 12b of the second heat exchanger 4b so that the flow of liquefied natural gas 30 can circulate therein to be used as a second cooling fluid within the second heat exchanger 4b and thus participate in the desublimation of the carbon dioxide contained in the flow of gas loaded with carbon dioxide 2. At the inlet of the second pass 12b of the second heat exchanger 4b, the flow of liquefied natural gas 30 is at a temperature of approximately -161°C.In the case where it is another refrigerant fluid which circulates in the third supply circuit 28, said refrigerant fluid can for example be at a temperature of -125°C. At the outlet of the second pass 12b of the second heat exchanger 4b, the flow of liquefied natural gas 30 is at a temperature of approximately -101°C.

[0102] Advantageously, the decarbonized gas flow 3 circulates within the first pass 12a and the liquefied natural gas flow 30 circulates within the second pass 12b of the heat exchanger 4 operated according to the first operating mode. This arrangement allows the carbon dioxide-laden gas flow 2, as it passes through the chamber 14, to be cooled initially by the decarbonized gas flow 3, then by the liquefied natural gas flow 30 which is colder than the decarbonized gas flow 3. The cooling of the carbon dioxide-laden gas flow 2 is thus progressive and contributes to distributing the carbon dioxide snow over the cold surfaces successively crossed by the carbon dioxide-laden gas flow 2.

[0103] At the outlet of the second pass 12b of the second heat exchanger 4b, the flow of liquefied natural gas 30 can subsequently be used for a subsequent heat exchange. Indeed, as mentioned, the first supply circuit 8 is divided into the first path 8a and the second path 8b. The circulation of the flow of gas loaded with carbon dioxide 2 within the path 8a has been described previously.

[0104] The flow of gas loaded with carbon dioxide 2 circulating in the second path 8b also circulates to the heat exchangers 4, but must be pre-cooled before passing through the chamber 14 of at least one of the heat exchangers 4 operated according to the first operating mode, just like the flow of gas loaded with carbon dioxide 2 circulating in the first path 8a.

[0105] To do this, the capture system 1 comprises a third heat exchanger 18 configured to carry out a heat exchange between the flow of gas loaded with carbon dioxide 2 circulating in the second path 8b and the flow of liquefied natural gas 30 circulating in the third supply circuit 28 after having circulated in one and / or the other of the passes 12 of at least one of the heat exchangers 4 operated according to the first operating mode. The division of the first supply circuit 8 into two paths 8a, 8b allows a distribution of the pre-cooling of the flow of gas loaded with carbon dioxide 2 to several heat exchangers. In addition, the low temperature of the flow of liquefied natural gas 30 can be exploited.

[0106] Thus, the third heat exchanger 18 comprises a first pass 18a within which the flow of gas loaded with carbon dioxide 2 circulates and a second pass 18b within which the flow of liquefied natural gas 30 circulates. The latter being at a temperature of approximately -101°C, it can then cool the flow of gas loaded with carbon dioxide 2 to the temperature limit threshold for the change of state of the carbon dioxide, for example to a temperature of approximately -99°C.

[0107] Downstream of the third heat exchanger 18, the second path 8b joins the first path 8a downstream of the first heat exchanger 16 and upstream of the heat exchangers 4. The flows of gas loaded with carbon dioxide 2 circulating in each of the paths 8a, 8b thus join while having an identical or substantially identical temperature relative to each other.

[0108] At the outlet of the third heat exchanger 18, the flow of liquefied natural gas 30 or any other refrigerant fluid is in the vapor state at a temperature of approximately +3°C and can circulate to a receiving member 35 which can heat said flow and circulate it to a gas-consuming device, for example the emission source 6 which generates the flow of gas loaded with carbon dioxide 2 that the capture system 1 according to the invention seeks to treat.

[0109] In particular, in order to regulate the temperature of the gas flows at the first heat exchanger 16, the capture system 1 is also provided with a regulation system 46 and a regulation device 61.

