System for capturing carbon dioxide within gas loaded with carbon dioxide

Abstract

The invention relates to a system (1) for capturing carbon dioxide within gas loaded with carbon dioxide, comprising a first heat exchanger (4a) and a second heat exchanger (4b), each of the heat exchangers (4, 4a, 4b) comprising a chamber (14, 14a, 14b), a first pass (12a) and a second pass (12b), the chamber (14, 14a, 14b) being passed through by a carbon dioxide-loaded gas flow (2) and, in order to capture by desublimation the carbon dioxide present in said carbon dioxide-loaded gas flow (2) with a view to generating a decarbonated gas flow (3), the capture system (1) is configured to cause the decarbonated gas flow (3) from either of the two chambers (14, 14a, 14b) to circulate within the first pass (12a) and / or within the second pass (12b) of at least one of the two heat exchangers (4, 4a, 4b).

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 gas loaded with carbon dioxide and more particularly concerns a system for capturing carbon dioxide within said gas loaded with carbon dioxide.

[0004] When a gas emission source, for example carbon dioxide-laden gas, 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, causing environmental damage, particularly because of the carbon dioxide they contain.

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

[0006] It may then 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 capturing carbon dioxide by desublimation of a carbon dioxide-laden gas stream consumes a lot of energy because it requires cooling to very low temperatures. The systems known to date are not optimized, and this is one of the reasons why these systems are not used.

[0007] The present invention overcomes these drawbacks by proposing a system for capturing carbon dioxide within a gas loaded 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, the chamber being configured to be traversed 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, characterized in that the capture system is configured to circulate the flow of decarbonized gas coming from any one of the two chambers within the first pass and / or within the second pass of at least one of the two heat exchangers.

[0008] 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 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 refrigerant gas. 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.

[0009] The capture system according to the invention aims to capture the carbon dioxide present in the carbon dioxide-laden gas emitted by an emission source by desublimation of said carbon dioxide-laden gas. By desublimating a carbon dioxide-laden gas stream, a decarbonized gas stream is obtained. According to the invention, this decarbonized gas stream is then used as a cooling means for the heat exchanger(s) belonging to the capture system, so as to implement the desublimation of the carbon dioxide-laden gas stream supplied to the heat exchanger(s).

[0010] The first heat exchanger and the second heat exchanger are configured to transform the carbon dioxide-laden gas stream entering said heat exchangers into a decarbonized gas stream, by desublimation of the carbon dioxide. One of the two heat exchangers operates according to a first operating mode in order to achieve the cooling parameters allowing the desublimation of the carbon dioxide. The desublimated carbon dioxide solidifies on the walls and passes of the heat exchanger operated according to the first operating mode.In order to ensure desublimation when the flow of gas laden 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 present in the chamber are crossed by one or more fluids, at least one of which is the flow of decarbonized gas having passed through the chamber of the heat exchanger. This contributes to the cooling of the gases laden with carbon dioxide by means of energy already present within the capture system. Advantageously, another fluid can participate in this cooling. The flow of decarbonized gas can 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 flow is, for example, at a temperature of -120°C between the chamber outlet and an inlet of the first pass and / or the second pass.

[0011] The system thus causes a heat exchange between said flow of gas loaded with carbon dioxide and the low-temperature fluid(s) circulating in the pass(es) of the heat exchanger, inducing the formation of dry ice, i.e. carbon dioxide in the solid state. When dry ice forms, we can say that the heat exchanger is in "desublimation" mode.

[0012] Following the capture of carbon dioxide in the form of dry ice, the carbon dioxide-laden gas stream that has passed through the heat exchanger chamber emerges decarbonized. The decarbonized carbon dioxide-laden gas stream exits at a very low temperature, for example -120°C.

[0013] The flow of decarbonized gas leaving the heat exchanger is thus available to supply the first pass and / or the second pass of another heat exchanger constituting the capture system according to the invention. In a second operating mode, the first and / or the second pass of the heat exchanger may be crossed by a flow of gas loaded with carbon dioxide in order to heat said passes and the chamber of the heat exchanger, to cause the melting of the dry ice surrounding said passes. In the case of an internal combustion engine, the flow of gas loaded with carbon dioxide passing through the first pass and / or the second pass may for example be at an inlet temperature between the temperature of the exhaust gases of the internal combustion engine and -33°C. When there is melting of the dry ice, it can be said that the heat exchanger is in “regeneration” mode.

[0014] In a particular embodiment, the capture system is configured such that the flow of gas laden with carbon dioxide passing through the chamber during the first mode of operation is the same flow of gas as the flow of gas laden with carbon dioxide 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 flow of gas laden with carbon dioxide 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 flow of gas laden with carbon dioxide 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] According to another feature, a line is configured to channel the decarbonized gas flow to the first pass and / or the second pass of each of the heat exchangers.

[0016] This is a common line connected to each heat exchanger in order to provide them with the flow of decarbonized gas which constitutes a source of cold used during the desublimation operation.

[0017] According to another feature, a collector recovers the decarbonized gas flow after it has passed through the first pass and / or the second pass of each of the heat exchangers. The decarbonized gas flow discharged by the first and / or the second pass of the heat exchanger continues its circulation within a collector responsible for sending said decarbonized gas flow into a heat exchanger and / or into a bypass branch of said heat exchanger.

[0018] According to another characteristic, a pipe is configured to channel the flow of decarbonized gas coming from one of the heat exchangers towards the first pass and / or the second pass exclusively of said heat exchanger.

[0019] In this embodiment, the pipe channels the flow of decarbonized gas coming from one of the two heat exchangers to reinject it into the pass(es) of this same heat exchanger. Unlike the line mentioned above which commonly supplies the heat exchangers, the pipe is specific to each heat exchanger.

[0020] According to one option of the invention, the capture system comprises at least one regulating member configured to regulate the desublimation temperature within each of the chambers. This regulating member operates by diverting a portion of the decarbonized gases so as to prevent them from passing through the pass(es) of the heat exchanger. This portion of the diverted gases is sent to an outlet of the capture system, for example downstream of the passes and upstream of a first heat exchanger. By regulating the flow rate of decarbonized gas within the pass of the heat exchanger, the temperature within the chamber is managed. This regulating member may in particular be used at the start of the desublimation phase when the dry ice thickness is low and the heat transfer coefficient is high.

[0021] The regulating member comprises at least one channel which connects the line of decarbonized gas leaving the chamber to a circuit for evacuating the flow of decarbonized gas, a circulation of decarbonized gas in this channel being placed under the control of a member for measuring the temperature within the chamber from which the decarbonized gas comes.

[0022] The same configuration is reproduced on each device. According to another characteristic, at least one management unit is configured to control the circulation of the decarbonized gas flow within one and / or the other of the passes of one and / or the other of the heat exchangers.

