Carbon dioxide-laden gas cooling system

Abstract

Title: Carbon Dioxide Gas Cooling System Carbon dioxide gas cooling system comprising a first circuit configured to be traversed by the carbon dioxide gas and a second circuit configured to be traversed by a decarbonized gas, said system comprising at least one heat exchange zone between the first circuit and the second circuit, said zone comprising at least one heat exchanger configured to operate a heat exchange between the carbon dioxide gas and the decarbonized gas, the cooling system comprising a third circuit configured to be traversed by a heat transfer fluid and which includes at least one heat exchanger configured to vaporize said heat transfer fluid by heat exchange with the carbon dioxide gas, said heat exchanger being disposed in the heat exchange zone, the third circuit being connected to the second circuit.Figure from the summary: figure 1.

Description

Title of the invention: Cooling system for a gas containing carbon dioxide

[0001] The present invention relates to the field of treatment of gas charged with carbon dioxide and more particularly concerns a cooling system for said gas charged with carbon dioxide.

[0002] When a source of carbon dioxide-laden gas emissions is in operation, for example an internal combustion engine of a vehicle such as a floating structure, carbon dioxide-laden gases are generated. These gases are generally released into the atmosphere, causing environmental damage, particularly due to the carbon dioxide they contain.

[0003] In addition to the ecological impact, this release into the atmosphere is a loss of energy because carbon dioxide has multiple uses in various technical fields and can, for example, be used as a cooling agent in a gas treatment system.

[0004] It may then be advantageous to treat carbon dioxide-laden gases from a gas emission source in order to extract the carbon dioxide for subsequent use or commercialization. However, a system for cooling a carbon dioxide-laden gas currently does not allow for the full utilization of the heat available in the carbon dioxide-laden gas flue gases. The systems known to date are not optimized, and this is one of the reasons why these systems need to be improved.

[0005] The present invention overcomes these drawbacks by providing a cooling system for a carbon dioxide-laden gas stream comprising a first circuit configured to be traversed by the carbon dioxide-laden gas stream and a second circuit configured to be traversed by a decarbonized gas stream, said system comprising at least one heat exchange zone between the first circuit and the second circuit, said zone comprising at least one heat exchanger configured to perform a heat exchange between the carbon dioxide-laden gas stream and the decarbonized gas stream, the cooling system comprising a third circuit configured to be traversed by a heat transfer fluid and which includes at least one heat exchanger configured to vaporize said heat transfer fluid by heat exchange with the carbon dioxide-laden gas stream, said heat exchanger being disposed in the heat exchange zone,the third circuit being connected to the second circuit.

[0006] The cooling system according to the invention is designed to recover heat from a carbon dioxide-laden gas stream emitted by an emission source. It is observed that, in prior art systems, this energy in the form of heat is not utilized. The emission source may consist of a heat engine, for example, which raises the temperature of the carbon dioxide-laden gas stream. This is only one example; the emission source covers any device that releases a hot gas stream laden with carbon dioxide.

[0007] The recovered heat reduces the specific energy consumption of the carbon dioxide-laden gas stream treatment device by approximately 25% and also reduces the overconsumption of the emission source when it is associated with this treatment device. Injecting the heat transfer fluid, previously evaporated by heat exchange with the carbon dioxide-laden gas stream, into the decarbonized gas stream lowers the temperature of this decarbonized gas stream sent to one or more turbines. The work performed by this turbine is then significantly more efficient.

[0008] To recover this heat, the cooling system includes at least one heat exchanger configured to perform a heat exchange between the carbon dioxide-laden gas stream circulating in the first circuit and the heat transfer fluid circulating in the third circuit, the heat transfer fluid being configured to recover the heat present in the carbon dioxide-laden gas stream. The invention makes use of a maximum of the heat present in the carbon dioxide-laden gas stream. More specifically, the heat exchanger includes a first pass through which the carbon dioxide-laden gas stream circulating in the first circuit flows and a second pass through which the heat transfer fluid circulating in the third circuit flows, the first and second passes being close to each other so that the heat present in the carbon dioxide-laden gas stream leads to evaporation of the heat transfer fluid.