[0110] The regulation system 46 comprises a detection device 48, a bypass branch 26 and a ninth valve 50. The detection device 48 makes it possible to measure the temperature of the gas flow loaded with carbon dioxide 2 at the outlet of the first heat exchanger 16. The bypass branch 26 is integrated within the second supply circuit 20 and is arranged in parallel with the first heat exchanger 16. The ninth valve 50 is arranged on the bypass branch 26.

[0111] The function of the regulation system 46 is to prevent premature desublimation of the carbon dioxide within the first heat exchanger 16 which is not configured to ensure the storage of carbon dioxide in the solid state. The temperature of the gas flow loaded with carbon dioxide 2 is thus controlled at the outlet of said first heat exchanger 16. If the detection device 48 measures a temperature lower than a defined temperature threshold, this means that the decarbonized gas flow 3 is cooling the gas flow loaded with carbon dioxide 2 too much within the first heat exchanger 16.

[0112] In order to limit such cooling, the ninth valve 50 can be opened so that at least a fraction of the decarbonized gas flow 3 circulates within the bypass branch 26 instead of passing through the first heat exchanger 16. This thus limits the flow rate of the decarbonized gas flow 3 passing through the first heat exchanger 16 and avoids cooling the carbon dioxide-laden gas flow 2 too intensively.

[0113] The detection device 48 can be configured to directly control the ninth valve 50. The latter can be opened so as to vary a passage section of the bypass branch 26. In this way, it is possible to control the flow rate of decarbonized gas circulating in the bypass branch 26 and therefore to indirectly control the flow rate of decarbonized gas passing through the first heat exchanger 16. In the case where the flow of decarbonized gas 3 is divided into a fraction circulating in the bypass branch 26 and into a fraction passing through the first heat exchanger 16, the two fractions join downstream of the latter and the flow of decarbonized gas 3 continues its circulation to the second heat exchanger 10.

[0114] The regulation device 61 comprises a bypass line 62 of the first pass 12a and / or of the second pass 12b of one or other of the heat exchangers 4, a control valve 63 configured to control the circulation of the flow of gas loaded with carbon dioxide 2 within the bypass line 62, and a member 64 for detecting the temperature of the flow of gas loaded with carbon dioxide 2 upstream of the first heat exchanger 16. The bypass line 62 is integrated within the first path 8a of the first supply circuit 8 and is arranged in parallel with the passes 12 of the heat exchangers 4. The control valve 63 is arranged on the bypass line 62.

[0115] The regulating device 61 has the function of controlling the melting speed of the carbon dioxide within the chamber 14 of at least one of the heat exchangers 4 operated according to the second operating mode. The temperature of the gas flow loaded with carbon dioxide 2 is controlled by the detection member 64 upstream of the first heat exchanger 16 and therefore downstream of the passes 12 of at least one of the heat exchangers 4, here the first pass 12a and the second pass 12b of the first heat exchanger 4a. If the detection member 64 measures a temperature lower than a defined temperature threshold, this means that the gas flow loaded with carbon dioxide 2 is carrying out too much heat exchange within at least one of the heat exchangers 4 operated according to the second operating mode and therefore that the melting of the carbon dioxide is potentially carried out too quickly.

[0116] In order to limit the melting rate of the carbon dioxide, the control valve 63 can be opened so that at least a fraction of the carbon dioxide-laden gas flow 2 circulates within the bypass line 62 instead of passing through the first pass 12a and the second pass 12b of the first heat exchanger 4a. This thus limits the flow rate of the carbon dioxide-laden gas flow 2 circulating in the first pass 12a and in the second pass 12b of the first heat exchanger 4a and prevents the carbon dioxide contained in the chamber 14a of the first heat exchanger 4a from melting too quickly.

[0117] The detection member 64 can be configured to directly control the control valve 63. The latter can be opened so as to vary a passage section of the bypass line 62. In this way, it is possible to control the flow rate of gas loaded with carbon dioxide circulating in the bypass line 62 and therefore to indirectly control the flow rate of gas loaded with carbon dioxide circulating in the first pass 12a and in the second pass 12b of the first heat exchanger 4a.

