System for capturing carbon dioxide from gas containing carbon dioxide

Abstract

The invention relates to a carbon dioxide capture system (1) comprising a first heat exchanger (4a) and a second heat exchanger (4b), each heat exchanger (4) comprising a chamber (14), a first channel (12a) and a second channel (12b), the first heat exchanger (4a) and the second heat exchanger (4b) being configured to operate according to a first operating mode and according to a second operating mode, the capture system (1) comprising control means (5), the invention relates to a capture system (1) comprising control means (5) configured to effect an alternation between a first mode of operation and a second mode of operation, characterized in that the capture system (1) comprises decompression means (11) configured to reduce the pressure of the chamber (14).

Description

Technical Field

[0001] This invention relates to the field of processing gases containing carbon dioxide, and more particularly to a system for capturing carbon dioxide from said gases containing carbon dioxide. Background Technology

[0002] When carbon dioxide emission sources (such as combustion gases) operate, such as vehicles with floating structures, they produce gases containing carbon dioxide. These gases are typically released into the atmosphere. However, carbon dioxide is known to cause environmental damage when released into the atmosphere.

[0003] To prevent this, a carbon dioxide capture system can be implemented to capture carbon dioxide from gases emitted from emission sources via sublimation. Such a capture system may include a heat exchanger specifically designed to capture the element via sublimation. The captured carbon dioxide can then be melted to recover liquid carbon dioxide and stored for other subsequent uses.

[0004] During carbon dioxide sublimation, it is trapped in the chamber of a heat exchanger. The gas stream containing carbon dioxide is pressurized, for example, to a pressure of 3.5 barg. Later, during the melting of carbon dioxide, the pressure in the chamber can continue to increase to approximately 8.7 bar. This pressure level necessitates increasing the thickness of the heat exchanger walls so that the overpressure in the chamber does not cause them to warp. This results in an increase in the total weight of the heat exchanger and its thermal inertia. Furthermore, this leads to an increase in the amount of heat required to facilitate the later transition to the melting of carbon dioxide, and most importantly, an increase in the amount of cooling required in the subsequent steps from melting mode to sublimation mode, which impairs the efficiency of the carbon dioxide capture process. Summary of the Invention

[0005] This invention prevents the aforementioned problems by providing a system for capturing carbon dioxide from a carbon dioxide-containing gas. The system includes at least a first heat exchanger and a second heat exchanger, each heat exchanger including at least a chamber, a first line, and a second line extending through the chamber. The first and second heat exchangers are configured to operate in a first operating mode and a second operating mode. In the first operating mode, the chamber is configured such that a carbon dioxide-containing gas stream flows through the chamber and captures carbon dioxide from the gas stream by sublimation to produce a decarbonized gas stream. In the second operating mode, the carbon dioxide-containing gas stream flows through the first line and / or the second line to melt the captured carbon dioxide in the chamber. The capture system includes a control device configured to alternate between the first and second operating modes. The system is characterized by including at least one pressure-reducing device operating on at least one chamber of the heat exchanger and configured to reduce the pressure in the chamber. The control device is configured to activate the pressure-reducing device during the transition from the first operating mode to the second operating mode.

[0006] Therefore, once carbon dioxide is captured from the gas stream containing carbon dioxide, the capture system can reduce the pressure in the chamber before the carbon dioxide melts. This prevents overpressure caused by the partial pressure of carbon dioxide, which is captured in combination with the partial pressures of other gases such as nitrogen or oxygen. The pressure in the chamber is then limited, and there is no need to increase the wall thickness of the first and / or second heat exchangers. Furthermore, the efficiency of the capture process is improved.

[0007] The first and second heat exchangers are specifically designed to induce the sublimation of components (e.g., fluids). When either of the heat exchangers operates according to a first operating mode, cooling parameters associated with that heat exchanger allow for the sublimation of carbon dioxide. The sublimated carbon dioxide, i.e., solid carbon dioxide, then settles onto the walls of the heat exchanger in the first operating mode. To induce sublimation as the carbon dioxide-containing gas flows through the chambers of one and / or the other heat exchanger, at least one fluid flows at a sufficiently low temperature through the first and / or second lines of one and / or the other heat exchanger to cool the carbon dioxide-containing gas stream, causing the carbon dioxide component to change directly from a gaseous state to a solid state. As the carbon dioxide is captured, the carbon dioxide-containing gas stream passing through the chambers is decarbonized.

[0008] Therefore, it should be understood that because of the additional external cooling capacity from liquefied natural gas or any other refrigerant fluid from the refrigeration unit, carbon dioxide is captured by sublimation in the heat exchanger, and thus the decarbonized gas stream is a gas stream in which the carbon dioxide content is lower than that of the carbon dioxide-containing gas stream. As a non-limiting example, the carbon dioxide-containing gas stream 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, about 0.2 to 0.3% mol.

[0009] In the context of this invention, a chamber should be understood as a heat transfer region between a cold flow and a hot flow. This chamber can be physically defined by walls, as shown in the figures and described below. However, the chamber may also be without walls. In this case, the chamber is a heat transfer region between a gas flow containing carbon dioxide on one side and a decarbonized gas flow and / or any other refrigerant fluid flow on the other side during the implementation of a first operating mode. A heat exchanger having such a chamber is called a multi-flow chamber. Similarly, the case of pipes through which refrigerant fluid flows is also not beyond the scope of this invention, with a finned annular space around the pipe through which the carbon dioxide-containing gas flow will pass. Therefore, those skilled in the art will understand that all pipes and the annular space constitute a heat exchanger, and thus the chamber is the heat exchange region around the pipes.

[0010] During the second operating mode of either of the heat exchangers, the solid or sublimated carbon dioxide previously deposited on the walls of the heat exchanger is melted, meaning it changes from a solid to a liquid state. To melt the carbon dioxide, a gas stream containing carbon dioxide flows through a first and / or a second pipeline to heat the chamber of the heat exchanger in which the solid carbon dioxide must be melted.

[0011] In one embodiment, the capture system is configured such that the carbon dioxide-containing gas flow through the chamber during a first operating mode is the same as the carbon dioxide-containing gas flow through the first and / or second lines during a second operating mode. In other words, the capture system is configured such that the carbon dioxide-containing gas flow first flows through the first and / or second lines of at least one heat exchanger operating in the second operating mode to melt the carbon dioxide already captured in the chamber, and then the same carbon dioxide-containing gas flow also flows through the chamber of the at least one heat exchanger operating in the first operating mode.

[0012] As described above, the first and second heat exchangers can operate according to two different operating modes: the first operating mode allows carbon dioxide to be captured by sublimation, and the second operating mode allows the captured carbon dioxide to be melted and recovered. The controller allows management of each of the two operating modes by applying either one to the heat exchanger, but also allows switching between the two operating modes.

[0013] The depressurization in any of the chambers of the heat exchanger occurs after carbon dioxide is captured but before it melts. Therefore, the controller can activate the depressurization device to reduce the pressure in the chamber. Once the pressure is reduced, the controller can implement a second operating mode to melt the carbon dioxide.

[0014] According to features of the invention, the pressure-reducing device includes a pressure-reducing line and a pressure-reducing valve, the pressure-reducing line leading to a chamber of at least one of the heat exchangers, and a control device configured to activate the pressure-reducing valve. Advantageously, the capture system includes as many pressure-reducing lines as the heat exchangers. The pressure-reducing lines lead to the chambers such that during pressure reduction in the heat exchangers, gas can be released from the chambers to reduce the pressure within the chambers. The pressure-reducing valve is arranged on the pressure-reducing line and can alternate between an open and a closed position to allow or prevent fluid flow through the pressure-reducing line. Since the chambers of the heat exchangers are under pressure after a first operating mode, when the pressure-reducing valve is open, gas in the chambers will flow through the pressure-reducing line due to the pressure difference between the chambers of the heat exchangers and the pressure-reducing line.

[0015] According to a feature of the invention, the pressure-reducing line is connected to a vent. The vent allows gas to be discharged from the chambers of the heat exchanger and the pressure-reducing device.

[0016] According to the features of the invention, the control device includes at least one management device configured to regulate the flow of a first coolant in any of the lines flowing through any of the heat exchangers.

[0017] According to the features of the invention, the management device includes at least a first valve located upstream of any one of the pipelines in any of the heat exchangers and / or at least a second valve located downstream of any one of the pipelines in any of the heat exchangers.

