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

Abstract

The present invention relates to a system (1) for treating carbon dioxide-laden gases, comprising a liquefied natural gas storage tank, a consumer supplied with natural gas, a device (28) for condensing carbon dioxide and a device for separating carbon dioxide, the condensing device (28) comprising a first heat exchanger (40) comprising a plurality of passages (44, 52, 72), a second heat exchanger (42) comprising a plurality of layers (46, 54), and a cooling loop (36) comprising a first branch (48) and a second branch (50) that are parallel, the first branch (48) comprising a passage (52) of the first heat exchanger (40) and the second branch (50) comprising a layer (54) of the second heat exchanger (42).

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 used 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 capture carbon dioxide cryogenically, for example by condensing the carbon dioxide contained in exhaust gases. However, depending on the fluid chosen to condense the carbon dioxide, there is a risk of the carbon dioxide freezing, which could lead to malfunction or even damage to the condensation equipment.

[0009] The present invention aims to overcome this drawback by providing an exhaust gas treatment system that allows the condensation of carbon dioxide present in these exhaust gases without risk of damage to the system equipment. Advantageously, the treatment system incorporates a fluid loop that acts as an intermediary between liquefied natural gas, used as a cooling source for condensation, and the exhaust gases. The presence of this fluid loop prevents the carbon dioxide in the exhaust gases from freezing.

[0010] The present invention thus has as its main object a system for treating gases charged at least with carbon dioxide and emitted by a consumer, comprising a liquefied natural gas storage tank, a consumer configured to be supplied with a fuel produced from natural gas stored in the storage tank and a device for condensing the carbon dioxide present in the gases charged with carbon dioxide, the condensing device comprising a first heat exchanger having a plurality of passes, a second heat exchanger having a plurality of layers, and a cooling loop comprising a first branch and a second branch parallel to each other, the first branch comprising a pass of the first heat exchanger and the second branch comprising a layer of the second heat exchanger.The treatment system according to the invention is configured to treat 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, and could be, in particular, a fuel cell. Within the treatment system, the carbon dioxide present in the carbon dioxide-laden gases is captured by condensation, this condensation being carried out within a condensation device of the treatment system. The carbon dioxide is then separated from the remaining exhaust gases using a carbon dioxide separation device. This separation device extracts any gases dissolved in the liquid phase of the carbon dioxide.

[0011] The condensing unit consists of at least two heat exchangers, including a first heat exchanger and a second heat exchanger. The first heat exchanger includes at least one pass configured to channel carbon dioxide-laden gases, and similarly, the second heat exchanger includes at least one layer configured to channel carbon dioxide-laden gases. The first heat exchanger may be a gas cooler or a condenser, while the second heat exchanger is a condenser.

[0012] The first and second heat exchangers are connected via a cooling loop through which a coolant circulates. The heat exchangers are configured to exchange heat between the carbon dioxide-laden gases and this coolant, thereby condensing the carbon dioxide present in the gases. Using a cooling loop allows for the selection of a coolant with a temperature compatible with the cooling source, such as liquefied natural gas, and also suitable for cooling without freezing the carbon dioxide within the heat exchangers, as such freezing could clog them.

[0013] The first heat exchanger is configured to pre-cool the carbon dioxide-laden gases and potentially partially condense the carbon dioxide present in them, while the second heat exchanger is configured to condense the carbon dioxide present in the same gases. The cooling loop has two parallel branches, each dedicated to supplying one of the two heat exchangers. These two parallel branches allow for adjusting the flow rate within each heat exchanger, depending on its function: pre-cooling or condensation. Modifying the flow rate between the two heat exchangers allows for adjusting the required cooling temperature for each, preventing temperature crossover between them.

[0014] The plurality of passes in the first heat exchanger includes at least one hot pass and at least two cold passes, the cold passes being intended to cool the hot pass.

[0015] According to an optional feature of the invention, the condensation device includes a heat exchanger configured to perform a heat exchange between a cooling fluid circulating within the cooling loop and at least natural gas in liquid form and / or natural gas in vapor form and / or a refrigerant separate from natural gas in liquid form and natural gas in vapor form, this natural gas being taken from the storage tank.

[0016] The cooling fluid cools the carbon dioxide-laden gases circulating within the first heat exchanger and the second heat exchanger, and this cooling fluid discharges its heat into the natural gas in liquid form and / or the natural gas in vapor form.

[0017] Within the condensing unit, carbon dioxide-laden gases exchange heat either with natural gas in its liquid state only, with natural gas in its vapor state only, or with both simultaneously. Natural gas in its vapor state, for example, is a gas resulting from the natural evaporation of liquefied natural gas, also known as boil-off gas (BOG). It is understood here that the natural gas from the tank is intended both to indirectly condense the carbon dioxide, via the cooling fluid loop, and to supply the consumer.

[0018] As an alternative or in addition to liquefied natural gas (LNG) in its liquid state and liquefied natural gas in its vapor state, carbon dioxide-rich gases can exchange heat with another refrigerant. This refrigerant could be, for example, ethane, propane, or another fluid with an operating temperature between -56 and -60 °C. The refrigerant might, for example, come from a refrigeration system.

[0019] According to an optional feature of the invention, the heat exchanger of the condensation device comprises a first line and a second line, the first branch of the cooling loop forming the first line and the second branch of the cooling loop forming the second line.

[0020] Both the first and second lines of the heat exchanger are configured to channel the cooling fluid. Each of the first and second lines is capable of recovering cold from the natural gas circulating in another pass of the heat exchanger.

[0021] According to an optional feature of the invention, the cooling loop includes a means for distributing the cooling fluid between the first branch and the second branch of the cooling loop.

[0022] The distribution system allows control of the cooling fluid flow within each of these branches.

[0023] In some embodiments, the distribution means comprises a first valve located on the first branch and a second valve located on the second branch. Alternatively, the distribution means comprises a three-way valve located at a separation point between the first and second branches. In other embodiments, the distribution means consists of a restriction on one or both of the pipes forming the first or second branch.

[0024] According to an optional feature of the invention, the treatment system includes a device for compressing gases charged with carbon dioxide and a device for drying these gases charged with carbon dioxide, the compression device and the drying device being fluidly arranged between an outlet of the consumer and an inlet of the condensation device, the treatment system including a device for separating the carbon dioxide present in the gases emitted by the consumer, the first heat exchanger and the second heat exchanger being fluidly arranged between an outlet of the drying device and an inlet of the separation device.

[0025] The treatment system allows the carbon dioxide-laden gases emitted by the consumer to be successively compressed, dried and condensed, respectively using a compression device, a drying device and a condensation device.

[0026] The drying device, the first heat exchanger, the second heat exchanger and the separation device are arranged in this order according to a direction of flow of gases charged with carbon dioxide.

[0027] According to an optional feature of the invention, the first heat exchanger includes a first pass configured to be used by carbon dioxide-laden gases and a plurality of other passes configured to cool the carbon dioxide-laden gases flowing through the first pass of the first heat exchanger, including the pass of the first heat exchanger included in the first branch of the cooling loop.

[0028] Carbon dioxide-laden gases flow through the first heat exchanger in the first pass, which is the section requiring cooling. To achieve this, the first heat exchanger has at least two passes configured to cool the carbon dioxide-laden gases. The first heat exchanger includes at least one pass supplied by the cooling fluid circulating within the cooling loop, 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 in the first pass.

[0029] According to an optional feature of the invention, the treatment system includes a cooling circuit comprising at least two of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass of the first heat exchanger.