[0118] In the case where the gas flow loaded with carbon dioxide 2 is divided into a fraction circulating in the bypass line 62 and into a fraction circulating in the first pass 12a and in the second pass 12b of the first heat exchanger 4a, the two fractions join downstream of the latter and upstream of the measurement of the temperature of the gas flow loaded with carbon dioxide 2 by the detection member 64. Although the temperature of the fraction of the gas flow loaded with carbon dioxide 2 circulating in the first pass 12a and in the second pass 12b of the first heat exchanger 4a has been lowered during the heat exchange carried out within the latter, this drop in temperature is compensated by the temperature of the fraction of the gas flow loaded with carbon dioxide 2 circulating in the bypass line 62 and which has therefore not undergone heat exchange when the two fractions join and mix.

[0119] Figure 3 illustrates the same capture system 1 as that illustrated in Figure 1 and Figure 2. Figure 3 illustrates a second example of circulation of the different fluids within the capture system 1 when the latter is in operation. The difference with Figure 2 lies in the fact that this time it is the first heat exchanger 4a which is operated according to the first operating mode and it is the second heat exchanger 4b which is operated according to the second operating mode.

[0120] It is thus understood that the configuration illustrated in Figure 3 is successive to the configuration illustrated in Figure 2. Indeed, the capture system 1 implements a method of capturing carbon dioxide within a flow of gas loaded with carbon dioxide during which each heat exchanger 4 is operated according to one of the operating modes and subsequently switches to the other operating mode. This capture method thus allows capture of the carbon dioxide present in the flow of gas loaded with carbon dioxide 2 within each heat exchanger 4 during the operation of the first operating mode, then to merge the captured carbon dioxide in said heat exchangers 4 during the operation of the second operating mode, thus forming a capture / merge cycle.Subsequently, the capture / fusion cycle is repeated by iterations so as to be able to continuously capture the carbon dioxide within the flow of gas loaded with carbon dioxide 2. The control means 5 ensure the switching of the heat exchangers 4 from one operating mode to the other via the opening and closing of the various valves mentioned previously.

[0121] Furthermore, in a capture system 1 comprising two heat exchangers 4 as illustrated in FIGS. 1 to 3, the capture method is configured so that each of the two heat exchangers 4 is operated according to a different operating mode, and so that the switching from one operating mode to the other is done simultaneously or substantially simultaneously at the level of the two heat exchangers 4. Such a configuration makes it possible to permanently have a heat exchanger 4 operated according to the first operating mode, and thus to be able to permanently capture the carbon dioxide present in the flow of gas loaded with carbon dioxide 2, this being continuous as long as the emission source 6 is in operation.

[0122] For example, when switching from the configuration illustrated in Figure 2 to the configuration illustrated in Figure 3, the first heat exchanger 4a, initially operated according to the second operating mode, must switch to an operation of the first operating mode. The fifth valves 38a and the sixth valves 38b arranged on either side of the passes 12 of the first heat exchanger 4a are closed in order to stop the circulation of the flow of gas loaded with carbon dioxide 2 within said passes 12. The recovery valve 19 is also closed. The first valve 42a and the second valve 42b located on either side of the first pass 12a of the first heat exchanger 4a are open in order to allow circulation of the flow of decarbonized gas 3 within the first pass 12a.The third valve 40a and the fourth valve 40b located on either side of the second pass 12b of the first heat exchanger 4a are also open in order to allow circulation of the flow of liquefied natural gas 30 within the second pass 12b. Finally, the seventh valve 44a and the eighth valve 44b located on either side of the chamber 14a of the first heat exchanger 4a are open in order to allow circulation of the flow of gas loaded with carbon dioxide 2 through the chamber 14a. The first heat exchanger 4a is then ready to be operated according to the first operating mode and to capture the carbon dioxide contained in the flow of gas loaded with carbon dioxide 2, as illustrated in FIG. 3.