[0018] The management device allows or prevents the flow of the first coolant through one of the pipelines via a first valve and a second valve at both ends of the pipeline. The first valve and the second valve can be opened or closed to allow or prevent the flow of the first coolant through the pipeline regulated by the management device.

[0019] According to the features of the invention, the control device includes at least one management device configured to regulate the flow of a second coolant in any of the pipelines flowing through any of the heat exchangers.

[0020] According to the features of the invention, the management device includes at least a third valve located upstream of any one of the pipelines in any of the heat exchangers and / or at least a fourth valve located downstream of any one of the pipelines in any of the heat exchangers.

[0021] The management device allows or prevents the flow of a first coolant through one of the pipelines via a third and a fourth valve at both ends of the pipeline. The third and fourth valves can be opened or closed to allow or prevent the flow of a second coolant through the pipeline regulated by the management device.

[0022] The control system may include management devices and management units, each regulating the flow of coolant through the same heat exchanger's pipelines. Thus, a management device regulates the flow of a first coolant through one of the pipelines, and a management unit regulates the flow of a second coolant through another pipeline. It should be noted that the first and second coolants may be the same fluid or different fluids.

[0023] According to the features of the invention, the control device includes at least one monitoring device configured to regulate the flow of a gas stream containing carbon dioxide through one and / or another pipeline in any of the heat exchangers.

[0024] According to another feature of the invention, the monitoring device includes at least a fifth valve located upstream of any one of the pipelines in any of the heat exchangers and / or at least a sixth valve located downstream of any one of the pipelines in any of the heat exchangers.

[0025] The monitoring device allows or blocks the flow of carbon dioxide-containing gas through at least one pipeline of the heat exchanger via a fifth and a sixth valve at both ends of the pipeline. The fifth and sixth valves can be opened or closed to allow or block the flow of carbon dioxide-containing gas through at least one of the pipelines regulated by the monitoring device.

[0026] Advantageously, the monitoring device includes four valves, two of which are located upstream of each of the two lines in any one of the heat exchangers, and two of which are located downstream of each of the two lines in any one of the heat exchangers, so that the gas flow containing carbon dioxide flows through the two lines to make the melting of the captured carbon dioxide more uniform.

[0027] All of the above valves can be used independently, and can be assembled into, for example, a three-way valve.

[0028] According to the features of the invention, the control device includes at least one monitoring device configured to regulate the flow of a gas stream containing carbon dioxide through any of the heat exchangers and around any of their pipelines.

[0029] According to the features of the invention, the monitoring device includes at least one seventh valve located upstream of a chamber in any one of the heat exchangers and / or at least one eighth valve located downstream of a chamber in any one of the heat exchangers.

[0030] In other words, the monitoring device regulates the flow of carbon dioxide-containing gas through the chamber, where the carbon dioxide is captured. The seventh and eighth valves are located on opposite sides of either chamber in the heat exchanger and can be switched between open and closed positions to allow or block the flow of carbon dioxide-containing gas through the chamber.

[0031] According to the features of the invention, the capture system is associated with an emission source of a gas stream containing carbon dioxide, the gas stream exiting from the emission source. The emission source can be an internal combustion engine, such as an engine used to propel vehicles and / or generate electricity or for any other function. The internal combustion engine operates due to fuel, and the resulting internal combustion produces a gas stream containing carbon dioxide. The emission source can also be, non-exhaustively, a chimney, a boiler, or any plant.

[0032] According to features of the invention, the capture system includes a third heat exchanger configured to operate according to a first operating mode and a second operating mode, wherein a controller is configured to alternate between the first and second operating modes on the third heat exchanger, and at least a pressure-reducing device of the capture system is associated with the third heat exchanger and configured to reduce the pressure in the chamber of the third heat exchanger, the controller being configured to activate the pressure-reducing device during transition from the first operating mode to the second operating mode. This is an alternative to the foregoing, wherein the capture system includes three heat exchangers instead of two. The third heat exchanger is structurally and functionally identical to the first and second heat exchangers. Therefore, the capture system may include additional pressure-reducing devices to reduce the pressure in the chamber of the third heat exchanger.

[0033] According to the features of the invention, the capture system is configured to keep the pressure-reducing valve closed when the first heat exchanger and / or the second heat exchanger are in a first operating mode and / or a second operating mode. The closure of the pressure-reducing valve prevents fluid from being released from the chamber during carbon dioxide capture or during its melting.

[0034] According to the features of the invention, the capture system is configured to open the pressure reducing valve after the first operating mode ends and before the second operating mode begins. This configuration allows for optimized pressure reduction by simply opening the pressure reducing valve without enabling any operating mode on the heat exchanger in question.

[0035] The scope of the invention also covers a method for capturing carbon dioxide from a gas stream containing carbon dioxide, the method being carried out by a system for capturing carbon dioxide from a gas stream containing carbon dioxide according to any of the above features, wherein:

[0036] At least one of the heat exchangers is operated according to a first operating mode to cause carbon dioxide in a carbon dioxide-containing gas stream passing through the chamber of the heat exchanger to sublimate.

[0037] The first operating mode of the heat exchanger was interrupted.

[0038] The pressure reduction operation is initiated by activating the pressure reduction device to reduce the pressure in the chamber.

[0039] When the pressure in the chamber reaches the pressure threshold, the second operating mode of the heat exchanger is activated to melt the condensed carbon dioxide in the chamber.

[0040] Therefore, the capture method allows for the prevention of overpressure in the chamber, as in the case of directly switching from the first operating mode to the second operating mode. Depressurization occurs after the capture of carbon dioxide and before its melting. The pressure threshold can be, for example, equal to or substantially equal to atmospheric pressure, meaning between 0 and approximately 1 barg. Once this pressure threshold is reached, heat exchange can be operated in the second operating mode, allowing the carbon dioxide to melt in the chamber. Considering that the uniform partial pressure of carbon dioxide at 1 bar or 2 bar absolute pressure in the radiator at the end of depressurization is negligible, i.e., approximately 0.03 bar and 0.06 bar respectively, the melting of carbon dioxide can result in an increase in carbon dioxide partial pressure of approximately 5.2 bar, which corresponds to the partial pressure of carbon dioxide required for the melting of solid carbon dioxide. Therefore, the pressure reached during the implementation of the second operating mode is approximately 6.2 to 7.2 bar absolute pressure in a steady state, which corresponds to the permissible pressure.

[0041] According to the characteristics of this method, the pressure reducing valve is closed during both the first and second operating modes. This closure prevents the release of a carbon dioxide-containing gas flow through the chamber in the first operating mode or the release of carbon dioxide in the second operating mode.

[0042] According to the characteristics of this method, the pressure-reducing valve opens during a transition period following the first operating mode, said transition period lasting, for example, 300 seconds. More generally, the duration of activation of the pressure-reducing device is shorter than the time required for the pressure in the heat exchanger chamber to reach a pressure threshold.

[0043] According to the characteristics of this method, the transition period occurs before the second operating mode.

[0044] According to the characteristics of this method, the first, second, third, fourth, fifth, sixth, seventh, and eighth valves are closed during pressure reduction operation. This configuration ensures that the pressure reduction in the chamber only results in the release of gas or any other fluid in the chamber through the pressure-reducing line, rather than through another part of the capture system. Furthermore, this prevents any flow of fluid through the heat exchanger's lines, which could potentially impair the pressure reduction of the heat exchanger's chambers.

[0045] According to the characteristics of this method, solid carbon dioxide captured in the chamber of a heat exchanger in a first operating mode partially sublimates during depressurization operation. Sublimation occurs at the surface during depressurization operation to produce a pure carbon dioxide limiting layer at an absolute pressure of 1 to 2 bar.

[0046] In practice, the pressure reduction in the chamber during depressurization leads to a decrease in the solid / gas equilibrium pressure. Therefore, carbon dioxide can partially sublimate during this pressure reduction. Upon initiation of the second operating mode, sublimation of solid carbon dioxide occurs until the partial pressure of carbon dioxide in the radiator reaches an absolute value of 5.2 bar, which is the partial pressure threshold at which sublimation ceases and melting begins. If heat input continues, the system remains locked at the triple point as long as carbon dioxide exists in three phases (i.e., solid, gas, and liquid).

[0047] Therefore, at the end of the second operating mode, carbon dioxide is completely recovered in liquid form.