[0030] According to an optional feature of the invention, the cooling circuit includes at least one expansion device disposed between the two passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass of the first heat exchanger included in the cooling circuit.

[0031] The cooling circuit is configured to lower the pressure of the fluid circulating within it, and consequently its temperature. The expansion device is, for example, a turbine.

[0032] According to an optional feature of the invention, the separation device is fluidly arranged between an outlet of the second heat exchanger and an inlet of one of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass.

[0033] Thus, the gases circulating in the pass configured to cool the carbon dioxide-laden gases from the first heat exchanger correspond to residual gases extracted by the separation device.

[0034] According to an optional feature of the invention, the first heat exchanger comprises at least three passes configured to cool the carbon dioxide-laden gases circulating in the first pass of the first heat exchanger, the cooling circuit comprising at least one expansion element disposed between two of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass.

[0035] The expansion element corresponds, for example, to a second turbine in the cooling circuit, which supplements the expansion element.

[0036] According to an optional feature of the invention, the second heat exchanger includes a first layer configured to be used by the carbon dioxide-laden gases and at least the layer included in the second branch of the cooling loop, the layer included in the second branch of the cooling loop being configured to cool the carbon dioxide-laden gases circulating in the first layer of the second heat exchanger.

[0037] Carbon dioxide-laden gases circulate in the second heat exchanger within the first layer, which corresponds to a layer that needs to be cooled. To achieve this, the second heat exchanger presents at least the layer supplied by the cooling fluid circulating within the cooling loop.

[0038] According to an optional feature of the invention, the separation device comprises at least one separator and one purifier, the separator being fluidly arranged between an outlet of the condenser and an inlet of the purifier. Within the separation device, the separator constitutes a primary carbon dioxide separation stage, while the purifier forms a secondary separation stage. The primary separation stage is designed to recover carbon dioxide in liquid form from residual gases in vapor form. Conversely, the secondary separation stage purifies the carbon dioxide in liquid form by extracting gases still dissolved in the liquid carbon dioxide phase present at the outlet of the primary separation stage. The separator is, for example, a separation flask, while the purifier is, for example, a distillation column.The separator is fluidly arranged between an outlet of the second heat exchanger and an inlet of the purifier. According to an optional feature of the invention, the separator is 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, the treatment system comprising a fluid circulation line in the liquid state connecting the separator to the purifier and forming a layer of the second heat exchanger.

[0039] The layer of the second heat exchanger through which the liquid phase from the separator flows is distinct from the first layer configured to be used by the gases charged with carbon dioxide and from the layer included in the second branch configured to cool the gases charged with carbon dioxide circulating in the first layer.

[0040] The layer of the second heat exchanger through which the liquid phase, consisting mainly of carbon dioxide and originating from the separator, flows is configured to subcool said liquid phase by exchange with the cooling fluid circulating in another layer of the second heat exchanger. According to an optional feature of the invention, the separation device comprises at least one separator and one purifier, the separator being fluidly arranged between an outlet of the first layer of the second heat exchanger and an inlet of one of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass of the first heat exchanger.

[0041] Thus, within the first heat exchanger, the gases circulating in the pass configured to cool the carbon dioxide-laden gases circulating in the first pass correspond to the vapor phase, mainly consisting of residual gases, and separated by the separator.

[0042] According to an optional feature of the invention, the separation device comprises at least one separator and one purifier, the separator being fluidly disposed between an outlet of the condensation device and an inlet of the purifier and / or between an outlet of the first layer of the second heat exchanger and an inlet of one of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass of the first heat exchanger.

[0043] According to an optional feature of the invention, the separation device includes a pressure reducer disposed fluidly between an outlet of the second heat exchanger and an inlet of the purifier or between an outlet of the separator and an inlet of the purifier.

[0044] The pressure regulator is specifically positioned on a pipe carrying the liquid phase and connecting the second heat exchanger or separator to the purifier. The presence of the pressure regulator allows for adjusting the pressure of the liquid phase, which consists primarily of carbon dioxide, and in particular, for adjusting the pressure of the residual gases dissolved within it before they enter the purifier, and, if applicable, before they are recycled to the fuel cell.

[0045] According to an optional feature of the invention, the treatment system includes a bypass line for the first pass of the first heat exchanger, the purifier comprising a heat exchanger configured to implement heat exchange between liquid carbon dioxide contained in the purifier and gases charged at least with carbon dioxide.

[0046] The bypass line is configured to channel a portion of the carbon dioxide-laden gases. This bypass line is connected to a main line linking the drying unit to the condensing unit, specifically to its first heat exchanger. This bypass line diverts the carbon dioxide-laden gases from the first pass, sending them directly to the separation unit. The carbon dioxide-laden gases then exchange heat within a heat exchange device in the purifier, such as a reboiler.

[0047] According to an optional feature of the invention, the heat exchanger of the cooling loop is a main heat exchanger, the condensation device comprising a refrigeration loop having an additional heat exchanger configured to operate a heat exchange using a refrigerant fluid circulating within the main heat exchanger.

[0048] The additional heat exchanger and the main heat exchanger are both positioned on the refrigeration loop of the condensing unit. The refrigerant circulating within the refrigeration loop helps to cool the refrigerant circulating within the cooling loop.

[0049] According to an optional feature of the invention, the additional heat exchanger comprises a first channel configured to channel the refrigeration fluid and a second channel, the cooling circuit comprising said second channel.

[0050] It is understood here that within the additional heat exchanger, the refrigerant fluid circulating in the first channel exchanges heat with residual gases circulating in the second channel.

[0051] According to an optional feature of the invention, the treatment system includes a device for storing carbon dioxide in liquid form.

[0052] The storage device is located downstream of the separation device within the processing system. For example, the storage device may be directly connected to the separation device or connected to a subcooling device which is itself connected to the separation device.

[0053] According to an optional feature of the invention, the consumer is a fuel cell comprising an anode and a cathode, the condensation device being configured to process carbon dioxide-laden gases emitted by the anode, the anode being configured to be supplied with fuel produced from natural gas stored in the storage tank.

[0054] According to an optional feature of the invention, the fuel cell is a solid oxide fuel cell. Alternatively, the fuel cell is a molten carbonate fuel cell. The fuel cell is supplied with air, which is delivered to the cathode, and with fuel stored in the tank, which is delivered to the anode. The fuel cell produces electrical energy from redox reactions, resulting in the formation of effluents at both the anode and the cathode. It is the carbon dioxide-laden gases emitted by the anode that are intended to be treated using the treatment system according to the invention.

[0055] According to an optional feature of the invention, the treatment system includes at least one return circuit configured to channel residual gases separated by the separation device, the return circuit including one of the passes of the first heat exchanger configured to cool the carbon dioxide-laden gases circulating in the first pass, the return circuit connecting the separation device to the fuel cell.

[0056] 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 anode-emitted gas stream. The return circuit also contributes to cooling the carbon dioxide-laden gases circulating in the first pass using the residual gases. The return circuit connects the purifier and / or separator of the separation device to the fuel cell. According to an optional feature of the invention, the treatment system includes a bypass line connecting the purifier to the return circuit, the bypass line bypassing the condenser.

[0057] In certain embodiments, particularly when the separation device includes both a separator and a purifier, the residual gases from the purifier can be returned directly to the fuel cell without exchanging heat with the carbon dioxide-laden gases circulating in the first heat exchanger. This is especially relevant because, with both a separator and a purifier, the quantity of residual gases from the purifier is negligible. Furthermore, when there is a residual gas stream from the separator and a residual gas stream from the purifier, these gas streams have different pressures, and this pressure difference complicates their mixing and impacts heat exchange within the first heat exchanger.