[0023] A management body may, for example, be an on-off valve authorizing or prohibiting the circulation of the decarbonized gas flow in one and / or the other of the passes of the heat exchanger. It is thus understood that the circulation of the decarbonized gas flow is authorized by the management body when the heat exchanger in question is operated according to the first operating mode.

[0024] Advantageously, the capture system comprises at least one management unit per heat exchanger.

[0025] According to another characteristic, the management body comprises at least one first valve arranged upstream of one and / or the other of the passes of one and / or the other of the heat exchangers and / or at least one second valve arranged downstream of one and / or the other of the passes of one and / or the other of the heat exchangers.

[0026] The first valve is arranged upstream of the heat exchanger to control the inlet of the decarbonized gas flow within one and / or the other of the passes. The second valve is arranged downstream of the heat exchanger to control the outlet of the decarbonized gas flow present within one and / or the other of the passes.

[0027] The first valve and the second valve are arranged on either side of one of the passes of one and / or the 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 decarbonized gas within the pass in question, for example the second pass of one and / or the other of the heat exchangers, the first pass then being used by another fluid.

[0028] According to another characteristic, at least one management device is configured to regulate the circulation of a fluid which circulates within one and / or the other of the passes of one and / or the other of the heat exchangers. Such a management device may for example be a valve authorizing or prohibiting the circulation of the fluid in one and / or the other of the passes of the heat exchanger.

[0029] The capture system is configured so that this fluid is different from the decarbonized gas stream. This could be, for example, liquefied natural gas.

[0030] According to another characteristic, the management device comprises at least one third valve arranged upstream of one and / or the other of the passes of one and / or the other of the heat exchangers and / or at least one fourth valve arranged downstream of one and / or the other of the passes of one and / or the other of the heat exchangers.

[0031] The third valve is located upstream of the heat exchanger to control the entry of fluid into either pass.

[0032] The fourth valve is located downstream of the heat exchanger to control the exit of the fluid present in either pass.

[0033] The third and fourth valves can switch between an open and a closed position in order to allow or prohibit the circulation of the fluid within the pass in question, for example the first pass of one or other of the heat exchangers, the second pass then being taken by the flow of decarbonized gas.

[0034] 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 the circulation of fluid within one or other of the two passes of one or other of the heat exchangers. The management member is associated with the flow of decarbonized gas while the management device is associated with the fluid, for example liquefied natural gas.

[0035] It is thus understood that the capture system is configured to operate with liquefied natural gas, the latter being one of the fluids circulating in one of the passes of at least one of the heat exchangers. The invention takes advantage of the cooling capacity of a refrigerant, for example liquefied natural gas, to cool the flow of gas loaded with carbon dioxide and thus desublimate the carbon dioxide.

[0036] In the case where the capture system is arranged within a floating structure for transporting and / or storing liquefied natural gas or any other entity capable of transporting and / or storing liquefied natural gas, said gas is used as a means of desublimating carbon dioxide. The floating structure 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. Finally, it does not depart from the scope of the invention in the case where the floating structure transports and / or stores a liquefied gas other than liquefied natural gas.In this case, we therefore understand that it is this liquefied gas which can circulate to the first pass and / or the second pass of at least one of the heat exchangers in order to contribute to the cooling of the flow of gas loaded with carbon dioxide.

[0037] It is thus understood that the circulation of the fluid, for example liquefied natural gas, is authorized by the management device when the heat exchanger considered is operated according to the first operating mode.

[0038] According to another characteristic, at least one control member is 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 and / or the other of the heat exchangers.

[0039] A control device may, for example, be a valve authorizing or prohibiting the circulation of the flow of gas loaded with carbon dioxide within at least one and / or the other of the passes of the heat exchanger.

[0040] Advantageously, the capture system comprises a control member per heat exchanger. According to another characteristic, the control member takes the form of at least one fifth valve arranged upstream of one and / or the other of the passes of one and / or the other of the heat exchangers and / or at least one sixth valve arranged downstream of one and / or the other of the passes of one and / or the other of the heat exchangers.

[0041] The fifth valve is arranged upstream of the heat exchanger to control the entry of the carbon dioxide-laden gas flow into one and / or the other of the passes.

[0042] The sixth valve is arranged downstream of the heat exchanger to control the outlet of the carbon dioxide-laden gas flow present in one and / or the other of the passes.

[0043] The fifth valve and the sixth valve 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 within the pass in question, for example the first pass of one or other of the heat exchangers to which they are assigned.

[0044] According to another characteristic, at least one control device is configured to regulate the circulation of a flow of gas loaded with carbon dioxide which circulates in the chamber of one and / or the other of the heat exchangers around one and / or the other of its passes.

[0045] A control device may, for example, be a valve allowing or preventing the flow of gas loaded with carbon dioxide through one or other of the passes of the heat exchanger.

[0046] 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 comes out in the form of the flow of decarbonized gas.

[0047] Advantageously, the capture system comprises a heat exchanger control device. It is thus understood that the circulation of the flow of gas loaded with carbon dioxide is authorized by the control device when the heat exchanger in question is operated according to the first operating mode.

[0048] According to another characteristic, the control device comprises at least a seventh valve arranged upstream of the chamber of one and / or the other of the heat exchangers and / or at least an eighth valve arranged downstream of the chamber of one and / or the other of the heat exchangers.

[0049] The seventh valve is arranged upstream of the heat exchanger to control the entry of the flow of gas loaded with carbon dioxide into the chamber of said heat exchanger.

[0050] The eighth valve is arranged downstream of the heat exchanger to control the outlet of the flow of gas loaded with carbon dioxide present within the chamber of said heat exchanger.

[0051] The seventh valve and the eighth valve 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 within the chamber of the heat exchanger in question.

[0052] According to another characteristic, a first heat exchanger is 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 intended to be traversed by the flow of gas loaded with carbon dioxide and a second pass intended to be traversed by the flow of decarbonized gas, said first pass being arranged upstream of the chamber of one and / or the other of the heat exchangers and said second pass being arranged downstream of the chamber.

[0053] The first heat exchanger makes it possible to pre-cool the carbon dioxide-laden gas stream to a temperature close to the carbon dioxide desublimation temperature. Thus, the carbon dioxide-laden gas stream arriving within the chamber of the heat exchanger operated according to the first operating mode is at a low temperature, thus facilitating the desublimation. The heat exchange carried out in the first heat exchanger is between the decarbonized gas stream leaving the chamber of one of the heat exchangers operated according to the first operating mode and the carbon dioxide-laden gas stream circulating in the second pass of the first heat exchanger and originating from the carbon dioxide-laden gas emission source.The decarbonized gas flow having passed through one and / or the other of the passes of one and / or the other of the heat exchangers can therefore be used to cool the flow of gas loaded with carbon dioxide circulating within the first pass of the first heat exchanger. Again, the invention exploits the frigories present in the decarbonized gas flow to pre-cool the gas loaded with carbon dioxide, prior to its desublimation in the heart of the chamber.