[0009] The third circuit then directs the heat transfer fluid, having recovered heat from the carbon dioxide-laden gas stream, to a heat exchange zone. This heat exchange zone is, for example, a chamber in which heat exchange occurs, notably between the carbon dioxide-laden gas stream from the emission source and the heat transfer fluid. Upon contact with the carbon dioxide-laden gas stream in the thermal zone, the heat transfer fluid vaporizes within the heat exchanger. The third circuit includes a section through which the vaporized heat transfer fluid flows to the second circuit, in which the decarbonized gas stream flows, so that the mixture of heat transfer fluid and decarbonized gas increases the mass of gas to be expanded and, consequently, optimizes the energy performance of the system.

[0010] According to another feature, at least one device for compressing the carbon dioxide-laden gas flow is arranged on the first circuit. Advantageously, the compression device is arranged downstream of the heat exchange zone. Complementarily, an expansion device may be arranged upstream of the heat exchange zone.

[0011] The compression device is configured to raise the pressure of the carbon dioxide-laden gas flow.

[0012] According to another feature, the heat exchanger configured to vaporize the heat transfer fluid by heat exchange with the carbon dioxide-charged gas stream is a first heat exchanger, the third circuit comprising a second heat exchanger configured to operate a heat exchange between the carbon dioxide-charged gas stream and the heat transfer fluid, said second heat exchanger being disposed on the first circuit, downstream of the compression device, in particular a first compression device.

[0013] The first and second heat exchangers each comprise a first pass and a second pass, the first pass of which is traversed by the carbon dioxide-laden gas stream and the second pass by the heat transfer fluid. Thus, said heat exchangers are configured to perform a heat exchange between said streams, enabling, on the one hand, the lowering of the temperature of the carbon dioxide-laden gas stream destined to pass through a carbon dioxide capture system in order to generate a decarbonized gas stream, and on the other hand, the recovery of the heat present in said carbon dioxide-laden gas.

[0014] According to another feature, the heat transfer fluid comprises mainly water. For example, the heat transfer fluid comprises at least 50% water by volume, preferably at least 75% water by volume, and even more preferably at least 90% water by volume. According to one aspect, the heat transfer fluid is exclusively water. The water may come from the cooling system according to the invention, thus avoiding the need for storage. The water may also come from a component external to the cooling system according to the invention. In all cases, the advantage of water is that it is readily available at low cost and is non-polluting, which allows it to be discharged into the environment, if necessary.

[0015] According to another feature, the cooling system includes at least one separator configured to collect the heat transfer fluid present within the carbon dioxide-laden gas stream. The water present in the carbon dioxide-laden gas stream tends to condense within the separator, thus allowing the water to be recovered in liquid form in a lower portion of said separator.

[0016] According to another feature, the third circuit includes a heat transfer fluid softening device. The softening device is configured to separate and / or extract acidic gases present in the heat transfer fluid, thus limiting the risk of corrosion for the components through which this heat transfer fluid flows.

[0017] According to another feature, the system comprises a plurality of separators configured to collect the heat transfer fluid present within the carbon dioxide-laden gas stream, said separators being connected to the softening device.

[0018] Each separator is positioned upstream of a compression device to ensure that the flow sent to said compression device is free of a liquid phase. To this end, the third circuit comprises several circulation branches for the heat transfer fluid extracted from the carbon dioxide-laden gas flow, extending from each separator to the softening device. The invention thus makes it possible to collect the heat transfer fluid at various points in the cooling system according to the invention.

[0019] According to another feature, the second circuit includes a device for recovering energy generated by the decarbonized gas flow, the connection of the third circuit to the second circuit being made between an outlet of the heat exchanger and an inlet of the energy recovery device. The injection of the heat transfer fluid takes place outside the heat exchange zone, downstream of it, but before the inlet to the energy recovery device.

[0020] The energy recovery device consists of a turbine coupled to a generator, for example an electric one. It is understood that said recovery device is located downstream of the heat exchanger, in the direction of flow of the decarbonized gas within the second circuit.