[0058] Other features, details and advantages of the invention will become clearer from the reading of the following description on the one hand, and of examples of embodiment given by way of indication and not limitation with reference to the attached drawings on the other hand, on which: [Fig. 1] illustrates, schematically, a general view of a system for treating gases charged with carbon dioxide emitted by a consumer according to the invention;

[0059] [Fig. 2] illustrates, schematically, a portion of the processing system of figure 1 which corresponds to a first variant of a first embodiment;

[0060] [Fig. 3] illustrates, schematically, illustrates, schematically, a second variant of the portion of the processing system according to the first embodiment of figure 2;

[0061] [Fig. 4] illustrates, schematically, a third variant of the portion of the processing system according to the first embodiment of figure 2;

[0062] [Fig. 5] illustrates, schematically, a fourth variant of the portion of the processing system according to the first embodiment of figure 2;

[0063] [Fig. 5bis] illustrates, schematically, an alternative to the fourth variant of the portion of the processing system according to the first embodiment of Figure 2; [Fig. 6] illustrates, schematically, a fifth variant of the portion of the processing system according to the first embodiment of Figure 2;

[0064] [Fig. 7] illustrates, schematically, the portion of the processing system according to a first variant of a second embodiment;

[0065] [Fig. 7bis] illustrates, schematically, an alternative to the first variant of the portion of the processing system according to the second embodiment;

[0066] [Fig. 7ter] illustrates, schematically, a second variant of the portion of the processing system according to the second embodiment of figure 7;

[0067] [Fig. 8] illustrates, schematically, a third variant of the portion of the processing system according to the second embodiment of Figure 7; [Fig. 9] illustrates, schematically, a fourth variant of the portion of the processing system according to the second embodiment of Figure 7;

[0068] [Fig. 10] illustrates, schematically, a fifth variant of the portion of the processing system according to the second embodiment of Figure 7.

[0069] 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.

[0070] In the figures, elements common to several figures retain the same reference. Furthermore, in the figures, the direction of fluid flow within the pipes is illustrated by arrows, this direction being an integral part of this text.

[0071] In the description that follows, the terms "pass", "sheet", "line" and "channel" are synonyms intended to refer to the same type of component, namely a circulation duct of a heat exchanger.

[0072] Furthermore, the term "between" here 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 in any order, provided that these components follow a fluidic sequence in which the compression device receives the carbon dioxide-laden gases before the drying device, which in turn receives them before the condensation device. Specifically, two devices of the treatment system are considered "connected" when they are linked to each other by a treatment system pipe, without any other treatment component being interposed between the two devices.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 pass directly from the first device to the second device without undergoing any treatment or heat exchange with another fluid.

[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 in the treatment system 1 before being conveyed to the cathode 4 of the fuel cell 2 by an air supply line 3. The air is then evacuated from the cathode 4 by an outlet line 5. The fuel feeds the anode 6 of the fuel cell 2.The fuel used to power anode 6 is, for example, liquefied natural gas previously stored in a storage tank 10 of the facility. Alternatively, the fuel used to power anode 6 is gas resulting 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. 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.

[0077] The treatment circuit 14 connects the fuel cell 2, and more specifically its anode 6, to a heat exchange means of the treatment system 1. This heat exchange means is, for example, a heat recovery unit 16. The heat recovery unit 16 is connected by the treatment circuit 14 to a compression device 18, within which some of the water present in the carbon dioxide-laden gases is discharged through a first water outlet duct 20. 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 duct 24.It is understood from the above that the compression device 18 is arranged on the processing circuit 14 between the heat recovery unit 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 exchanger 16 while an outlet of this compression device 18 is connected to an inlet of the drying device 22.

[0078] At the outlet of the drying unit 22, the carbon dioxide-laden gases consist of carbon dioxide, hydrogen, carbon monoxide, and nitrogen, the water having previously been discharged through the first and second water outlet pipes 20, 24. These carbon dioxide-laden gases are conveyed by a main line 26 of the treatment circuit 14 from the drying unit 22 to a condensation unit 28. It is understood that the main line 26 connects the drying unit 22 to the condensation unit 28. The condensation unit 28 comprises several components and subunits which will be detailed later in relation to Figures 2 to 10.

[0079] The condensation device 28 is configured to cool the carbon dioxide present in the carbon dioxide-laden gases so that it changes state, passing from a vapor state to a liquid state.

[0080] At the outlet of the condensation 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. In Figure 1, the carbon dioxide-laden gases are first conveyed to a separator 30 and then to a purifier 32. The separator 30 and the purifier 32 together form a separation device within the treatment system 1. The separator 30 separates a liquid phase of carbon dioxide from a vapor phase of the residual gases. The separator 30 is, for example, a separation flask. The purifier 32 separates residual gases dissolved in the liquid phase. The purifier 32 is, for example, a distillation column.

[0081] The separator 30 and the purifier 32 represent two stages of carbon dioxide separation, with the separator 30 positioned between the condenser 28 and the purifier 32. The separator 30 constitutes a primary separation stage, which separates the carbon dioxide in liquid form from the residual gases within the carbon dioxide-laden gases. The purifier 32 constitutes a secondary separation stage, which purifies the carbon dioxide by extracting the dissolved gases from the liquid carbon dioxide. Alternatively, embodiments could be considered in which the separation device of the treatment system 1 comprises a single unit for separating the carbon dioxide, i.e., a single separation stage, as will be described later.The separation device is connected via the processing circuit 14 to a storage device 34, in which the carbon dioxide is stored in liquid form. The liquid carbon dioxide is, for example, stored at a pressure between 7 and 15 bar in the storage device 34. As will be described later, the condensing device 28 is configured to cool the carbon dioxide-laden gases by indirect heat exchange with natural gas from the 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 or additionally, the condensing device 28 can operate by exchanging heat between the carbon dioxide-laden gases and another cooling source, for example, a refrigerant from a refrigeration system.

[0082] Here, "indirect heat exchange" means that the carbon dioxide-laden gases and the natural gas from storage tank 10 exchange heat through another fluid rather than directly within a heat exchanger.

[0083] According to the invention, the condensing device 28 includes a cooling loop 36, illustrated in Figures 2 to 10. This cooling loop 36 is configured to channel a cooling fluid intended to exchange heat with the carbon dioxide-laden gases and with the natural gas from the storage tank 10. The cooling loop is designed to prevent the carbon dioxide in the carbon dioxide-laden gases, which have a freezing point of -56°C, from freezing. To achieve this, the cooling fluid has, for example, a temperature greater than or equal to -56°C, or even greater than or equal to -60°C. Furthermore, the cooling fluid has a freezing point below -160°C, so as not to freeze during heat exchange with the natural gas from the storage tank 10.The cooling fluid may be selected from butane, isopentane, and 1-pentene, among other options, but this is not a limitation of the invention. In cases where the condensing device 28 cools the carbon dioxide-laden gases using natural gas, it is understood that this natural gas is used within the condensing device 28 before being used as fuel in the fuel cell 2. In return for cooling the carbon dioxide-laden gases for carbon dioxide capture, the condensing device 2 contributes to heating the natural gas, particularly to supply the natural gas in a gaseous state as fuel for the fuel cell 2.

[0084] 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 allows in particular the connection of the condensation device 28 to the fuel cell 2.

