Method of treating gas loaded with carbon dioxide

Abstract

Title of the invention: Method for treating gas loaded with carbon dioxide The present invention relates to a method for treating exhaust gases comprising: - a first cooling step in a heat exchanger (6); - a second compression step in a compression device (12); - a third drying step in a drying unit (14); - a fourth decarbonization step in a carbon dioxide capture device (20); - a fifth step of sampling the exhaust gases at a temperature of the order of 180°C; - a sixth step of regenerating the drying unit (14); - a seventh step of sampling the exhaust gases at a temperature of 5°C; - an eighth step of cooling the drying unit (14). Abstract figure: Figure 1

Description

Title of the invention: Method for treating gas loaded with carbon dioxide

[0001] The present invention relates to the field of gases loaded with carbon dioxide, and more particularly to the methods used to treat such gases.

[0002] When a carbon dioxide-laden gas emission source is in operation, for example an internal combustion engine of a vehicle such as a floating structure, carbon dioxide-laden gases are generated. These gases are generally released into the atmosphere, causing environmental damage, in particular because of the carbon dioxide they contain. It is therefore advisable to treat the carbon dioxide-laden gases from a gas emission source in order to extract the carbon dioxide therefrom with a view to exploiting it for subsequent use or marketing.

[0003] The emission source may consist of a heat engine for example, or more generally any device which releases a flow of hot gas loaded with carbon dioxide. In the following, the invention will be described by way of example in the context of heat engines, and more particularly of engines powered by natural gas. However, the invention is in no way limited thereto.

[0004] Engines powered by natural gas are, for example, a propulsion engine or an accessory drive engine equipping a floating or land-based structure capable of containing and / or transporting liquefied natural gas (LNG).

[0005] Such structures conventionally comprise storage tanks which contain liquefied natural gas, also called natural gas in the liquid state. This natural gas is liquid at temperatures below -163°C at atmospheric pressure. The storage tanks are never perfectly thermally insulated, so that the natural gas evaporates at least partially therein. Thus, these tanks comprise both natural gas in a liquid form and natural gas in a gaseous form. In a known manner, at least a portion of the natural gas present in the tank in a gaseous form can thus be used to power, among other things, propulsion engines of the floating structure or accessory engines of the floating or land-based structure.

[0006] These engines consume natural gas and emit exhaust gases, which can be used to drive turbines before being released into the atmosphere. However, these exhaust gases, resulting from combustion of the natural gas supplied to the engines, contain carbon dioxide. It is therefore necessary to implement methods for treating these exhaust gases in order to limit the pollution caused by the carbon dioxide they contain.

[0007] It is thus known from the prior art to use, in order to isolate the carbon dioxide contained in the exhaust gases, a treatment method during which the exhaust gases pass through a carbon dioxide capture device. Such a carbon dioxide capture device, however, requires having a dry exhaust gas flow, and therefore requires the exhaust gases to pass through a drying unit comprising, for example, molecular sieves. The drying unit conventionally operates in two modes, an adsorption mode by which it adsorbs the moisture present in the exhaust gases and a desorption mode by which the moisture is removed from the drying unit itself. This desorption mode comprises a regeneration phase during which the drying unit is heated and a cooling phase during which it is cooled.The desorption method requires, in the first phase, a hot source and, in the second phase, a cold source which are not always available. Furthermore, it induces a multiplication of the components necessary for the implementation of the exhaust gas treatment method, which results in a significant bulk within the floating or terrestrial structure.

[0008] The present invention falls within this context by proposing a method for treating gases loaded with carbon dioxide which does away with the need for additional cold gas, while also simplifying the design of a treatment system configured to implement the treatment method.

[0009] The main object of the present invention is thus a method for treating gases loaded with carbon dioxide emitted by an emission source, comprising, during a circulation of the gases loaded with carbon dioxide within a treatment circuit: - a first stage during which the gases loaded with carbon dioxide are cooled within a heat exchanger; - a second stage during which the cooled carbon dioxide-laden gases are compressed within a compression device; - a third stage during which the gases loaded with compressed carbon dioxide are dried in a drying unit; - a fourth stage during which the gases loaded with dry carbon dioxide are freed from carbon dioxide within a carbon dioxide capture device, generating decarbonized gases; - a fifth stage during which a first portion of the decarbonized gases is taken from a first point in the treatment circuit where they have a temperature above 180°C and is sent to the drying unit; - a sixth stage during which the first portion of decarbonized gases regenerates the drying unit; - a seventh stage during which a second portion of the decarbonized gases is taken from a second point in the treatment circuit where they have a temperature of around 5°C and is sent to the drying unit; - an eighth stage during which the second portion of decarbonized gases cools the regenerated drying unit.

[0010] The treatment method according to the invention is intended to enable capture of the carbon dioxide present in the gases laden with carbon dioxide which come from a source of emission of gases laden with carbon dioxide, for example a propulsion engine or an accessory drive engine of a floating or land-based structure.

[0011] The treatment method consists of circulating a flow of gas loaded with carbon dioxide emitted by the emission source within a treatment circuit to a carbon dioxide capture device, while allowing optimal and simplified operation of the other components arranged on this treatment circuit. The treatment method provides for this purpose a plurality of steps which make it possible on the one hand to decarbonize the gases loaded with carbon dioxide and on the other hand to ensure proper operation of the components participating in the decarbonization. It should however be noted that the components of the treatment circuit participating in the performance of one or other of the steps of the treatment method can operate, depending on the case, either continuously or in different modes in a cyclical manner.In the context of this invention, the term "step" will thus refer either to an operation carried out on the gases loaded with carbon dioxide, or to a temporal phase of operation of a component operating cyclically.

[0012] Thus, the treatment method begins with a first step or cooling step, during which the gases loaded with carbon dioxide pass through a heat exchanger, for example a heat recovery boiler, within which they exchange calories for the purpose of cooling them. During a second step, or compression step, the gases loaded with carbon dioxide leaving the heat exchanger pass through a compression device. They are then compressed. At the outlet of the compression device, the gases loaded with carbon dioxide undergo a third step or drying step, during which the moisture they contain is adsorbed by a drying unit.These first, second and third stages are necessary to bring the carbon dioxide-laden gases to an optimum temperature and humidity level for decarbonization, which occurs in the carbon dioxide capture device during a fourth stage or carbon dioxide capture stage.