[0021] According to another feature, the heat exchange zone includes a chamber intended to be traversed by the flow of gas charged with carbon dioxide, the heat exchanger and the heat exchanger extending within the chamber.

[0022] The invention also covers a device for treating a carbon dioxide-laden gas stream comprising a cooling system as described in this document and a system for capturing the carbon dioxide present in the carbon dioxide-laden gas stream, the capture system being configured to extract at least part of the carbon dioxide and return the decarbonized gas stream to the cooling system.

[0023] The invention also covers a method for cooling a carbon dioxide-laden gas stream implementing a cooling system as described in this document, during which the heat transfer fluid is evaporated by heat exchange with the carbon dioxide-laden gas stream and during which the evaporated heat transfer fluid is injected into the decarbonized gas stream.

[0024] According to an optional feature of this process, the decarbonized gas stream is saturated with heat transfer fluid before entering the heat exchanger.

[0025] Other features, details and advantages of the invention will become clearer upon reading the following detailed description of an embodiment, given by way of example and not limitation with reference to the accompanying schematic drawings, on which the:

[0026] [Fig-1] schematically represents a cooling system for a charged gas in carbon dioxide according to the invention;

[0027] [Fig.2] represents an embodiment of a gas cooling system charged with carbon dioxide according to the invention;

[0028] [Fig.3] schematically represents the operation of the cooling system of the [Fig.2].

[0029] The features, variants, and different embodiments of the invention, as described or as they will be presented in the detailed description that follows, can be combined in various ways, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0030] This document uses the terms "upstream" and "downstream" to define the relative arrangement of the components. These terms are interpreted according to the direction of flow of the fluid that passes through said components or that circulates within the circuit concerned.

[0031] Fig. 1 illustrates a treatment device 1 for a carbon dioxide-charged gas stream 2 according to the invention which is configured to recover the treated carbon dioxide for reuse in subsequent applications.

[0032] Such a treatment device 1 includes a capture system 4 and a cooling system 6 for carbon dioxide present in the carbon dioxide-laden gas stream 2.

[0033] The capture system 4 is configured to extract at least part of the carbon dioxide, thus generating a decarbonized gas stream 8. In other words, the capture system 4 according to the invention makes it possible to produce a decarbonized gas stream 8 after capturing the carbon dioxide contained in the combustion gas stream loaded with carbon dioxide 2.

[0034] This decarbonized gas stream 8 is subsequently directed to the cooling system 6 in order to increase the overall energy performance of the treatment device 1, as will be detailed in the description below. Indeed, the gas stream The decarbonized gas 8 reaches the cooling system 6 at a pressure exceeding 4 bar (i.e., 4 x 10⁵ Pa). Therefore, this decarbonized gas flow 8 can be expanded, the efficiency of such expansion being improved by the injection of a heat transfer fluid. It is understood here that the capture system 4 and the cooling system 6 work together to fulfill the overall function of the treatment device 1.

[0035] Such a treatment device 1 can, for example, be integrated into a vehicle, at the outlet of a chimney, in a factory, or any other entity comprising an emission source 10 of carbon dioxide-laden gas. The emission source 10 can, for example, be an internal combustion engine such as an engine providing propulsion for a vehicle or the engine of an electric generator for said vehicle, for example, a floating structure.

[0036] When the emission source 10 is in operation, it emits gases including carbon dioxide, in other words, a carbon dioxide-laden stream 2. The capture system 4 thus makes it possible to capture the carbon dioxide present within the carbon dioxide-laden stream 2 in order to reuse it, instead of releasing it directly into the atmosphere, at the risk of polluting the environment.

[0037] In order to treat the carbon dioxide-laden gas stream 2, it flows from the emission source 10 to the capture system 4 via a first circuit 12. Before reaching the capture system 4, the carbon dioxide-laden gas stream 2 is expanded by an expansion device 14 to reach a pressure of approximately 1.04 bar absolute, such an expansion device 14 being in particular an exhaust turbine of a turbocharger of an internal combustion engine, the latter forming the emission source 10. It can be noted that the expansion device 14 is optional and its presence depends in particular on the type of emission source 10. Thus, the carbon dioxide-laden gas stream from the emission source 10 may not undergo expansion.In other words, within the framework of the invention, the pressure of the gas flow is irrelevant; such a gas flow from an emission source 10 can be considered and treated at a pressure greater than 1.04 bar. In the example cited above, a pressure of 1.04 bar is used, which corresponds to the exhaust gas outlet pressure of the ship's engine.