[0123] Simultaneously with the switching of the operating mode of the first heat exchanger 4a, the second heat exchanger 4b, initially operated according to the first operating mode, must switch to an operation of the second operating mode. The first valve 42a and the second valve 42b located on either side of the first pass 12a of the second heat exchanger 4b are closed in order to stop the circulation of the flow of decarbonized gas 3 within the first pass 12a. The third valve 40a and the fourth valve 40b located on either side of the second pass 12b of the second heat exchanger 4b are also closed in order to stop the circulation of the flow of liquefied natural gas 30 or any other refrigerant within the second pass 12b.The seventh valve 44a and the eighth valve 44b located on either side of the chamber 14b of the second heat exchanger 4b are also closed in order to stop the circulation of the flow of gas loaded with carbon dioxide 2 through the chamber 14b.

[0124] Finally, the fifth valves 38a and the sixth valves 38b arranged on either side of the passes 12 of the second heat exchanger 4b are open in order to allow circulation of the flow of gas loaded with carbon dioxide 2 within said passes 12. The recovery valve 19 is also open in order to allow circulation of the carbon dioxide in the liquid state within the recovery branch 31. The second heat exchanger 4b is then ready to be operated according to the second operating mode and to merge the carbon dioxide captured in the chamber 14b, as illustrated in FIG. 3. All of the operations intended to control the operating modes of the heat exchangers 4 and to operate the switches from one operating mode to the other are carried out by the control means 5.

[0125] The switching of the operating modes of the heat exchangers 4 continues as long as the emission source 6 is in operation, and therefore as long as there is carbon dioxide to be captured. The circulation of the different fluids is identical to that described in Figure 2, but by interchanging the first heat exchanger 4a and the second heat exchanger 4b.

[0126] Figure 4 illustrates a second embodiment of the capture system 1 according to the invention. The second embodiment differs from the first embodiment, illustrated in Figures 1 to 3, in that the capture system 1 comprises three heat exchangers 4 responsible for capturing or merging the carbon dioxide.

[0127] The capture system 1 thus comprises a third heat exchanger 4c structurally and functionally identical to the first heat exchanger 4a and to the second heat exchanger 4b. Thus, the third heat exchanger 4c can be operated according to the two operating modes mentioned above and the control means 5 can switch the third heat exchanger 4c from one operating mode to the other.

[0128] In order to have the same functional characteristics as the first heat exchanger 4a and the second heat exchanger 4b, the third heat exchanger 4c is connected to all of the different supply circuits in an identical manner to the first heat exchanger 4a and the second heat exchanger 4b. The capture system 1 further comprises control means 5 associated with the third heat exchanger 4c. The control means 5 thus comprise a management member 42, a management device 40, a control member 38 and a control device 44, each associated with the third heat exchanger 4c and each being provided with its respective valves as described previously.

[0129] The circulation of the different fluids depending on the operating mode operated on the third heat exchanger 4c therefore takes place in an identical manner to that described previously, the different fluids being able for example to be divided into two fractions at the level of portions of different circuits when two heat exchangers 4 are operated according to the same operating mode. Thus, reference will be made to the description of figures 1 to 3 which forms the support and / or the detailed description of the identical or identically functioning elements present in these figures.

[0130] Within the second embodiment of the capture system 1, the carbon dioxide capture process is operated such that there are constantly two heat exchangers 4 which are operated according to the first mode of operation, that is to say two heat exchangers 4 which ensure the capture of carbon dioxide within their respective chamber 14. As illustrated in FIG. 4, the first heat exchanger 4a is operated according to the second mode of operation, while the second heat exchanger 4b and the third heat exchanger 4c are operated according to the first mode of operation. Having two heat exchangers 4 operated according to the first mode of operation makes it possible to treat a higher flow rate of the carbon dioxide-laden gas stream 2 and thus to increase the treatment capacity of the capture system 1.The sequence of the capture process and the various operating mode switches in a capture system 1 with three heat exchangers 4 is detailed below.

[0131] When, according to this embodiment, two heat exchangers 4 are operated according to the first operating mode, the capture system 1 may comprise a flow sensor 94 upstream of the chamber 14 of each of the heat exchangers 4, for example in the vicinity of the seventh valve 44a of the control device 44 of each heat exchanger 4. Each flow sensor 94 makes it possible to measure the flow rate of gas loaded with carbon dioxide 2 passing through the chamber 14 of the heat exchangers 4 operated according to the first operating mode.

