System for treating gases laden with carbon dioxide emitted by a consumer

Abstract

The present invention relates to a system (1) for treating gases laden with carbon dioxide emitted by a consumer, comprising a tank (10) for storing liquefied natural gas, a consumer configured to be supplied with a fuel produced from liquefied natural gas stored in the storage tank (10), a device (18) for compressing the gases laden with carbon dioxide, a device (22) for drying these gases laden with carbon dioxide, a device (28) for condensing the carbon dioxide present in the gases laden with carbon dioxide, and a device (30, 32) for separating the carbon dioxide present in the gases emitted by the consumer, the condensation device (28) being arranged between the drying device (22) and the separation device (30, 32).

Description

[0001] DESCRIPTION

[0002] Title: System for treating gases laden with carbon dioxide emitted by a consumer

[0003] The present invention relates to the field of gases emitted by consumers, and more particularly to the methods implemented to treat such gases.

[0004] When a carbon dioxide emission source is in operation, carbon dioxide-laden gases are generated. These gases are generally released into the atmosphere, causing environmental damage, particularly due to their carbon dioxide content. Therefore, it is advisable to treat the carbon dioxide-laden gases from an emission source in order to extract the carbon dioxide for later use or commercialization.

[0005] The emission source may consist of a fuel cell, for example, or more generally any device that releases a stream of gas charged with carbon dioxide. In what follows, the invention will be described by way of example in the context of fuel cells; however, the invention is by no means limited to this.

[0006] Fuel cells are devices capable of generating electricity from a redox reaction. Typically, fuel cells consist of two electrodes, an anode and a cathode, separated by an electrolyte membrane. The anode is supplied with a reducing fuel, while the cathode is supplied with an oxidant, such as oxygen from the air. The electrolyte membrane allows oxygen ions to pass from the cathode to the anode.

[0007] Solid oxide fuel cells, also known by their English acronym SOFC, exist. In these solid oxide fuel cells, which generally operate at very high temperatures, the electrolyte membrane consists of solid oxides. These solid oxide fuel cells are used, for example, to provide electrical power within a floating structure. The fuel cell consumes fuel and emits exhaust gases from its anode. These exhaust gases contain carbon dioxide, and it is therefore necessary to implement exhaust gas treatment methods to limit carbon dioxide emissions.

[0008] It is known from prior art to preserve carbon dioxide in its purest possible form to improve capture efficiency. This is achieved by avoiding dilution of the anode effluent with the cathode effluent, keeping these two effluents separate at the fuel cell outlet. The anode effluent is then post-combusted with pure oxygen to recover carbon dioxide, which must be stored. However, this post-combustion requires pure oxygen, which necessitates either pure oxygen storage within the floating structure or the presence of an oxygen production unit. Both solutions entail high costs and a significant footprint that is difficult to reconcile with the available space on a floating structure.

[0009] The present invention aims to overcome this drawback by proposing a system and a method for treating the exhaust gases of a consumer which, by eliminating the post-combustion stage, makes it possible in particular to limit the constraints related to the use of pure oxygen.

[0010] The main object of the present invention is a system for treating gases containing at least carbon dioxide emitted by a consumer, comprising a liquefied natural gas storage tank, a consumer configured to be fueled by a product made from liquefied natural gas stored in the storage tank, a device for compressing the carbon dioxide-laden gases, a device for drying these carbon dioxide-laden gases, a device for condensing the carbon dioxide present in the carbon dioxide-laden gases, and a device for separating the carbon dioxide present in the gases emitted by the consumer, the condensation device being arranged between the drying device and the separation device. The treatment system according to the invention is configured to treat the carbon dioxide present in the exhaust gases emitted by a consumer.This consumer is, for example, intended for the production of electrical energy within a floating structure; the consumer could be, in particular, a fuel cell. More generally, the treatment system is adapted to the treatment of a gas stream laden with carbon dioxide, where the carbon dioxide concentration is at least 20% molar.

[0011] The treatment system successively compresses, dries, and condenses the carbon dioxide-laden gases emitted by the consumer, respectively using a compression device, a drying device, and a condensation device. The carbon dioxide is then separated from the remaining exhaust gases using at least one carbon dioxide separation device. This separation device includes at least one purification device, such as a distillation column. Its role is to extract any gases dissolved in the liquid phase of the carbon dioxide.

[0012] The separation device is configured to separate carbon dioxide on the one hand and residual gases on the other. To this end, the separation device is connected to at least one circulation line for carbon dioxide in liquid form, and at least one circulation line for the residual gases.

[0013] The presence of the separation device within the treatment system allows carbon dioxide to be stored in liquid form above the triple point of carbon dioxide; this allows large quantities of carbon dioxide to be stored in liquid form before exporting it, for example, to a sequestration chain, for reinjection into the subsoil after pumping or vaporization, or possibly before it undergoes treatment, for example, conversion into synthetic methane.

[0014] The separation device differs from other devices such as dry ice machines, which are designed to produce carbon dioxide in solid form for storage at a pressure and temperature below the triple point of carbon dioxide. The capacity of a dry ice machine is lower compared to the separation device, which is also less expensive and requires no energy input.

[0015] The condensing unit is positioned between the drying unit and the separation unit. Here, "between" refers to a fluidic arrangement rather than a physical one; in other words, within an installation that receives the treatment system, the components can be physically arranged as they see fit, provided that these components follow a fluidic order in which the drying unit receives the carbon dioxide-laden gases before the condensing unit, which in turn receives them before the separation unit. Specifically, two devices in the treatment system are considered "connected" when they are linked to each other by a line within the treatment system, without any other treatment component being interposed between them.In other words, the outlet of the first device is connected by a simple pipe to the inlet of the second device, so that the carbon dioxide-laden gases do not undergo any treatment or exchange of heat as they pass from the first device to the second device.

[0016] According to an optional feature of the invention, the condensation device is configured to operate a heat exchange between the gases charged with carbon dioxide and at least natural gas in liquid state and / or natural gas in vapor state, this natural gas being from the storage tank.

[0017] Within the condensing unit, the carbon dioxide-laden gases exchange heat either with natural gas in its liquid state only, or with natural gas in its vapor state only, or with both. Natural gas in its vapor state is, for example, a gas resulting from the natural evaporation of liquefied natural gas, also known by its English name boil-off gas (BOG).

[0018] As an alternative to liquefied natural gas in its liquid state and liquefied natural gas in its vapor state, gases containing carbon dioxide can exchange heat with a refrigerant. According to an optional feature of the invention, the condensation device comprises a condensing unit and an intermediate fluid heat exchanger arranged in series with the condensing unit, the intermediate fluid having a phase change temperature between -56 °C and -45 °C.

[0019] The condensing unit and the intermediate fluid heat exchanger constitute two subunits of the condensing device. The purpose of the intermediate fluid heat exchanger is to prevent the carbon dioxide contained in the carbon dioxide-laden gases, whose freezing temperature is -56 °C, from freezing.

[0020] Since the liquefied natural gas or decarbonized gas streams are intended to be introduced into the condensation device at temperatures much lower than -56 °C, for example around -160 °C in the case of liquefied natural gas, in the absence of an intermediate fluid exchanger the skin temperatures of the tubes with which the carbon dioxide-laden gas would be in contact would be much lower than -56 °C, which would lead to the solidification of the carbon dioxide and consequently the clogging of the condensation device.