[0048] Based on the characteristics of this process, at least one of the heat exchangers is in the first operating mode while the other heat exchanger is in the second operating mode. The capture process is implemented so that carbon dioxide can be continuously captured by sublimation, ensuring that the gas is never released into the atmosphere along with the carbon dioxide.

[0049] Based on the characteristics of this process, a second operating mode follows the first operating mode, constituting a carbon dioxide capture / melting cycle, which is repeated iteratively. The capture / melting cycle ensures the alternation of the heat exchanger between the first and second operating modes.

[0050] According to the characteristics of this method, when implemented through a capture system comprising three heat exchangers, two heat exchangers are in a first operating mode, while the last heat exchanger is in a second operating mode. In other words, in a capture system with three heat exchangers, the capture system is configured such that two heat exchangers are always in the first operating mode, and the remaining heat exchanger is in the second operating mode. This configuration allows for a greater processing capacity relative to a given size of heat exchanger. Furthermore, the configuration with three heat exchangers also makes the displacement operation easier to manage. However, it is important to consider the duration of the transition period, during which the chamber of any one of the heat exchangers is in a depressurized mode, so as not to produce involuntary shifts between the capture / melting cycles of the heat exchangers, and to always keep two heat exchangers in the first operating mode during the capture process.

[0051] According to the characteristics of this method, when the heat exchanger is in a first operating mode, a first coolant and a second coolant flow through a first line and a second line of the heat exchanger, respectively. The coolant allows for the cooling of a carbon dioxide-containing gas stream passing through the chamber in order to capture the carbon dioxide through sublimation. Therefore, the coolant must flow through the first line and / or the second line at a sufficiently low temperature to ensure the sublimation of carbon dioxide as the carbon dioxide-containing gas flows through the chamber.

[0052] According to the characteristics of this method, when the heat exchanger under consideration is in the first operating mode, valves one, two, three, four, seven, and eight are open, while valves five and six are closed. Valvees one, two, three, and four must be open to allow coolant flow through the first and second lines of the heat exchanger under consideration. Valvees seven and eight are also open to allow the flow of carbon dioxide-containing gas through the chamber.

[0053] According to the characteristics of this method, when the heat exchanger under consideration is in the second operating mode, valves one, two, three, four, seven, and eight are closed, while valves five and six are open. When the heat exchanger is in the second operating mode, valves one, two, three, four, seven, and eight are closed to prevent the flow of coolant through the pipelines and the flow of carbon dioxide-containing gas through the chamber. Valve five and six are open, allowing decarbonized gas to flow through the first and / or second pipelines of the heat exchanger under consideration to melt the previously captured carbon dioxide in the chamber.

[0054] According to the features of the invention, the first and / or second coolant can be a decarbonized gas stream. In fact, after flowing through the chamber and after carbon dioxide capture, the decarbonized stream has a very low temperature because it has been cooled to ensure carbon dioxide capture. Therefore, the decarbonized gas stream can be used as a coolant by flowing to the inlet of at least one of two lines in a heat exchanger operating according to the first operating mode. The liquefied natural gas has a temperature, for example, -120°C, before flowing through the first and / or second lines.

[0055] Depending on the characteristics of the process, the first and / or second coolant can be a liquefied natural gas (LNG) gas stream or another refrigerant fluid. In cases where the capture system is arranged within a structure that generates combustion gases from the combustion of LNG, the gases can be used as a means of sublimating carbon dioxide. The structure may include transport tanks and / or storage tanks for LNG, and first and / or second pipelines that pump LNG from the tanks and circulate it to at least one in a heat exchanger to participate in capturing carbon dioxide by sublimation. The LNG has a temperature, for example, -161°C, before flowing through the first and / or second pipelines.

[0056] In cases where the capture system is arranged in a structure that does not interact with liquefied natural gas, the structure may be equipped with a cooling loop in which another refrigerant fluid flows. Therefore, the refrigerant fluid is treated to flow through a first and / or second line of a heat exchanger at a sufficiently low temperature (e.g., -125°C) to participate in the sublimation of carbon dioxide.

[0057] According to the characteristics of this method, molten carbon dioxide from the heat exchanger is stored in a second operating mode. Once the carbon dioxide melts, it flows in a liquid state through the aforementioned recovery line for storage in the storage device. Attached Figure Description

[0058] Other features and advantages of the invention will become apparent, on the one hand, by means of the following description and on the other hand, by reference to the accompanying drawings as a guide and non-limiting example of several embodiments, in which:

[0059] [ Figure 1 This illustrates a first embodiment of a system for capturing carbon dioxide from a gas stream containing carbon dioxide according to the present invention.

[0060] [ Figure 2 This illustrates examples of the flow of various fluids through a first embodiment of the capture system.

[0061] [ Figure 3 The illustration shows a second embodiment of the capture system according to the present invention and the flow of various fluids through the second embodiment.

[0062] [ Figure 4 This illustrates a heat exchanger integrated into one or another embodiment, wherein a first operating mode is operated.

[0063] [ Figure 5 The diagram illustrates a heat exchanger integrated into one or another embodiment of a capture system, wherein a pressure reduction operation is performed within the chamber of the heat exchanger.

[0064] [ Figure 6 A heat exchanger integrated into one or another embodiment of a capture system is shown, wherein a second operating mode is operated.

[0065] [ Figure 7 [ ] is a curve showing the evolution of pressure in the chamber of a heat exchanger over time. Detailed Implementation

[0066] This document uses the terms upstream and downstream to define the relative positions of components. These terms should be considered relative to the direction of fluid flow through these components or through the relevant loop.

[0067] Figure 1 A first embodiment of a system 1 for capturing carbon dioxide from a carbon dioxide-containing gas according to the present invention is shown. For example, such a capture system 1 can be integrated into a vehicle, chimney, factory, or any other entity that includes an emission source 6 containing carbon dioxide-containing gas. For example, the emission source 6 can be an internal combustion engine, such as an engine for propelling a vehicle or the engine of a generator of said vehicle.

[0068] When emission source 6 is operational, fuel is burned, and emission source 6 naturally emits gases containing carbon dioxide, such as combustion gases. The capture system 1 allows carbon dioxide to be captured from the gas stream 2, rather than being released directly into the atmosphere.

[0069] To process the gas stream containing carbon dioxide, it flows through a pipe from the emission source 6 to the capture system 1 according to the invention. Before reaching the capture system 1, the gas stream containing carbon dioxide is compressed by a compression device ( Figure 1 (Not shown) is compressed to achieve an absolute pressure of approximately 4.5 bar. The gas stream 2 containing carbon dioxide can also pass through a drying device (also not shown), which ensures the removal of any possible trace amounts of water from the carbon dioxide-containing gas stream.

[0070] Capture System 1 in Figure 1 The diagram shows the components of the system, but not the flow of any fluids. Therefore, the diagram shows the components of the system without any fluid flow.

[0071] To ensure the capture of carbon dioxide from the gas stream 2 containing carbon dioxide, the capture system 1 includes at least two heat exchangers 4, specifically a first heat exchanger 4a and a second heat exchanger 4b.

[0072] Each heat exchanger 4 includes a chamber 14 defined by the internal volume of each of the heat exchangers 4 and two lines 12 extending through the chamber 14. More specifically, each heat exchanger 4 includes a first line 12a and a second line 12b through which fluid can flow. Both the first line 12a and the second line 12b pass through the chamber 14. A heat exchanger can then be implemented between the lines 12 and the chamber 14.

[0073] The heat exchanger 4 has the special characteristic of operating according to two operating modes. In the first operating mode, carbon dioxide is captured from the carbon dioxide-containing gas stream 2 by sublimation. The carbon dioxide-containing gas 2 flows through any of the chambers 14 of the heat exchanger 4, and the carbon dioxide component of the carbon dioxide-containing gas stream 2 is sublimated and deposited in a solid state on the wall of the heat exchanger 4 under consideration.

[0074] To allow carbon dioxide to sublimate in the carbon dioxide-containing gas stream 2, coolant flows through the first line 12a and / or the second line 12b. These lines ensure cooling of the carbon dioxide-containing gas stream 2 passing through chamber 14, providing suitable temperature conditions for capturing carbon dioxide through sublimation. This allows for the generation of a decarbonized gas stream 3 at the outlet of chamber 14 of the heat exchanger 4.

[0075] The heat exchanger 4 can also operate in a second operating mode, which ensures that the previously captured carbon dioxide melts in the chamber 14 of the heat exchanger 4 under consideration. Preferably, the second operating mode is implemented on the heat exchanger 4 that was previously operated in the first operating mode.