[0132] In addition, each eighth valve 44b of the control device 44 of each heat exchanger 4 may be a valve capable of varying a passage section of the decarbonized gas flow 3. Thus, the distribution of the flow rate of the gas flow loaded with carbon dioxide 2 is controlled between the two heat exchangers 4 operated according to the first operating mode. Figure 5 illustrates a third embodiment of the carbon dioxide capture system 1 according to the invention. Compared to what has been described in the previous figures, the second embodiment is distinguished by the absence of the line 22, the role of which is replaced by at least one pipe 54.

[0133] In this third embodiment, the first heat exchanger 4a is connected to a first pipe 54a, the second heat exchanger 4b is connected to a second pipe 54b and the third heat exchanger 4c is connected to a third pipe 54c. It is obvious that such a configuration of the pipes 54 is also applicable to a capture system 1 comprising only two heat exchangers 4.

[0134] For each of the heat exchangers 4, the pipe 54 begins downstream of the chamber 14 of the heat exchanger 4 in question, then is connected to the second pass 12b which extends into said chamber 14. In this way, each heat exchanger 4 can only receive the flow of decarbonized gas 3 which it has itself produced. This configuration makes it possible to operate at different temperatures if necessary at the outlet of each heat exchanger 4. This configuration also makes it possible to avoid interference between the two devices operating according to the first operating mode.

[0135] According to the example of circulation of the fluids illustrated in Figure 5, the second heat exchanger 4b and the third heat exchanger 4c are operated according to the first operating mode. The second pipe 54b and the third pipe 54c respectively channel the flow of decarbonized gas 3 coming from the chamber 14 constituting the second heat exchanger 4b and from the chamber 14 constituting the third heat exchanger 4c, and this up to the second pass 12b of each heat exchanger 4.

[0136] All of the structural and functional elements with the exception of the pipes 54 being identical to what was described previously, reference will be made to the description of figures 1 to 4 for understanding the elements common to all of the embodiments of the capture system 1.

[0137] Figure 6 is a graph detailing the progress of the capture / fusion cycles 81 of each of the three heat exchangers 4a, 4b, 4c over time so that there are constantly two heat exchangers operated according to the first operating mode 101.

[0138] The graph illustrates the operating mode on the ordinate of each of the three heat exchangers 4 over time. The time is divided into periods of use 80, all of equal duration relative to each other. In Figure 6, eight periods of use 80 are represented, but the periods of use 80 can be repeated as many times as necessary. A period of use 80 can for example be equal to four hours.

[0139] In Figure 6, the time T0 may correspond to a random time during which the emission source is operating and therefore the carbon dioxide needs to be captured. The time T0 may for example correspond to the moment when the first heat exchanger 4a begins a new capture / fusion cycle 81. At time T0, the first heat exchanger 4a is operated according to the first operating mode 101 in order to begin capturing the carbon dioxide present within the gas flow loaded with carbon dioxide.

[0140] At time T1, that is to say after a period of use 80, a new period of use 80 begins, between time T1 and time T2. From time T1, the second heat exchanger 4b begins a new capture / fusion cycle 81 and is therefore operated according to the first operating mode 101, while the first heat exchanger 4a is kept operated according to the first operating mode

[0141] 101 and therefore continues to capture carbon dioxide.

[0142] From time T2, the first heat exchanger 4a, which has captured a significant quantity of carbon dioxide, switches to the second operating mode

[0143] 102 so that the carbon dioxide captured in the chamber of the first heat exchanger 4a is merged. At the same time, the third heat exchanger 4c begins a new capture / merging cycle 81 and is operated according to the first operating mode 101 to capture the carbon dioxide contained in the gas flow loaded with carbon dioxide. The second heat exchanger 4b is maintained according to the first operating mode 101 to continue capturing the carbon dioxide in its chamber.