[0054] According to another feature, a temperature control system of the first heat exchanger is configured to lower the temperature of the carbon dioxide-laden gas stream to a limit temperature for desublimation of the carbon dioxide present in the carbon dioxide-laden gas stream.

[0055] The conditions required to enable desublimation are a temperature between -100°C and -120°C for an operating pressure of around 4.5 bar absolute.

[0056] The desublimation limit temperature is a temperature that guarantees the absence of desublimation within the first heat exchanger. For example, this temperature value is equal to the desublimation temperature mentioned below minus a value between 1°C and 5°C.

[0057] According to another characteristic, the regulation system comprises at least one bypass branch of the second pass of the first heat exchanger, a ninth valve configured to control the circulation of the decarbonized gas flow within the bypass branch and a device for detecting the temperature of the gas flow loaded with carbon dioxide at the outlet of the first pass of said first heat exchanger.

[0058] The regulating device makes it possible to control the temperature of the gas flow loaded with carbon dioxide in order to control the change of state of the carbon dioxide, in particular by preventing the carbon dioxide from desubliming when passing through the first heat exchanger instead of desubliming within the chamber of one of the heat exchangers operated according to the first operating mode.

[0059] The detection device is, for example, a temperature probe installed in the flow of gas loaded with carbon dioxide.

[0060] The ninth valve is configured to allow or prohibit the flow of the decarbonized gas flow in the bypass branch, so as to avoid circulating in the second pass of the first heat exchanger. When the ninth valve allows the flow of decarbonized gas to pass within the bypass branch, said flow of decarbonized gas does not cool the flow of gas loaded with carbon dioxide circulating in the first pass of the first heat exchanger.

[0061] When the ninth valve prevents the flow of decarbonized gas from passing into the bypass branch, the said flow of decarbonized gas passes through the first heat exchanger. Consequently, the flow of gas loaded with carbon dioxide circulating in the first pass of the first heat exchanger is cooled by heat exchange with the flow of decarbonized gas.

[0062] According to another feature, the carbon dioxide-laden gas stream may originate from an internal combustion engine. The engine operates using a fuel, and the resulting exhaust gases generate the carbon dioxide-laden gas stream. Such a fuel may be liquefied natural gas stored in a floating structure. In such a case, the internal combustion engine and the capture system form a unit.

[0063] According to another feature, the system for capturing carbon dioxide within carbon dioxide-laden gas is configured to provide a liquid stream of carbon dioxide.

[0064] When the captured carbon dioxide formed under dry ice in the chamber is melted, it is recovered to be collected in the liquid state in a storage member, for example a tank or a reservoir. The invention also covers a method for desublimating carbon dioxide within a gas flow loaded with carbon dioxide, implementing the capture system as presented in this document, during which the carbon dioxide present within the gas flow loaded with carbon dioxide is desublimated within a chamber of one or other of the heat exchangers in a first step, and at least a portion of the decarbonized gas flow is sent to one and / or other of the passes of one or other of the heat exchangers.

[0065] The invention also covers a method for regulating the temperature of the flow of gas loaded with carbon dioxide using the capture system described in the present document, during which the temperature of the flow of gas loaded with carbon dioxide is regulated so that this temperature is higher than a limit temperature for desublimation of the carbon dioxide by a value between 1°C and 5°C. This regulation is carried out by the temperature regulation system of the first heat exchanger mentioned above.

[0066] More precisely, the temperature of the carbon dioxide-laden gas stream is measured, for example by means of the detection device; the measured value of the temperature of the carbon dioxide-laden gas stream is compared with the carbon dioxide desublimation limit temperature; the temperature of the carbon dioxide-laden gas stream is regulated so that its temperature is equal to a carbon dioxide desublimation limit temperature increased by a value of 1°C to 5°C. This ensures that desublimation will not start in the first heat exchanger.

[0067] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description of a detailed embodiment which follows, given for informational and non-limiting purposes with reference to the appended schematic drawings, in which:

[0068] [Fig. 1] schematically represents a system for capturing carbon dioxide within a gas loaded with carbon dioxide of the invention according to a first embodiment; [Fig. 2] schematically represents the operation of the first embodiment of the system for capturing carbon dioxide within a gas loaded with carbon dioxide of the invention of FIG. 1;

[0069] [Fig.3] schematically represents the system for capturing carbon dioxide within gas loaded with carbon dioxide of the invention of figures 1 and 2 with three heat exchangers;

[0070] [Fig. 4] schematically represents a system for capturing carbon dioxide within gas loaded with carbon dioxide of the invention according to a second embodiment;

[0071] [Fig. 5] schematically represents the operation of the second embodiment of the carbon dioxide capture system within gas loaded with carbon dioxide of the invention of FIG. 4;

[0072] [Fig.6] schematically represents the carbon dioxide capture system within carbon dioxide-laden gas of the invention of figures 4 and 5 with three heat exchangers.

[0073] The features, variants and different embodiments of the invention, as described or as will be presented in the detailed description which follows, may be combined with each other, in various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the state of the prior art.

[0074] This document uses the words "upstream" and "downstream" to define the relative arrangement of the components. These words are assessed according to the direction of circulation of the fluid which passes through said components or which circulates within the circuit concerned. Figure 1 illustrates a first embodiment of a system 1 for capturing carbon dioxide present within a gas loaded with carbon dioxide according to the invention. Such a capture system 1 can for example be integrated within a vehicle, at the outlet of a chimney, a factory, or any other entity comprising an emission source 6 of gas loaded with carbon dioxide. The emission source 6 can for example be an internal combustion engine such as an engine providing propulsion for a vehicle or the engine of an electric generator of said vehicle.

[0075] When the emission source 6 is in operation, it emits carbon dioxide-laden gases comprising carbon dioxide. The capture system 1 is thus configured to capture the carbon dioxide present within a flow of carbon dioxide-laden gas 2 released by the emission source 6 in order to limit the greenhouse effect induced by the carbon dioxide when it is released into the atmosphere.

[0076] In other words, the capture system 1 according to the invention makes it possible to produce a flow of decarbonized gas 3 after capturing the carbon dioxide contained in the flow of gas loaded with carbon dioxide 2. In order to ensure the capture of carbon dioxide, the capture system 1 comprises at least two heat exchangers 4, more particularly a first heat exchanger 4a and a second heat exchanger 4b.

[0077] Each heat exchanger 4 comprises a chamber 14 which can for example be defined as a closed internal space constituting the heat exchanger 4 considered. Each chamber 14 comprises two passes 12 which extend within a volume delimited by the chamber 14. More precisely, each chamber housed within a heat exchanger 4 comprises a first pass 12a and a second pass 12b within which a fluid can circulate. A heat exchange can thus be implemented between the passes 12 in which a fluid circulates and the chamber 14.