[0038] At the outlet of the expansion device 14, the flow of gas charged with carbon dioxide 2 emitted by the emission source 10 passes through a heat exchange zone 16 delimited by a chamber 18 which can for example be defined as a closed internal space, which has an inlet and an outlet each used by the flow of gas charged with carbon dioxide 2.

[0039] Chamber 18 houses a first heat exchanger 20 and a first heat exchanger 22. Optionally, chamber 18 also houses a second heat exchanger 24.

[0040] The first heat exchanger 20 is arranged upstream of the first heat exchanger 22 which is itself arranged upstream of the second heat exchanger 24, according to the direction of circulation of the carbon dioxide-laden gas flow 2 within the heat exchange zone 16.

[0041] Alternatively, tubes of the first heat exchanger 20, of the first heat exchanger 22 and / or of the second heat exchanger 24 can be arranged in parallel with each other.

[0042] At the outlet of the heat exchange zone 16, the flow of gas charged with carbon dioxide 2 joins a compression unit 7 whose role is to raise the pressure of the gas charged with carbon dioxide 2, to cool it and possibly ensure a separation of certain products present in these gases charged with carbon dioxide 2.

[0043] As illustrated in [Fig.1], such a compression unit 7 comprises a first inlet which receives the carbon dioxide-laden gas 2 from the heat exchange zone 16, a second inlet connected to the capture system 4 and through which the decarbonized gas 8 enters the compression unit 7 and a third inlet through which the heat transfer fluid enters the compression unit 7.

[0044] The compression unit 7 also includes outlets, among which there is a first outlet of decarbonized gas 8, a second outlet of gas charged with carbon dioxide 2, and a third, a fourth, a fifth and a sixth outlet of heat transfer fluid.

[0045] Figure 2 illustrates in detail the constitution of such a compression unit 7.

[0046] The carbon dioxide-laden gas flow 2 circulating in the first circuit 12 passes through at least one separator, possibly a plurality of separators, among which there is a first separator 26 and a second separator 28 configured to separate a heat transfer fluid 30 from said carbon dioxide-laden gas flow 2. The second separator 28 is disposed within the first circuit 12 downstream of the first separator 26.

[0047] The role of the separator(s) is, in particular, to collect the heat transfer fluid 30. This heat transfer fluid 30 is water and is configured to recover the heat present in the carbon dioxide-laden gas stream 2 by heat exchange within heat exchangers 36, 38. In the invention, the heat transfer fluid 30 circulates in a third circuit 54. The heat transfer fluid 30 recovered in the separator 26, 28 must be degassed at atmospheric pressure before it can be taken up by a pump 60.

[0048] Furthermore, the carbon dioxide-laden gas flow 2 passes through several compression devices, more particularly a first compression device 32 and a second compression device 34 arranged on the first circuit 12 and configured to raise the pressure of the carbon dioxide-laden gas flow 2. The The pressure at the outlet of the first compression device 32 is, for example, equal to 5.4 absolute bars.

[0049] The second compression device 34 is arranged downstream of the first compression device 32. More specifically, the first compression device 32 is arranged downstream of the first separator 26 and the second compression device 34 is arranged downstream of the second separator 28.

[0050] The carbon dioxide-laden gas flow 2 exiting the first compression device 32 passes through a second heat exchanger 36, the latter operating a heat exchange between the carbon dioxide-laden gas flow compressed by the first compression device 32 and the heat transfer fluid 30. The carbon dioxide-laden gas flow 2 exiting the second compression device 34 passes through a third heat exchanger 38, the latter operating a heat exchange between the carbon dioxide-laden gas flow 2 compressed by the second compression device 34 and the heat transfer fluid 30.

[0051] The carbon dioxide-laden gas stream 2 exiting the third heat exchanger 38 is subsequently directed to a third heat exchanger 40 before reaching the capture system 4 in order to produce the decarbonized gas stream 8.