[0144] Between time T2 and time T3, the first heat exchanger 4a is operated according to the second operating mode 102 while the second heat exchanger 4b and the third heat exchanger 4c are operated according to the first operating mode 101. The circulation of the different fluids during this period of use 80 therefore corresponds to the circulation of the fluids illustrated in FIG. 4.

[0145] At time T3, the first heat exchanger 4a switches back to the first operating mode 101. Since the carbon dioxide was fully fused during the previous usage period 80, the first heat exchanger 4a is able to capture the carbon dioxide again from the carbon dioxide-laden gas stream.

[0146] Thus, between time T0 and time T3, the first heat exchanger 4a has completed a complete capture / fusion cycle 81. It is thus understood that a capture / fusion cycle 81 lasts three periods of use 80, including two periods of use 80 during which the heat exchanger considered is operated according to the first mode of use 101 then one period of use 80 during which the heat exchanger considered is operated according to the second mode of use 102. The carbon dioxide fusion time therefore lasts half as long as the carbon dioxide capture time.

[0147] In parallel, at time T3, the second heat exchanger 4b has been operated according to the first operating mode 101 for two periods of use 80 and therefore switches to the second operating mode 102 so that the carbon dioxide is fused. Having only been operated according to the first operating mode 101 for one period of use 80, the third heat exchanger 4c is therefore kept operated according to the first operating mode 101.

[0148] At time T4, the second heat exchanger 4b switches back to the first operating mode 101 to complete its capture / fusion cycle 81 and start a new one. The carbon dioxide is therefore again captured within the chamber of the second heat exchanger 4b.

[0149] The third heat exchanger 4c in turn switches to the second operating mode 102 so that the captured carbon dioxide is merged. The first heat exchanger 4a is kept operating according to the first operating mode 101.

[0150] The capture / melting cycle 81 of the third heat exchanger 4c ends at time T5 when switching to the first operating mode 101, while the first heat exchanger 4a switches back to the second operating mode 102 and the second heat exchanger 4b is kept operating according to the first operating mode 101. The capture process thus continues until times T6, T7, T8 and following and as long as necessary.

[0151] It is understood from Figure 6 that the capture / fusion cycles 81 of the three heat exchangers are offset relative to each other by a period of use 80. The capture / fusion cycle 81 during three periods of use 80, two of which are according to the first operating mode 101 and one according to the second operating mode 102, the offset of the capture / fusion cycles 81 makes it possible, at each period of use 80 where the three heat exchangers are in operation, to systematically have two heat exchangers operated according to the first operating mode 101, the last heat exchanger being operated according to the second operating mode 102. The carbon dioxide is thus captured optimally when the capture system is equipped with three heat exchangers.

[0152] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0153] The invention, as just described, achieves the aim it set itself, and makes it possible to propose a system for capturing carbon dioxide within gas loaded with carbon dioxide comprising at least two exchangers capable of being operated according to a first operating mode where the carbon dioxide is captured and according to a second operating mode where the captured carbon dioxide is merged. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they comprise a capture system in accordance with the invention.