[0078] The heat exchangers 4 have the possibility of being operated according to a first operating mode and according to a second operating mode.

[0079] The first operating mode is a so-called "desublimation" mode which allows the capture of carbon dioxide present within the gas flow loaded with carbon dioxide 2. In this first operating mode, the gas flow loaded with carbon dioxide 2 passes through the chamber 14 of one or the other heat exchanger 4, so that the carbon dioxide is desublimated. The capture of carbon dioxide by desublimation forms dry ice. The dry ice is thus deposited on the passes 12 and against the walls of the chamber 14 of the heat exchanger 4. This desublimation is obtained by cooling by means of fluid which circulates in the passes 12 of the heat exchanger 4. Once the carbon dioxide is in the solid state, the gas flow loaded with carbon dioxide 2 becomes a decarbonized gas flow 3.

[0080] The second operating mode is a so-called "regeneration" mode which allows the melting of the dry ice formed on the passes 12 of the heat exchanger 4, during the implementation of the first operating mode. Once the passes 12 of one of the heat exchangers 4 are saturated with dry ice, the heat exchanger 4 switches from the first operating mode to the second operating mode in order to cause the melting of the dry ice and allow a new desublimation / regeneration cycle. The dry ice melts thanks to the supply of calories present in the flow of gas loaded with carbon dioxide 2 which circulates in the passes 12 of the heat exchanger 4. Its temperature is sufficiently high to allow the transformation of the dry ice into carbon dioxide in the liquid state 52.

[0081] The liquid carbon dioxide 52 coming from the heat exchanger(s) 4, 4a, 4b is recovered and directed to a storage member 53, so that it can be recycled or reused. The emptying of the liquid carbon dioxide present in the chamber(s) 14, 14a, 14b, 14c is controlled by a purge valve 60.

[0082] Each heat exchanger 4 must periodically switch from the first operating mode to the second operating mode to ensure the continuity of carbon dioxide capture in the carbon dioxide-laden gas stream 2 continuously produced by the emission source 6.

[0083] In order to switch from one or the other operating mode, the heat exchangers 4 both comprise 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, all participating in the management of the circulation of the different fluids passing through the passes 12 of the heat exchangers 4, depending on the operating mode operated.

[0084] Whatever the embodiment of the invention or its variants, a regulating member 62 is provided whose role is to control the temperature which prevails within at least one of the two chambers 14, 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 62 comprises at least one channel 63 which connects the line 22, in the case of figures 1 to 3, or the pipe 54 in the case of figures 4 to 6, to an evacuation circuit 20 of the flow of decarbonized gas 3. This channel 63 allows a portion of the decarbonized gas 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 can be reduced and therefore the cold supply within chamber 14 can be adjusted.

[0085] The circulation of decarbonized gas 3 in this channel 63 is placed under the control of a measuring member 64 for measuring the temperature within at least one of the two chambers 14, 14a, 14b. This measuring member 64 is for example a temperature sensor installed inside the chamber 14, or outside it but immersed in the gas flow. This measuring member 64 acts on a valve 65 placed on the channel 63 and which adjusts the flow rate of decarbonized gas 3 which circulates in the channel 63.

[0086] The management member 42 makes it possible to control the circulation of the flow of decarbonized gas 3 within one or other of the passes 12 of the heat exchangers 4. The management member 42 thus comprises a first valve 42a and a second valve 42b, the first valve 42a being arranged upstream of the heat exchanger 4 while the second valve 42b is arranged downstream of the heat exchanger 4. The management member 42 can be an all-or-nothing member or be a variable-opening member.

[0087] The management device 40 makes it possible to control the circulation of liquefied natural gas 30 within one and / or the other of the passes 12 of the heat exchangers 4. The management device 40 thus comprises a third valve 40a and a fourth valve 40b, the third valve 40a being arranged upstream of the heat exchanger 4 while the fourth valve 40b is arranged downstream of the heat exchanger 4. The management device 40 can be an all-or-nothing member or be a variable-opening member.

[0088] The liquefied natural gas 30 constitutes a cooling source for the heat exchanger 4 in order to participate in the desublimation when said heat exchanger 4 operates according to the first operating mode.

[0089] It is thus understood that when the heat exchanger 4 operates according to the first operating mode, 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 that are the flow of decarbonized gas 3 and the liquefied natural gas 30 in the passes 12 of the exchanger 4 to allow a temperature suitable for desublimation to be reached.

[0090] 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. The control member 38 thus comprises a fifth valve 38a and a sixth valve 38b, the fifth valve 38a being arranged upstream of the heat exchanger 4 while the sixth valve 38b is arranged downstream of the heat exchanger 4. The control member 38 can be an all-or-nothing member or be a variable-opening member.

[0091] 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.

[0092] It is thus understood that, when the heat exchanger 4 operates according to the second operating mode, 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 in the passes 12 of the exchanger 4, in order to participate in the melting of the dry ice formed within said heat exchanger 4. The control device 44 makes it possible to control the circulation of a flow of gas loaded with carbon dioxide 2 within the chamber 14 of the heat exchangers 4. The control device 44 thus comprises a seventh valve 44a and an eighth valve 44b, the seventh valve 44a being arranged upstream of the heat exchanger 4 while the eighth valve 44b is arranged downstream of the heat exchanger 4. The management device 44 can be an all-or-nothing member or be a variable opening member.

[0093] It is thus understood that, when the heat exchanger 4 operates according to the first operating mode, 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 in the chambers 14 of the heat exchanger 4, with a view to capturing the carbon dioxide present within said flow.

[0094] The capture system 1 also comprises a first heat exchanger 16 and a second heat exchanger 10, both configured to carry out a heat exchange between the carbon dioxide-laden gas flow 2 and the decarbonized gas flow 3. It can be considered that this first heat exchanger 16 and this second heat exchanger 10 are part of both the supply circuit 8 and the evacuation circuit 20.

[0095] The decarbonized gas flow 3 leaving the heat exchanger 4 has a low temperature due to the implementation of the first operating mode. In contrast to the decarbonized gas flow 3, the carbon dioxide-laden gas flow 2 has a high temperature due to its origin from the emission source 6.

[0096] Thus, the decarbonized gas flow 3 has the capacity to cool the gas flow loaded with carbon dioxide 2. For this purpose, the first heat exchanger 16 and the second heat exchanger 10 each have a first pass 16a, 10a and a second pass 16b, 10b.