[0013] At the end of the fourth stage, the gases initially loaded with carbon dioxide are decarbonized and they could therefore be released into the atmosphere without risk of pollution. However, the present invention aims to reuse at least part of these decarbonized exhaust gases in order to regenerate and cool the drying unit. These two regeneration and cooling steps, which correspond to a desorption mode, are essential to enable the implementation of an adsorption mode of the drying unit which allows the drying of the gases loaded with carbon dioxide. The regeneration step corresponds to a sixth step of the treatment method, which is carried out subsequently to a fifth step or step of sampling a first portion of the decarbonized gases. During this fifth step, the decarbonized gases are more precisely sampled at a temperature above 180 °C, advantageously of the order of 200 °C, and possibly reaching 240 °C. Here, "of the order of" is understood to mean a temperature of 200 °C plus or minus 10 °C. Such a temperature is necessary to enable the regeneration of the drying unit, i.e. its heating to remove the moisture.Then, during a seventh step which is also a sampling step, a second portion of the decarbonized gases is sampled at a temperature of around 5°C. Here, "around" is understood to mean a temperature of 5°C plus or minus 10°C. This second portion of the decarbonized gases is used to carry out an eighth step of the treatment method, namely a cooling step. This cooling step is possible because the decarbonized gases leave the carbon dioxide capture device at low temperatures. The cooling step necessarily occurs after the regeneration step within the drying unit, but it is understood that due to the nature of the treatment method which applies to a treatment circuit within which the gases circulate continuously, certain steps may take place simultaneously.

[0014] By way of example and in relation to the aforementioned definition given to the term “step”, the seventh step corresponds to the continuous operation of a circuit for withdrawing the second portion of the decarbonized gases and therefore applies to the component as a whole, while the eighth step corresponds to a temporal phase of operation of the drying unit and therefore applies to a portion of the drying unit only.

[0015] According to an optional characteristic of the invention, the treatment method comprises a first calorie exchange step and a second calorie exchange step during which the decarbonized gases pass through the heat exchanger to cool the gases loaded with carbon dioxide emitted by the emission source.

[0016] It is thus understood that the gases pass twice within the heat exchanger, in counter-current so as to form a first pass and a second pass.

[0017] According to an optional characteristic of the invention, the treatment method comprises, between the first calorie exchange step and the second calorie exchange step, a first energy production step during which the decarbonized gases pass into a first turbine of the treatment circuit.

[0018] Thus, during the treatment method, the decarbonized gases pass through the heat exchanger for the first time in order to form its first pass, then they pass through the first turbine within which they participate in the generation of mechanical energy, and finally they pass through the heat exchanger again, of which they form the second pass. Thus, the decarbonized gases exchange calories before and after their passage through the first turbine.

[0019] According to an optional characteristic of the invention, the treatment method comprises, successively to the second step of heat exchange, a second step of energy production during which the decarbonized gases pass into a second turbine of the treatment circuit.

[0020] In other words, at the outlet of the heat exchanger the decarbonized gases pass through the second turbine, once again participating in the generation of mechanical energy.

[0021] According to an optional characteristic of the invention, the fifth step occurs after the second step of energy production.

[0022] The sampling of decarbonized gases then takes place at the outlet of the second turbine. This corresponds to a first embodiment of the treatment method according to the invention.

[0023] According to an optional characteristic of the invention, the fifth step occurs between the first step of calorie exchange and the first step of energy production.

[0024] It is understood that the sampling of decarbonized gases takes place between the first pass of the heat exchanger and the first turbine. This is a second embodiment of the treatment method according to the invention.

[0025] According to an optional characteristic of the invention, the treatment method comprises a step of humidifying the decarbonized gases by injecting water into the treatment circuit, the fifth step occurring prior to this humidification step.

[0026] In this case, which corresponds to a third embodiment of the treatment method according to the invention, the sampling of decarbonized gases takes place between the compression device and a water injection point.

[0027] According to an optional characteristic of the invention, the humidification step occurs prior to the first step of heat exchange.

[0028] The injection of water makes it possible to humidify the flow of decarbonized gases before it passes through the heat exchanger.

[0029] According to an optional characteristic of the invention, the treatment method comprises, following the sixth step, a step of releasing the first portion of the decarbonized gases into the atmosphere.

[0030] This corresponds to the first embodiment, in which the decarbonized gases having participated in the regeneration are rejected from the treatment circuit as soon as they leave the drying unit.

[0031] According to an optional characteristic of the invention, the treatment method comprises, following the sixth step, a step of returning the first portion of the decarbonized gases to a point in the treatment circuit arranged between the heat exchanger and the first turbine.

[0032] Such a return step is valid for the second and third embodiments. The first portion of the decarbonized gases used to regenerate the drying unit is thus reinjected into the treatment circuit upstream of the first turbine, so as to be recycled within the treatment circuit.

[0033] According to an optional characteristic of the invention, the treatment method comprises, following the fourth step, a heating step during which the decarbonized gases pass through the compression device.

[0034] The decarbonized gases then exchange calories with the carbon dioxide-laden gases from the emission source, for example from the fuel consumer, which still contain carbon dioxide.

[0035] According to an optional characteristic of the invention, the treatment method comprises, following the eighth step, a step of returning the second portion of the decarbonized gases to a point in the treatment circuit arranged between the compression device and the heat exchanger.

[0036] This corresponds to the first embodiment, for which the decarbonized gases used for cooling the drying unit are recycled within the treatment circuit, more particularly upstream of the first pass of the heat exchanger.

[0037] According to an optional characteristic of the invention, the treatment method comprises, following the eighth step, a step of returning the second portion of the decarbonized gases to a point in the treatment circuit arranged between the heat exchanger and the first turbine.