[0085] The return circuit 38 thus makes it possible to channel the residual gases from the gases charged with carbon dioxide, either to supply them to the fuel cell 2 or to evacuate them from the treatment system 1. The return circuit 38 has for this purpose a first pipe which is connected to the fuel cell 2 and a second pipe which is connected to an outlet of the treatment system 1.

[0086] As illustrated in Figure 1, the return circuit 38 forms a pass through the heat recovery unit 16, such that the waste gases exchange heat with the carbon dioxide-laden gases supplied to this heat recovery unit 16 at the outlet of the fuel cell 2. After passing through the heat recovery unit 16, the waste gases can be supplied to the fuel cell 2 as fuel or recycled within the treatment system 1. In this case, the waste gases flow through the first line of the return circuit 38, this first line being connected to the fuel cell 2. Alternatively, some or all of the waste gases can be vented from the treatment system 1 using a purge device 39. This purge device 39 is carried by the second line of the return circuit 38, which is connected to an outlet of the treatment system 1.A flow rate of residual gases using this second pipe and passing through the purge device 39 is controlled so as to optimize the operation of the fuel cell 2.

[0087] The treatment system 1 is configured to implement a method for treating carbon dioxide-laden gases from the fuel cell 2, which will now be described in relation to Figure 1.

[0088] The treatment method includes a step of supplying the consumer, here the fuel cell 2, via the supply circuit 12. This fuel cell 2 supply step 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 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 indirect heat exchange with the carbon dioxide-laden gases, which will be described later. At the end of the heating step, the liquefied natural gas is converted back into natural gas in a gaseous state. Alternatively, the natural gas used for the heating step can be natural gas in a gaseous state from the storage tank 10.

[0089] 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.

[0090] The carbon dioxide-laden gases are sent, via the treatment circuit 14, to the heat recovery unit 16 where they undergo a cooling stage. The carbon dioxide-laden gases are then transferred, again via the exhaust circuit 14, to the compression device 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 device 22. The compression and drying stages allow the removal of the water contained in the carbon dioxide-laden gases, which is discharged from the treatment system 1 through the first water outlet 20 and the second water outlet 24, respectively.

[0091] 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 a cooling source, via indirect cooling involving the cooling loop 36.

[0092] The carbon dioxide-laden gases then undergo at least one separation stage. Here, the carbon dioxide-laden gases undergo a first separation stage, or primary separation, within separator 30, which separates the carbon dioxide in its liquid state from the residual gases in the gaseous phase.

[0093] The liquid phase of carbon dioxide then undergoes a second separation stage, or secondary separation, within the purifier 32, which allows the liquid carbon dioxide to be separated from the residual gases that are dissolved within it.

[0094] The treatment method finally includes a step of storing carbon dioxide in liquid form in the storage device 34.

[0095] It should be noted that the condensation and separation stages 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 10, in particular to detail the operation of the condensation device 28 and the separation device.

[0096] Figures 2 to 6 represent variants of a first embodiment of the treatment system 1, in which the treatment system 1 comprises only one device for separating carbon dioxide, here only the purifier 32. The separation device of the treatment system 1 then corresponds only to the purifier 32.

[0097] Figures 7 to 10 illustrate variants of a second embodiment in which the treatment system 1 comprises both the separator 30 and the purifier 32. The separation device of the treatment system 1 then corresponds to an assembly formed by the separator 30 and the purifier 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 one of the embodiments are applicable, mutatis mutandis, to other variants or embodiments.

[0098] In each of these embodiments, the condensation device 28 comprises a first heat exchanger 40 and a second heat exchanger 42. The first heat exchanger 40 is configured to cool the carbon dioxide-laden gases from the drying device 26, and the second heat exchanger 42 is configured to condense the carbon dioxide present in the carbon dioxide-laden gases as they exit the first heat exchanger 40. It is understood that the first heat exchanger 40 and the second heat exchanger 42 are arranged in that order on the treatment circuit 14. The first heat exchanger 40 comprises a plurality of passes, among which a first pass 44 formed by the treatment circuit 14 and configured to channel the carbon dioxide-laden gases.Similarly, the second heat exchanger 42 comprises a plurality of layers, among which is a first layer 46 formed by the treatment circuit 14 and configured to channel the gases charged with carbon dioxide.

[0099] In the first variant illustrated in Figure 2, the first heat exchanger 40 has four passes. Among these four passes, the first heat exchanger 40 includes the first pass 44, which is configured to carry the carbon dioxide-laden gases from the drying device 32. Thus, the first pass 44 forms part of the main line 26 that connects this drying device 32 to the first heat exchanger 40. The first pass 44 is configured to exchange heat with the other passes. Consequently, the other passes of the first heat exchanger 40 are configured to cool the carbon dioxide-laden gases circulating in the first pass 44.

[0100] The first heat exchanger 40 and the second heat exchanger 42 are both traversed by a cooling fluid circulating within the cooling loop 36. As can be seen in Figures 2 to 10, the cooling loop 26 is divided into at least two branches 48, 50, among which a first branch 48 and a second branch 50, these two branches 48, 50 extending parallel to each other.

[0101] The first branch 48 includes a pass of the first heat exchanger 40, which here corresponds to a second pass 52, one of the passes configured to cool the carbon dioxide-laden gases circulating in the first pass 44. Similarly, the second branch 50 includes a layer of the second heat exchanger 42, which here corresponds to a second layer 54. The second layer 54 is configured to exchange heat with the first layer 46 in order to cool it.

[0102] The cooling fluid circulating within the cooling loop 36 is cooled within a heat exchanger 56 of the condensation device 28.

[0103] The heat exchanger 56 is here a primary heat exchanger. More specifically, this heat exchanger 56 comprises a first line 58 which forms part of the first branch 48 of the cooling loop 36, a second line 60 which forms part of the second branch 50 of the cooling loop 36, and at least one third line 62 configured to cool the first line 58 and the second line 60. This third line 62 is configured here to carry natural gas in the vapor state, natural gas in the liquid state, or the refrigerant. In cases where the third line 62 is configured to carry natural gas in the vapor or liquid state, this third line 62 forms, for example, a portion of the supply circuit 12 connecting the storage tank 10 to the fuel cell 2.It is understood here that the natural gas from the storage tank 10 is used to cool the cooling fluid circulating within the cooling loop 36 prior to its use as fuel within the fuel cell 2.

[0104] It should be noted that while in Figure 2, which represents a simplified variant, the heat exchanger 56 includes only the third line 62 for cooling the first line 58 and the second line 60, in the embodiments illustrated in Figures 3 to 10, the heat exchanger 56 includes, in addition to the third line 62, a fourth line 64 configured to cool the first line 58 and the second line 60. This fourth line 64 can, depending on the embodiment, be configured to carry natural gas in vapor form, natural gas in liquid form, or a refrigerant. The presence of a fourth line 64 improves the cooling of the refrigerant circulating in the first line 58 and the second line 60.

[0105] Between an outlet of the heat exchanger 56 and a separation point of the cooling loop 36 where the first branch 48 and the second branch 50 separate, the cooling loop 36 carries a pump 66. This pump 66 implements a circulation of the cooling fluid within the cooling loop 36.

[0106] A distribution of the cooling fluid between the first branch 48 and the second branch 50 is ensured by means of a cooling fluid distribution means which equips the cooling loop 36. As shown in figures 2 to 10, the distribution means corresponds to a first valve 68 disposed on the first branch 48 and a second valve 70 disposed on the second branch 50, but in other embodiments this distribution means could be a three-way valve disposed on the separation point between the first branch 48 and the second branch 50, or even a restriction of one and / or the other of the first and second branches 48, 50.