Claims

CLAIMS 1- System for capturing (1) carbon dioxide within gas loaded with carbon dioxide, comprising at least a first heat exchanger (4a) and a second heat exchanger (4b), each of the heat exchangers (4) comprising at least one chamber (14), a first pass (12a) and a second pass (12b) which both extend into the chamber (14),characterized in that the first heat exchanger (4a) and the second heat exchanger (4b) are configured to be operated according to a first operating mode (101) where the chamber (14) is configured to be crossed by a flow of gas loaded with carbon dioxide (2) and to capture by desublimation the carbon dioxide present in said flow of gas loaded with carbon dioxide (2) in order to generate a flow of decarbonized gas (3) and according to a second operating mode (102) where the first pass (12a) and / or the second pass (12b) are crossed by the flow of gas loaded with carbon dioxide (2) to merge the carbon dioxide captured in the chamber (14), the capture system (1) comprising control means (5) configured to operate an alternation between the first operating mode (101) and the second operating mode (102)., 2- Capture system (1) according to claim 1, wherein the control means (5) are configured to operate an alternation of one heat exchanger (4) with respect to the other between the first operating mode (101) and the second operating mode (102). 3- Capture system (1) according to claim 1 or 2, wherein the control means (5) comprise at least one management member (42) configured to regulate a circulation of a first cooling fluid which circulates within one or other of the passes (12) of one or other of the heat exchangers (4). 4- Capture system (1) according to the preceding claim, in which the management member (42) comprises at least one first valve (42a) arranged upstream of one or other of the passes (12) of one or other of the heat exchangers (4) and / or at least one second valve (42b) arranged downstream of one or other of the passes (12) of one or other of the heat exchangers (4). 5- Capture system (1) according to any one of the preceding claims, in which the control means (5) comprise at least one management device (40) configured to regulate a circulation of a second cooling fluid which circulates within one or other of the passes (12) of one or other of the heat exchangers (4). 6- Capture system (1) according to the preceding claim, in which the management device (40) comprises at least one third valve (40a) arranged upstream of one or other of the passes (12) of one or other of the heat exchangers (4) and / or at least one fourth valve (40b) arranged downstream of one or other of the passes (12) of one or other of the heat exchangers (4). 7- Capture system (1) according to claim 5 or 6, wherein the first cooling fluid and / or the second cooling fluid is the decarbonized gas flow (3). 8- Capture system (1) according to any one of claims 5 to 7, wherein the first cooling fluid and / or the second cooling fluid is a stream of liquefied natural gas (30) or a refrigerant. 9- Capture system (1) according to any one of the preceding claims, in which the control means (5) comprise at least one control member (38) configured to regulate the circulation of the flow of gas loaded with carbon dioxide (2) within one and / or the other of the passes (12) of one or the other of the heat exchangers (4). 10- Capture system (1) according to the preceding claim, in which the control member (38) comprises at least one fifth valve (38a) arranged upstream of one or other of the passes (12) of one or other of the heat exchangers (4) and / or at least one sixth valve (38b) arranged downstream of one or other of the passes (12) of one or other of the heat exchangers (4). 11- Capture system (1) according to any one of the preceding claims, in which the control means (5) comprise at least one control device (44) configured to regulate the circulation of the flow of gas loaded with carbon dioxide (2) which circulates through one or other of the heat exchangers (4) around one or other of its passes (12). 12- Capture system (1) according to the preceding claim, characterized in that the control device (44) comprises at least one seventh valve (44a) arranged upstream of the chamber (14) of one or other of the heat exchangers (4) and / or at least one eighth valve (44b) arranged downstream of the chamber (14) of one or other of the heat exchangers (4). 13- Capture system (1) according to any one of the preceding claims, comprising a first heat exchanger (16) configured to carry out a heat exchange between the flow of gas loaded with carbon dioxide (2) and the flow of decarbonized gas (3), the first heat exchanger (16) comprising a first pass (16a) traversed by the flow of gas loaded with carbon dioxide (2) and a second pass (16b) traversed by the flow of decarbonized gas (3), said first pass (16a) being arranged upstream of the chamber (14) of one or other of the heat exchangers (4) and said second pass (16b) being arranged downstream of the chamber (14). 14- Capture system (1) according to the preceding claim, comprising a device (61) for regulating the temperature of the flow of gas loaded with carbon dioxide (2) upstream of the first pass (16a) of the first heat exchanger (16), configured to regulate the temperature of the flow of gas loaded with carbon dioxide (2) after its passage through the first pass (12a) and / or the second pass (12b) of one or other of the heat exchangers (4), the regulating device (61) comprising a bypass line (62) of the first pass (12a) and / or the second pass (12b) of one or other of the heat exchangers (4), a control valve (63) configured to control the circulation of the flow of gas loaded with carbon dioxide (2) within the bypass line (62), and a member (64) for detecting the temperature of the flow of gas loaded with carbon dioxide (2) upstream of the first pass (16a) of said heat exchanger (16). 