[0097] The first pass 16a of the first heat exchanger 16 is crossed by the flow of gas loaded with carbon dioxide 2 and the second pass 16b is crossed by the flow of decarbonized gas 3. Similarly, the first pass 10a of the second exchanger 10 is crossed by the flow of decarbonized gas 3 and the second pass 10b is crossed by the flow of gas loaded with carbon dioxide 2. Thus, the first heat exchanger 16 and the second heat exchanger 10 both make it possible to carry out a heat exchange between the two flows stated above in order to lower the temperature of the flow of gas loaded with carbon dioxide 2.

[0098] The capture system 1 may also comprise a third heat exchanger 18 which, unlike the first and second heat exchangers, carries out a heat exchange between the flow of gas loaded with carbon dioxide 2 and the liquefied natural gas 30.

[0099] The liquefied natural gas 30 is stored in a tank 34 at low temperature, i.e. below -161°C at atmospheric pressure. Thus, the liquefied natural gas 30 has the capacity to cool the gas flow loaded with carbon dioxide 2. For this purpose, the third heat exchanger 18 has a first pass 18a and a second pass 18b.

[0100] The first pass 18a of the third heat exchanger 18 is crossed by the flow of gas loaded with carbon dioxide 2 and the second pass 18b is crossed by the liquefied natural gas 30. Thus, the third heat exchanger 18 allows an exchange of heat between the two flows stated above.

[0101] Figure 2 corresponds to the circulation of the different fluids stated above in the capture system 1 according to the first embodiment.

[0102] In Figures 2 and 3, 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 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.

[0103] In Figure 2, the second heat exchanger 4b operates according to the first mode of operation. In other words, it is in the second heat exchanger 4b, more precisely in the chamber 14b, that the capture by desublimation of the carbon dioxide contained in the flow of gas loaded with carbon dioxide 2 takes place.

[0104] The first heat exchanger 4a operates according to the second operating mode. In other words, it is in the first heat exchanger 4a, more precisely in the chamber 14a, that the melting of the dry ice formed by the desublimation of the gas flow loaded with carbon dioxide 2 occurs, when the first heat exchanger 4a has been used according to the first operating mode.

[0105] In order to ensure the circulation of the flow of gas loaded with carbon dioxide 2 to the heat exchanger 4b to carry out the desublimation, the capture system 1 is provided with a supply circuit 8. This first supply circuit comprises a main path 8a and a secondary path 8b. The main path 8a transports the flow loaded with carbon dioxide 2 to the second heat exchanger 10 in a first stage, within which said flow is pre-cooled thanks to the heat exchange carried out with the flow of decarbonized gas 3 circulating within the second pass 10b of the second heat exchanger 10.

[0106] Once the second heat exchanger 10 has passed through, the supply circuit 8 directs the flow of gas loaded with carbon dioxide 2 towards the passes 12 of the first heat exchanger 4a.

[0107] The control member 38 authorizes the passage of the flow of gas loaded with carbon dioxide 2 within one or both passes 12 of the first heat exchanger 4a, by keeping the fifth valves 38a and the sixth valves 38b open. The passage of the flow of gas loaded with carbon dioxide 2 within the passes 12 makes it possible to supply heat to the chamber 14a of the first heat exchanger 4a, thus allowing the melting of the dry ice formed within said first heat exchanger 4a. The flow of gas loaded with carbon dioxide, by giving off heat to the dry ice, sees its temperature decrease and thus leaves the passes 12a and 12b colder than it entered.

[0108] After passing through the passes 12 of the first heat exchanger 4a, the flow of gas loaded with carbon dioxide 2 passes through the first heat exchanger 16 within which said flow is cooled again thanks to the heat exchange carried out with the flow of decarbonized gas 3 circulating within the second pass 16b of the first heat exchanger 16.

[0109] Once the first heat exchanger 16 has passed through, the flow of gas loaded with carbon dioxide 2 continues its circulation within the supply circuit 8 towards the second heat exchanger 4b.

[0110] The control device 44 allows the flow of gas loaded with carbon dioxide 2 to pass into the chamber 14b of the second heat exchanger 4b by keeping the seventh valve 44a and the eighth valve 44b in the open position. The passage of the flow of gas loaded with carbon dioxide 2 into the second chamber 14b allows this flow of gas loaded with carbon dioxide 2 to circulate in order to desublimate the carbon dioxide.

[0111] Thus, the flow of gas loaded with carbon dioxide 2 arriving in the second chamber 14b is pre-cooled in three stages: through the exchanger 10, then by its passage within at least one of the passes of the first heat exchanger 4a and finally by its passage within the first heat exchanger 16. The flow of gas loaded with carbon dioxide is additionally pre-cooled by the second heat exchanger 10.

[0112] Once this pre-cooling has taken place, this flow of gas loaded with carbon dioxide 2 is cooled due to the passage of the flow of decarbonized gas 3 on the one hand and the passage of the liquid natural gas fluid 30 on the other hand, in the passes 12 of the second heat exchanger 4b. It is here and at this time that the carbon dioxide present in the flow of gas loaded with carbon dioxide 2 is desublimated.

[0113] The capture of carbon dioxide present within the carbon dioxide-laden gas stream 2 generates the decarbonized gas stream 3. The decarbonized gas stream 3 is transported by an evacuation circuit 20.

[0114] The evacuation circuit 20 comprises at least the line 22 configured to channel the flow of decarbonized gas 3 leaving at least one of the chambers 14 of at least one of the heat exchangers 4, operated according to the first operating mode, to at least one of the passes 12 of at least one of the heat exchangers 4, also operated according to the first operating mode. It is advantageous to distribute the flow of decarbonized gas 3 leaving the heat exchangers 4 in this way because it constitutes a source of cooling useful for carrying out desublimation.

[0115] Line 22 directs the flow of decarbonized gas 3 from the second chamber 14b of the second heat exchanger 4b to the second pass 12b of the second heat exchanger 4b.

[0116] A portion of the decarbonized gas flow 3 can also be sent directly to the first heat exchanger 16, without passing through the heat exchanger(s) 14. The flow rate within the pass 12 is thus reduced. It is the measuring member 64 which controls the flow rate of decarbonized gas 3 within the pass 12, and this control is a function of the temperature within the chamber 14.

[0117] The management body 42 authorizes the passage of the decarbonized gas flow 3 within only one of the two passes 12 of the second heat exchanger 4b, by keeping the first valve 42a and the second valve 42b open. The passage of the decarbonized gas flow 3 within the second pass 12b makes it possible to cool the chamber 14b of the second heat exchanger 4b, thus participating in the desublimation.

[0118] Leaving the second pass 12b of the second heat exchanger 4b, the decarbonized gas flow 3 is received in a collector 24. The collector 24 may be part of the evacuation circuit 20. The collector 24 recovers the decarbonized gas flow 3 leaving the second pass 12b of the second heat exchanger 4b. The collector 24 makes it possible in particular to circulate the decarbonized gas flow 3 towards the second pass 16b of the first heat exchanger 16 to cool the carbon dioxide-laden gas flow 2 circulating in the first pass 16a of the first heat exchanger 16, as mentioned above.