[0021] Therefore, an intermediate fluid heat exchanger is necessary. The intermediate fluid vaporizes by condensing the carbon dioxide contained in the carbon dioxide-laden gas and condenses by exchanging heat with the liquefied natural gas and / or the decarbonized gas. The condensation and evaporation temperatures are identical or very close, as the temperature of this intermediate fluid is controlled at a level greater than or equal to -56°C, which eliminates the risk of the carbon dioxide freezing. The intermediate fluid is, for example, R410A.

[0022] According to an optional feature of the invention, the treatment system includes a device for storing carbon dioxide in liquid form.

[0023] The storage device is located downstream of the separation device. For example, the storage device may be connected directly to the separation device or connected to a subcooling device, which is itself connected to the separation device. According to an optional feature of the invention, the consumer is a fuel cell comprising an anode and a cathode, with the compression and drying devices configured to process carbon dioxide-laden gases emitted at the anode.

[0024] The fuel cell is supplied with air, which is delivered to the cathode, and fuel stored in the tank, which is delivered to the anode. The fuel cell produces electrical energy through redox reactions, resulting in the formation of effluents at both the anode and the cathode. It is the carbon dioxide-rich gases emitted by the anode that are treated by the treatment system.

[0025] According to an optional feature of the invention, the treatment system includes at least one return circuit linking the condensation device to the fuel cell and configured to channel residual gases separated by the separation device.

[0026] The return circuit allows for the recycling of gases emitted by the anode within the treatment system. More specifically, the return circuit allows for the recycling of residual gases once the carbon dioxide has been removed from the gas stream emitted by the anode.

[0027] According to an optional feature of the invention, the return circuit is equipped with a purge device configured to evacuate residual gases circulating in the return circuit.

[0028] This purge device is an alternative to returning waste gases to the fuel cell. It allows, for example, the waste gases to be released into the atmosphere.

[0029] According to an optional feature of the invention, the return circuit is equipped with a pressure relief valve configured to lower the pressure of the residual gases circulating in the return circuit, before their entry into the fuel cell.

[0030] Within the return circuit, the pressure relief valve allows the pressure of the residual gases to be adjusted before their recycling to the fuel cell.

[0031] According to an optional feature of the invention, the condensation means comprises a primary pass configured to be used by carbon dioxide-laden gases and a plurality of passes configured to cool the carbon dioxide-laden gases circulating in the primary pass.

[0032] Carbon dioxide-laden gases circulate within the condensing unit in the primary pass, which is the section requiring cooling. To achieve this, the condensing unit has at least two passes configured to cool the carbon dioxide-laden gases. The condensing unit includes at least one pass supplied, depending on the embodiment, by natural gas from the storage tank, liquid and / or vapor gas, or by the refrigerant, and at least one pass through which a fluid from other components of the treatment system flows. The presence of multiple passes enhances the cooling of the carbon dioxide-laden gases circulating within the primary pass.

[0033] According to an optional feature of the invention, the treatment system includes an expansion circuit comprising at least one expansion device disposed between two of the passes of the condensation means configured to cool the carbon dioxide-laden gases circulating in the primary pass.

[0034] The expansion circuit is configured to lower the pressure of the fluid circulating within it. The expansion device is, for example, a turbine.

[0035] According to an optional feature of the invention, the separation device is disposed between the primary pass and one of the passes of the condensation means configured to cool the carbon dioxide-laden gases circulating in the primary pass.

[0036] Thus, the gases circulating in the pass configured to cool the carbon dioxide-laden gases correspond to the residual gases extracted from the liquid phase by the separation device.

[0037] According to an optional feature of the invention, the condensation means comprises at least three passes configured to cool the carbon dioxide-laden gases circulating in the primary pass, the expansion circuit comprising at least one expansion element disposed between two of the passes of the condensation means configured to cool the carbon dioxide-laden gases circulating in the primary pass.

[0038] The expansion element corresponds, for example, to a second turbine in the expansion circuit, which is in addition to the expansion element.

[0039] According to an optional feature of the invention, the separation device comprises a purification device and a separator, the separator being disposed between the condensation device and the purification device, the separator being configured to operate a separation between a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer and a vapor phase comprising mainly residual gases present in the gases emitted by the consumer.

[0040] Within the separation system, the separator constitutes a primary carbon dioxide separation stage, while the purification device forms a secondary separation stage. The primary separation stage is designed to recover both the carbon dioxide in liquid form and the residual gases in vapor form. Conversely, the secondary separation stage purifies the carbon dioxide in its liquid state by extracting gases still dissolved in the liquid carbon dioxide phase present at the outlet of the primary separation stage. A separator, for example, is a separation vessel.

[0041] According to an optional feature of the invention, the separator is disposed between the primary pass and one of the passes configured to cool the carbon dioxide-laden gases circulating in the primary pass.

[0042] Thus, the gases flowing through the pass configured to cool the carbon dioxide-laden gases flowing through the primary pass correspond to the vapor phase separated by the separator.

[0043] According to an optional feature of the invention, the condensation means includes a secondary pass disposed between the separator and the purification device, said secondary pass being configured to be used by a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer.

[0044] The passes configured to cool the carbon dioxide-laden gases flowing in the primary pass are thus also configured to cool the liquid phase of the carbon dioxide-laden gases flowing in the secondary pass.

[0045] According to an optional feature of the invention, the treatment system includes a bypass line of the primary pass of the condensation means, the purification device including a heat exchanger configured to implement heat exchange between the liquid carbon dioxide present in the purification device and the gases charged at least with carbon dioxide.

[0046] The bypass line is connected to a main line linking the drying unit to the condensation unit, specifically to its condensing unit. This bypass line diverts the carbon dioxide-laden gases from the primary pass, sending them directly to the purification unit. The carbon dioxide-laden gases exchange heat within a heat exchanger in the purification unit, such as a reboiler.

[0047] According to an optional feature of the invention, the intermediate fluid exchanger is configured to operate a heat exchange between the gases that have flowed through the primary pass and at least the fuel produced from liquefied natural gas stored in the storage tank.

[0048] Such heat exchange is achieved using an intermediate fluid circulating within the intermediate fluid exchanger, in particular an intermediate fluid operating at a temperature above -56 °C.

[0049] According to an optional feature of the invention, the intermediate fluid exchanger includes at least one layer configured to be traversed by the fluid circulating in the expansion circuit.

[0050] This layer, configured to be traversed by the fluid circulating in the expansion circuit, is for example placed between the expansion element and one of the passes of the condensation unit configured to cool the gases charged with carbon dioxide circulating in the primary pass.

[0051] According to an optional feature of the invention, the intermediate fluid exchanger comprises a primary layer configured to be traversed by the gases that have flowed through the primary pass of the condensation means and a secondary layer disposed between the separator and the purification device, said secondary layer being configured to be traversed by a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer.

[0052] The primary and secondary layers are both intended to be cooled by the intermediate fluid from the intermediate fluid heat exchanger.