[0052] Figures 2 and 3 show the existence of two separators, referenced 26 and 28, each located upstream of a compression device 32, 34. Interestingly, the invention may include another separator located downstream of the third heat exchanger 38. It is also possible to provide an additional separator located downstream of the third heat exchanger 40. These additional separators recover the heat transfer fluid for use within the system according to the invention.

[0053] The decarbonized gas flow 8 travels through a second circuit 42 of the cooling system 6 according to the invention. The second circuit 42 channels the decarbonized gas flow 8 to the third heat exchanger 40, and it is understood that the third heat exchanger 40 performs a heat exchange between the carbon dioxide-laden gas flow 2 circulating in the first circuit 12 and the decarbonized gas flow 8 circulating in the second circuit 42. The decarbonized gas flow 8 is subsequently routed to a fourth heat exchanger 44, which performs a heat exchange between the decarbonized gas flow 8 upstream of the heat exchange zone 16 and the same decarbonized gas flow 8 downstream of the heat exchange zone 16.

[0054] The second circuit 42 channels the flow of decarbonized gas 8 towards the first heat exchanger 22, in particular via the branch referenced 42b, and then possibly towards the second heat exchanger 24.

[0055] After passing through the first heat exchanger 22, the decarbonized gas flow 8 passes through a first energy recovery device 50, as well as after having Having passed through the second heat exchanger 24, the decarbonized gas stream 8 passes through a second energy recovery device 52. The energy recovery devices 50, 52 consist of a turbine that expands the decarbonized gas stream 8. Such a turbine can be a drive turbine that directly supplies mechanical energy to the first or second compression device 32, 34. Alternatively, this turbine can be coupled with an electric generator so as to convert the mechanical energy of the turbine into electrical energy.

[0056] At the outlet of the second energy recovery device 52, the second circuit 42 conducts the flow of decarbonized gas 8 to the fourth heat exchanger 44, then to a third separator 46, in order to reach a management unit 48 so that it can be recycled or reused or released into the atmosphere.

[0057] It is understood here that the heat exchange zone 16 is an enclosure where a heat exchange takes place between the carbon dioxide-laden gas flow 2 from the emission source 10 and the decarbonized gas flow 8 alone or a mixture of this decarbonized gas flow 8 and heat transfer fluid 30, by means of the heat exchanger 20 and the heat exchanger 22.

[0058] The heat transfer fluid 30 extracted from the carbon dioxide-laden gas stream 2 circulates in the third circuit 54. The third circuit 54 includes a first branch 54a connecting the first separator 26 to a softening device 56. The circulation of the heat transfer fluid 30 to the softening device 56 is permitted, for example, by means of a first control valve 58 and a first pump 60.

[0059] The softening device 56 is configured to remove potentially present acidic gases from the heat transfer fluid 30. The softening device 56 includes a drain line 62 configured to remove acidic residues from the heat transfer fluid 30 from the treatment device 1 in order to limit the risk of corrosion of all components belonging to said cooling system 6.

[0060] The third circuit 54 also includes a second branch 54b which connects the softening device 56 to the third heat exchanger 38 before returning to said softening device 56, thus forming a closed loop for the circulation of the heat transfer fluid 30. The circulation of the heat transfer fluid 30 towards the softening device 56 within the second branch 54b is controlled by a second regulating valve 58b and implemented by a second pump 61. It is understood here that the third heat exchanger 38 performs a heat exchange between the carbon dioxide-laden gas stream 2 and the heat transfer fluid 30.

[0061] Furthermore, a third branch 54c belonging to the third circuit 54 connects the second branch 54b to the second heat exchanger 36. It is thus understood that the second heat exchanger 36 operates a heat exchange between the carbon dioxide-laden gas stream 2 and the heat transfer fluid 30.