[0038] In this case, which covers both the second and third embodiments, the decarbonized gases used to cool the drying unit are also recycled but are here reinjected upstream of the first turbine.

[0039] According to an optional characteristic of the invention, the carrying out of the fifth step and the carrying out of the seventh step depend on a method for controlling a state of the drying unit.

[0040] It is understood that the treatment method is based on a control method which, depending on the state of the drying unit, controls either the implementation of the regeneration step or the implementation of the cooling step, both of which correspond to the desorption mode of the drying unit. The control method controls by elsewhere the adsorption mode of the drying unit once these two stages have been completed.

[0041] The invention further relates to a treatment system configured to implement the treatment method described above, the treatment system comprising a circuit for treating gases loaded with carbon dioxide on which are arranged, in this order, the heat exchanger, the compression device, the drying unit, and the carbon dioxide capture device.

[0042] The treatment system comprises the treatment circuit, which corresponds to all the pipes and components involved in implementing the treatment method. “In this order” means that the carbon dioxide-laden gases from the emission source circulate, within the treatment circuit, first in the heat exchanger, then in the compression device, then in the drying unit, and finally in the carbon dioxide capture device. Once decarbonized, the decarbonized gases can circulate within these different components in a different order.

[0043] In order to decarbonize the carbon dioxide-laden gases, the heat exchanger is configured to decrease a temperature of the carbon dioxide-laden gases for supply to the compression device. This compression device is configured to increase a pressure of the carbon dioxide-laden gases that it receives from the heat exchanger. The drying unit is configured to dry the carbon dioxide-laden gases once they have been compressed, and the carbon dioxide capture device is configured to decarbonize the dried carbon dioxide-laden gases so as to provide a decarbonized gas.

[0044] According to an optional characteristic of the invention, the drying unit is configured to alternately have a first adsorption configuration and a second desorption configuration.

[0045] The first adsorption configuration allows moisture to be removed from the carbon dioxide-laden gases, while the second desorption configuration aims to dehumidify the drying unit itself. The third step of the treatment method, i.e., the drying of the carbon dioxide-laden gases, thus occurs when the drying unit is in the first adsorption configuration, and conversely, the sixth and eighth steps, which are respectively regeneration and cooling, take place in the second desorption configuration of the drying unit.

[0046] According to an optional characteristic of the invention, the treatment circuit comprises a sampling line dedicated to conveying the first portion of the decarbonized gases to the drying unit, and a sampling pipe dedicated to conveying the second portion of the decarbonized gases to the drying unit.

[0047] It is understood that the sampling line participates in the regeneration of the drying unit, while the sampling pipe participates in its cooling.

[0048] According to an optional characteristic of the invention, the treatment circuit comprises a control valve and / or a valve for cutting off the sampling line and a control valve for the sampling pipe.

[0049] The control or shut-off valve of the sampling line allows or prevents the passage of the first portion of decarbonized gases within the sampling line. Similarly, the control valve of the sampling line allows or prevents the passage of the second portion of decarbonized gases within the sampling line.

[0050] According to an optional characteristic of the invention, the heat exchanger comprises at least a first pass and a second pass, the first turbine being arranged on the treatment circuit between the first pass and the second pass of the heat exchanger and the second turbine connecting the second pass of the heat exchanger to an outlet conduit of the treatment circuit.

[0051] The outlet conduit of the treatment circuit opens outside the treatment system, into the atmosphere.

[0052] According to an optional characteristic of the invention, the treatment circuit comprises an outlet pipe dedicated to evacuating the first portion of the decarbonized gases from the drying unit to the atmosphere.

[0053] This outlet pipe is used in the first embodiment. It is for example connected to the outlet pipe which is connected to the second turbine. As soon as they leave the drying unit, the decarbonized gases which participated in its regeneration can thus be evacuated from the treatment circuit.

[0054] According to an optional characteristic of the invention, the treatment circuit comprises a return pipe dedicated to evacuating the first portion of the decarbonized gases and / or the second portion of the decarbonized gases from the drying unit.

[0055] This return pipe is present in all three embodiments. It allows the decarbonized gases used, depending on the case, for the regeneration and / or cooling of the drying unit to be reinjected into the treatment circuit.

[0056] According to an optional characteristic of the invention, the return pipe is dedicated to the evacuation of the second portion of the decarbonized gases, the return pipe comprising a first end connected to the drying unit and a second end connected between the compression device and the heat exchanger.

[0057] This is the first embodiment, for which the return pipe is dedicated solely to the decarbonized gases that participated in the cooling. The return pipe then allows the return of these gases to the first pass of the heat exchanger.

[0058] According to an optional characteristic of the invention, the return pipe comprises a first end connected to the drying unit and a second end connected between the first pass of the heat exchanger and the first turbine.

[0059] This corresponds to the second and third embodiments, in which both the first portion and the second portion of the decarbonized gases, i.e. both the decarbonized gases used for regeneration and those used for cooling, are sent between the first pass of the heat exchanger and the first turbine.

[0060] According to an optional characteristic of the invention, the treatment circuit comprises a flow regulating valve between the heat exchanger and the second end of the return pipe.

[0061] The flow regulating valve is thus arranged, in the second embodiment, between the sampling point of the first portion of decarbonized gases and a return point of the decarbonized gases used to desorb the drying unit.

[0062] According to an optional characteristic of the invention, the treatment circuit comprises a control valve for the outlet pipe.

[0063] This pilot valve allows the passage of decarbonized gases which participated in the desorption mode of the drying unit into the outlet pipe to be authorized or not.

[0064] According to an optional characteristic of the invention, the treatment circuit comprises a control valve for the return pipe.

[0065] This pilot valve allows the passage of decarbonized gases which participated in the desorption mode of the drying unit into the return pipe to be authorized or not.

[0066] According to an optional characteristic of the invention, the treatment system comprises a system for controlling a circulation of gases loaded with carbon dioxide within the treatment circuit.