[0053] According to an optional feature of the invention, the processing system includes a heat recovery system disposed between the fuel cell and the compression device.

[0054] According to an optional feature of the invention, the fuel cell is a solid oxide fuel cell.

[0055] SOFCs are also referred to as solid oxide fuel cells. Alternatively, another possible type of fuel cell is a molten carbonate fuel cell (MCFC).

[0056] The invention further relates to a method for treating gases containing at least carbon dioxide emitted by a consumer using a treatment system as described above, comprising a step of supplying the consumer with air and a fuel produced from liquefied natural gas, a step of compressing the carbon dioxide-laden gases from the consumer, a step of drying the compressed carbon dioxide-laden gases, a step of condensing the carbon dioxide contained in the dried carbon dioxide-laden gases, and at least one step of separating the condensed carbon dioxide from the other gases contained in the gases emitted by the consumer. During the supply step, both air and a fuel produced from liquefied natural gas are delivered to the consumer.Fuel produced from liquefied natural gas consists, for example, of a mixture of natural gas and water vapor, the natural gas having previously been used in the condensation stage.

[0057] At least one separation step may correspond to a separation step within the separator, i.e. a primary separation step which allows the separation of a vapor phase of various gases from a liquid phase of carbon dioxide, as well as to a separation step within the purification device, or secondary separation step which is intended to purify the carbon dioxide to the liquid phase by promoting the extraction of gases other than carbon dioxide from the liquid phase of carbon dioxide.

[0058] According to an optional feature of the invention, the treatment method includes a step of storing carbon dioxide in liquid following the separation step.

[0059] The carbon dioxide storage step in liquid form takes place within the storage device. This storage step can occur after a carbon dioxide subcooling step following the separation step.

[0060] According to an optional feature of the invention, the treatment method includes an additional step of compressing the carbon dioxide-laden gases, the additional compression step occurring between the drying step and the condensation step.

[0061] In this case, the treatment method includes two compression stages between which the carbon dioxide-laden gases are dried.

[0062] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which:

[0063] [Fig. 1] illustrates, schematically, a general view of a system for treating gases loaded with carbon dioxide emitted by a consumer according to the invention; [Fig. 2] illustrates, schematically, a portion of the treatment system of figure 1 which corresponds to a first variant of a first embodiment;

[0064] [Fig. 3] illustrates, schematically, a second variant of the portion of the processing system according to the first embodiment of figure 2;

[0065] [Fig. 4] illustrates, schematically, a third variant of the portion of the processing system according to the first embodiment of figure 2;

[0066] [Fig. 5] illustrates, schematically, the portion of the processing system according to a first variant of the second embodiment;

[0067] [Fig. 6] illustrates, schematically, a second variant of the portion of the processing system according to the second embodiment of figure 5;

[0068] [Fig. 7] illustrates, schematically, a third variant of the portion of the processing system according to the second embodiment of figure 5;

[0069] [Fig. 8] illustrates, schematically, a fourth variant of the portion of the processing system according to the second embodiment of Figure 5.

[0070] The features, variations, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variations of the invention may include only a selection of features, described hereafter in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from prior art.

[0071] In the figures, elements common to several figures retain the same reference.

[0072] In the figures, the direction of fluid flow within the pipes is illustrated by arrows, such a direction being an integral part of this text.

[0073] Figure 1 schematically illustrates an overview of a gas treatment system 1 for gases containing at least carbon dioxide according to the invention. The treatment system 1 is intended to equip a floating or land-based structure, particularly for capturing carbon dioxide contained in gases containing at least carbon dioxide emitted by a consumer carried by the structure. This consumer is a fuel cell 2. This is a non-limiting example of a consumer on the structure. The fuel cell 2 is configured to supply electrical power within the structure.

[0074] Fuel cell 2 is a solid oxide fuel cell, but could alternatively be a molten carbonate fuel cell. It consists of a cathode 4 and an anode 6, which correspond to the two electrodes of fuel cell 2 and are separated from each other by an electrolyte membrane, which in this case is a solid oxide. To generate electrical energy, fuel cell 2 is supplied with air and a fuel. More specifically, the cathode 4 of fuel cell 2 is supplied with air, for example, ambient air within the building. This ambient air passes through a compressor of the treatment system 1 before being conveyed to the cathode 4 of the fuel cell 2. The fuel supplies the anode 6 of the fuel cell 2. The fuel used to supply the anode 6 is, for example, liquefied natural gas previously stored in a storage tank 10 of the structure.Alternatively, the fuel used to power anode 6 is a gas produced from the evaporation of liquefied natural gas stored in storage tank 10.

[0075] The conduits which carry natural gas in liquid or vapor form from the storage tank 10 to the anode 6 constitute a supply circuit 12 within the processing system 1.

[0076] At the end of energy production, cathode 4 and anode 6 release effluents. More specifically, cathode 4 emits exhaust gases, while anode 6 emits gases containing at least carbon dioxide. These gases circulate within the treatment system in a treatment circuit 14. Thus, the supply circuit 12 is dedicated to delivering fluid to an inlet of the fuel cell 2, while the treatment circuit 14 is dedicated to removing fluid from an outlet of this fuel cell 2.

[0077] At the outlet of fuel cell 2, the carbon dioxide-laden gases it emits contain, in addition to carbon dioxide, hydrogen, carbon monoxide, nitrogen, and water. These carbon dioxide-laden gases have a pressure of approximately one bar and a temperature of approximately 200 °C at the outlet of fuel cell 2. Here, "approximately" refers to pressure and temperature variations of plus or minus 10%.

[0078] The treatment circuit 14 connects the fuel cell 2, and more specifically its anode 6, to a heat exchanger 16 of the treatment system 1. This heat exchanger 16 is, for example, a heat recovery boiler 16. At the outlet of the heat recovery boiler 16, the carbon dioxide-laden gases have a pressure of approximately one bar and a temperature between 70 and 40 °C. The heat recovery boiler 16 is connected via the treatment circuit 14 to a compression device 18, in which some of the water present in the carbon dioxide-laden gases is discharged through a first water outlet 20. In the embodiments illustrated in the figures, the compression device 18 is connected to a drying device 22 of the treatment system 1, for example, a molecular sieve, from which the remaining water present in the carbon dioxide-laden gases is discharged through a second water outlet 24.It is understood from the above that the compression device 18 is here arranged on the treatment circuit 14 between the recovery boiler 16 and the drying device 22, that is to say that an inlet of the compression device 18 is connected to an outlet of the recovery boiler 16 while an outlet of this compression device 18 is connected to an inlet of the drying device 22.

[0079] Between the compression device 18 and the drying device 22, the carbon dioxide-laden gases have a pressure of approximately 30 bar and a temperature of approximately 40 °C. At the outlet of the drying device 22, the carbon dioxide-laden gases consist of carbon dioxide, hydrogen, carbon monoxide, and nitrogen, the water having been previously removed through the first and second water outlet pipes 20 and 24. In the embodiments presented here, the carbon dioxide-laden gases are conveyed by a main line 26 of the treatment circuit 14 from the drying device 22 to a condensation device 28. It is understood that the main line 26 connects the drying device 22 to the condensation device 28.