[0076] To melt the captured carbon dioxide, a gas stream 2 containing carbon dioxide flows through a first line 12a and / or a second line 12b of a heat exchanger 4. Because the gas stream containing carbon dioxide has a relatively high temperature, for example, between approximately -25°C and -35°C, the chamber 14 receives heat generated by cooling the gas stream containing carbon dioxide, and the captured carbon dioxide becomes liquid.

[0077] This is why the capture system 1 includes a recovery line 31 connected to the chamber 14 of each heat exchanger 4, which allows liquid carbon dioxide to flow into the storage device 53. Thus, in addition to preventing carbon dioxide from being released into the atmosphere, the capture system 1 according to the invention makes it possible to store carbon dioxide in liquid form, which can then be used or commercialized for various other activities. The recovery line 31 includes a recovery valve 19, which can be opened to allow liquid carbon dioxide to flow into the recovery line 31.

[0078] As described above, the gas stream 2 containing carbon dioxide flows through the capture system 1, and thus flows through the chamber 14 of the heat exchanger 4 in the first operating mode at a pressure of 3.5 barg. Therefore, during the implementation of the first operating mode, the pressure in the chamber 14 also increases to a value of approximately 3.5 barg.

[0079] Subsequently, during the implementation of the second operating mode, the melting of carbon dioxide also leads to an increase in pressure, which can reach 5.2 barg, meaning a total pressure of approximately 8.7 barg. To withstand this pressure, the wall thickness of heat exchanger 4 needs to be increased, which increases manufacturing costs but also impairs the efficiency of heat exchanger 4.

[0080] To avoid this situation, the capture system 1 includes at least one pressure reducing device 11 for at least one chamber 14 of one of the heat exchangers 4. Advantageously, in a capture system including two heat exchangers 4, the capture system 1 includes two pressure reducing devices 11, each of which is associated with a chamber 14 of one of the heat exchangers 4.

[0081] The pressure reducing device 11 reduces the pressure in chamber 14 of the heat exchanger 4 when switching from the first operating mode to the second operating mode. Therefore, by reducing the pressure in chamber 14 during the transition period between the implementation of the two operating modes, the pressure reducing device 11 utilizes the partial pressure of carbon dioxide in chamber 14 during the implementation of the second operating mode to remedy the accumulation of gas partial pressures other than carbon dioxide in chamber 14 during the implementation of the first operating mode. This prevents overpressure in chamber 14 and eliminates the need to increase the wall thickness of the heat exchanger 4.

[0082] exist Figure 1 In this embodiment, the pressure reducing device 11 includes a pressure reducing line 13, which is configured with a pressure reducing valve 15 and a vent 17. However, the pressure reducing device 11 can have another form, as long as it can reduce the pressure in the chamber 14 of one or more heat exchangers 4.

[0083] A pressure-reducing line 13 extends between chamber 14 of heat exchanger 4 and vent 17 to release fluid from chamber 14, such as a portion of a carbon dioxide-containing gas stream 2 remaining in chamber 14 in a gaseous state, thereby causing a pressure drop in chamber 14. Vent 17 allows this fluid to be removed from capture system 1.

[0084] When it is necessary to reduce the pressure in chamber 14, pressure reducing valve 15 is opened to release the fluid contained in chamber 14. When the first or second operating mode is implemented, pressure reducing valve 15 remains closed to prevent any release of carbon dioxide or any other fluid via pressure reducing device 11.

[0085] In order to operate the heat exchanger 4 in any of the operating modes, and to switch the heat exchanger 4 from one operating mode to another, the capture system 1 includes a control device 5 that enables the management of the flow of various fluids through the pipeline 12 and / or through the chamber 14 of each heat exchanger 4. The control device 5 is capable of activating the pressure reducing valve 15 of the pressure reducing device 11.

[0086] The control device 5 specifically includes at least one management device 42, at least one management unit 40, at least one monitoring device 38, and at least one monitoring unit. Advantageously, the number of control devices 5 for each heat exchanger 4 is the same, such that each of them can operate in any of the aforementioned operating modes.

[0087] The management device 42 enables monitoring of the flow of the first coolant through any of the pipes 12 in any of the heat exchangers 4. For example, in Figure 1 In this system, there is a management device 42 for each heat exchanger 4, and each management device 42 monitors the flow of the first coolant through the first pipeline 12a. Each management device 42 includes a first valve 42a and a second valve 42b at both ends of the first pipeline 12a of each heat exchanger 4, which means upstream and downstream of the first pipeline 12a.

[0088] The management device 40 allows monitoring of the flow of a second coolant through any of the pipes 12 in any of the heat exchangers 4; this second coolant may be the same as or different from the first coolant. For example, in Figure 1 In this system, there is a management device 40 for each heat exchanger 4, and each management device 40 monitors the flow of the second coolant through the second pipeline 12b. Each management device 40 includes a third valve 40a and a fourth valve 40b at both ends of the second pipeline 12b of each heat exchanger 4, which means upstream and downstream of the second pipeline 12b.

[0089] Therefore, it should be understood that when the heat exchanger 4 under consideration is in the first operating mode, the first valve 42a, the second valve 42b, the third valve 40a and the fourth valve 40b are opened to allow the flow of coolant, wherein the flow of coolant through line 12 causes carbon dioxide to be captured by sublimation.

[0090] Monitoring device 38 enables monitoring of the flow of carbon dioxide-containing gas 2 through one and / or the other of the pipes 12 of the heat exchanger 4. For example, in Figure 1In this configuration, for each heat exchanger 4, there is a monitoring device 38, and each monitoring device 38 monitors the flow of carbon dioxide-containing gas 2 through a first pipeline 12a and / or through a second pipeline 12b. Each monitoring device 38 includes at least a fifth valve 38a and a sixth valve 38b located at both ends of one or the other of the pipelines 12 in each heat exchanger 4, meaning upstream and downstream of either of the pipelines 12. Advantageously, as Figure 1 As shown, each monitoring device 38 includes two fifth valves 38a and two sixth valves 38b, which means that there are fifth valves 38a and sixth valves 38b upstream and downstream of each line 12 of the heat exchanger 4 under consideration.

[0091] Therefore, it should be understood that when the heat exchanger 4 under consideration is in the second operating mode, the fifth valve 38a and the sixth valve 38b are opened to allow a gas flow 2 containing carbon dioxide to pass through the line 12, wherein the gas flow 2 containing carbon dioxide through the line 12 causes the captured carbon dioxide to melt in the chamber 14 of the heat exchanger 4 under consideration.

[0092] exist Figures 1 to 6 In this context, all the valves mentioned above are independent of each other, and some of them can be assembled into, for example, a three-way valve.

[0093] The monitoring device allows for the monitoring of the flow of carbon dioxide-containing gas 2 through chamber 14 of heat exchanger 4. More specifically, the carbon dioxide-containing gas 2 flows around pipe 12 through chamber 14 and is cooled to capture carbon dioxide through sublimation. For example, in Figure 1 In the process, there is a monitoring device for each heat exchanger 4. Each monitoring device includes at least a seventh valve 44a and an eighth valve 44b located on both sides of the chamber 14 of each heat exchanger 4, which means upstream and downstream of the chamber 14 of each heat exchanger 4.

[0094] Therefore, it should be understood that when the heat exchanger 4 under consideration is in the first operating mode, the seventh valve 44a and the eighth valve 44b are opened to allow a gas flow 2 containing carbon dioxide to pass through the chamber 14, wherein the gas flow 2 containing carbon dioxide through the chamber 14 makes it possible to capture the carbon dioxide it holds.

[0095] It should be noted that the management device 42, management unit 40, monitoring device 38, and monitoring unit are not physical objects, but rather names of each of the aforementioned valves. Furthermore, the aforementioned recovery valve 19 can also be monitored by the control device 5.

[0096] Regardless of the embodiment or variation thereof, a regulating device 90 is present, which functions to control the temperature in at least one of the two chambers 14a, 14b in a first operating mode, and advantageously control the temperature in a single chamber or all chambers. By controlling the temperature in chamber 14, sublimation occurring in that chamber 14 can be induced. For this purpose, according to the considered embodiment, the regulating device 90 includes at least one channel 93 that allows a portion of the decarbonization gas flow 3 to bypass one or more lines 12 of one or more heat exchangers 4. Thus, the flow rate through one or more lines 12 can be reduced, which means that the supply of cold energy into chamber 14 can be regulated.