[0119] Leaving the first heat exchanger 16, the decarbonized gas flow 3 continues its circulation towards the second heat exchanger 10 to allow the cooling of the carbon dioxide-laden gas flow 2 circulating in the second pass 10b of the second heat exchanger 10. The decarbonized gas flow 3 then leaves the capture system 1. The capture system 1 also comprises a third supply circuit 28 within which the liquefied natural gas 30 circulates. The liquefied natural gas 30 stored in the tank 34 is sucked in by a pump 32 arranged for example within said tank. The liquefied natural gas 30 is thus taken from the tank 34 and circulates until it reaches the heat exchangers 4 when at least one of said heat exchangers operates according to the first operating mode.The flow rate of this liquefied natural gas 30 is controlled by a control valve 61 arranged on the third supply circuit 28, between an outlet of the pump 32 and upstream of the pass 12 of the heat exchanger 14, for example by being connected to an inlet of the fourth valve 40b.

[0120] It is thus understood that the liquefied natural gas 30 constitutes a cooling source participating in the desublimation in order to capture the carbon dioxide present in the flow of gas loaded with carbon dioxide 2.

[0121] The management device 40 authorizes the passage of the liquefied natural gas 30 within only one of the passes 12 of the second heat exchanger 4b by keeping the third valve 40a and the fourth valve 40b in the open position. The passage of the liquefied natural gas 30 within the first pass 12a of the second heat exchanger 4b makes it possible to provide a cooling source external to that constituted by the decarbonized gas flow 3 to participate in the desublimation of the carbon dioxide contained in the gas flow loaded with carbon dioxide 2 which constitutes an additional cooling source making it possible to reduce the quantity of cold which must be provided by the LNG, in other words by the external source.

[0122] Thus, the flow of gas loaded with carbon dioxide 2 arriving in the second chamber 14b is cooled due to the flow of decarbonized gas3 and the liquid natural gas 30 passing through the passes 12 of the second heat exchanger 4b, consequently cooling the chamber 14b.

[0123] Once exiting the first pass 12a of the second heat exchanger 4b, the liquefied natural gas 30 is directed towards the third heat exchanger 18.

[0124] It is then understood that the third heat exchanger 18 comprises both a first pass 18a which is part of the first supply circuit 8, precisely of the secondary path 8b, and a second pass 18b which is part of the third supply circuit 28. Thus, the third heat exchanger 18 is configured to lower the temperature of the flow of gas loaded with carbon dioxide 2 circulating in the first pass 18a by heat exchange with the liquefied natural gas 30 circulating within the second pass 18b of the third heat exchanger 18.

[0125] It is understood that the three heat exchangers 10, 16, and 18 are configured to pre-cool the flow of gas loaded with carbon dioxide 2 to a temperature close to a desublimation limit temperature before the entry of said flow into the heat exchanger 4 operating according to the first operating mode. By limit temperature is meant a temperature such that the desublimation of carbon dioxide cannot occur.

[0126] Downstream of the third heat exchanger 18, the secondary path 8b joins the main path 8a downstream of the first heat exchanger 16 and upstream of the heat exchangers 4. The flow of gas loaded with carbon dioxide 2 circulating in each of the paths 8a, 8b thus joins while having an identical or substantially identical temperature. At the outlet of the third heat exchanger 18, the flow of liquefied natural gas 30 is vaporized and circulates towards a receiving member 35.

[0127] In order to adjust the temperature of the flow of gas loaded with carbon dioxide 2 within the first heat exchanger 16, the capture system 1 comprises a regulation system 46 and at least one detection device 48 for detecting the temperature of the flow of gas loaded with carbon dioxide 2 circulating in the first pass 16a of the first heat exchanger 16. The regulation system 46 comprises a bypass branch 26 and a ninth valve 50. The ninth valve 50 is arranged on the bypass branch 26. Furthermore, the ninth valve 50 is configured to control the circulation of the flow of decarbonized gas 3 circulating within the bypass branch 26 and coming from the second pass 12b of the second heat exchanger 4b. The detection device 48 is connected to the regulation system 46 since the information detected by the detection device 48 is used to control a passage section within the ninth valve 50.The detection device 48 measures the temperature of the flow of gas loaded with carbon dioxide 2 downstream of the first heat exchanger 16. When the temperature of the flow of gas loaded with carbon dioxide 2 circulating after passing through the first heat exchanger 16 measured by the detection device 48 is higher than a desublimation limit temperature, the regulation system 46 authorizes the passage of the flow of decarbonized gas 3 within the second pass 16b of the first heat exchanger 16 via the ninth valve 50. The passage section within the ninth valve 50 is thus at least partially closed to force the passage of the flow of decarbonized gas 3 within the first heat exchanger 16.Thus, the heat exchange between the flow of gas loaded with carbon dioxide 2, in other words the gas circulating in the first pass 16a of the first heat exchanger 16, and the flow of decarbonized gas 3, in other words the gas circulating in the second pass 16b of the first heat exchanger 16, allows the cooling of the flow of gas loaded with carbon dioxide 2 to lower its temperature to a temperature slightly higher than the desublimation temperature of carbon dioxide, at the pressure considered in the system.

[0128] The temperature detection device 48 is for example a temperature sensor or probe. Conversely, when the temperature of the carbon dioxide-laden gas flow 2 measured downstream of the first heat exchanger 16 by the detection device 48 is lower than the desublimation limit temperature, the regulation system 46 limits the passage of the decarbonized gas flow 3 within the second pass 16b of the first heat exchanger 16. To do this, the ninth valve 50 opens to allow the passage of the decarbonized gas flow 3 within the bypass branch 26. Thus, the decarbonized carbon dioxide-laden gas flow 3 passes by-pass the first heat exchanger 16, which makes it possible to avoid desublimation within the first heat exchanger 16, whereas this is sought in the internal volume of the chamber 14 of the heat exchanger 4 in question.

[0129] The regulation system 46 participates in the cooling of the flow of gas loaded with carbon dioxide 2 circulating within the first supply circuit 8, so as to prevent its desublimation within the first heat exchanger 16. Tl

[0130] Figure 3 represents a variant of the first embodiment of the capture system 1 according to the invention. Compared to what has been described in the previous figures, the variant is distinguished by the presence of an additional third heat exchanger 4c, identical to the configuration of the second heat exchanger 4b, which means that the heat exchanger 4c is operated according to the first operating mode.

[0131] The third heat exchanger 4c also comprises a first pass 12a and a second pass 12b housed in a chamber 14c of this third heat exchanger and connected to the line 22 in which the flow of decarbonized gas 3 circulates. Here, this line 22 is common to the three heat exchangers, in the sense that it channels the flow of decarbonized gas 3 towards each of these three heat exchangers.