[0067] According to an optional characteristic of the invention, the control system controls the opening and / or closing of the control valve of the sampling line, the control valve of the sampling pipe, the pilot valve of the outlet pipe and the pilot valve of the return pipe.

[0068] According to an optional characteristic of the invention, the control system controls the opening and / or closing of the flow regulating valve.

[0069] Thus, the control system controls the opening and / or closing of the various valves present within the treatment circuit in order to implement, as required, the regeneration of the drying unit or its cooling.

[0070] According to an optional characteristic of the invention, the control carried out by the control system is dependent on a flow rate of gases loaded with carbon dioxide within the treatment circuit.

[0071] According to an optional characteristic of the invention, the heat exchanger is a recovery boiler.

[0072] According to an optional characteristic of the invention, the drying unit comprises a plurality of dryers including at least a first dryer and a second dryer, the first dryer being in the first adsorption configuration when the second dryer is in the second desorption configuration.

[0073] It is thus understood that the two dryers are in opposite configurations; the first dryer participates in drying the gases loaded with carbon dioxide while the second dryer is regenerated then cooled, then vice versa. These dryers are identical and take turns in time to ensure the continuity of the drying of the gas. This makes it possible to implement the treatment method without interruption which would be due to a need to desorb the dryers. Each dryer, taken individually, operates cyclically; in other words, it undergoes a cycle of operations succeeding one another in time, namely an adsorption and a desorption.

[0074] The invention further relates to a floating structure, comprising a source of emission of gases loaded with carbon dioxide and a system for treating the gases loaded with carbon dioxide emitted by the emission source, namely the exhaust gases emitted by this fuel consumer.

[0075] The emission source here is a fuel consumer, for example a propulsion engine or an accessory drive engine of the floating structure, such a consumer being supplied with gas resulting from the evaporation of liquefied gas stored in a storage tank of the floating structure, for example liquefied natural gas.

[0076] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which:

[0077] [Fig-1] illustrates, schematically, a first embodiment of a system of treatment implementing an exhaust gas treatment method according to the invention;

[0078] [Fig.2] illustrates, schematically, a second embodiment of the processing system implementing the processing method according to the invention;

[0079] [Fig.3] illustrates, schematically, a third embodiment of the processing system implementing the processing method according to the invention.

[0080] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art. of the prior art.

[0081] In the figures, the elements common to several figures retain the same reference.

[0082] In this description, the invention is described in a non-limiting manner in the context of a floating structure with a fuel consumer which represents the source of emission of gases loaded with carbon dioxide. The gases loaded with carbon dioxide are the exhaust gases emitted by this fuel consumer. After passing through the carbon dioxide capture device, these gases become decarbonized exhaust gases. However, the invention applies in a similar manner to any device which releases a flow of hot gas loaded with carbon dioxide.

[0083] Figures 1 to 3 thus illustrate, schematically, an exhaust gas treatment system 1 according to the invention. The treatment system 1 is intended to equip a floating or land-based structure for the purpose of capturing the carbon dioxide contained in exhaust gases from a fuel consumer 2 of the structure. Such a fuel consumer 2, for example an engine, is supplied with gas which may be derived from the natural evaporation of liquefied natural gas which is stored in one or more storage tanks of the floating or land-based structure, the exhaust gases resulting from the use of the gas derived from the natural evaporation of liquefied natural gas by the fuel consumer 2.

[0084] The treatment system 1 comprises a treatment circuit 4, within which the exhaust gases circulate. This treatment circuit 4 comprises on the one hand various lines and conduits which make it possible to channel the exhaust gases, and on the other hand various components which participate in the treatment of these exhaust gases.

[0085] The treatment circuit 4 comprises on the one hand a conveying line 3 and an evacuation line 5. The conveying line 3 makes it possible to circulate the exhaust gases within the treatment circuit 4 with a view to their decarbonization, while the evacuation line 5 allows the decarbonized exhaust gases to flow.

[0086] The treatment circuit 4 is connected to the fuel consumer 2 via the routing line 3 so as to channel the exhaust gases that it emits. At the outlet of the fuel consumer 2, these exhaust gases are directed via the routing line 3 to a heat exchanger 6, here a recovery boiler 6. This heat exchanger 6 is composed of a first pass 8 and a second pass 10. The heat exchanger 6 is configured to cool the exhaust gases, these exhaust gases exchanging calories successively with a gas circulating within the first pass 8 then with a gas circulating within the second pass 10.

[0087] The treatment circuit 4 also has a compression device 12 which is connected to the heat exchanger 6 by the routing line 3. This compression device 12 may, according to alternative embodiments, have one or more compression stages. The compression device 12 is configured to compress the exhaust gases which it receives from the heat exchanger 6.

[0088] The routing line 3 connects an outlet of the compression device 12 to an inlet of a drying unit 14 of the treatment circuit 4 of the treatment system 1. This drying unit 14 is configured to remove the moisture that comprises the exhaust gases. For this purpose, the drying unit 14 is configured to have a first adsorption configuration and a second desorption configuration. The first adsorption configuration corresponds to an effective capture of the moisture present in the exhaust gases, while the second desorption configuration is adopted in the absence of exhaust gases and makes it possible to remove the moisture present in the drying unit 14 after it has been removed from the exhaust gases.The second desorption configuration more precisely covers a first regeneration phase of the drying unit 14, during which it is dried, then a second cooling phase, during which it is cooled so as to be brought to temperatures allowing the resumption of the first adsorption configuration.

[0089] The drying unit 14 comprises, as shown in the figures, a plurality of dryers 16 including a first dryer 16A, a second dryer 16B and a third dryer 16C. In order to enable continuous implementation of the removal of moisture present in the exhaust gases, at least one of the dryers 16 is in the first adsorption configuration while at least one other of these dryers 16 is in the second desorption configuration. For example, the first dryer 16A and the second dryer 16B are in the first adsorption configuration while the third dryer 16C is in the second desorption configuration. The implementation of one or other of these configurations is made possible thanks to the presence, within the treatment circuit 4, of the valves 18 associated with each of the dryers 16.Due to the countercurrent operation of the first adsorption configuration and the second desorption configuration, these valves 18 are arranged both at the inlet of the dryers 16 and at their outlet. It is understood that the inlet of the dryers 16 corresponds to their portion connected to the compression device 12.