[0097] The flow of decarbonized gas through channel 93 depends on a measuring device 91 used to measure the temperature in at least one of the two chambers 14, 14a, 14b. This measuring device 91 is, for example, a temperature sensor in chamber 14. The measuring device 91 acts on a regulating valve 92 located on channel 93, which regulates the flow rate of the decarbonized gas flow 3 through channel 93.

[0098] The capture system 1 also includes a first heat exchanger 16 and a second heat exchanger 10, each of which is configured to exchange heat between a carbon dioxide-containing gas stream 2 and a decarbonized gas stream 3 in a first operating mode after the decarbonized gas stream 3 leaves the chamber 14 of at least one heat exchanger 4.

[0099] Because the decarbonized gas stream 3 flows through the chamber 14 of one of the heat exchangers 4 in the first operating mode, its temperature is very low. Therefore, the first heat exchanger 16 and the second heat exchanger 10 allow the carbon dioxide-containing gas stream 2 to be pre-cooled by this temperature before it flows through the chamber 14 of the heat exchanger 4 in the first operating mode. Thus, the first heat exchanger 16 includes a first line 16a and a second line 16b, through which the carbon dioxide-containing gas stream 2 flows and the decarbonized gas stream 3 flows. The second heat exchanger 10 includes a first line 10a and a second line 10b, through which the carbon dioxide-containing gas stream 2 flows and the decarbonized gas stream 3 flows. As detailed later, the second heat exchanger 10 is located upstream of the first heat exchanger 16 relative to the flow direction of the carbon dioxide-containing gas stream 2.

[0100] Figure 2 It shows the relationship with Figure 1 The same capture system 1 is shown. However, Figure 2 This illustrates a first example of the flow of various fluids through the capture system 1 when it is in operation.

[0101] exist Figures 2 to 6In the diagram, under the consideration of the operating mode, the thick solid line represents the flow of gas containing carbon dioxide 2, the thin solid line represents the flow of decarbonized gas 3, the mixed line represents the flow of liquefied natural gas, the long dashed line corresponds to the flow of liquid carbon dioxide, and the short dashed line corresponds to the pipes with no fluid flow.

[0102] exist Figure 2 In this configuration, the second heat exchanger 4b is operated by the control device 5 in a first operating mode. In other words, the capture of carbon dioxide from the carbon dioxide-containing gas stream 2 occurs within the chamber 14b of the second heat exchanger 4b. The first heat exchanger 4a is operated by the control device 5 in a second operating mode. In other words, some carbon dioxide has previously been captured in the chamber 14a of the heat exchanger 4a, and the carbon dioxide is melting.

[0103] When the gas stream 2 containing carbon dioxide is discharged from the emission source 6, it flows into the capture system 1 after being previously compressed and dried as described above. At the inlet of the capture system 1, the gas stream 2 containing carbon dioxide has a temperature, for example, between +5°C and +15°C.

[0104] Then, the carbon dioxide-containing gas stream 2 flows through the capture system 1, or more precisely, through the first supply loop 8. The first supply loop 8 is divided into a first line 8a and a second line 8b, and connects the inlet fluid of the carbon dioxide-containing gas stream 2 to the heat exchanger 4.

[0105] The gas stream 2 containing carbon dioxide flows through the first pipeline 8a to the second heat exchanger 10, where it is pre-cooled to a temperature of -25°C to -33°C by the decarbonized gas stream 3.

[0106] The carbon dioxide-containing gas stream 2 continues to flow through the first conduit 8a to the first heat exchanger 4a. The control device 5, particularly the monitoring device 38 associated with the first heat exchanger 4a, is configured to keep the fifth valve 38a and the sixth valve 38b on both sides of the conduit 12a of the first heat exchanger 4a open. This configuration allows the carbon dioxide-containing gas stream 2 to flow through the first conduit 12a and the second conduit 12b of the first heat exchanger 4a. Since the temperature of the carbon dioxide-containing gas stream 2 is between -25°C and -33°C, heat exchange occurs, cooling the carbon dioxide-containing gas stream 2 to a temperature, for example, between -42°C and -49°C, while simultaneously heating the chamber 14a of the first heat exchanger 4a, causing the carbon dioxide to melt in said chamber 14a of the first heat exchanger 4a. The recovery valve 19 opens, and the liquid carbon dioxide produced in this way can flow through the recovery conduit 31 to the storage device 53.

[0107] At the outlet of line 12 of the first heat exchanger 4a, the carbon dioxide-containing gas stream 2 continues to flow to the first heat exchanger 16, where it is cooled again by the decarbonized gas stream 3. The carbon dioxide-containing gas stream 2 is cooled to the threshold temperature for carbon dioxide phase change, for example, to a temperature of approximately -99°C.

[0108] Then, the gas stream 2 containing carbon dioxide flows to the second heat exchanger 4b. The control device 5, in particular the monitoring device associated with the second heat exchanger 4b, is configured to keep the seventh valve 44a and the eighth valve 44b on both sides of the chamber 14b of the second heat exchanger 4b open, so that the gas stream 2 containing carbon dioxide can flow through it.

[0109] Heat exchange occurs when the gas stream 2 containing carbon dioxide flows through the chamber 14b of the second heat exchanger 4b, as the first and second coolants flow through the pipes 12 of the second heat exchanger 4b. The gas stream 2 containing carbon dioxide is then cooled to a temperature that causes the carbon dioxide in the gas stream 2 to sublimate, meaning it changes from a gaseous state to a solid state. The carbon dioxide then precipitates as frost on the walls of the chamber 14b of the second heat exchanger 4b and around its pipes 12. Details regarding the properties and characteristics of the coolant are described below.

[0110] The passage through chamber 14b of the second heat exchanger 4b results in the generation of a decarbonized gas stream 3 from the carbon dioxide-containing gas stream 2. The decarbonized gas stream 3 has a temperature of approximately -120°C. The capture system 1 includes a second supply loop 20 that allows the decarbonized gas stream 3 to flow through the capture system 1. The second supply loop 20 specifically includes a line 22 that flows the decarbonized gas stream 3 from chamber 14b of the heat exchanger 4 to line 12 of the heat exchanger.

[0111] In fact, since the decarbonized gas stream 3 is at approximately -120°C, it can be used as a coolant for at least one of the heat exchangers 4 in the first operating mode. Figure 2 In the middle, pipeline 22 allows the decarbonized gas flow 3 to flow through the first pipeline 12a to the second heat exchanger 4b.

[0112] The control device 5, particularly the management device 42 associated with the second heat exchanger 4b, is configured to keep the first valve 42a and the second valve 42b open on both sides of the first line 12a of the second heat exchanger 4b, allowing the decarbonized gas 3 to flow through it as a first coolant in the second heat exchanger 4b, thereby participating in the sublimation of carbon dioxide in the carbon dioxide-containing gas stream 2. At the outlet of the first line 12a of the second heat exchanger 4b, the decarbonized gas stream 3 has a temperature of approximately -102°C. The recovery valve 19 of the second heat exchanger 4b is closed to maintain the watertightness of the chamber 14b.

[0113] The second supply loop 20 also includes a collector 24 for collecting the decarbonized gas stream 3 after it has exited from any of the lines 12 of at least one of the heat exchangers 4 in the first operating mode: here, the first line 12a of the second heat exchanger 4b. The collector 24 may in particular guide the decarbonized gas stream 3 to the first heat exchanger 16 to cool the carbon dioxide-containing gas stream 2.

[0114] Alternatively, based on the construction of the aforementioned measuring device 90, the decarbonized gas flow 3 can also bypass the pipeline 12 of the heat exchanger 4 by flowing directly to the first heat exchanger 16 through the passage 93.

[0115] At the outlet of the first heat exchanger 16, the temperature of the decarbonized gas stream 3 is between -52°C and -55°C. It flows to the first heat exchanger 10 to pre-cool the carbon dioxide-containing gas stream 2. At the outlet of the second heat exchanger 10, the temperature of the decarbonized gas stream 3 is between -19°C and -25°C. This continuous heat exchange allows most of the cooling capacity of the decarbonized gas stream 3 to be utilized. It then flows out of the capture system 1 and, for example, may participate in the cooling of the carbon dioxide-containing gas stream 2 during its compression and drying process before reaching the capture system 1.