[0080] However, in embodiments not shown here, the compression device 18 may be a multi-stage compressor, or the treatment system 1 may comprise a plurality of compression devices 18. In such cases, the drying unit 22 is then arranged between two stages of the compression device 18, or between two compression devices 18. Each compression stage, due to the pressure increase, generates condensation of the water present in the carbon dioxide-laden gases. The combination of carbon dioxide and liquid water leads to a risk of corrosion. Therefore, arranging the drying unit 22 between two stages of the compression device 18, or between two compression devices 18, prevents corrosion by separating the liquid water generated during the compression stage.This also allows for cost optimization within the treatment system 1, since using a drying step prior to the compression steps would require, due to the large volumetric flow rates of the carbon dioxide-laden gases to be treated, bulky and expensive equipment.

[0081] The condensation device 28 comprises several stages and subunits which will be detailed later in relation to figures 2 to 8.

[0082] The condensing unit 28 is configured to cool the carbon dioxide present in the carbon dioxide-laden gases so that it changes state from a vapor to a liquid. For this purpose, the carbon dioxide-laden gases are cooled within the condensing unit 28; at the outlet of the condensing unit 28, they thus have a pressure of approximately 15 to 30 bar and a temperature between -40 and -55 °C. From the outlet of the condensing unit 28, the carbon dioxide-laden gases are conveyed to at least one device for separating the carbon dioxide from the remaining gases, hereinafter referred to as residual gases. The carbon dioxide-laden gases are first conveyed to a separator 30 and then to a purification unit 32; the separator 30 and the purification unit 32 together form a separation device within the treatment system 1.Separator 30 allows the separation of a liquid phase of carbon dioxide from a vapor phase of residual gases. Separator 30 is, for example, a separation vessel.

[0083] The separator 30 and the purification device 32 correspond to two stages of carbon dioxide separation, the separator 30 being arranged between the condensation device 28 and the purification device 32. The separator 30 constitutes a primary separation stage, which allows the separation within the gases charged with carbon dioxide of this carbon dioxide in liquid form and of the residual gases.

[0084] The purification device 32 constitutes a secondary separation stage, which purifies carbon dioxide by extracting the gases dissolved within the liquid carbon dioxide. Embodiments could also be considered in which the treatment system 1 comprises a single device for separating the carbon dioxide, i.e., a single separation stage, as will be described later.

[0085] The purification device 32 is, in particular, a distillation column. Within this purification device 32, the carbon dioxide pressure is between 7 and 15 bar. The purification device 32 is connected via the treatment circuit 14 to a storage device 34. The carbon dioxide is stored in liquid form in the storage device 34 at a pressure between 7 and 15 bar. In some embodiments, a subcooling device 36 is interposed between the purification device 32 and the storage device 34. If necessary, this subcooling device allows the carbon dioxide to be brought to a temperature compatible with the operation of the storage device 34, for example, a temperature between -50 °C and -25 °C.

[0086] As will be described later, the condensing unit 28 is configured to cool carbon dioxide-laden gases by exchanging heat with natural gas from storage tank 10. The natural gas is either liquefied, i.e., in a liquid state, or in the form of vapor, resulting from the evaporation of liquefied natural gas. Alternatively, the condensing unit 28 can operate by exchanging heat between the carbon dioxide-laden gases and another cooling source, for example, a refrigerant or nitrogen.

[0087] In cases where the condensing unit 28 cools carbon dioxide-laden gases using natural gas, it is understood that this natural gas is used within the condensing unit 28 before being used as fuel in the fuel cell 2. The condensing unit 28 here includes at least one condensing means 29, which corresponds to a subunit of the condensing unit 28. The supply circuit 12 connecting the storage tank 10 to the fuel cell 2 and the processing circuit 14 constitute two passes of the condensing means 29. Between the storage tank 10 and the condensing means 29, the natural gas has, for example, a pressure of approximately 4 bar and a temperature of approximately -160 °C. Between the condensing means 29 and the fuel cell 2, the natural gas has, for example, a pressure of approximately 3 bar and a temperature of approximately 40 °C.

[0088] In return for cooling the carbon dioxide-laden gases for the purpose of carbon dioxide capture, the condensation device 28 contributes to warming the natural gas, in particular for the purpose of supplying natural gas in gaseous form as fuel for the fuel cell 2.

[0089] In addition to the supply circuit 12 and the treatment circuit 14, the treatment system 1 includes a return circuit 38. This return circuit 38 connects the condensation device 28, and more specifically its condensation unit 29, to the fuel cell 2. The return circuit 38 thus channels the residual gases from the carbon dioxide-laden gases, either to supply them to the fuel cell 2 or to remove them from the ventilation system 1. The return circuit 38 has, for this purpose, a first branch connected to the fuel cell 2 and a second branch connected to an outlet of the ventilation system 1. At the outlet of the condensation unit 29, the residual gases have a pressure of approximately 4 bar and a temperature of approximately 40 °C.The return circuit 38 forms a pass of the recovery boiler 16, so that the residual gases exchange heat with the carbon dioxide-laden gases supplied to this recovery boiler 16 at the outlet of the fuel cell 2. At the outlet of the recovery boiler 16, the residual gases have a pressure of around 3 bar.

[0090] After passing through the heat recovery boiler 16, the waste gases can be supplied to the fuel cell 2 as fuel or recycled within the waste system 1. In this case, the waste gases circulate within the first branch of the return circuit 38, this first branch being connected to the fuel cell 2. Alternatively, some or all of the waste gases can be vented from the waste system 1 using a purge device 40. This purge device 40 is carried by the second branch of the return circuit 38, which is connected to an outlet of the waste system 1. The flow rate of the waste gases through this second branch and passing through the purge device 40 is controlled to optimize the operation of the fuel cell 2.For example, a percentage of the residual gases that are evacuated from the ventilation system 1 via the purge device 40 corresponds to 15% of the residual gases circulating within the return circuit 38. The use of the purge device 40 makes it possible in particular to avoid an accumulation of nitrogen within the ventilation system 1.

[0091] The dispersal system 1 is configured to implement a dispersal method for carbon dioxide-charged gases from the fuel cell 2 according to the invention, which will now be described.

[0092] The heating method includes a step of supplying the consumer, here the fuel cell 2, via the supply circuit 12. This step of supplying the fuel cell 2 can be broken down into a substep of supplying the cathode 4 with air that has passed through the compressor, and a substep of supplying the anode 6 with fuel prepared from the liquefied natural gas from the storage tank 10. For this purpose, the liquefied natural gas undergoes a heating step within the condensing device 28. This heating step consists of an exchange of heat with the carbon dioxide-laden gases, which will be described later. At the end of the heating step, the liquefied natural gas is transformed into natural gas in a gaseous state. Alternatively, the natural gas used for the heating stage can be natural gas in a gaseous state from storage tank 10.

[0093] Following the feeding stage, the treatment method includes a power generation stage during which the fuel cell 2 supplies electrical energy to the system it powers. This power generation stage results from redox reactions between the cathode 4 and the anode 6. This power generation stage also produces the effluents from the fuel cell 2, including carbon dioxide-rich gases emitted by the anode 6.