[0090] The outlet of the drying unit is connected, by the routing line 3, to a carbon dioxide capture device 20, which is configured to remove carbon dioxide present in the exhaust gases. The carbon dioxide capture device carbon dioxide 20 comprises for this purpose a first sub-unit 22 capable of receiving the dried exhaust gases at their outlet from the drying unit 14, as well as a second sub-unit 24 capable of releasing the decarbonized exhaust gases at cryogenic temperatures. It is understood from the above that the first sub-unit 22 is connected to the routing line 3 while the second sub-unit 24 is connected to the evacuation line 5, this evacuation line 5 being dedicated to the circulation of the decarbonized exhaust gases.

[0091] Within the treatment circuit 4, the carbon dioxide capture device 20 and more particularly its second sub-unit 24 is connected to the compression device 12. Thus, the compression device 12 is crossed both by the exhaust gases loaded with carbon dioxide, via the conveying line 3, and by the decarbonized exhaust gases via the discharge line 5. In other words, the conveying line 3 makes it possible to bring the exhaust gases to the carbon dioxide capture device 20 while the discharge line 5 allows the decarbonized exhaust gases to leave this carbon dioxide capture device 20.

[0092] The discharge line 5 of the treatment circuit 4 further connects the compression device 12 to the heat exchanger 6, so that this discharge line 5 is connected to the first pass 8. Opposite the compression device 12, the first pass 8 is connected to a first turbine 26. This first turbine 26 uses the energy of the decarbonized exhaust gases to provide useful mechanical energy within the floating or terrestrial structure. The first turbine 26 is connected to the second pass 10 of the heat exchanger 6; it is therefore understood that the decarbonized exhaust gases circulate countercurrently in the first pass 8 and in the second pass 10 to exchange calories twice with the exhaust gases traveling in the supply line 3.

[0093] At the outlet of the second pass 10, the discharge line 5 connects the heat exchanger 6 to a second turbine 28, which, like the first turbine 26, is configured to supply mechanical energy to the floating or terrestrial structure. At the outlet of the second turbine 28, the discharge line 5 comprises an outlet conduit 30 through which it opens onto the atmosphere, that is to say outside the treatment circuit 4 and the treatment system 1.

[0094] In addition to the conveying line 3 and the evacuation line 5, which are used in the context of the first adsorption configuration of the drying unit 14, the treatment circuit 4 comprises conduits which allow the implementation of the second desorption configuration of this drying unit 14. Thus, the treatment circuit 4 comprises a sampling line 32 which allows the regeneration of the drying unit 14 and a sampling pipe 34 which allows its cooling. dissement.

[0095] The sampling line 32 is connected to the discharge line 5 in a zone where the decarbonized exhaust gases that it channels have a temperature greater than 180°C, which corresponds to a first portion of the decarbonized exhaust gases. Such a temperature is optimal for regenerating the dryers 16 of the drying unit 14. The sampling pipe 34 is connected to the discharge line 5 in a zone where the decarbonized exhaust gases that it channels have a temperature of the order of 5°C, which corresponds to a second portion of the decarbonized exhaust gases. This temperature of 5°C is suitable for cooling the dryers 16 of the drying unit 14 after their regeneration. It should be noted that such connections of the sampling line 32 and the sampling pipe 34 diverge according to different embodiments of the invention.

[0096] The treatment system 1 is shown according to a first embodiment in [Fig. 1], according to a second embodiment in [Fig. 2] and according to a third embodiment in [Fig. 3]. The first and second embodiments correspond respectively to a low-pressure treatment system 1 and a high-pressure treatment system 1. These first and second embodiments are suitable but not exclusive for a flow rate of exhaust gases which are decarbonized greater than 50% of a total of the exhaust gases at the outlet of the fuel consumer 2. The third embodiment corresponds on the contrary to a treatment system 1 providing water injection. This third embodiment is suitable for the case of a flow rate of exhaust gases which are decarbonized less than 50% of the total of the exhaust gases at the outlet of the fuel consumer 2.

[0097] In the first embodiment of [Fig.l], the sampling line 32 within which the first portion of the decarbonized exhaust gases circulates is connected to the discharge line 5 between the second turbine 28 and the outlet duct 30. Furthermore, this sampling line 32 opens into the drying unit 14. Within the sampling line 32 of the first embodiment, the first portion of the decarbonized exhaust gases has a pressure of the order of 1.1 bar abs. More generally, the first portion of the decarbonized exhaust gases has a pressure of between 1 and 1.3 bar abs.

[0098] In this first embodiment, the treatment circuit 4 comprises an outlet pipe 38 which is dedicated to the evacuation of the first portion of the decarbonized exhaust gases from the treatment system 1. This outlet pipe 38, visible in [Fig.l], connects the drying unit 14 to the atmosphere. It can for this purpose be connected to the outlet pipe 30, the first portion of the decarbonized exhaust gases taking the outlet pipe 38 then the outlet pipe 30 to be discharged into the atmosphere. Alternatively, the outlet pipe 38 can be a independent pipe opening onto the atmosphere. This outlet pipe 38 is equipped, in the vicinity of the drying unit 14, with a pilot valve 40 which, when open, allows passage of the first portion of the decarbonized exhaust gases into the outlet pipe 38 and, when closed, prevents such passage.

[0099] In the second embodiment illustrated in [Fig.2], the sampling line 32 which channels the first portion of the decarbonized exhaust gases is connected to the discharge line 5 between the first pass 8 of the heat exchanger 6 and the first turbine 26, and it opens into the drying unit 14. In this sampling line 32 of the second embodiment, the first portion of the decarbonized exhaust gases has a pressure of the order of 4 bar abs. More generally, the first portion of the decarbonized exhaust gases has a pressure of between 3 and 5 bar abs.