[0116] The capture system 1 also includes a third supply loop 28 in which the flow of liquefied natural gas 30 or any other refrigerant fluid can circulate. In practice, as described above, the capture system 1 can be integrated into a vehicle, such as a floating structure. This floating structure may include a transport and / or storage tank 34 for liquefied natural gas. Furthermore, it can be used as fuel for emission source 6. Therefore, in all... Figures 2 to 3 In this circuit, the liquefied natural gas flow 30 flows through the third supply circuit 28. However, the third supply circuit 28 could be a cooling circuit in which refrigerant fluid flows, thus providing the same function to the liquefied natural gas flow 30.

[0117] Tank 34 includes a pump 32 that circulates liquefied natural gas flow 30. It then flows to heat exchanger 4 via a third supply loop 28. Therefore, it should be understood that liquefied natural gas can be used as a coolant to participate in the capture of carbon dioxide from the carbon dioxide-containing gas flow 2.

[0118] exist Figure 2In this process, liquefied natural gas (LNG) gas flow 30 flows to the second line 12b of the second heat exchanger 4b, which operates in the first operating mode. The control device 5, particularly the management device 40 associated with the second heat exchanger 4b, is configured to keep the third valve 40a and the fourth valve 40b at both ends of the second line 12b open, allowing LNG gas flow 30 to flow through it as a second coolant in the second heat exchanger 4b, thereby participating in the sublimation of carbon dioxide in the carbon dioxide-containing gas flow 2. At the inlet of the second line 12b of the second heat exchanger 4b, the LNG gas flow 30 has a temperature of approximately -161°C. In the case where another refrigerant fluid flows through the third supply loop 28, the refrigerant fluid may have a temperature of, for example, -125°C. At the outlet of the second line 12b of the second heat exchanger 4b, the LNG gas flow 30 has a temperature of approximately -101°C.

[0119] Advantageously, in the first operating mode, the decarbonized gas stream 3 flows through the first line 12a, and the liquefied natural gas lift stream 30 flows through the second line 12b of the heat exchanger 4. This design allows the carbon dioxide-containing gas stream 2 to be cooled first by the decarbonized gas stream 3 as it flows through the chamber 14, and then by the liquefied natural gas stream 30, which is colder than the decarbonized gas stream 3. Thus, the cooling of the carbon dioxide-containing gas stream 2 is gradual and participates in the diffusion of dry ice on the cold surfaces over which the carbon dioxide-containing gas stream 2 continuously flows.

[0120] At the outlet of the second pipeline 12b of the second heat exchanger 4b, the liquefied natural gas flow 30 can be used for subsequent heat exchange. In fact, as previously described, the first supply loop 8 is divided into a first pipeline 8a and a second pipeline 8b. The flow of carbon dioxide-containing gas 2 through pipeline 8a is as described above.

[0121] The carbon dioxide-containing gas stream 2 through the second line 8b also flows to the heat exchanger 4, but must be pre-cooled before flowing through at least one of the chambers 14 of the heat exchanger 4 in the first operating mode, just like the carbon dioxide-containing gas stream 2 through the first line 8a.

[0122] To this end, the capture system 1 includes a third heat exchanger 18 configured to operate heat exchange between a carbon dioxide-containing gas stream 2 via a second line 8b and a liquefied natural gas (LNG) gas stream 30 via a third supply loop 28—the LNG gas stream 30 having already flowed through one and / or another of the lines 12 of at least one heat exchanger 4 in a first operating mode. The first supply loop 8 is split into two lines 8a, 8b so that pre-cooling of the carbon dioxide-containing gas stream 2 can be shared among the heat exchangers. Additionally, the cryogenic temperature of the LNG gas stream 30 can be utilized.

[0123] Therefore, the third heat exchanger 18 includes a first pipeline 18a and a second pipeline 18b, through which carbon dioxide-containing gas 2 flows and liquefied natural gas gas 30 flows. Because it has a temperature of approximately -101°C, it is able to cool the carbon dioxide-containing gas stream 2 to the threshold temperature of the carbon dioxide's state change, for example, to approximately -99°C.

[0124] Downstream of the third heat exchanger 18, the second pipeline 8b connects to the first pipeline 8a downstream of the first heat exchanger 16 and upstream of the heat exchanger 4. Therefore, the carbon dioxide-containing gas stream 2 flowing through each of pipelines 8a and 8b accumulates at the same or substantially the same temperature.

[0125] At the outlet of the third heat exchanger 18, the liquefied natural gas flow 30 or any other refrigerant fluid is in a gaseous state at a temperature of about +3°C and can flow to the receiving device 35, which can heat the flow and flow it to a gas-consuming device, such as generating an emission source 6 of a gas flow 2 containing carbon dioxide that the capture system 1 according to the invention is attempting to process.

[0126] In particular, in order to regulate the temperature of the gas flow at the first heat exchanger 16, the capture system 1 is also provided with a regulating system 46 and a regulating device 61.

[0127] The regulating system 46 includes a detection device 48, a bypass line 26, and a ninth valve 50. System 48 allows the temperature of the carbon dioxide-containing gas stream 2 to be measured at the outlet of the first heat exchanger 16. The bypass line 26 is integrated into the second supply loop 20 and is arranged in parallel with the first heat exchanger 16. The ninth valve 50 is located on the bypass line 26.

[0128] The function of the regulating system 46 is to prevent premature sublimation of carbon dioxide in the first heat exchanger 16, which is not configured to store solid carbon dioxide. Therefore, the temperature of the carbon dioxide-containing gas stream 2 is checked at the outlet of the first heat exchanger 16. If the detection device 48 measures a temperature below a preset temperature threshold, it means that the decarbonized gas stream 3 has overcooled the carbon dioxide-containing gas stream 2 in the first heat exchanger 16.

[0129] To reduce this cooling, the ninth valve 50 can be opened, allowing at least a portion of the decarbonized gas 3 to flow through the bypass line 26 instead of through the first heat exchanger 16. This limits the flow rate of the decarbonized gas stream 3 through the first heat exchanger 16 and prevents overcooling of the carbon dioxide-containing gas stream 2.

[0130] The detection device 48 can be configured to directly monitor the ninth valve 50. It can be opened to change the cross-section of the bypass line 26. In this way, the decarbonized gas flow 3 passing through the bypass 26 can be monitored, thereby indirectly monitoring the decarbonized gas flow 3 passing through the first heat exchanger 16. In the case where the decarbonized gas flow 3 is divided into a portion flowing through the bypass line 26 and a portion flowing through the first heat exchanger 16, these two portions converge downstream, and then the decarbonized gas flow 3 continues to flow to the second heat exchanger 10.

[0131] The regulating device 61 includes a bypass line 62 for a first line 12a and / or a second line 12b of any of the heat exchangers 4, a monitoring valve 63 configured to monitor the flow of a carbon dioxide-containing gas stream 2 through the bypass line 62, and a sensing device 64 upstream of the first heat exchanger 16 to detect the temperature of the carbon dioxide-containing gas stream 2. The bypass line 62 is integrated into the first line 8a of the first supply circuit 8 and is arranged in parallel with the line 12 of the heat exchangers 4. The monitoring valve 63 is located on the bypass line 62.

[0132] The function of the regulating device 61 is to monitor the melting rate of carbon dioxide in the chamber 14 of at least one of the considered heat exchangers 4 in the second operating mode. The temperature of the carbon dioxide-containing gas stream 2 is monitored by a detection device 64 upstream of the first heat exchanger 16, which means downstream of the line 12 of at least one heat exchanger 4, specifically the first line 12a and the second line 12b of the first heat exchanger 4a. If the detection device 64 measures a temperature below a preset temperature threshold, it means that the carbon dioxide-containing gas stream 2 is undergoing excessive heat exchange in one of the heat exchangers 4 in the second operating mode, and therefore the carbon dioxide may be melting too quickly.

[0133] To reduce the rate of carbon dioxide melting, monitoring valve 63 can be opened, allowing at least a portion of the carbon dioxide-containing gas stream 2 to flow through bypass line 62 instead of through the first line 12a and the second line 12b of the first heat exchanger 4a. This limits the flow rate of the carbon dioxide-containing gas stream 2 through the first line 12a and the second line 12b of the first heat exchanger 4a, preventing the carbon dioxide from melting too quickly in the chamber 14a of the first heat exchanger 4a, and simultaneously preventing the carbon dioxide-containing gas stream 2 from cooling too quickly before undergoing heat exchange in the first heat exchanger 16.