[0107] In addition to the second pass 52, the passes configured to cool the carbon dioxide-laden gases circulating in the first pass 44 include, as shown in Figure 2, a third pass 72 configured to channel a fluid that has passed through the first pass 44 and at least one other component of the treatment system 1. In other words, this fluid corresponds 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 separation device formed by the separator 30 and / or the purifier 32. Thus, this fluid corresponds, for example, to residual gases separated from the carbon dioxide.

[0108] In Figure 2, the third pass 72 is configured to receive the residual gases from the purifier 32. The purifier 32 is therefore located between the first pass 44 and the third pass 72; more generally, the purifier 32 is fluidically located between an outlet of the first layer 46 of the second heat exchanger 42 and the third pass 72 of the first heat exchanger 40. Once they have passed through this third pass 72, the residual gases circulate within the return circuit 38 and are thus directed, depending on the case, to the purge device 39 or to the fuel cell 2. The return circuit 38 includes a pressure-reducing valve 74 located on the first line of the return circuit 38, between the first heat exchanger 40 of the condensing unit 28 and the fuel cell 2. The pressure-reducing valve 74 allows the pressure of the residual gases returned to the fuel cell 2 to be adjusted.

[0109] It is understood from the above that within the purifier 32, the gases charged with carbon dioxide exiting the condensation device 38 are separated into, on the one hand, residual gases which circulate within the return circuit 38, and on the other hand, liquid carbon dioxide which is conveyed to the storage device 34.

[0110] Thus, in the first variant of the first embodiment of Figure 2, the carbon dioxide-laden gases from the drying device 22 flow through the main line 26 to the first heat exchanger 40 of the condensing device 28, where they are channeled into the first pass 44. Within the first heat exchanger 40, the carbon dioxide-laden gases exchange heat with, on the one hand, the cooling fluid channeled into the second pass 52 and, on the other hand, the residual gases channeled into the third pass 72. The carbon dioxide-laden gases are thus pre-cooled. The carbon dioxide-laden gases then flow to the second heat exchanger 42, where they are channeled into the first layer 46. They exchange heat with the cooling fluid channeled into the second layer 54 of the second heat exchanger 42.Upon exiting the second heat exchanger 42 and the condensing unit 28, the carbon dioxide-laden gases are conveyed to the purifier 32, which forms the separation unit. In the purifier 32, the residual gases are separated from the liquid carbon dioxide, which is then sent to the storage unit 34. The residual gases are recirculated to the first heat exchanger 40, where they are channeled into the third pass 72 and exchange heat with the first pass 44, as described above. Finally, the residual gases are either sent to the fuel cell 2 via the first return line 38 or released from the treatment system 1 via the second return line and the purge valve 39.

[0111] A second embodiment variant is shown in Figure 3. In this second variant, the heat exchanger 56 carried by the cooling loop 36 of the condensation device 28 includes both the third line 62 and the fourth line 64 as lines configured to cool the first line 58 and the second line 60 which channel the cooling fluid.

[0112] In both the second and first variants of Figure 2, the treatment circuit 14 includes a bypass line 76 for the first pass 44 of the first heat exchanger 40. This bypass line 76 is connected on one side to the main line 26 between the drying device 22 and the first heat exchanger 40, and on the other side to a heat exchanger 78 of the separation device. This heat exchanger 78 is a reboiler associated with the purifier 32. The heat exchanger 78 is configured to perform a heat exchange between liquid carbon dioxide contained in the purifier 32 and gases containing at least carbon dioxide that have passed through the bypass line 76.

[0113] The carbon dioxide-laden gases collected by the bypass line 76, after passing through the heat exchanger 78, are returned via another section of the bypass line 76 to the first heat exchanger 40, where they are channeled into a dedicated pass 80. In both the first and second variants, the first heat exchanger 40 therefore comprises four passes. The carbon dioxide-laden gases circulating in the first pass 44 and the carbon dioxide-laden gases circulating in the dedicated pass 80 are then mixed in a pipe of the treatment circuit 14 connecting the first pass 44 of the first heat exchanger 40 to the second heat exchanger 42, so that both the carbon dioxide-laden gases circulating in the first pass 44 and the carbon dioxide-laden gases circulating in the dedicated pass 80 flow within T1

[0114] the first layer 46 of the second heat exchanger 42.

[0115] It is thus understood that in the first variant and the second variant, within the first heat exchanger 40 the gases charged with carbon dioxide circulate both in the first pass 44 and in the dedicated pass 80, these two passes being cooled on the one hand by the cooling fluid circulating within the second pass 52, and on the other hand by the residual gases circulating within the third pass 72.

[0116] In the first variant of Figure 2 and the second variant of Figure 3, the liquid carbon dioxide storage device 34 is connected to the heat exchange device 78.

[0117] Figure 4 illustrates a third variant of the first embodiment. In this third variant, natural gas and / or refrigerant are channeled both in the third line 62 and in the fourth line 64 of the heat exchanger 56 of the cooling loop 36.

[0118] The third variant also features the bypass line 76 and the dedicated pass 80 of the first heat exchanger 40 which allow the gases charged with carbon dioxide to bypass the first pass 44 of the first heat exchanger 40. In the third variant, the storage device 34 for carbon dioxide in liquid form is connected to the heat exchange device 78.

[0119] Notably, the third variant differs from the second variant in Figure 3 in that the third pass 72 of the first heat exchanger 40 is not directly connected to the return circuit 38 at the outlet of this first heat exchanger 40. In the third variant, the treatment circuit 14 includes a cooling circuit 84 connected to the third pass 72 of the first heat exchanger 40. This cooling circuit 84 is designed to utilize the pressure of the decarbonized gases to obtain cooling through isentropic expansion. To this end, the cooling circuit 84 includes an expansion device 86, for example, a turbine, in which the isentropic expansion takes place.

[0120] The cooling circuit 84 forms a loop around the first heat exchanger 40. Thus, it is connected on one side to the third pass 72 and on the other side to a fourth pass 82 of the first heat exchanger 40, this fourth pass 82 being one of the passes configured to cool the carbon dioxide-laden gases circulating in the first pass 44. The expansion device 86 is therefore located between the third pass 72 and the fourth pass 82. Consequently, in the third variant, the residual gases separated within the purifier 32 circulate within the third pass 72, then within the cooling circuit 84 in which they are expanded via the expansion device 64, then within the fourth pass 82 of the first heat exchanger 40, and finally within the return circuit 38.Therefore, in this third variant the first heat exchanger 40 comprises five passes, among which the first pass 44 is configured to channel a portion of the carbon dioxide-laden gases; the second pass 52 is configured to channel the cooling fluid; the third pass 72 is configured to channel the residual gases from the purifier 32; the dedicated pass 80 is configured to channel another portion of the carbon dioxide-laden gases that have passed through the bypass line 76; and the fourth pass 82 is configured to channel the residual gases expanded by the expansion device 86 into the cooling circuit 84.Thus, in the third variant of the first embodiment of Figure 4, the carbon dioxide-laden gases circulating in the first pass 44 and in the dedicated pass 80 exchange heat with the second pass 52 which channels the cooling fluid, as well as with the third pass 72 and the fourth pass 82 which channel the separated residual gases within the purifier 32.