[0094] The carbon dioxide-laden gases are sent, via the treatment circuit 14, to the heat recovery boiler 16 where they undergo a cooling stage. The carbon dioxide-laden gases are then transferred, again via the exhaust circuit 14, to the compression unit 18 where a compression stage takes place. The compression stage is followed by a drying stage of the carbon dioxide-laden gases in the drying unit 22.In the aforementioned embodiments where the compression device 18 comprises several compression stages or where the treatment system 1 comprises a plurality of compression devices 18, the carbon dioxide-laden gases flow, in this order, within a first stage or first compression device 18, within the drying unit 22, and then within a second stage or second compression device 18. The compression stage(s) and the drying stage allow the removal of the water contained in the carbon dioxide-laden gases, which is discharged from the treatment system 1 respectively through the first water outlet duct 20 and the second water outlet duct 24.

[0095] The treatment method continues by capturing the carbon dioxide contained in the carbon dioxide-laden gases. To do this, the treatment method includes a step of condensing the carbon dioxide within the condensation device 28. This condensation step uses natural gas in liquid or gaseous form from the storage tank 10 as the cooling source.

[0096] The carbon dioxide-laden gases then undergo at least one separation stage. The carbon dioxide-laden gases undergo a first separation stage, or primary separation, within separator 30, which separates the carbon dioxide in liquid form from the residual gases in gaseous phase.

[0097] The liquid phase of carbon dioxide then undergoes a second separation stage, or secondary separation, within the purification device 32, which allows the liquid carbon dioxide to be separated from the residual gases that are dissolved within it.

[0098] The treatment method finally includes a step of storing carbon dioxide in liquid form in the storage device 34. Optionally, the treatment method includes a subcooling step within the subcooling device 36 between the separation step, where applicable the second separation step, and the storage step.

[0099] It should be noted that the condensation step can be implemented in different ways depending on the various possible configurations of the condensation device 28. Different embodiments of the treatment system 1 according to the invention will now be described with respect to figures 2 to 8, in particular to detail the operation of this condensation device 28.

[0100] Figures 2 to 4 show variants of a first embodiment of the treatment system 1, in which the treatment system 1 comprises only a device for separating carbon dioxide, here only the purification device 32. The separation device of the treatment system 1 then corresponds solely to the purification device 32. Figures 5 to 8 illustrate variants of a second embodiment in which the treatment system 1 comprises both the separator 30 and the purification device 32. The separation device of the treatment system 1 then corresponds to an assembly formed by the separator 30 and the purification device 32. It should be noted that, unless otherwise stated or in the event of a manifest incompatibility, the characteristics described in relation to one of the variants or embodiments are applicable, mutatis mutandis, to other variants or embodiments.

[0101] A first variant of the first embodiment will now be detailed with reference to Figure 2. In this variant, the condensation means 29 has four passes. Among these four passes, the condensation means 29 includes a primary pass 42 which is configured to carry the carbon dioxide-laden gases from the drying device 32. Thus, the primary pass 42 forms part of the main line connecting this drying device 32 to the condensation means 29.

[0102] The primary pass 42 is configured to exchange heat with the other passes. Therefore, the other passes of the condensing unit 29 are configured to cool the carbon dioxide-laden gases circulating in the primary pass 42. As part of these passes configured to cool the carbon dioxide-laden gases circulating in the primary pass 42, the condensing unit 29 includes a cooling pass 44 which is configured to channel, as appropriate, the natural gas in liquid form from the storage tank 10, the natural gas in vapor form from the storage tank 10, or the refrigerant.In addition to this cooling pass 44, the passes configured to cool the carbon dioxide-laden gases circulating in the primary pass 42 include a first pass 46 and a second pass 48, both of which are configured to channel fluids that have passed through the primary pass 42 and at least one other component of the treatment system 1. In other words, these fluids correspond to the carbon dioxide-laden gases once they have been treated within at least one other component of the treatment system 1, for example the purification device 32. Thus, these fluids correspond, for example, to the residual gases separated from the carbon dioxide, or to the carbon dioxide separated from the residual gases.

[0103] In Figure 2, the first pass 46 is configured to receive the residual gases from the purification device 32. The purification device 32 is therefore located between the primary pass 42 and the first pass 46. Once they have passed through this first pass 46, the residual gases circulate within the return circuit 38 and are thus directed, depending on the case, to the purge device 40 or to the fuel cell 2. The return circuit 38 includes a pressure-reducing valve 49 located on the first branch of the return circuit 38, between the condensing element 29 of the condensing device 28 and the fuel cell 2. The pressure-reducing valve 49 allows adjustment of the pressure of the residual gases returned to the fuel cell 2.

[0104] A portion of the carbon dioxide that has been separated from the residual gases within the purification device 32 is sent to the storage device 34.

[0105] Notably, in the first variant of the first embodiment, the treatment circuit 14 includes a bypass line 58 of the condensing unit 29, and more specifically of its primary pass 42. This bypass line 58 is connected on one side to the main line 26 between the drying unit 22 and the condensing unit 29, and on the other side to a heat exchanger 50 of the purification unit 32. This heat exchanger is a reboiler. The carbon dioxide-laden gases traveling along the bypass line 58 are, after passing through the heat exchanger 50, returned to the condensing unit 29, where they are channeled into a dedicated pass 60.The carbon dioxide-laden gases circulating within the primary pass 42 and the carbon dioxide-laden gases circulating within the dedicated pass 60 are then mixed within a pipe of the treatment circuit 14 connecting the primary pass 42 of the condensing unit 29 to the purification device 32. The second pass 48 is configured here to be fed by liquid from the bottom of the purification device 32. This is possible thanks to the presence of the bypass line 58, which allows a portion of the carbon dioxide-laden gases to be drawn off and cooled by the liquid present at the bottom of the purification device 32. This portion of the carbon dioxide-laden gases then passes through the heat exchanger 50 and then through the dedicated pass 60 before being mixed with the carbon dioxide-laden gases that have passed through the primary pass 42.

[0106] Thus, in the first variant of the first embodiment of Figure 2, the carbon dioxide-laden gases circulating in the primary pass 42 exchange heat on the one hand with the cooling pass 44 which channels the natural gas from the storage tank 10, on the other hand with the first pass 46 which channels the separated residual gases within the purification device 32, and finally with the second pass 48 which channels carbon dioxide from the heat exchanger 50 of the purification device 32. It should be noted that the carbon dioxide circulating within the second pass 48 is recycled to the purification device 32; in other words, the second pass 48 is connected to this purification device 32 by at least one line of the treatment circuit 14.

[0107] A second variant of the first embodiment is detailed in Figure 3. In this second variant, the treatment circuit 14 of the treatment system 1 includes an intermediate fluid heat exchanger 52. The intermediate fluid heat exchanger 52 is a subunit of the condensing device 28, as is the condensing unit 29. The intermediate fluid heat exchanger 52 includes a primary layer 54 configured to carry the gases that have flowed through the primary pass 42 of the condensing unit 29, i.e., the gases containing carbon dioxide. The intermediate fluid heat exchanger 52 also includes a layer configured to cool the carbon dioxide-laden gases flowing through the primary layer 54, which is a cooling layer 56. This cooling layer 56 is configured to carry the natural gas in vapor or liquid form, or the refrigerant.Carbon dioxide-laden gases circulating in the primary layer 54 and natural gas or refrigerant circulating in the cooling layer 56 exchange heat through an intermediate fluid confined within the intermediate fluid exchanger 52. For example, this intermediate fluid has a phase change temperature between -56 and -45 °C.