[0134] The detection device 64 can be configured to directly monitor the monitoring valve 63. It can open to change the cross-section of the bypass line 62. In this way, the flow rate of the carbon dioxide-containing gas flow 2 through the bypass line 62 can be monitored, thereby indirectly monitoring the flow rate of the carbon dioxide-containing gas flow 2 through the first line 12a and the second line 12b of the first heat exchanger 4a.

[0135] In the case where the carbon dioxide-containing gas stream 2 is divided into a portion flowing through bypass line 62 and a portion flowing through first line 12a and second line 12b of the first heat exchanger 4a, these two portions converge downstream and upstream of the measurement of the temperature of the carbon dioxide-containing gas stream 2 by detection device 64. Although the temperature of the portion of the carbon dioxide-containing gas stream 2 flowing through first line 12a and second line 12b of the first heat exchanger 4a decreases during the heat exchange therein, this temperature decrease is compensated by the temperature of the portion of the carbon dioxide-containing gas stream 2 flowing through bypass line 62. Therefore, when the two portions converge and mix, no heat exchange occurs.

[0136] As previously described, the controller 5 can switch between operating modes of the heat exchanger 4 to capture carbon dioxide, then melt it for recovery in liquid form, thereby realizing the process of capturing carbon dioxide from the carbon dioxide-containing gas stream 2. Figure 2 As shown, the first heat exchanger 4a can switch from the second operating mode to the first operating mode. Simultaneously, the second heat exchanger 4b switches from the first operating mode to the second operating mode.

[0137] As described below, the depressurization of chamber 14 of heat exchanger 4 occurs during the transition period after the implementation of the first operating mode and before the implementation of the second operating mode.

[0138] Figure 3 A second embodiment of the capture system 1 according to the present invention is shown. The second embodiment is related to... Figures 1 to 2 The difference in the first embodiment is that the capture system 1 includes three heat exchangers 4 designed to capture or melt carbon dioxide.

[0139] Therefore, the capture system 1 includes a third heat exchanger 4c, whose structure and function are the same as those of the first heat exchanger 4a and the second heat exchanger 4b. Thus, the third heat exchanger 4c can operate in both of the aforementioned operating modes, and the control device 5 can switch the third heat exchanger 4c from one operating mode to the other.

[0140] 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 the various supply loops in the same manner as the first heat exchanger 4a and the second heat exchanger 4b. The capture system 1 also includes a control device 5 associated with the third heat exchanger 4c. Therefore, the control device 5 includes a management device 42, a management unit 40, a monitoring device 38, and a monitoring unit, each of which is associated with the third heat exchanger 4c, and each of which has its corresponding valve as described above.

[0141] Therefore, the flow of various fluids through the third heat exchanger 4c, according to the operating mode, is the same as described above. This is the reference. Figures 1 to 2 The way in which they are described constitutes support and / or a detailed description of projects that are the same on these diagrams or work in the same way.

[0142] In a second embodiment of the capture system 1, the carbon dioxide capture method is implemented such that two heat exchangers 4 are constantly present in a first operating mode, meaning that the two heat exchangers 4 capture carbon dioxide in their respective chambers 14. Having two heat exchangers 4 in the first operating mode allows for the processing of carbon dioxide-containing gas 2 at higher flow rates, which increases the processing capacity of the capture system 1.

[0143] In this embodiment, when the two heat exchangers 4 are operating in a first operating mode, the capture system 1 may include a flow rate sensor 94 located upstream of the chamber 14 of each heat exchanger 4, such as a seventh valve 44a of the monitoring device near each heat exchanger 4. Each flow rate sensor 94 enables the measurement of the flow rate of the carbon dioxide-containing gas stream 2 through the chamber 14 of the heat exchanger 4 in the first operating mode.

[0144] Furthermore, each eighth valve 44b of the monitoring device in each heat exchanger 4 can be a valve capable of changing the cross-section of the decarbonized gas flow 3. The process monitors the shared flow rate of the carbon dioxide-containing gas flow 2 between the two heat exchangers 4 in the first operating mode.

[0145] Figures 4 to 6 One of the heat exchangers 4 is shown, which can be the first, second, or third heat exchanger as described above. More precisely, Figures 4 to 6 The time sequence of various configurations associated with the heat exchanger 4 is shown to illustrate in detail how the pressure drop in chamber 14 occurs.

[0146] exist Figure 4 In the middle, heat exchanger 4 is in the first operating mode, such as Figure 2 and Figure 3 The second heat exchanger 4b or as Figure 3 The case of the third heat exchanger 4c is shown.

[0147] Figure 4 The heat exchanger 4 shown captures carbon dioxide from the gas stream 2 containing carbon dioxide. Therefore, the first valve 42a and the second valve 42b open to allow the decarbonized gas stream 3 to pass through the first line 12a. The third valve 40a and the fourth valve 40b also open to allow the liquefied natural gas gas stream 30 to flow through the second line 12b.

[0148] The seventh valve 44a and the eighth valve 44b are opened to allow gas 2 containing carbon dioxide to flow through chamber 14 and out of chamber 14 as decarbonized gas stream 3, wherein carbon dioxide is captured from chamber 14 by sublimation.

[0149] Since the first operating mode is activated, no liquid carbon dioxide flows through the recovery line 31. Therefore, the recovery valve 19 is closed. The pressure reducing valve 15 is closed to prevent the release of the carbon dioxide-containing gas flow 2 via the pressure reducing line 13.

[0150] As previously mentioned, the gas stream 2 containing carbon dioxide has a pressure of approximately 3.5 barg. Therefore, the pressure in chamber 14 is also approximately 3.5 barg.

[0151] At a given time, the implementation of the first operating mode is stopped. In order to reduce the pressure in chamber 14 after the implementation of the first operating mode, a decompression operation is initiated before the implementation of the second operating mode.

[0152] exist Figure 5 The diagram shows the configuration of heat exchanger 4 during reduced pressure operation. At the end of the first operating mode, 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.

[0153] Then, the pressure reducing valve 15 is opened. Fluid at approximately 3.5 bar pressure is generated in chamber 14 and then flows through pressure reducing line 13 to vent 17 to be released from chamber 14. This release then reduces the pressure in chamber 14. The pressure reduction operation continues until the pressure in chamber 14 reaches a preset pressure threshold. The pressure in chamber 14 can be measured, for example, by a pressure sensor not shown. The pressure threshold can be, for example, about 0 barg, meaning essentially equal to ambient pressure, or it could be about 1 barg to allow liquid carbon dioxide to flow toward the storage device without a pump when in the second operating mode.

[0154] Once the pressure in chamber 14 reaches the pressure threshold, the decompression operation ends. Then, the pressure reducing valve 15 is closed, and a second operating mode can be implemented to melt the captured carbon dioxide in chamber 14. Figure 2 and Figure 3 The first heat exchanger 4a shown is the same as that shown. Figure 6 The diagram shows the construction relative to the second operating mode.

[0155] To implement the second operating mode, fifth valve 38a and sixth valve 38b are opened to allow a gas flow 2 containing carbon dioxide to pass through the first line 12a and the second line 12b of the heat exchanger 4. The temperature in chamber 14 then rises, and the carbon dioxide melts and becomes liquid. Recovery valve 19 is also opened to allow liquid carbon dioxide to flow into recovery line 31.

[0156] As previously stated, during the implementation of the second operating mode, the melting of carbon dioxide in chamber 14 can cause a pressure increase, which can reach 5.2 bar. However, due to the prior depressurization operation, this will not result in overpressure in chamber 14.

[0157] Figure 7 Two examples of curves are shown, illustrating the evolution of pressure P in barg within the chamber of one of the heat exchangers as a function of time. Pressure P also depends on the timely switching between operating modes of the heat exchanger.

[0158] The pressure curve for P in the chamber begins after the first operating mode has been implemented for a duration resulting in a pressure P of 3.5 bar (meaning equal to or substantially equal to the pressure of the gas stream containing carbon dioxide). At this point, the configuration of the heat exchanger under consideration corresponds to... Figure 4 The construction shown.

[0159] Once the first operating mode 101 ceases, the pressure reduction operation 103 is initiated following the first operating mode 101. As described above, the pressure P in the heat exchanger chamber decreases during the pressure reduction operation 103 until the pressure P reaches a pressure threshold 82. As mentioned above, the pressure threshold 82 can be substantially equal to 0 bar (as depicted by the flat curve) or 1 bar (as depicted by the dashed line). The transition period 83 for implementing the pressure reduction operation 103 can have a given duration, for example, 300 seconds ± 10%. During the pressure reduction operation 103, the configuration of the heat exchanger under consideration corresponds to... Figure 5 The construction shown.