[0121] Figures 5 and 5bis are representations of a fourth variant of the first embodiment of the processing system 1 according to the invention. As illustrated in Figure 5 and Figure 5bis, the cooling circuit 84 of the first heat exchanger 40 here comprises the expansion member 86 and an expansion element 88. The expansion member 86 is, for example, a first turbine of the cooling circuit 84, while the expansion element 88 is a second turbine of this cooling circuit 84. In this fourth variant, the cooling circuit 84 comprises a first loop 90 carrying the expansion member 86, this first loop 90 being located between the third pass 72 of the first heat exchanger 40 and its fourth pass 82. The fourth pass 82 of the first heat exchanger 40 is connected to a second loop 92 of the cooling circuit 84, this second loop 92 carrying the expansion element 88.The second loop 92 is arranged between the fourth pass 82 of the first heat exchanger 40 and a fifth pass 94 of said first heat exchanger 40. This fifth pass 94 is connected to the return circuit 38. It is thus understood that the expansion member 86 and the expansion element 88 are both arranged between two passes of the first heat exchanger 40 configured to cool the carbon dioxide-laden gases circulating in the first pass 44.

[0122] Thus, in the fourth variant of the first embodiment shown in Figures 5 and 5bis, the carbon dioxide-laden gases circulating in the first pass 44 of the first heat exchanger 40 exchange heat with the second pass 52, which channels the cooling fluid; with the third pass 72, which channels the separated residual gases within the purifier 32; with the fourth pass 82, which channels the residual gases that have been expanded by the expansion device 86; and with the fifth pass 94, which channels the residual gases that have been expanded by the expansion element 88. This successive double expansion prevents the expanded residual gases from being cooled below the freezing point of carbon dioxide. This has the effect, on the one hand, of preventing the formation of a solid fraction at the outlet of the expansion device 86, and on the other hand, of preventing the carbon dioxide from freezing within the first heat exchanger 40.

[0123] It should be noted that in Figure 5bis, which is an alternative to the fourth variant shown in Figure 5, the heat exchanger 56 includes, in addition to the third line 62 and the fourth line 64, an additional line 63 configured to cool the first line 58 and the second line 60. This additional line 63 is configured for the refrigerant fluid piping. This refrigerant fluid is, for example, but not limited to the invention, ethane or propane. The use of an additional line 63 improves the cooling of the refrigerant circulating in the first line 58 and the second line 60. A fifth variant of the first embodiment will now be explained with reference to Figure 6. In particular, the fifth variant includes a refrigeration loop 96 configured for the circulation of a refrigerant fluid.The refrigeration fluid can, depending on the embodiment, be identical or distinct from the cooling fluid channeled within the cooling loop 36.

[0124] The refrigeration loop extends between the heat exchanger 56, or main heat exchanger 56 described previously, and an additional heat exchanger 98. More specifically, the main heat exchanger 56 includes a fifth line 100 configured for the circulation of the refrigerant. This fifth line 100 is in addition to the first line 58 and the second line 60, which channel the refrigerant circulating respectively in the first branch 48 and the second branch 50 of the cooling loop 36, as well as to the third line 62 and the fourth line 64, which channel, depending on the embodiment, natural gas in the vapor state, natural gas in the liquid state, or refrigerant.

[0125] The additional heat exchanger 98 includes a first channel 102 configured to channel the refrigerant. Between the first channel 102 of the additional heat exchanger 98 and the fifth line 100 of the main heat exchanger 56, the refrigeration loop 96 includes a pumping element 104 which facilitates circulation of the refrigerant within the refrigeration loop 96.

[0126] The additional heat exchanger 98 also includes a second channel 106 configured to channel residual gases that have circulated within the cooling circuit 84. More generally, the second channel 106 of the additional heat exchanger 98 is included in the cooling circuit 84.

[0127] As illustrated in Figure 6, the residual gases from the purifier 32 circulate within the third pass 72 of the first heat exchanger 40, then through the first loop 90 carrying the expansion element 86, then through the fourth pass 82 of the first heat exchanger 40, and finally through the second loop 92 carrying the expansion element 88. Unlike the fourth variant in Figure 5 and Figure 5bis, this second loop 92 is not connected to the fifth pass 94 of the first heat exchanger 40, which is not present in the fifth variant in Figure 6. Rather, the second loop 92 is connected here to the second channel 106 of the additional heat exchanger 98. The expansion element 88 is thus positioned between the fourth pass 82 of the first heat exchanger 40 and the second channel 106 of the additional heat exchanger 98.An outlet of the second channel 106 is connected to the return circuit 38, so that the residual gases flowing in the second channel 106 are either returned to the fuel cell 2, or evacuated out of the treatment system 1.

[0128] It is understood from the above that the residual gases having passed through the first heat exchanger 40 are used within the second channel 106 of the additional heat exchanger 98 to cool the refrigerant fluid channeled in the first channel 102. The refrigerant fluid is subsequently used within the fifth line 100 of the main heat exchanger to participate, together with the third and fourth lines 62, 64 channeling natural gas or refrigerant, in cooling the first line 58 and the second line 60 which channel the refrigerant circulating within the cooling loop 36.

[0129] A second embodiment of the treatment system 1 will now be detailed with reference to Figures 7, 7bis, 7ter, 8, 9, and 10, which correspond respectively to a first variant, an alternative to the first variant, a second variant, a third variant, a fourth variant, and a fifth variant of this second embodiment. The variants of the second embodiment are counterparts to the variants of the first embodiment, differing particularly in the composition of the separation device. In the variants of the second embodiment, the separation device of the treatment system 1 comprises both the separator 30 and the purifier 32, whereas in the variants of the first embodiment, it comprises only the purifier 32.As a reminder, the separator 30 is configured to separate a liquid phase of carbon dioxide and a vapor phase of residual gases, and the purifier 32 is configured to separate residual gases dissolved in the liquid phase. The purifier 32 is, for example, a distillation column. In the first variant of the second embodiment, the treatment system includes the bypass line 76, which is connected at its first end to the main line 26 between the drying device 22 and the first heat exchanger 40, and at its second end between the first heat exchanger 40 and the second heat exchanger 42.

[0130] In this variant of Figure 7, the first heat exchanger 40 comprises the first pass 44, which channels the carbon dioxide-laden gases; the second pass 52, which channels the cooling fluid; and the third pass 72, which channels the residual gases from the separation device. However, unlike what was described previously in relation to the first embodiment, in this second embodiment the residual gases originate from the separator 30 of the separation device and not from the purifier 32. Here, the separator 30 is located at the outlet of the first layer 46 of the second heat exchanger 42. Within the separator, the carbon dioxide-laden gases are separated into, on the one hand, a vapor phase containing the residual gases and, on the other hand, a liquid phase comprising the liquid carbon dioxide condensed within the second heat exchanger 42.

[0131] As illustrated in Figure 7, the vapor phase separated within the separator 30 is sent to the first heat exchanger 40 via a vapor-phase fluid circulation line 108. This vapor-phase fluid circulation line 108 channels the vapor phase to the third pass 72 of the first heat exchanger 42, and then the vapor phase rejoins the return circuit 30. It is therefore understood that in this first variant of the second embodiment, within the first heat exchanger 40 the carbon dioxide-laden gases circulating in the first pass 42 exchange heat both with the cooling fluid channeled in the second pass 52 and with the residual vapor-phase gases channeled in the third pass 72.