[0108] In this second variant of the first embodiment, the condensation unit 29 has the primary pass 42, the cooling pass 44 and the first pass 46 connected as they were described in relation to the first variant of Figure 2. The cooling pass 44 of the condensation unit 29 is connected to the cooling layer 56 of the intermediate fluid heat exchanger by a conduit of the treatment circuit 14. Similarly, the primary pass 42 of the condensation unit 29 is connected to the primary layer 54 of the intermediate fluid heat exchanger by a conduit of the treatment circuit 14.

[0109] As was the case for the first variant of the first embodiment, in the second variant of the first embodiment, the treatment circuit 14 includes the bypass line 58 of the primary pass 42 of the condensation means 29 which is connected on the one hand to the main line 26 between the drying device 22 and the condensation means 29 and on the other hand connected to the heat exchanger 50 of the purification device 32. The carbon dioxide-laden gases which take this bypass line 58 are, after passing through the heat exchanger 50, returned to the condensation means 29 within which they are channeled into the dedicated pass 60.The carbon dioxide-laden gases circulating within the primary pass 42 and the carbon dioxide-laden gases circulating within the dedicated pass 60 are then mixed within the conduit of the treatment circuit 14 linking the primary pass 42 of the condensation unit 29 to the primary layer 54 of the intermediate fluid exchanger 52.

[0110] A third variant of the first embodiment is illustrated in Figure 4. In this third variant, the treatment system 1 is devoid of the intermediate fluid exchanger 52 mentioned in relation to the second variant of Figure 3. Compared with the first and second variants, the third variant retains the primary pass 42, the cooling pass 44 and the second pass 48 as described above.

[0111] Like the first variant and the second variant, the treatment system 1 according to the third variant has the bypass line 58 which allows a portion of the gases charged with carbon dioxide to be circulated to the heat exchanger 50 of the purification device 52 before this portion is returned to the dedicated pass 60 of the condensation means 29.

[0112] The third variant differs from the first variant in Figure 2 in that the first pass 46 of the condensing unit 29 is not directly connected to the return circuit 38 at the outlet of this condensing unit 29. In the third variant, the treatment circuit 14 includes an expansion circuit 62 connected to the first pass 46 of the condensing unit 29. This expansion circuit 62 is designed to utilize the pressure of the decarbonized gases for cooling purposes, through isentropic expansion. To this end, the expansion circuit 62 includes an expansion device 64, for example, a turbine, in which the isentropic expansion takes place.

[0113] The expansion circuit 62 forms a loop around the condensing unit 29. Thus, it is connected on one side to the first pass 46 and on the other side to a third pass 66 of the condensing unit 29, this third pass 66 being one of the passes configured to cool the carbon dioxide-laden gases circulating in the primary pass 42. The expansion device 64 is therefore located between the first pass 46 and the third pass 66. Consequently, in the third variant, the residual gases separated within the purification device 32 circulate within the first pass 46, then within the expansion circuit 62 in which they are released via the expansion device 64, then within the third pass 66 of the condensing unit 29, and finally within the return circuit 38.

[0114] Thus, in the third variant of the first embodiment of Figure 4, the carbon dioxide-laden gases circulating in the primary pass 42 exchange heat with the cooling pass 44 which channels the natural gas from the storage tank 10; with the first pass 46 which channels the residual gases separated within the purification device 32; with the second pass 48 which channels carbon dioxide from the heat exchanger 50 of the purification device 32; and with the third pass 66 which channels the residual gases which have been released by the expansion device 64.

[0115] The second embodiment of the treatment system 1 will now be derailed with respect to figures 5 to 7. As a reminder, this second embodiment includes both the separator 30 and the purification device 32.

[0116] A first variant of the second embodiment is shown in Figure 5. In this first variant, the condensation means 29 comprises four passes, among which the primary pass 42 channels the carbon dioxide-laden gases from the main line 26 connecting the drying device 22 to the condensation means 29. The condensation means 29 also comprises, at the level of its passes configured to cool the carbon dioxide-laden gases circulating in the primary pass 42, the cooling pass 44 which channels the natural gas from the storage tank 10 or the refrigerant.

[0117] As can be seen in Figure 5, the primary pass 42 is connected to the separator 30, which is configured to separate the liquid phase carbon dioxide from the vapor phase of the waste gases. The separator 30 is connected to the primary pass 42 by a line from the treatment circuit 14. The separator 30 is further connected to the condenser 29 by a fluid circulation line to the vapor separator 68, configured to channel the vapor phase of the waste gases, and by a circulation line 70, configured to channel carbon dioxide to the liquid separator from the separator 30.

[0118] The fluid circulation line to the vapor separator 68 is connected to the first pass 46 of the condensing unit 29, which is itself connected to the return circuit 38. The carbon dioxide circulation line 70 to the liquid separator is connected to a secondary pass 72 of the condensing unit 29. This secondary pass 72 is therefore dedicated to the circulation of the liquid phase of carbon dioxide. The secondary pass 72 of the condensing unit 29 is connected to the purification device 32. Thus, the secondary pass 72 is located between the separator 30 and the purification device 32. Furthermore, as illustrated here, a pressure-reducing valve can be installed on a line of the treatment circuit 14 connecting the secondary pass 72 to the purification device 32.

[0119] In the first variant of the second embodiment, the treatment circuit 14 includes the bypass line 58 of the primary pass 42 of the condensing unit 29. However, unlike what was described in relation to the first embodiment, this bypass line 58 is not connected to a dedicated pass 60 of the condensing unit 29; rather, it bypasses the condensing unit 29. It is thus connected downstream of the condensing unit 29 to the conduit of the treatment circuit 14 which connects this condensing unit 29 to the separator 30. Such a connection of the bypass line 58 occurs after a heat exchange with the heat exchanger 50 of the purification device 32.

[0120] In Figure 5, the residual gases separated within the purification device 32 are not returned to the condensation unit 29. It is thus understood that the residual gases circulate within a bypass line 73 of the treatment circuit 14 which directly connects the purification device 32 to the return circuit 38, i.e. which bypasses the condensation unit 29. The carbon dioxide in liquid form separated from the residual gases within the purification device 32 is here sent to the storage unit 34.

[0121] In a second variant of the second embodiment illustrated in Figure 6, the treatment system 1 includes the expansion circuit 62. This expansion circuit 62 here includes the expansion member 64 as well as an expansion element 74. The expansion member 64 is, for example, a first turbine of the expansion circuit 62 while the expansion element 74 is a second turbine of this expansion circuit 62.

[0122] In the second variant of Figure 6, the condensation means 29 has the primary pass 42, the secondary pass 72 and the cooling pass 44 as described in the first variant of the second embodiment of Figure 5.