[0160] Once the pressure threshold 82 is reached, the pressure reduction operation 103 is stopped and the second operating mode 102 is implemented. Before implementing the second operating mode 102, the pressure reduction operation 103, as follows: Figure 7 As shown. During the implementation of the second operating mode 102, the configuration of the heat exchanger under consideration corresponds to Figure 6 The structure is described in the diagram. Then, the melting of carbon dioxide increases the pressure P in the heat exchanger chamber to the partial pressure of carbon dioxide, 4.2 barg. This means that if the pressure threshold 82 reaches 0 barg during the depressurization operation, the total pressure is 5.2 barg, as shown by the flat curve. If the pressure threshold 82 reached during the depressurization operation is 1 barg, as shown by the dashed line, the melting of carbon dioxide will increase the pressure P in the heat exchanger chamber to the partial pressure of carbon dioxide, 5.2 barg, which means the total pressure is 6.2 barg.

[0161] During the pressure change P, the phase transition threshold 84 of carbon dioxide is crossed. In fact, due to the pressure drop in the chamber during depressurization operation 103, solid carbon dioxide can partially sublimate and become vapor in the chamber. However, due to the increase in pressure P during the implementation of the second operating mode 102, the phase transition threshold 84 is crossed again. The portion of solid carbon dioxide then directly transforms into a liquid state during its melting, while the portion of sublimated carbon dioxide that remained in the sublimation state during depressurization operation 103 remains in the gaseous state.

[0162] Of course, the present invention is not limited to the examples described above, and many improvements can be made to these examples within the framework of the present invention.

[0163] As described above, the present invention achieves its objective and enables the provision of a system for capturing carbon dioxide, comprising at least two heat exchangers operable in a first operating mode for capturing carbon dioxide and a second operating mode for melting the captured carbon dioxide, and further comprising a pressure-reducing device that allows for reduction of pressure deviation within the chambers of the heat exchangers. According to the invention, variations not described herein can be implemented within the framework of the invention, provided they incorporate the capture system according to the invention.

Claims

1. A system (1) for capturing carbon dioxide from a gas containing carbon dioxide, comprising at least a first heat exchanger (4a) and a second heat exchanger (4b), wherein each heat exchanger (4) comprises at least a chamber (14), a first conduit (12a) and a second conduit (12b) extending through the chamber (14), wherein the first heat exchanger (4a) and the second heat exchanger (4b) are configured to operate in a first operating mode (101) and a second operating mode (102), wherein in the first operating mode the chamber (14) is configured to contain carbon dioxide. A carbon gas stream (2) flows through the chamber and captures carbon dioxide from the carbon dioxide-containing gas stream (2) by sublimation to produce a decarbonized gas stream (3). In the second operating mode (102), the carbon dioxide-containing gas stream (2) flows through the first line (12a) and / or the second line (12b) to melt the carbon dioxide captured in the chamber (14). The capture system (1) includes a control device (5) configured to operate alternately between the first operating mode (101) and the second operating mode (102). The capture system (1) includes at least a pressure reducing device (11) that operates on a chamber (14) of at least one of the heat exchangers (4) and is configured to reduce the pressure (P) of the chamber (14), and the control device (5) is configured to activate the pressure reducing device (11) during a transition from the first operating mode (101) to the second operating mode (102).

2. The capture system (1) according to claim 1, wherein, The pressure reducing device (11) includes a pressure reducing line (13) and a pressure reducing valve (15), the pressure reducing line (13) leading to a chamber (14) of at least one of the heat exchangers (4), and the control device (5) being configured to activate the pressure reducing valve (15).

3. The capture system according to claim 2, wherein, The pressure relief line (13) is connected to the vent (17).

4. The capture system (1) according to any one of the preceding claims, wherein, The control device (5) includes at least one management device (42) configured to regulate the flow of the first coolant through any of the lines (12) of any of the heat exchangers (4).

5. The capture system (1) according to claim 4, wherein, The management device (42) includes at least one valve (42a) upstream of any one of the lines (12) in the heat exchangers (4) and / or at least one second valve (42b) downstream of any one of the lines (12) in the heat exchangers (4).

6. The capture system (1) according to any one of the preceding claims, wherein, The control device (5) includes at least one management device (40) configured to regulate the flow of the second coolant through any of the lines (12) of any of the heat exchangers (4).

7. The capture system (1) according to claim 6, wherein, The management device (40) includes at least a third valve (40a) upstream of any of the pipelines (12) in any of the heat exchangers (4) and / or at least a fourth valve (40b) downstream of any of the pipelines (12) in any of the heat exchangers (4).

8. The capture system (1) according to any one of the preceding claims, wherein, The control device (5) includes at least one monitoring device (38) configured to regulate the flow of the carbon dioxide-containing gas stream (2) through one or another pipeline (12) of any of the heat exchangers (4).

9. The capture system (1) according to claim 8, wherein, The monitoring device (38) includes at least a fifth valve (38a) upstream of any of the lines (12) in any of the heat exchangers (4) and / or at least a sixth valve (38b) downstream of any of the lines (12) in any of the heat exchangers (4).

10. The capture system (1) according to any one of the preceding claims, wherein, The control device (5) includes at least one monitoring device configured to regulate the flow of the carbon dioxide-containing gas stream (2) through any of the heat exchangers (4) and around any of their pipelines (12).

11. The capture system (1) according to the preceding claim, characterized in that, The monitoring device includes at least a seventh valve (44a) upstream of the chamber (14) of any of the heat exchangers (4) and / or at least an eighth valve (44b) downstream of the chamber (14) of any of the heat exchangers (4).

12. The capture system (1) according to any one of the preceding claims, comprising a third heat exchanger (4c) configured to operate according to a first operating mode (101) and a second operating mode (102), wherein the control device (5) is configured to operate alternation between the first operating mode (101) and the second operating mode (102) on the third heat exchanger (4c), wherein at least a pressure reducing device (11) of the capture system (1) is associated with the third heat exchanger (4c) and configured to reduce the pressure in a chamber (14) of the third heat exchanger (4c), and the control device (5) is configured to activate the pressure reducing device (11) during transition from the first operating mode (101) to the second operating mode (102).

13. The capture system (1) according to any one of claims 2 to 12, in conjunction with claim 2, is configured to keep the pressure reducing valve (15) closed when the first heat exchanger (4a) and / or the second heat exchanger (4b) are in the first operating mode (101) and / or the second operating mode (102).

14. The capture system (1) according to any one of claims 2 to 13, in conjunction with claim 2, wherein the capture system (1) is configured to open the pressure reducing valve (15) after the end of the first operating mode (101) and before the start of the second operating mode (102).

15. A method for capturing carbon dioxide from a gas stream (2) containing carbon dioxide, said method being carried out by a system (1) for capturing carbon dioxide from a gas stream (2) containing carbon dioxide according to any one of the preceding claims, wherein: At least one of the heat exchangers (4) is operated according to the first operating mode (101) to cause carbon dioxide in the carbon dioxide-containing gas stream (2) passing through the chamber (14) of the heat exchanger (4) to sublimate. The first operating mode (101) of the heat exchanger (4) is interrupted. The pressure reduction operation (103) is initiated by activating the pressure reduction device (11) to reduce the pressure (P) in the chamber (14). When the pressure (P) in the chamber (14) reaches the pressure threshold (82), the second operating mode (102) of the heat exchanger (4) is activated to melt the sublimated carbon dioxide in the chamber (14).

16. The capture method according to claim 15, implemented by the capture system (1) according to any one of claims 2 to 14 in conjunction with claim 2, wherein the pressure reducing valve (15) is closed during the first operating mode (101) and the second operating mode (102).

17. The capture method according to claim 15, wherein, The pressure reducing valve (15) is opened during a transition period (83) following the first operating mode (101), wherein the transition period (83) lasts for 300 seconds.

18. The capture process according to claim 17, wherein, The transition period (83) is before the second operating mode (102).

19. The capture method according to any one of claims 15 to 18 in combination with claims 5, 7, 9 and 11, wherein the first valve (42a), the second valve (42b), the third valve (40a), the fourth valve (40b), the fifth valve (38a), the sixth valve (38b), the seventh valve (44a) and the eighth valve (44b) are closed during the pressure reduction operation (103).

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