[0132] The liquid phase separated within the separator 30 is channeled through a liquid fluid circulation line 110 to be delivered to the purifier 32. This liquid fluid circulation line 110 is equipped with a pressure regulator 114 configured to reduce the liquid phase pressure, so that the liquid phase pressure is adapted to the carbon dioxide storage pressure. For this purpose, the purifier 32 is connected to the return circuit 38 by a bypass line 116. More precisely, the bypass line 116 connects the purifier 32 to the return circuit 38 upstream of a separation between its first and second pipes. It is understood that the bypass line 116 allows the residual gases separated in the purifier to bypass the condensing device 28.

[0133] In the alternative of the first variant illustrated in Figure 7bis, the heat exchanger 56 includes the additional line 63, which contributes to cooling the first line 58 and the second line 60, supplementing the cooling provided by the third line 62 and the fourth line 64. As described in relation to Figure 5bis, the additional line 63 is dedicated to the refrigerant fluid conduit. The second variant of the second embodiment, illustrated in Figure 7ter, differs from the first variant in Figure 7 in that the liquid phase separated within the separator 30, which is channeled by the liquid fluid circulation line 110, is recirculated within the second heat exchanger 42.More specifically, this vapor fluid circulation line 110 extends here from an outlet of the separator 30 to an inlet of the purifier 32 via the second heat exchanger 42, within which it forms a third layer 112. Thus, within the second heat exchanger 42, the carbon dioxide-laden gases channeled in the first layer 46 exchange heat with the cooling fluid channeled in the second layer 54, this cooling fluid also helping to cool the liquid phase channeled in the third layer 112.

[0134] At the outlet of the third layer 112, the liquid phase is channeled by the liquid fluid circulation line 110 to the purifier 32.

[0135] The third variant of the second embodiment illustrated in Figure 8 differs from the second variant in Figure 7ter in that the treatment system 1 incorporates the cooling circuit 84 as described in relation to Figure 4. Thus, as with the second variant, the liquid phase separated within the separator 30 circulates in the liquid fluid circulation line 110, which forms the third pass 112 of the second heat exchanger 42, and is then conveyed to the purifier 32. In the purifier 32, the carbon dioxide in liquid form is separated from the residual gases dissolved in the liquid phase. The liquid carbon dioxide is conveyed to the storage device 34 via the heat exchanger 78, while the residual gases return to the return circuit 38 via the bypass line 116.

[0136] The vapor phase separated in separator 30, which contains residual gases, flows through the vapor fluid circulation line 108 to the first heat exchanger 40. There, it passes through the third pass 72 to exchange heat with the first pass 44, which channels the carbon dioxide-laden gases. The vapor phase then enters the cooling circuit 84 and is expanded by the expansion valve 86. It then passes through the fourth pass 82 of the first heat exchanger 40. In the fourth pass 82, the vapor phase again exchanges heat with the first pass 44, which channels the carbon dioxide-laden gases, before flowing through the return circuit 38 to be discharged from the treatment system I and / or sent to the fuel cell 2.

[0137] It follows from the above that in this third variant of the second embodiment, within the first heat exchanger 40 the carbon dioxide-laden gases circulating in the first pass 42 exchange heat both with the cooling fluid channeled in the second pass 52, with the residual gases present in the vapor phase which is channeled in the third pass 72, and with these same residual gases from the vapor phase circulating in the fourth pass 82 once this vapor phase has been expanded within the cooling circuit 84.

[0138] Furthermore, within the second heat exchanger 42, the carbon dioxide-laden gases channeled in the first layer 46 exchange heat with the cooling fluid channeled in the second layer 54. The cooling fluid circulating in the second layer 54 is also used to cool the liquid phase separated in the separator 30, which is channeled into the third layer 112 of the second heat exchanger 40.

[0139] In Figure 9, the treatment system 1 is illustrated according to a fourth variant of the second embodiment, this fourth variant including the cooling circuit 84 as described with reference to Figure 5 in the third variant of Figure 8. In fact, in the treatment system 1 of Figure 9, the vapor phase containing residual gases, which has been separated in the separator 30, is conveyed to the third pass 72 of the first heat exchanger 40 via the vapor circulation line 108. Within the third pass 72, the vapor phase exchanges heat with the carbon dioxide-laden gases circulating in the first pass 44. At the outlet of the third pass 72, the vapor phase circulates in the first loop 90 of the cooling circuit 84 where it is expanded by the expansion valve 86.The vapor phase then passes through the fourth pass 82 to exchange heat again with the carbon dioxide-laden gases channeled through the first pass 44. Following the fourth pass 82, the vapor phase enters the second loop 92 of the cooling circuit 84 and is expanded by the expansion element 88. The vapor phase then passes through the fifth pass 94 of the first heat exchanger 40 and exchanges heat a third time with the carbon dioxide-laden gases circulating in the first pass 44. Upon exiting this fifth pass 94, the vapor phase is discharged from the condensing unit 28 via the return circuit 38.It is understood here that the carbon dioxide-laden gases channeled by the first pass 44 of the first heat exchanger 40 exchange heat with the second pass 52 which channels the cooling fluid; with the third pass 72 which channels the vapor phase comprising residual gases separated within the separator 30; with the fourth pass 82 which channels this vapor phase which has been expanded by the expansion element 86; and with the fifth pass 94 which channels the vapor phase which has again been expanded, this time by the expansion element 88. In addition, in the second heat exchanger 42 the carbon dioxide-laden gases circulating within the first layer 46 exchange heat with the cooling fluid circulating within the second layer 54.The liquid phase from the separator 30 which is channeled into the third layer 112 of the second heat exchanger 40 exchanges heat with the cooling fluid circulating in the second layer 54 for the purpose of cooling said liquid phase.

[0140] A fifth variant of the second embodiment is shown in Figure 10. This fifth variant includes, in the second embodiment having both the separator 30 and the purifier 32 as the separation device, the refrigeration loop 96 which was previously described in relation to the fifth variant of the first embodiment of Figure 6.

[0141] As described in Figure 9, the vapor phase containing residual gases, which was separated in the separator 30, is conveyed to the third pass 72 of the first heat exchanger 40 via the vapor circulation line 108. Within the third pass 72, the vapor phase exchanges heat with the carbon dioxide-laden gases circulating in the first pass 44. At the outlet of the third pass 72, the vapor phase flows into the first loop 90 of the cooling circuit 84, where it is expanded by the expansion valve 86. The vapor phase then passes into the fourth pass 82 to exchange heat again with the carbon dioxide-laden gases channeled by the first pass 44. Following the fourth pass 82, the vapor phase enters the second loop 92 of the cooling circuit 84 and is expanded by the expansion valve 88.However, at the outlet of the second loop 92 of the cooling circuit 84, the vapor phase is not directed to the fifth pass 94 of the first heat exchanger 40, as this fifth pass 94 is absent from the fifth variant. Rather, the vapor phase, expanded by the expansion element 88 in the second loop 92 of the cooling circuit 84, flows to the second channel 106 of the additional heat exchanger 98. In this second channel 106, the vapor phase helps to cool the refrigerant circulating in the first channel 102, which is channeled into the cooling loop 96. The refrigerant is subsequently used in the main heat exchanger 56 to cool the refrigerant that is channeled into the first and second lines 58, 60 of said main heat exchanger 56.The refrigerant fluid is used here as a source of cold in addition to the natural gas and / or refrigerant circulating within the third and fourth lines of the main heat exchanger 56.

[0142] Upon exiting the second channel 106 of the additional heat exchanger 98, the vapor phase which includes residual gases is conveyed to the fuel cell 2 via the first pipe of the return circuit 38, and / or evacuated from the treatment system 1 via the second pipe of this return circuit 38.