[0062] At the outlet of the second heat exchanger 36, the third branch 54c extends to the first heat exchanger 20 located within the heat exchange zone 16. The first heat exchanger 20 performs a heat exchange between the carbon dioxide-laden gas flow 2 emitted by the emission source 10 and the heat transfer fluid 30 circulating within the third branch 54c, and this heat exchange leads to an evaporation of the heat transfer fluid 30, so as to create a superheated vapor which, in the end, will increase the mass of the expanded gases at the level of the energy recovery devices. The third branch 54c terminates with a connecting section 66 from the third circuit 54 to the second circuit 42. This connecting section 66 is located downstream of an outlet 51 of the first heat exchanger 20, outside the heat exchange zone 16, and upstream of an inlet 53 of the first energy recovery device 50.The connecting section 66 is terminated by an injection port into the second circuit 42.

[0063] The third circuit 54 also includes a fourth branch 54d connecting the second separator 28 to the first separator 26. Within this fourth branch 54d, the circulation of the heat transfer fluid 30 is allowed via a third regulating valve 58c.

[0064] The third circuit 54 includes a fifth branch 54e configured to channel the heat transfer fluid 30 from the third separator 46 to the softening device 56, in particular via a third pump 64.

[0065] The third circuit 54 further includes a conduit 54f connected at its inlet to the third branch 54c and at its outlet to branch 42b of the second circuit 42. This conduit allows the heat transfer fluid to be mixed with the decarbonized gas stream 8. The heat transfer fluid is then evaporated and advantageously superheated. As a result, a larger volume of gas is directed to the energy recovery device 50. The mechanical energy of expansion is thus increased. In other words, the residual heat available in the decarbonized gas stream recovered by the fourth heat exchanger 44 is used to produce heat transfer fluid vapor, preferably water vapor, which is mixed and expanded with the decarbonized gas stream.

[0066] The different branches 54a, 54b, 54c, 54d, 54e are configured to supply the heat transfer fluid 30 necessary for carrying out the heat exchange within the heat exchanger associated with the branch concerned.

[0067] Figure 3 shows the same processing device 1 as that illustrated in Figure 2. Unlike the latter, Figure 3 illustrates the circulation of the different flows within the cooling system 6 when the latter is in operation. operation. The flow of carbon dioxide-laden gas 2 is illustrated in bold. The flow of decarbonized gas 8 is illustrated in thin line and the heat transfer fluid 30 is illustrated in dotted line, both in liquid and gaseous state.

[0068] In [Fig. 3], the carbon dioxide-laden gas stream 2 produced by the emission source 10, after being previously expanded by the expansion device 14, reaches the chamber 18 of the heat exchange zone 16 via the first circuit 12. The first circuit 12 then directs the carbon dioxide-laden gas stream 2 exiting the heat exchange zone 16 to the first separator 26. The first separator 26 is located at a confluence between the first circuit 12 and the third circuit 54, specifically the first branch 54a of the third circuit 54. The first separator 26 comprises a carbon dioxide-laden gas stream inlet, a carbon dioxide-laden gas stream outlet, and a heat transfer fluid outlet. The carbon dioxide-laden gas stream inlet and outlet form part of the first circuit 12, while the heat transfer fluid outlet delimits the third circuit 54.Thus, the first separator 26 is configured to recover the heat transfer fluid 30 present in the carbon dioxide-laden gas stream 2 in order to send it to the first branch 54a of the third circuit 54. .

[0069] The carbon dioxide-laden gas stream 2 exiting the first separator 26 is then directed to the first compression device 32 to increase its pressure, and then to the second heat exchanger 36 to lower its temperature. The second heat exchanger 36 comprises both a first pass, which is part of the first circuit 12, and a second pass, which is part of the third circuit 54. It is thus understood that the first pass is used by the carbon dioxide-laden gas stream 2 and that the second pass is used by the heat transfer fluid 30. Therefore, the second heat exchanger 36 is configured to lower the temperature of the carbon dioxide-laden gas stream 2 circulating in the first pass by exchanging heat with the heat transfer fluid 30 circulating in the second pass.It is understood here that the heat transfer fluid 30 recovers the heat present within the carbon dioxide-laden gas flow 2 via the second heat exchanger 36. .