[0132] Thus, the decarbonized gas flows 3 leaving the second heat exchanger 4b and the third heat exchanger 4c are channeled by line 22 to the second pass 12b of the third heat exchanger 4c and to the second pass 12b of the second heat exchanger 4b.

[0133] Since all of the structural and functional elements, with the exception of the third heat exchanger 4c, are identical to what has been described previously, reference will be made to the description in Figure 2 concerning the elements common to the first embodiment and its variant.

[0134] Within the variant of the first embodiment, the carbon dioxide capture method is configured so that there are constantly two heat exchangers 4 which are operated according to the first operating mode, that is to say two heat exchangers 4 which ensure the capture of carbon dioxide within their respective chamber 14. In Figure 3, the first heat exchanger 4a is operated according to the second operating mode, while the second heat exchanger 4b and the third heat exchanger 4c operate according to the first operating mode. Having two heat exchangers 4 operated according to the first operating mode makes it possible to process a higher flow rate of the gas stream loaded with carbon dioxide 2, which makes the capture system 1 more efficient. Figure 4 illustrates a second 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 line 22, the role of which is replaced by a pipe 54.

[0135] In this second embodiment, the first heat exchanger 4a comprises a first pipe 54a and the second heat exchanger 4b comprises a second pipe 54b.

[0136] The pipe 54 begins downstream of the chamber 14 of the heat exchanger 4 and is then 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 in the first mode (in desublimation mode).

[0137] Figure 5 corresponds to the circulation of the different flows and fluids stated above within the capture system 1 according to the second embodiment.

[0138] When the second heat exchanger 4b operates according to the first operating mode, the first pipe 54a channels the flow of decarbonized gas 3 coming exclusively from the second chamber 14b associated with the second heat exchanger 4b, to the second pass 12b of said heat exchanger.

[0139] When the first heat exchanger 4a operates according to the second operating mode, the second pipe 54b does not channel the flow of decarbonized gas 3 coming from the second chamber 14a respectively associated with the first heat exchanger 4a. The eighth valve 44b of the control device 44 prevents the passage of the flow of decarbonized gas 3 so as not to disrupt the proper functioning of the second operating mode. Since all of the structural and functional elements are identical to those described previously, reference will be made to the description of FIG. 2 concerning the elements common to the first embodiment and the second embodiment.

[0140] Figure 6 represents a variant of the second embodiment. Compared to what has been described for the previous figures, the variant is distinguished by the presence of an additional third heat exchanger 4c in desublimation mode, identical to the configuration of the second heat exchanger 4b. The third heat exchanger 4c also comprises a third pipe 54c which channels the flow of decarbonized gas 3 coming exclusively from said heat exchanger 4c to exclusively reinject said flow of decarbonized gas 3 into said heat exchanger 4c.

[0141] When the third heat exchanger 4c is operated according to the first operating mode, the third pipe 54c channels the flow of decarbonized gas 3 coming from the third chamber 14c constituting the third heat exchanger 4c to the second pass 12b of said heat exchanger.

[0142] All of the structural and functional elements, with the exception of the third heat exchanger 4c, being identical to what was described previously, reference will be made to the description of figures 3 and 5 for understanding the elements common to this variant and to the second embodiment.

[0143] As for the variant of the first embodiment illustrated in Figure 3, 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 operate according to the first mode of operation. Having two heat exchangers 4 operated according to the first mode of operation makes it possible to process a higher flow rate of the carbon dioxide-laden gas stream 2, which makes the capture system 1 capable of processing higher gas flow rates to make the transitions from the first to the second mode of operation and vice versa more fluid.

[0144] The invention also relates to a method for desublimating carbon dioxide within a flow of gas loaded with carbon dioxide 2 using the system 1 for capturing carbon dioxide within the gas loaded with carbon dioxide as described above.

[0145] In a first step, the carbon dioxide present in the gas flow loaded with carbon dioxide 2 is desublimated by means of one or other of the heat exchangers 4b, 4c, in order to retain the carbon dioxide present in the gas flow loaded with carbon dioxide 2.

[0146] According to a second step, at least a portion of the decarbonized gas flow 3 is sent to one and / or the other of the passes 12a, 12b of one and / or the other of the heat exchangers 4b, 4c when it(they) is(are) operated in desublimation mode. This step of returning the decarbonized gas flow 3 has the role of providing the heat exchangers 4b, 4c with a source of cold useful for carrying out the desublimation.

[0147] The invention also relates to a method for regulating the temperature of the flow of gas loaded with carbon dioxide 2 using the system 1 for capturing carbon dioxide within the gas loaded with carbon dioxide, where the temperature of the flow of gas loaded with carbon dioxide 2 is regulated so that this temperature is higher than the limit temperature for desublimation of carbon dioxide by a value between 1°C and 5°C.

[0148] The temperature of the gas flow loaded with carbon dioxide 2 exiting through the first pass 16a of the first heat exchanger 16 is thus measured. This measured temperature is compared with a limit temperature for desublimation of carbon dioxide, at a determined pressure.

[0149] In the case where the temperature of the gas flow loaded with carbon dioxide 2 measured by the regulation system 46 is lower than the desublimation limit temperature, the regulation method comprises a step of increasing the temperature of the gas flow loaded with carbon dioxide 2 carried out via the regulation system 46. To do this, the ninth valve 50 is at least partially open so that the decarbonized gas flow 3 bypasses the first heat exchanger 16. In the case where the temperature of the gas flow loaded with carbon dioxide 2 measured by the regulation system 46 is higher than the desublimation limit temperature, the regulation method comprises a step of lowering the temperature of the gas flow loaded with carbon dioxide 2 carried out via the regulation system 46.To do this, the ninth valve 50 is at least partially closed so that the flow of decarbonized gas 3 passes through the first heat exchanger 16 and does not pass or passes only slightly through the bypass branch 26. This step is carried out until the temperature of the flow of gas loaded with carbon dioxide 2 measured by the regulation system 46 is equal to the desublimation limit temperature increased by a value between 1°C and 5°C.

[0150] The invention, as just described, achieves the goal it set itself, namely to propose an optimized solution for industrially desublimating a large quantity of carbon dioxide present in gases loaded with carbon dioxide, in order to then exploit the thermal energy of this decarbonized gas flow 3 in a heat exchanger 4 operated in desublimation mode. Applied to carbon dioxide, such a solution makes it possible to reduce the greenhouse effect.

[0151] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically effective combination of such means.

