System for treating carbon dioxide-rich gases

Abstract

The present invention relates to a system (1) for treating carbon dioxide-rich gases, comprising a liquefied natural gas tank (10), a distribution line (13) connecting the tank (10) to a connection terminal (11), the treatment system (1) comprising a reforming unit (2) comprising a reforming device (6), and a feed line (12) connecting the distribution line (13) to the reforming unit (2), the treatment system (1) comprising a carbon dioxide capture unit (24) comprising a carbon dioxide desublimation device (38, 38A, 38B), the treatment system (1) comprising a fluid loop (44) between the distribution line (13) and the desublimation device (38, 38A, 38B).

Description

[0001] DESCRIPTION

[0002] Title: Carbon Dioxide-Laden Gas Treatment System

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

[0004] When a carbon dioxide (CO2) 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. It is therefore advantageous to treat the carbon dioxide-laden gases from a gas emission source in order to extract the carbon dioxide for later use or commercialization, or for deep geological disposal. An example of such an emission source is a reforming unit. Reforming units are notably used in applications for producing hydrogen from natural gas, either through steam methane reforming (SMR) or autothermal reforming (ATR).In the absence of carbon dioxide capture during these applications, the hydrogen produced is called "grey hydrogen." To reduce the carbon footprint of such hydrogen production, it is known to capture the carbon dioxide from the gases emitted by the reforming section; this is then referred to as "blue hydrogen." In steam reforming of methane, the reforming unit consists of a combustion section and a reforming section that are separate from each other, with the gases to be treated originating primarily from the reforming section. In autothermal reforming, there is no distinction between combustion and reforming.

[0005] The present invention falls within this context by proposing a system for treating gases emitted by a reforming unit, capturing the carbon dioxide contained in these gases in order to produce blue hydrogen. The main object of the present invention is thus a system for treating gases laden with carbon dioxide, comprising a liquefied natural gas storage tank, a distribution line configured to connect the storage tank to a natural gas connection terminal, the treatment system comprising a reforming unit including at least one reforming device emitting the carbon dioxide-laden gases, the treatment system comprising a feed line connecting the distribution line to the reforming unit, the treatment system comprising at least one carbon dioxide capture unit including at least one carbon dioxide desublimation device.The treatment system comprises a fluid loop extending between the distribution line and the desublimation device, the fluid loop being configured to exchange heat between the carbon dioxide-laden gases circulating within the desublimation device and the liquefied natural gas circulating within the distribution line.

[0006] According to an optional feature of the invention, the reforming unit is a steam reforming unit of methane, the reforming unit comprising the reforming device configured to emit carbon dioxide-laden gases and a combustion device.

[0007] According to an optional feature of the invention, the reforming unit is an autothermal reforming unit comprising the reforming device.

[0008] The treatment system according to the invention enables the capture of carbon dioxide present in gases emitted by a reforming unit. The gases emitted by the reforming unit are rich in carbon dioxide and under pressure. When the reforming unit is a steam reforming unit of methane comprising both a reforming device and a combustion device, the carbon dioxide capture occurs on the exhaust gases emitted by the reforming device. The treatment system enables the production of blue dihydrogen, this dihydrogen being produced within the reforming unit during a reaction of natural gas with steam. Dihydrogen is therefore, along with carbon dioxide, present in a stream of various gases emitted by the reforming device. The carbon dioxide is extracted from the gases emitted by the reforming device using a carbon dioxide capture unit, here within a desublimation device.This desublimation unit is advantageously cooled indirectly using liquefied natural gas (LNG), which is either used to supply the reforming unit or injected into a gas network from a connection terminal. In the first case, the LNG intended for supply to the reforming unit is, prior to being connected to the supply line, used to cool a fluid loop that captures carbon dioxide within the desublimation unit. The use of a fluid loop facilitates the transfer of the LNG's cooling capacity to the desublimation unit. Furthermore, managing the temperature generated by this loop within the desublimation unit is easier. Finally, the fluid loop provides a readily available supply of fluid at the appropriate temperature when the treatment system is started up.The fluid is, for example, a heat transfer fluid in the liquid state, at every point of the fluid loop. The fluid loop is an intermediary between the natural gas in the liquid state and the desublimation device.

[0009] The storage tank constitutes a reserve of fuel available to supply the reforming unit. Liquefied natural gas (LNG) flows to the reforming unit via a feed line connected to a distribution line extending from the storage tank to a connection terminal. This connection terminal allows the LNG to be transformed from its liquid to its gaseous state for injection into a distribution network. The presence of a connection terminal ensures the availability of LNG. The processing system according to the invention uses the LNG as a cooling source to help desublimate carbon dioxide, while simultaneously heating the LNG to prepare it for its transition to a gaseous state for delivery to both the reforming unit and the connection terminal.