[0070] Subsequently, the first circuit 12 carries the carbon dioxide-laden gas stream 2 to the second separator 28. The second separator 28 is located at a junction between the first circuit 12 and the third circuit 54, specifically the fourth branch 54d of the third circuit 54. The second separator 28 comprises a carbon dioxide-laden gas stream inlet, a carbon dioxide-laden gas stream outlet, and a heat transfer fluid outlet. The carbon dioxide-laden gas stream inlet and outlet form part of the first circuit 12, while the heat transfer fluid outlet delimits the third circuit 54. Thus, the second separator 28 is configured to recover the heat transfer fluid 30 present in the carbon dioxide-charged gas stream 2 in order to lead it to the softening device 56, via the fourth branch 54d.

[0071] The carbon dioxide-laden gas stream 2 exiting the second separator 28 is directed to the second compression device 34 to increase its pressure, and then to the third heat exchanger 38 to lower its temperature. The third heat exchanger 38 comprises a first pass and a second pass. Thus, the third heat exchanger 38 is configured to lower the temperature of the carbon dioxide-laden gas stream 2 circulating in the first pass of the third heat exchanger 38 by exchanging heat with the heat transfer fluid 30 circulating in the second pass of the third heat exchanger 38, in order to recover the heat present within the carbon dioxide-laden gas stream 2.

[0072] Exiting the third heat exchanger 38, the first circuit 12 transports the carbon dioxide-laden gas stream 2 to the third heat exchanger 40 in order to lower its temperature before conveying said cooled stream to the capture system 4 configured to generate the decarbonized gas stream 8.

[0073] The decarbonized gas stream 8 exiting the capture system 4 is recovered by the second circuit 42 which directs it to the third heat exchanger 40. Thus, it is understood that the third heat exchanger 40 is configured to lower the temperature of the carbon dioxide-laden gas stream 2 by exchanging heat with the decarbonized gas stream 8.

[0074] Upon exiting the third heat exchanger 40, the decarbonized gas flow 8, having a temperature of, for example, 37°C at that point, is directed towards the fourth heat exchanger 44. At the exit of the fourth heat exchanger 44, the decarbonized gas flow 8 is mixed with the heat transfer fluid coming from the pipe 54f, and the whole is directed towards the second heat exchanger 22 operating a heat exchange between the carbon dioxide-laden gas flow 2 present within the heat exchange zone 16 and the decarbonized gas flow 8 mixed with the evaporated heat transfer fluid. This last flow is then routed to the first energy recovery device 50. This flow of decarbonized gas 8 mixed with the evaporated heat transfer fluid then circulates through the second heat exchanger 24 and exchanges heat once again with the flow of gas charged with carbon dioxide 2 present within the heat exchange zone 16.The decarbonized gases containing superheated water vapor are then reheated before a second expansion stage which takes place in the second energy recovery device 52.

[0075] This flow of decarbonized gas 8 mixed with the evaporated heat transfer fluid thus continues its path to reach the second energy recovery device 52, where the expansion of this flow makes it possible to generate energy that can be exploited elsewhere. In Downstream of the latter, the decarbonized gas flow 8 circulates towards the fourth heat exchanger 44, then towards the third separator 46 to reach the control unit 48.

[0076] The first heat exchanger 20 through which the heat transfer fluid 30 flows in the third branch 54c belonging to the third circuit 54 is configured to vaporize the heat transfer fluid 30, by heat exchange with the carbon dioxide-laden gas flow 2 from the emission source 10. The vaporized heat transfer fluid 30 circulating within this first heat exchanger 20 is connected to the second circuit 42 by the connecting section 66, the latter being an injection port of the heat transfer fluid 30 into the decarbonized gas flow 8.

[0077] It is understood here that the vaporized heat transfer fluid 30 circulating in the third circuit 54c is mixed with the flow of decarbonized gas 8 circulating in the second circuit 42 in order to increase heat exchange, which has the effect of improving the overall performance of the treatment device 1.

[0078] The invention also relates to a cooling method implementing the cooling system 6 of the carbon dioxide-charged gas stream 2, where the heat transfer fluid 30 is evaporated and superheated by heat exchange with the carbon dioxide-charged gas stream 2 via the heat exchanger 20 disposed within the thermal zone 16, then the evaporated heat transfer fluid 30 is injected into the decarbonized gas stream 8 circulating in the second circuit 42, in particular upstream of the energy recovery device 50, 52.