Claims

CLAIMS 1. System (1) for capturing carbon dioxide from carbon dioxide-laden gas, comprising at least a first heat exchanger (4a) and a second heat exchanger (4b), each of the heat exchangers (4, 4a, 4b) comprising at least one chamber (14, 14a, 14b), a first pass (12a) and a second pass (12b) which both extend into the chamber (14, 14a, 14b), the chamber (14, 14a, 14b) being configured to be traversed by a carbon dioxide-laden gas flow (2) and to capture by desublimation the carbon dioxide present in said carbon dioxide-laden gas flow (2) in order to generate a decarbonized gas flow (3), characterized in that the capture system (1) is configured to circulate the decarbonized gas flow (3) coming from either of the two chambers (14, 14a, 14b) in the first pass (12a) and the second pass (12b). 14a, 14b) within the first pass (12a) and / or within the second pass (12b) of at least one of the two heat exchangers (4, 4a, 4b).

2. Capture system (1) according to claim 1, comprising a line (22) configured to channel the flow of decarbonized gas (3) towards the first pass (12a) and / or the second pass (12b) of each of the heat exchangers (4, 4a, 4b).

3. Capture system (1) according to any one of claims 1 to 2, comprising a collector (24) which recovers the decarbonized gas flow (3) after its passage within the first pass (12a) and / or the second pass (12b) of each of the heat exchangers (4, 4a, 4b).

4. Capture system (1) according to claim 1, comprising a conduit (54) configured to channel the flow of decarbonized gas (3) coming from one of the heat exchangers (4, 4a, 4b) towards the first pass (12a) and / or the second pass (12b) exclusively of said heat exchanger (4, 4a, 4b).

5. Capture system (1) according to any one of claims 1 to 4, comprising at least one regulating member (62) configured to regulate the desublimation temperature within at least one of the chambers (14, 14a, 14b).

6. Capture system (1) according to claim 5 in combination with claim 2 or 4, in which the regulating member (62) comprises at least one channel (63) which connects the line (22), or the conduit (54), to an evacuation circuit (20) of the flow of decarbonized gas (3), a circulation of decarbonized gas (3) in this channel (63) being placed under the control of a measuring member (64) of the temperature within at least one of the two chambers (14, 14a, 14b).

7. Capture system (1) according to any one of claims 1 to 6, comprising at least one management member (42) configured to control the circulation of the flow of decarbonized gas (3) within one and / or the other of the passes (12a, 12b) of one and / or the other of the heat exchangers (4, 4a, 4b).

8. Capture system (1) according to claim 7, wherein the management member (42) comprises at least one first valve (42a) arranged upstream of one and / or the other of the passes (4a, 4b) of one and / or the other of the heat exchangers (4, 4a, 4b) and / or at least one second valve (42b) arranged downstream of one and / or the other of the passes (12a, 12b) of one and / or the other of the heat exchangers (4, 4a, 4b).

9. Capture system (1) according to any one of claims 1 to 8, comprising at least one management device (40) configured to regulate the circulation of a fluid (30) which circulates within one or other of the passes (12a, 12b) of one and / or other of the heat exchangers (4, 4a, 4b).

10. Capture system (1) according to claim 9, wherein the management device (40) comprises at least one third valve (40a) arranged upstream of one or other of the passes (12a, 12b) of one and / or other of the heat exchangers (4, 4a, 4b) and / or at least one fourth valve (40b) arranged downstream of one or other of the passes (12a, 12b) of one and / or other of the heat exchangers (4, 4a, 4b).

11. Capture system (1) according to claims 9 or 10, configured to operate with a refrigerant fluid, for example liquefied natural gas (30), the latter being one of the fluids circulating in one of the passes (12a, 12b) of at least one of the heat exchangers (4, 4a, 4b).

12. Capture system (1) according to any one of claims 1 to 11, comprising 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 (12a, 12b) of one and / or the other of the heat exchangers (4, 4a, 4b).

13. Capture system (1) according to claim 12, wherein the control member (38) takes the form of at least one fifth valve (38a) arranged upstream of one and / or the other of the passes (12a, 12b) of one and / or the other of the heat exchangers (4, 4a, 4b) and / or at least one sixth valve (38b) arranged downstream of one and / or the other of the passes (12a, 12b) of one and / or the other of the heat exchangers (4, 4a, 4b).

14. Capture system (1) according to any one of claims 1 to 13, comprising at least one control device (44) configured to regulate the circulation of a flow of gas loaded with carbon dioxide (2) which circulates in the chamber (14, 14a, 14b) of one and / or the other of the heat exchangers (4, 4a, 4b) around one and / or the other of its passes (12a, 12b).

15. Capture system (1) according to claim 14, wherein the control device (44) comprises at least one seventh valve (44a) arranged upstream of the chamber (14, 14a, 14b) of one and / or the other of the heat exchangers (4, 4a, 4b) and / or at least one eighth valve (44b) arranged downstream of the chamber (14, 14a, 14b) of one and / or the other of the heat exchangers (4, 4a, 4b).

16. Capture system (1) according to any one of claims 1 to 15, 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) intended to be traversed by the flow of gas loaded with carbon dioxide (2) and a second pass (16b) intended to be traversed by the flow of decarbonized gas (3), said first pass (16a) being arranged upstream of the chamber (14, 14a, 14b) of one and / or the other of the heat exchangers (4, 4a, 4b) and said second pass (16b) being arranged downstream of said chamber (14, 14a, 14b).

17. Capture system (1) according to claim 16, comprising a system (46) for regulating the temperature of the first heat exchanger (16) configured to lower the temperature of the flow of gas loaded with carbon dioxide (2) to a limit temperature for desublimation of the carbon dioxide present in the flow of gas loaded with carbon dioxide (2).

18. Capture system (1) according to claim 17, wherein the regulation system (46) comprises at least one bypass branch (26) of the second pass (16b) of the first heat exchanger (16), a ninth valve (50) configured to control the circulation of the decarbonized gas flow (3) within the bypass branch (26) and a device (48) for detecting the temperature of the gas flow loaded with carbon dioxide (2) at the outlet of the first pass (16a) of said first heat exchanger (16).

19. Capture system (1) according to any one of claims 1 to 18 configured to provide a liquid stream (52) of carbon dioxide.

20. Method for desublimating carbon dioxide within a gas flow loaded with carbon dioxide (2) using a capture system (1) according to any one of claims 1 to 19, during which: the carbon dioxide present within the gas flow loaded with carbon dioxide (2) is desublimated within a chamber (14, 14a, 14b) of one or other of the heat exchangers (4, 4a, 4b); at least a portion of the decarbonized gas flow (3) is sent to one and / or other of the passes (12a, 12b) of one or other of the heat exchangers (4, 4a, 4b).

21. Method for regulating the temperature of the flow of gas loaded with carbon dioxide (2) using the capture system (1) according to claims 17 or 18, during which the temperature of the flow of gas loaded with carbon dioxide (2) is regulated so that this temperature is higher than a limit temperature for desublimation of carbon dioxide by a value between 1°C and 5°C.

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