[0100] In the third embodiment shown in [Fig.3], the discharge line 5 comprises a water injection point 36 at which water is injected into the treatment circuit 2 in order to humidify the decarbonized exhaust gases. This water injection point 36 is more precisely arranged between the compression device 12 and the first pass 8 of the heat exchanger 6. The sampling line 32 within which the first portion of the decarbonized exhaust gases circulates is in the third embodiment connected to the discharge line 5 between the compression device 12 and the water injection point 36, in other words upstream of the water injection point 36, and it opens into the drying unit 14. Within the sampling line 32 of this third embodiment, the first portion of the decarbonized exhaust gases has a pressure of the order of 4 bar abs, that is to say between 3 and 5 bar abs.

[0101] In the second embodiment and in the third embodiment, the treatment system 1 does not have an outlet pipe 38 such as that of the first embodiment. On the contrary, in these two embodiments the first portion of the decarbonized exhaust gases is intended to be reinjected into the treatment circuit 4. For this purpose, the treatment circuit 4 comprises a return pipe 42 which returns the first portion of the decarbonized exhaust gases having participated in the regeneration of the drying unit 14 into the treatment circuit 4. For the second embodiment as for the third embodiment, this return pipe 42 connects the drying unit 14 to the discharge line 5 between the first pass 8 of the heat exchanger 6 and the first turbine 26.The return line 42 is more precisely connected, in the second embodiment, between the sampling line 32 and the first turbine 26. In order to facilitate a flow of decarbonized exhaust gases within the portion of the . discharge line 5 arranged between the first pass 8 of the heat exchanger 6 and the first turbine 26, this discharge line 5 is equipped with a flow regulating valve 44 arranged between connection points of the sampling line 32 on the one hand and of the return pipe 42 on the other hand.

[0102] Furthermore, in this second embodiment the return pipe 42 is equipped with a pilot valve 46 which, when open, allows passage of the first portion of the decarbonized exhaust gases into the return pipe 42 and which, when closed, prevents such passage.

[0103] Whatever the embodiment, the sampling line 32 comprises a control valve 48 or shut-off valve which, when open, allows passage of the first portion of the decarbonized exhaust gases into the sampling line 32 for the purpose of regenerating the drying unit 14, and which, when closed, prevents such passage. In the first embodiment, the sampling line 32 further comprises a flow control valve 49.

[0104] The sampling line 34, which as mentioned above has the role of conveying the second portion of the decarbonized exhaust gases to the drying unit 14 for cooling, is connected to the discharge line 5 in a zone where the decarbonized exhaust gases that it channels have a temperature of the order of 5°C. In the three embodiments, the sampling line 34 thus connects an outlet of the compression device 12 to the drying unit 14. As shown in the figures, this sampling line 34 may have a portion for which it is merged with the sampling line 32 which is dedicated to regeneration. Since cooling and regeneration are not carried out at the same time but rather in turn, this allows the decarbonized exhaust gases to borrow a portion of the treatment circuit 4 otherwise unused.The sampling line 34 is provided with a control valve 50, which when open allows passage of the second portion of the decarbonized exhaust gases in order to cool the drying unit 14, and which when closed prevents such passage.

[0105] In the second and third embodiments, the return pipe 42 which allows the reinjection of the first portion of the decarbonized exhaust gases is also used by the second portion of the decarbonized exhaust gases. In other words, the return pipe 42 is common to the decarbonized exhaust gases used for the regeneration of the drying unit 14 and to the decarbonized exhaust gases used for its cooling.

[0106] On the contrary, in the first embodiment the treatment circuit 4 comprises a return pipe 42 which is exclusively dedicated to the channeling of the second portion of the decarbonized exhaust gases, the first portion of the decarbonized exhaust gases using the outlet pipe 30. In this first embodiment, as seen in [Fig.l] the return pipe 42 connects the drying unit 14 to the first pass 8 of the heat exchanger 6.

[0107] In all embodiments, the treatment system 1 comprises a control system 52 for the circulation of exhaust gases within the treatment circuit 4. This control system 52 is capable of controlling the opening and closing of the various valves of the treatment system 1, so as to operate the implementation of the first adsorption configuration of the drying unit 14 as well as the implementation of its second desorption configuration, and more precisely its regeneration or its cooling.

[0108] The treatment system 1 is configured to implement a method for treating exhaust gases according to the invention, which will now be described in relation to each of the embodiments.

[0109] The treatment method 1 begins with a first step or cooling step, for which the exhaust gases from the fuel consumer 2 are conveyed from this fuel consumer to the heat exchanger 6 via the supply line 3. This first cooling step is carried out by implementing heat exchange steps within the heat exchanger 6, with a first heat exchange step carried out between the exhaust gases from the fuel consumer 2 and the decarbonized exhaust gases circulating in the first pass 8, and a second heat exchange step carried out between the exhaust gases from the fuel consumer 2 and the decarbonized exhaust gases circulating in the second pass 10.

[0110] Following the first step, the treatment method comprises a second step or compression step during which the cooled exhaust gases are compressed within the compression device 12. Once compressed, the exhaust gases are conveyed via the conveying line 3 to the drying unit 14 for carrying out a third step or drying step. The compressed exhaust gases then pass through the dryer(s) 16 which are in their first adsorption configuration, i.e. for the embodiments shown here the first dryer 16A and the second dryer 16B.

[0111] During a fourth step or carbon dioxide capture step, the dried exhaust gases pass through both the first subunit 22 and the second subunit 24 of the carbon dioxide capture device 20 where they are decarbonized and cooled to cryogenic temperatures. The dried exhaust gases are, during the fourth step, cooled to cryogenic temperatures.

[0112] Once the exhaust gases have been decarbonized, they pass through the discharge line 5. The treatment method comprises a heating step during which the decarbonized exhaust gases circulating in this discharge line 5 pass through the compression device 12. They are then heated during an exchange of calories with the exhaust gases which circulate within this compression device 12 prior to their drying within the drying unit 14.