[0079] The invention, as described above, achieves its stated objective, namely to provide an optimized solution for recovering and utilizing the heat present in a carbon dioxide-laden gas stream emitted by an emission source, in order to improve the energy efficiency of a processing device integrated into said cooling system. Applied to carbon dioxide, such a solution makes it possible to reduce the greenhouse effect.

[0080] The present invention is not limited to the means and configurations described and illustrated herein, and it also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Demands

1. Cooling system (6) for a carbon dioxide-laden gas stream (2) comprising a first circuit (12) configured to be traversed by the carbon dioxide-laden gas stream (2) and a second circuit (42) configured to be traversed by a decarbonized gas stream (8), said system comprising at least one heat exchange zone (16) between the first circuit (12) and the second circuit (42), said zone (16) comprising at least one heat exchanger (22, 24) configured to perform heat exchange between the carbon dioxide-laden gas stream (2) and the decarbonized gas stream (8), the cooling system (6) comprising a third circuit (54) configured to be traversed by a heat transfer fluid (30) and which includes at least one heat exchanger (20) configured to vaporize said heat transfer fluid (30) by heat exchange with the carbon dioxide-laden gas stream (2),said heat exchanger (20) being disposed in the heat exchange zone (16), the third circuit (54) being connected to the second circuit (42).

2. Cooling system (6) according to claim 1, comprising at least one compression device (, 32, 34) of the carbon dioxide-charged gas flow (2) disposed on the first circuit (12).

3. Cooling system (6) according to any one of claims 1 or 2, wherein the heat exchanger configured to vaporize the heat transfer fluid (30) by heat exchange with the carbon dioxide-charged gas (2) is a first heat exchanger (20), the third circuit (54) comprising a second heat exchanger (36) configured to operate a heat exchange between the carbon dioxide-charged gas stream (2) and the heat transfer fluid (30), said second heat exchanger (36) being disposed on the first circuit (12), downstream of the compression device (, 32, 34).

4. Cooling system (6) according to any one of claims 1 to 3, comprising at least one separator (26, 28) configured to collect the heat transfer fluid (30) present within the carbon dioxide-charged gas stream (2).

5. Cooling system (6) according to any one of claims 1 to 4, wherein the third circuit (54) includes a device for softening (56) the heat transfer fluid (30).

6. Cooling system (6) according to claim 5, comprising a plurality of separators (26, 28) configured to collect the heat transfer fluid (30) present within the carbon dioxide-charged gas stream (2), said separators (26, 28) being connected to the softening device (56).

7. Cooling system (6) according to any one of claims 1 to 6, wherein the second circuit (42) comprises at least one energy recovery device (50) generated by the decarbonized gas flow (2), the connection of the third circuit (54) to the second circuit (42) being operated between an outlet (51) of the heat exchanger (22) and an inlet (53) of the energy recovery device (50).

8. Cooling system (6) according to any one of claims 1 to 7, wherein the heat exchange zone (16) comprises a chamber (18) intended to be traversed by the flow of carbon dioxide-charged gas (2), the heat exchanger (22) and the heat exchanger (20) extending within the chamber (18).

9. A device for treating (1) a carbon dioxide-laden gas comprising a cooling system (6) according to any one of claims 1 to 8 and a carbon dioxide capture system (4) for the carbon dioxide present in the carbon dioxide-laden gas stream (2), the capture system (4) being configured to extract at least part of the carbon dioxide and return the decarbonized gas stream (8) to the cooling system (6).

10. A method for cooling a carbon dioxide-laden gas stream (2) employing a cooling system (6) according to any one of claims 1 to 8, wherein: - the heat transfer fluid (30), preferably consisting mainly of water, is evaporated by heat exchange with the carbon dioxide-laden gas stream (2); - the evaporated heat transfer fluid (30) is injected into the decarbonized gas stream (8).

11. Cooling method according to claim 10, wherein the decarbonized gas stream (8) is saturated with heat transfer fluid (30) before entering the heat exchanger (22).

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