[0143] In conclusion, in this fifth variant of the second embodiment, the carbon dioxide-laden gases exchange heat both with the second pass 52, which channels the cooling fluid, with the third pass 72, which channels the vapor phase comprising residual gases separated within the separator 30, and with the fourth pass 82, which channels this vapor phase once it has been expanded by the expansion device 86. Additionally, in the second heat exchanger 42, the cooling fluid circulating within the second layer 54 is used on the one hand to cool the carbon dioxide-laden gases circulating within the first layer 46, and on the other hand to cool the liquid phase from the separator 30, which is channeled into the third layer 112.

[0144] The present invention thus proposes a system for treating gases charged with carbon dioxide from a consumer in which the condensation of the carbon dioxide present in said gases is ensured by means of a cooling loop and two heat exchangers, so as to avoid the risks of freezing of the carbon dioxide.

[0145] 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. A gas treatment system (1) for gases containing at least carbon dioxide and emitted by a consumer, comprising a liquefied natural gas storage tank (10), a consumer configured to be supplied with fuel produced from natural gas stored in the storage tank (10), and a carbon dioxide condensation device (28) for the carbon dioxide present in the carbon dioxide-laden gases, the condensation device (28) comprising a first heat exchanger (40) having a plurality of passes (44, 52, 72, 80, 82, 94), a second heat exchanger (42) having a plurality of layers (46, 54, 112), and a cooling loop (36) comprising a first branch (48) and a second branch (50) parallel to each other, the first branch (48) comprising a pass (52) of the first heat exchanger (40) and the second branch (50) comprising a layer (54) of the second heat exchanger (42).

2. Processing system (1) according to claim 1, wherein the condensation device (28) comprises a heat exchanger (56) configured to perform heat exchange between a cooling fluid circulating within the cooling loop (36) and at least natural gas in liquid form and / or natural gas in vapor form and / or a refrigerant separate from natural gas in liquid form and natural gas in vapor form, this natural gas being from the storage tank (10).

3. Processing system (1) according to claim 2, wherein the heat exchanger (56) of the condensation device (28) comprises a first line (58) and a second line (60), the first branch (48) of the cooling loop (36) forming the first line (58) and the second branch (50) of the cooling loop (36) forming the second line (60).

4. Treatment system (1) according to any one of claims 1 to 3, wherein the cooling loop (36) includes a means for distributing the cooling fluid between the first branch (48) and the second branch (50) of the cooling loop (36).

5. Treatment system (1) according to any one of claims 1 to 4, comprising a device for compressing gases charged with carbon dioxide and a device for drying these gases charged with carbon dioxide, the compression device (18) and the drying device (22) being fluidly arranged between an outlet of the consumer and an inlet of the condensation device (28), the treatment system (1) comprising a device for separating carbon dioxide present in the gases emitted by the consumer, the first heat exchanger (40) and the second heat exchanger (42) being fluidly arranged between an outlet of the drying device (22) and an inlet of the separation device.

6. Treatment system (1) according to any one of claims 1 to 5, wherein the first heat exchanger (40) comprises a first pass (44) configured to be used by carbon dioxide-laden gases and a plurality of other passes (52, 72, 82, 94) configured to cool the carbon dioxide-laden gases flowing in the first pass (44) of the first heat exchanger (40), including the pass (52) of the first heat exchanger (40) included in the first branch (48) of the cooling loop (36).

7. Processing system (1) according to claim 6, comprising a cooling circuit (84) comprising at least two of the passes (72, 82) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases circulating in the first pass (44) of the first heat exchanger (40).

8. A treatment system (1) according to claim 7, wherein the cooling circuit (84) comprises at least one expansion member (86) disposed between the two passes (72, 82) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases circulating in the first pass (44) of the first heat exchanger (40) included in the cooling circuit (84).

9. A treatment system (1) according to any one of claims 6 to 8, wherein the separation device is fluidly disposed between an outlet of the second heat exchanger (42) and an inlet of one of the passes (72) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases circulating in the first pass (44).

10. Processing system (1) according to any one of claims 1 to 9 in combination with claim 7, wherein the first heat exchanger (40) comprises at least three passes (72, 82, 94) configured to cool the carbon dioxide-laden gases circulating in the first pass (44) of the first heat exchanger (40), the cooling circuit (84) comprising at least one expansion element (88) disposed between two of the passes (82, 94) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases circulating in the first pass (44).

11. Treatment system (1) according to any one of claims 1 to 10, wherein the second heat exchanger (42) comprises a first layer (46) configured to be used by the carbon dioxide-laden gases and at least the layer (54) included in the second branch (50) of the cooling loop (36), the layer (54) included in the second branch (50) of the cooling loop (36) being configured to cool the carbon dioxide-laden gases circulating in the first layer (46) of the second heat exchanger (42).

12. Treatment system (1) according to any one of claims 1 to 11 in combination with claims 5 and 6, wherein the separation device comprises at least one separator (30) and one purifier (32), the separator (30) being fluidly disposed between an outlet of the condensation device (28) and an inlet of the purifier (32) and / or between an outlet of the first layer (46) of the second heat exchanger (42) and an inlet of one of the passes (72) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases circulating in the first pass (44) of the first heat exchanger (40). 13.Treatment system (1) according to claim 12, wherein the separator (30) is 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, the treatment system (1) comprising a fluid circulation line in the liquid state (110) connecting the separator (30) to the purifier (32) and forming a layer (112) of the second heat exchanger (42).

14. Processing system (1) according to any one of claims 12 and 13, wherein the separation device comprises a pressure reducer (114) disposed fluidly between an outlet of the second heat exchanger (42) and an inlet of the purifier (32) or between an outlet of the separator (30) and an inlet of the purifier (32).

15. Treatment system (1) according to any one of claims 1 to 14 in combination with claims 6 and 12, comprising a bypass line (76) of the first pass (44) of the first heat exchanger (40), the purifier (32) comprising a heat exchange device (78) configured to implement heat exchange between liquid carbon dioxide contained in the purifier (32) and gases charged at least with carbon dioxide.

16. Processing system (1) according to any one of claims 1 to 15 in combination with claim 2, wherein the heat exchanger (56) of the cooling loop (36) is a main heat exchanger (56), the condensation device (28) comprising a refrigeration loop (96) having an additional heat exchanger (98) configured to perform heat exchange using a refrigerant fluid circulating within the main heat exchanger (56).

17. Processing system (1) according to claim 16 in combination with claim 7, wherein the additional heat exchanger (98) comprises a first channel (102) configured to channel the refrigerant fluid and a second channel (106), the cooling circuit (84) comprising said second channel (106).

18. Processing system (1) according to any one of claims 1 to 17, wherein the consumer is a fuel cell (2) comprising an anode (6) and a cathode (4), the condensation device (28) being configured to process carbon dioxide-laden gases emitted by the anode (6), the anode (6) being configured to be supplied with fuel produced from natural gas stored in the storage tank (10).

19. Processing system (1) according to claim 18 in combination with claim 6, comprising at least one return circuit (38) configured to channel residual gases separated by the separation device, the return circuit (38) comprising one of the passes (72, 82, 94) of the first heat exchanger (40) configured to cool the carbon dioxide-laden gases flowing in the first pass (44), the return circuit (38) connecting the separation device to the fuel cell (2).

20. Treatment system (1) according to claim 19 in combination with claim 12, comprising a bypass line (116) connecting the purifier (32) to the return circuit (38), the bypass line (116) bypassing the condensation device (28).

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