[0123] However, contrary to what was described in relation to Figure 5, the first pass 46, configured to cool the carbon dioxide-laden gases circulating in the primary pass 42, is connected first to the expansion circuit 62, then to the return circuit 38. More precisely, in this second variant, the fluid circulation line to the steam generator 68 is connected to the first pass 46 of the condensing unit 29, which is itself connected to a first loop 61 of the expansion circuit 62 carrying the expansion element 64. This first loop 61 of the expansion circuit 62 carrying the expansion element 64 is connected to the third pass 66 of the condensing unit 29, which is itself connected to a second loop 63 of the expansion circuit 62 carrying the expansion element 74. This second loop 63 of the expansion circuit 62 carrying the expansion element 74 is connected to a fourth pass 76 of the condensation means

[0124] 29 which is itself connected to the return circuit 38. It is thus understood that the expansion member 64 and the expansion element 74 are both arranged between two passes of the condensation unit 29 configured to cool the carbon dioxide-laden gases circulating in the primary pass 42. It should be noted that in this second variant, due to the diversion line 73 of the treatment circuit 14 which directly connects the purification device 32 to the return circuit 38 without passing through the condensation unit 29, this condensation unit 29 is devoid of the second pass 48 which was described previously.

[0125] Thus, in the second variant of the second embodiment of Figure 6, the carbon dioxide-laden gases circulating in the primary pass 42 exchange heat with the cooling pass 44, which channels the natural gas from the storage tank 10; and with the first pass 46, which channels the residual gases separated within the separator.

[0126] 30; with the third pass 66 which channels the residual gases which have been released by the expansion member 64; and with the fourth pass 76 which channels the residual gases which have been released by the expansion element 74. This successive double expansion allows for more efficient cooling of the carbon dioxide-laden gases circulating in the primary pass 42.

[0127] A third variant of the second embodiment will now be explained with reference to Figure 7. This third variant differs from the second variant illustrated in Figure 6 in that the treatment system 1 here includes the intermediate fluid heat exchanger 52. The intermediate fluid heat exchanger 52 comprises the primary layer 54, which is configured to channel the gases that have flowed through the primary pass 42 of the condensing unit 29, and the cooling layer 56, which is configured to channel the natural gas in vapor or liquid form, or the refrigerant, as described previously in the first embodiment. The cooling layer 56 is connected to the cooling pass 44 of the condensing unit 29.

[0128] In this figure 7, the separator 30 is arranged between the primary layer 54 of the intermediate fluid exchanger 52 and a secondary layer 78 of this intermediate fluid exchanger 52. The secondary layer 78 is arranged between the separator 30 and the purification device 32, and more specifically between the liquid fluid circulation line 70 of the separator 30 and the purification device 32. The secondary layer 78 is thus configured to channel the liquid phase of the carbon dioxide that has been separated from the residual gases in the gaseous phase, within the separator 30.

[0129] Just as described for the second variant in Figure 6, in the third variant, the residual gases separated within the purification device 32 circulate within the bypass line 73 of the treatment circuit 14 which bypasses the condensation means 29 to connect directly to the return circuit 38.

[0130] In the third variant of the second embodiment, the vapor fluid circulation line 68 is connected to the first pass 46 of the condensing unit 29, which is itself connected to the expansion circuit 62. More specifically, the first pass 46 of the condensing unit 29 is connected to the first loop 61 of the expansion circuit 62, which carries the expansion element 64. This first loop 61 of the expansion circuit 62, carrying the expansion element 64, is connected to the third pass 66 of the condensing unit 29, which is itself connected to the second loop 63 of the expansion circuit 62, which carries the expansion element 74. This second loop 63 of the expansion circuit 62, which carries the expansion element 74, is connected to a temperature-reducing layer 80 of the intermediate fluid heat exchanger 52.This temperature-lowering layer 80 is configured, together with the cooling layer 56, to cool the carbon dioxide-laden gases circulating within the primary layer 54, as well as the liquid phase of carbon dioxide circulating within the secondary layer 78, via the intermediate fluid contained in the intermediate fluid exchanger 52. The temperature-lowering layer 80 is connected to the fourth pass 76 of the condensing unit 29, which is itself connected to the return circuit 38. Here, as in the second variant, the condensing unit 29 does not have a second pass 48 as described above, since the bypass line 73 directly connects the purification device 32 to the return circuit 38, bypassing the condensing unit 29.

[0131] Within the intermediate fluid heat exchanger 52, it is understood that the fluids circulating within the primary layer 54 and the secondary layer 78 exchange heat with the intermediate fluid, thereby lowering their temperature. Conversely, the fluids circulating within the cooling layer 56 and the temperature-reducing layer 80 exchange heat with the intermediate fluid, thereby raising their temperature.

[0132] Thus, in the third variant of the second embodiment of Figure 7, the carbon dioxide-laden gases circulating in the primary pass 42 exchange heat with the cooling pass 44, which channels the natural gas from the storage tank 10, this natural gas having been previously heated in the cooling layer 56 of the intermediate fluid exchanger 52; with the first pass 46, which channels the separated residual gases within the separator 30; with the third pass 66, which channels the residual gases that have been expanded by the expansion element 64; and with the fourth pass 76, which channels the residual gases that have been expanded by the expansion element 74 and that have been heated in the temperature reduction layer 80 of the intermediate fluid exchanger 52. In this embodiment, the intermediate fluid exchanger 52 is an exchanger with at least four layers.

[0133] Figure 8 illustrates a fourth variant of the second embodiment. In this figure 8, the treatment system 1 shows the intermediate fluid heat exchanger 52. The intermediate fluid heat exchanger 52 here comprises the primary layer 54 which is configured to channel the gases that have flowed through the primary pass 42 of the condensing unit 29, as well as the cooling layer 56 which is configured to channel the natural gas to the vapor or liquid gas or the refrigerant before their passage through the cooling pass 44 of the condensing unit 29.

[0134] In this fourth variant, the fluid circulation line to the steam generator 68 is connected to the first pass 46 of the condensing unit 29, which is itself connected to the expansion circuit 62. More specifically, the first pass 46 of the condensing unit 29 is connected to the first loop 61 of the expansion circuit 62, which carries the expansion element 64. This first loop 61 of the expansion circuit 62, carrying the expansion element 64, is connected to the third pass 66 of the condensing unit 29, which is itself connected to the second loop 63 of the expansion circuit 62, which carries the expansion element 74. Unlike the third variant of the second embodiment, in the fourth variant, the second loop 63 of the expansion circuit 62, which carries the expansion element 74, is not connected to the temperature-reducing layer 80. not present in the fourth variant.Rather, the second loop 63 of the expansion circuit 62 which carries the expansion element 74 is connected to the fourth pass 76 of the condensation means 29, which is itself connected to the return circuit 38.

[0135] Thus, in the fourth variant of the second embodiment of Figure 8, the carbon dioxide-laden gases circulating in the primary pass 42 exchange heat with the cooling pass 44 which channels the natural gas from the storage tank 10, this natural gas having previously been heated in the cooling layer 56 of the intermediate fluid exchanger 52; with the first pass 46 which channels the residual gases separated within the separator 30; with the third pass 66 which channels the residual gases which have been released by the expansion element 64; and with the fourth pass 76 which channels the residual gases which have been released by the expansion element 74.