[0113] When the treatment method is implemented within a treatment system 1 according to the third embodiment, this treatment method comprises a humidification step which corresponds to an injection of water within the treatment circuit 4 and more precisely of the discharge line 5 in order to humidify the decarbonized exhaust gases which circulate therein. This humidification step takes place after the heating step. The first and second embodiments do not have such a humidification step.

[0114] Following the heating step or following the humidification step for the embodiment where this is implemented, the decarbonized exhaust gases participate in the first heat exchange step and the second heat exchange step as described above. It should be noted that between these two heat exchange steps, the treatment method comprises the occurrence of a first energy production step during which the decarbonized exhaust gases pass into the first turbine 26. Another energy production step, in this case a second energy production step, takes place successively to the second heat exchange step. During this second energy production step, the decarbonized exhaust gases circulate within the second turbine 28.After this second energy production stage, the decarbonized exhaust gases are discharged from the treatment system 1 via a discharge stage during which they pass through the outlet conduit 30 to the atmosphere.

[0115] What has been described previously in relation to the treatment method according to the invention is applicable when the drying unit 14, or more particularly one of its dryers 16, is in its first adsorption configuration. The treatment method further comprises steps which allow the implementation of the second desorption configuration, which will now be detailed.

[0116] The second desorption configuration of the drying unit 14 requires the successive implementation of a regeneration step and a cooling step, which correspond respectively to a sixth step and an eighth step of the treatment method. Each of these sixth and eighth steps requires a supply of decarbonized exhaust gases within the drying unit 14, which take place respectively during a fifth step for the regeneration step and a seventh step for the cooling step.

[0117] The fifth step is a sampling step during which the first portion of the decarbonized exhaust gases is sampled at a first point in the circuit. treatment, variable depending on the embodiments, where these decarbonized exhaust gases are at a temperature between 35 and 250°C.

[0118] As previously described in relation to the treatment system 1 of [Fig.l], in the first embodiment the sampling point of the first portion of the decarbonized exhaust gases is arranged, within the treatment circuit 4, between the second turbine 28 and the outlet duct 30. It is understood that in this first embodiment, the fifth step therefore takes place, following the circulation of the decarbonized exhaust gases, following the second energy production step.

[0119] Once sampled, the first portion of the decarbonized exhaust gases is then sent to the drying unit 14 via the sampling line 32. This first portion of the decarbonized exhaust gases carries out the regeneration of the dryer(s) 16 of the drying unit 14 during the sixth step, then it is returned to the atmosphere via the outlet pipe 38 then the outlet pipe 30 during a discharge step.

[0120] In the case of the second embodiment of the treatment system 1, that is to say relative to [Fig.2], the fifth step of sampling the first portion of the decarbonized exhaust gases takes place between the heat exchanger 6 and the first turbine 26, in other words between the first step of heat exchange and the first step of energy production according to the circulation of the decarbonized exhaust gases.

[0121] Once sampled, the first portion of the decarbonized exhaust gases is then sent to the drying unit 14 via the sampling line 32. This first portion of the decarbonized exhaust gases carries out the regeneration of the dryer(s) 16 of the drying unit 14 during the sixth step, then it is reinjected into the treatment circuit 4 during a return step. It is more particularly reinjected between the sampling point of the first portion of the decarbonized exhaust gases and the first turbine 26, that is to say according to the circulation of the decarbonized exhaust gases between the first step of heat exchange and the first step of energy production.

[0122] Finally, for the third embodiment of [Fig. 3], the fifth step of sampling the first portion of the decarbonized exhaust gases takes place between the compression device 12 and the water injection point 36, i.e. according to the circulation of the decarbonized exhaust gases between the heating step and the humidification step.

[0123] Once sampled, the first portion of the decarbonized exhaust gases is then sent to the drying unit 14 via the sampling line 32. This first portion of the decarbonized exhaust gases carries out the regeneration of the dryer(s) 16 of the drying unit 14 during the sixth step, then it is reinjected into the treatment circuit 4 during the return stage. It is more particularly reinjected between the first pass 8 of the heat exchanger 6 and the first turbine 26, that is to say according to the circulation of the decarbonized exhaust gases between the first stage of heat exchange and the first stage of energy production, like the second embodiment.

[0124] The seventh step is a sampling step during which the second portion of the decarbonized exhaust gases is sampled, via the sampling line 34, at a second point in the treatment circuit where these decarbonized exhaust gases are at a temperature of the order of 5°C. This second sampling point, which is similar for the three embodiments, is arranged on the treatment circuit 4 at the outlet of the compression device 12, i.e. according to the circulation of the decarbonized exhaust gases following a first heating step.

[0125] The second portion of the exhaust gases taken during the seventh stage is conveyed to the drying unit 14, where it cools the dryers 16 during the eighth cooling stage.

[0126] At the end of this eighth cooling step, the second portion of the decarbonized exhaust gases is reinjected into the treatment circuit 4 via the return pipe 42 at points which differ according to the embodiments. For the first embodiment, the second portion of the decarbonized exhaust gases is reinjected upstream of the heat exchanger 6, that is to say prior to the first step of heat exchange according to the circulation of the decarbonized exhaust gases.

[0127] For the second embodiment as well as for the third embodiment, the reinjection of the second portion of the decarbonized exhaust gases takes place between the first pass 8 of the heat exchanger 6 and the first turbine 26, that is to say according to the circulation of the decarbonized exhaust gases between the first step of heat exchange and the first step of energy production.

[0128] It should be noted that whatever the embodiment chosen, the implementation of the treatment method is framed by a control method implemented by the control system 52, such a control method deciding for example on an alternation between the first adsorption configuration of the drying unit 14 and its second desorption configuration, and for the second desorption configuration on an alternation between the regeneration phase and the cooling phase, these alternations being a function of controlling the opening or closing of the various valves of the treatment circuit 4 of the treatment system 1.

[0129] The present invention thus provides a method of treating and a system for treating exhaust gases from a fuel consumer which limit a number of components necessary for the operation of a drying unit of the treatment system, by avoiding a demand for cold gas otherwise solely dedicated to the cooling of this drying unit.