15- Capture system (1) according to any one of the preceding claims, comprising a recovery branch (31) connected to each of the heat exchangers (4) and configured to collect carbon dioxide in the liquid state from at least one of the heat exchangers (4), the recovery branch (31) comprising a recovery valve (19). 16- Capture system (1) according to any one of the preceding claims, comprising a third heat exchanger (4c) configured to be operated according to the first operating mode (101) and according to the second operating mode (102), the control means (5) being configured to operate an alternation between the first operating mode (101) and the second operating mode (102) on the third heat exchanger (4c). 17- Method for capturing carbon dioxide within a flow of gas loaded with carbon dioxide (2) implemented by a system (1) for capturing carbon dioxide within gas loaded with carbon dioxide according to any one of the preceding claims, during which: at least one of the heat exchangers (4) is operated according to the first operating mode (101) in order to desublimate the carbon dioxide present within the flow of gas loaded with carbon dioxide (2) and passing through the chamber (14) of said heat exchanger (4); switching from the first operating mode (101) to the second operating mode (102) of said heat exchanger (4) in order to merge the desublimated carbon dioxide in the chamber (14) by circulating the flow of gas loaded with carbon dioxide (2) within the first pass (12a) and / or the second pass (12b) of said heat exchanger (4). 18- Capture method according to the preceding claim, during which at least one of the heat exchangers (4) is operated according to the first operating mode (101) when the other of the heat exchangers (4) is operated according to the second operating mode (102). 19- Capture method according to claim 17 or 18, during which the first operating mode (101) followed by the second operating mode (102) is a carbon dioxide capture / fusion cycle (81), said capture / fusion cycle (81) being repeated by iterations. 20- Capture method according to the preceding claim, implemented by a capture system (1) according to claim 16, during which two heat exchangers (4) are operated according to the first operating mode (101) while the last heat exchanger (4) is operated according to the second operating mode (102), the capture / fusion cycle (81) comprising three periods of use (80) of which two correspond to the first operating mode (101) and one corresponds to the second operating mode (102), the three periods of use (80) being of equal duration, the capture / fusion cycle (81) being operated so that each of the three heat exchangers (4) is operated according to each of the three periods of use (80) and so that a transition of the periods of use (80) takes place simultaneously between the three heat exchangers (4). 21- Capture method according to any one of claims 17 to 20, during which a first cooling fluid and a second cooling fluid circulate respectively in the first pass (12a) and in the second pass (12b) of at least one of the heat exchangers (4) when it is operated according to the first operating mode (101). 22- A capture method according to any one of claims 17 to 21 in combination with claims 4, 6, 10, 12 and 15, during which the first valve (42a), the second valve (42b), the third valve (40a), the fourth valve (40b), the seventh valve (44a) and the eighth valve (44b) are open while the fifth valve (38a), the sixth valve (38b) and the recovery valve (19) are closed when the heat exchanger (4) in question is operated according to the first operating mode (101). 23- A capture method according to any one of claims 17 to 22, in combination with claims 4, 6, 10, 12 and 15, during which the first valve (42a), the second valve (42b), the third valve (40a), the fourth valve (40b), the seventh valve (44a) and the eighth valve (44b) are closed while the fifth valve (38a), the sixth valve (38b) and the recovery valve (19) are open when the heat exchanger (4) in question is operated according to the second operating mode (102). 24- A capture method according to any one of claims 17 to 23, implemented by a capture system (1) according to claim 14, during which the temperature regulating device (61) controls an opening section of the control valve (63) in order to determine a flow rate of gas loaded with carbon dioxide (2) passing through the first pass (12a) and / or the second pass (12b) of the heat exchanger (4) operated according to the second operating mode (102) and a flow rate of gas loaded with carbon dioxide (2) circulating in the bypass branch (62), the opening section of the control valve (63) being dependent on at least one temperature of the gas flow loaded with carbon dioxide (2) recorded by the temperature detection member (64). 25- Capture method according to any one of claims 17 to 24, during which the fused carbon dioxide from the heat exchanger (4) operated according to the second operating mode (102) is stored.

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