[0136] In this fourth variant of the second embodiment, the intermediate fluid heat exchanger 52 is a heat exchanger with at least three layers. A specific configuration of the intermediate fluid heat exchanger is possible when the outlet temperature of the expansion element 74 is above the freezing point of carbon dioxide, i.e., above -56 °C. If, on the other hand, the outlet temperature of the expansion element 74 is below -56 °C, additional cooling is required within the intermediate fluid heat exchanger 52 using the temperature-reducing layer 80, as described in the third variant of the second embodiment shown in Figure 7.

[0137] Of course, and as mentioned above, it is possible, without departing from the scope of the invention, to associate features described in relation to one of the variants or embodiments with features described in relation to another variant or embodiment. By way of example, it is possible to consider variants of the first embodiment that would include both the detent member 64 and the detent element 74 within the detent circuit 62, or conversely, variants of the second embodiment comprising only the detent member 64 in the detent circuit 62.

[0138] The present invention thus proposes a system and a method for treating carbon dioxide-laden gases from a consumer which do not require post-combustion of these carbon dioxide-laden gases.

[0139] The present invention is not limited to the means and configurations described and illustrated herein, and also extends to any equivalent means and configuration as well as any technically operative combination of such means.

Claims

DEMANDS 1. System for treating (1) gases charged at least with carbon dioxide and emitted by a consumer, comprising a liquefied natural gas storage tank (10), a consumer configured to be supplied with a fuel produced from liquefied natural gas stored in the storage tank (10), a device for compressing the carbon dioxide-charged gases, a device for drying (22) these carbon dioxide-charged gases, a device for condensing (28) the carbon dioxide present in the carbon dioxide-charged gases and a device for separating (30, 32) the carbon dioxide present in the gases emitted by the consumer, the condensation device (28) being disposed between the drying device (22) and the separation device (30, 32).

2. Processing system (1) according to claim 1, wherein the condensation device (28) is configured to carry out heat exchange between the carbon dioxide-laden gases and at least natural gas in liquid form and / or natural gas in vapor form, this natural gas being from the storage tank (10).

3. Processing system (1) according to any one of claims 1 or 2, wherein the condensation device (28) comprises a condensation means (29) and an intermediate fluid exchanger (52) arranged in series with the condensation means (29), the intermediate fluid having a phase change temperature between -56 °C and -45 °C.

4. Treatment system (1) according to any one of claims 1 to 3, comprising a storage device (34) for carbon dioxide in liquid form.

5. Processing system (1) according to any one of claims 1 to 4, wherein the consumer is a fuel cell (2) comprising an anode (6) and a cathode (4), the compression device (18) and the drying device (22) being configured to process carbon dioxide-laden gases emitted at the anode (6).

6. Processing system (1) according to claim 5, comprising at least one return circuit (38) connecting the condensation device (28) to the fuel cell (2) and configured to channel residual gases separated by the separation device (30, 32).

7. Processing system (1) according to any one of claims 1 to 6 in combination with claim 3, wherein the condensation means (29) comprises a primary pass (42) configured to be used by carbon dioxide-laden gases and a plurality of passes (44, 46, 48, 66, 76) configured to cool the carbon dioxide-laden gases flowing through the primary pass (42).

8. Processing system (1) according to claim 7, comprising an expansion circuit (62) including at least one expansion member (64) disposed between two of the passes (44, 46, 48, 66, 76) of the condensation means (29) configured to cool the carbon dioxide-laden gases circulating in the primary pass (42).

9. Processing system (1) according to any one of claims 7 to 8, wherein the separation device (30, 32) is disposed between the primary pass (42) and one of the passes (44, 46, 66, 76) of the condensation means (29) configured to cool the carbon dioxide-laden gases circulating in the primary pass (42).

10. Processing system (1) according to any one of claims 1 to 9 in combination with claim 8, wherein the condensation means (29) comprises at least three passes (44, 46, 66, 76) configured to cool the carbon dioxide-laden gases circulating in the primary pass (42), the expansion circuit (62) comprising at least one expansion element (74) disposed between two of the passes (44, 46, 66, 76) of the condensation means (29) configured to cool the carbon dioxide-laden gases circulating in the primary pass (42).

11. Treatment system (1) according to any one of claims 1 to 10, wherein the separation device (30, 32) comprises a purification device (32) and a separator (30), the separator (30) being disposed between the condensation device (28) and the purification device (32), the separator (30) being configured to operate a separation between a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer and a vapor phase comprising mainly residual gases present in the gases emitted by the consumer.

12. Processing system (1) according to claim 11 in combination with claim 7, wherein the separator (30) is disposed between the primary pass (42) and one of the passes (44, 46, 48, 66, 76) configured to cool the carbon dioxide-laden gases circulating in the primary pass (42).

13. Treatment system (1) according to any one of claims 1 to 12 in combination with claims 7 and 11, wherein the condensation means (29) comprises a secondary pass (72) disposed between the separator (30) and the purification device (32), said secondary pass (72) being configured to be used by a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer.

14. Processing system (1) according to any one of claims 1 to 13 in combination with claims 7 and 11, comprising a bypass line (58) of the primary pass (42) of the condensation means (29), the purification device (32) comprising a heat exchanger (50) configured to implement heat exchange between the liquid carbon dioxide present in the purification device (32) and the gases charged at least with carbon dioxide.

15. Processing system (1) according to any one of the preceding claims in combination with claims 3 and 7, wherein the intermediate fluid exchanger (52) is configured to operate a heat exchange between the gases having flowed through the primary pass (42) and at least the fuel produced from liquefied natural gas stored in the storage tank (10).

16. Treatment system (1) according to any one of the preceding claims in combination with claim 8, wherein the intermediate fluid exchanger (52) comprises at least one layer (80) configured to be traversed by the fluid circulating in the expansion circuit (62).

17. A treatment system (1) according to any one of the preceding claims in combination with claims 7 and 11, wherein the intermediate fluid heat exchanger (52) comprises a primary layer (54) configured to be traversed by the gases having flowed through the primary pass (42) of the condensing means (29) and a secondary layer (78) disposed between the separator (30) and the purification device (32), said secondary layer (78) being configured to be used by a liquid phase comprising mainly carbon dioxide present in the gases emitted by the consumer.

18. Processing system (1) according to any one of claims 1 to 17, wherein the fuel cell (2) is a solid oxide fuel cell.

19. Method of treating gases charged at least with carbon dioxide emitted by a fuel cell (2) using a treatment system (1) according to any one of claims 1 to 18 in combination with claim 5, comprising a step of supplying the fuel cell (2) with air and a fuel made from liquefied natural gas, a step of compressing the carbon dioxide-charged gases from the fuel cell (2), a step of drying the compressed carbon dioxide-charged gases, a step of condensing the carbon dioxide contained in the dried carbon dioxide-charged gases, and at least one step of separating the condensed carbon dioxide from the other gases contained in the gases emitted by the consumer.

20. Treatment method according to claim 19, comprising a step of storing carbon dioxide in liquid form following the separation step.

21. A treatment method according to any one of claims 19 and 20, comprising an additional step of compressing the carbon dioxide-laden gases, the additional compression step occurring between the drying step and the condensation step.

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