[0130] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Claims

1. Method for treating carbon dioxide-laden gases emitted by an emission source (2), comprising, during a circulation of the carbon dioxide-laden gases within a treatment circuit (4): - a first step during which the carbon dioxide-laden gases are cooled within a heat exchanger (6); - a second step during which the cooled carbon dioxide-laden gases are compressed within a compression device (12); - a third step during which the compressed carbon dioxide-laden gases are dried within a drying unit (14); - a fourth step during which the dry carbon dioxide-laden gases are freed from carbon dioxide within a carbon dioxide capture device (20), generating decarbonized gases;- a fifth step during which a first portion of the decarbonized gases is taken from a first point of the treatment circuit (4) where they have a temperature greater than 180°C and is sent to the drying unit (14); - a sixth step during which the first portion of the decarbonized gases regenerates the drying unit (14); - a seventh step during which a second portion of the decarbonized gases is taken from a second point of the treatment circuit (4) where they have a temperature of the order of 5°C and is sent to the drying unit (14); - an eighth step during which the second portion of the decarbonized gases cools the regenerated drying unit (14).

2. Treatment method according to the preceding claim, comprising a first heat exchange step and a second heat exchange step during which the decarbonized gases pass through the heat exchanger (6) to cool the carbon dioxide-laden gases emitted by the emission source (2).

3. Treatment method according to the preceding claim, comprising, between the first calorie exchange step and the second calorie exchange step, a first energy production step during which the decarbonized gases pass through a first turbine (26) of the treatment circuit (4).

4. Treatment method according to the preceding claim, comprising, successively to the second step of heat exchange, a second step of energy production during which the decarbonized gases pass into a second turbine (28) of the treatment circuit (4).

5. A method of treatment according to any preceding claim in combination with claim 3, wherein the fifth step occurs between the first calorie exchange step and the first energy production step.

6. A treatment method according to claim 4, wherein the fifth step occurs after the second energy production step.

7. Treatment method according to any one of claims 1 to 4, comprising a step of humidifying the decarbonized gases by injecting water into the treatment circuit (4), the fifth step occurring prior to this humidification step.

8. Treatment method according to the preceding claim in combination with any one of claims 3 and 4, in which the humidification step occurs prior to the first step of heat exchange.

9. A treatment method according to any one of the preceding claims, comprising, following the sixth step, a step of releasing the first portion of the decarbonized gases into the atmosphere.

10. Treatment method according to any one of claims 1 to 8 in combination with claim 3, comprising, following the sixth step, a step of returning the first portion of the decarbonized gases to a point in the treatment circuit (4) arranged between the heat exchanger (6) and the first turbine (26).

11. A treatment method according to any preceding claim, comprising, following the fourth step, a heating step during which the decarbonized gases pass through the compression device (12).

12. Treatment method according to the preceding claim, comprising, following the eighth step, a step of returning the second portion of the decarbonized gases to a point in the treatment circuit (4) arranged between the compression device (12) and the heat exchanger (6).

13. A method of treatment according to any one of claims 1 to 11, comprising, following the eighth step, a step of returning the second portion of the decarbonized gases to a point in the treatment circuit (4) arranged between the heat exchanger (6) and the first turbine (26).

14. A treatment method according to any preceding claim, wherein carrying out the fifth step and carrying out the seventh step depend on a method of controlling a state of the drying unit (14).

15. Treatment system (1) configured to implement the treatment method according to any one of the preceding claims, the treatment system (1) comprising a treatment circuit (4) for gases loaded with carbon dioxide on which are arranged, in this order, the heat exchanger (6), the compression device (12), the drying unit (14), and the carbon dioxide capture device (20).

16. Treatment system (1) according to the preceding claim, wherein the drying unit (14) is configured to alternately have a first adsorption configuration and a second desorption configuration.

17. Treatment system (1) according to any one of claims 15 and 16, in which the treatment circuit (4) comprises a sampling line (32) dedicated to conveying the first portion of the decarbonized gases to the drying unit (14), and a sampling line (34) dedicated to conveying the second portion of the decarbonized gases to the drying unit (14).

18. Treatment system (1) according to the preceding claim, in which the treatment circuit (4) comprises a control valve (48) and / or a sectioning valve for the sampling line (32) and a control valve (50) for the sampling line (34).

19. Treatment system (1) according to any one of claims 15 to 18 in combination with claim 4, wherein the heat exchanger (6) comprises at least a first pass (8) and a second pass (10), the first turbine (26) being arranged on the treatment circuit (4) between the first pass (8) and the second pass (10) of the heat exchanger (6) and the second turbine (28) connecting the second pass (10) of the heat exchanger (6) to an outlet conduit (30) of the treatment circuit (4).

20. A processing system (1) according to any one of claims 15 to 19, in which the treatment circuit (4) comprises an outlet pipe (38) dedicated to discharging the first portion of the decarbonized gases from the drying unit (14) to the atmosphere.

21. Treatment system (1) according to any one of claims 15 to 20, wherein the treatment circuit (4) comprises a return pipe (42) dedicated to evacuating the first portion of the decarbonized gases and / or the second portion of the decarbonized gases from the drying unit (14).

22. Treatment system (1) according to any one of claims 15 to 21, comprising a control system (52) for a circulation of gases loaded with carbon dioxide within the treatment circuit (4).

23. Treatment system (1) according to claim 22, in which the control carried out by the control system (52) is dependent on a flow rate of gases loaded with carbon dioxide within the treatment circuit (4).

24. The treatment system (1) of claim 16, wherein the drying unit (14) comprises a plurality of dryers (16) including at least a first dryer (16A) and a second dryer (16B), the first dryer (16A) being in the first adsorption configuration when the second dryer (16B) is in the second desorption configuration.

25. Floating structure, comprising an emission source (2) of gases loaded with carbon dioxide and a treatment system (1) of the gases loaded with carbon dioxide emitted by the emission source (2) according to any one of claims 15 to 24.

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