[0010] Once the carbon dioxide has been desublimated, the hydrogen present in the decarbonized gases is extracted using a hydrogen separation unit, for example, by adsorption within this unit. The hydrogen separation unit allows for the separation of hydrogen from other gases contained in the carbon dioxide-laden gases.

[0011] According to an optional feature of the invention, the treatment system includes a drying unit and a unit for separating dihydrogen present in the gases emitted by the reforming device, the carbon dioxide capture unit being disposed between the drying unit and the dihydrogen separation unit.

[0012] In other words, at the outlet of the reforming unit, the drying unit, the carbon dioxide capture unit and the dihydrogen separation unit are arranged in that order within the treatment system, so that the carbon dioxide-laden gases emitted by the reforming unit pass through them successively.

[0013] Positioning the carbon dioxide capture unit after the drying unit prevents the water contained in the carbon dioxide-laden gases from freezing in a pre-cooling device of the carbon dioxide capture unit. Furthermore, this limits the amount of residual water that freezes with the carbon dioxide in the desublimation device; otherwise, the carbon dioxide would be recovered along with more water than desired.

[0014] Positioning the carbon dioxide capture unit before the hydrogen separation unit allows for carbon dioxide capture at a high absolute pressure. This prevents pressure drops and the compression of carbon dioxide-laden gases. Otherwise, if the hydrogen separation unit were positioned before the carbon dioxide capture unit, non-hydrogen carbon dioxide-laden gases would experience undesirable pressure loss within the hydrogen separation unit. Positioning the carbon dioxide capture unit before the hydrogen separation unit also allows for the use of more compact equipment.

[0015] According to an optional feature of the invention, the treatment system includes a return line connecting the hydrogen separation unit to the reforming unit. The return line is configured to channel hydrogen. This return line allows for the reuse of at least some of the hydrogen produced by the reforming unit within that reforming unit, in order to supply its combustion device. When the reforming unit is a steam reforming unit for methane, the return line connects the capture unit to the combustion device in order to supply it. According to an optional feature of the invention, the fluid loop includes a heat exchanger, one layer of which is formed by the distribution line.

[0016] The heat exchanger is a heat exchange device. Through this heat exchanger, the desublimation unit is indirectly cooled by liquefied natural gas (LNG). More specifically, within the heat exchanger connected to the distribution line, the LNG exchanges heat with a fluid channeled in the fluid loop. This fluid then exchanges heat with the carbon dioxide-rich gases within the desublimation unit. The fluid in the fluid loop is thus cooled by the LNG and heated by the carbon dioxide-rich gases.

[0017] According to an optional feature of the invention, the supply line is connected to the distribution line downstream of the heat exchanger.

[0018] The supply line is connected here to the distribution line between the storage tank and the connection terminal.

[0019] According to an optional feature of the invention, the treatment system includes a vaporization device disposed on the distribution line between the storage tank and the feed line.

[0020] The vaporization device helps to change the natural gas from its liquid state to its gaseous state, firstly for its supply to the reforming unit and secondly for its supply to the connection terminal.

[0021] According to an optional feature of the invention, the vaporization device is arranged between the heat exchanger and the feed line. The energy required to evaporate the natural gas before its entry into the reforming unit and / or its arrival at the connecting terminal is reduced by means of the calories collected during the carbon dioxide capture stage, which are transferred to the liquefied natural gas within the heat exchanger via the fluid loop.

[0022] According to an optional feature of the invention, the reforming unit includes a combustion device, the supply line comprising a first branch connected to the combustion device and a second branch parallel to the first branch and connected to the reforming device.

[0023] The reforming unit here is a steam reforming unit for methane. The feed line then splits into two parallel branches, each dedicated to one of the devices forming the reforming unit. The presence of two branches allows for independent regulation of the natural gas flow received by the combustion device and the reforming device, respectively.

[0024] According to an optional feature of the invention, the carbon dioxide capture unit includes a pre-cooling device.

[0025] The pre-cooling device allows the temperature of the carbon dioxide-laden gases to be adjusted before they pass through the desublimation unit. The pre-cooling device is therefore positioned between the drying unit and the desublimation unit.

[0026] According to an optional feature of the invention, the pre-cooling device includes at least one primary pass configured for the circulation of gases charged with carbon dioxide and one secondary pass configured for the circulation of decarbonized gases.

[0027] The primary pass of the pre-cooling device is located upstream of the desublimation device, while its secondary pass is downstream. Within the pre-cooling device, decarbonized gases are therefore used to cool the carbon dioxide-laden gases. According to an optional feature of the invention, the treatment system includes a decarbonized gas return line connecting the hydrogen separation unit to the reforming unit.

[0028] The decarbonized gas return line is configured to channel decarbonized gases. When the reforming unit is a steam reformer of methane, the waste gas return line connects the separation device to the combustion device. This decarbonized gas return line allows the gases to be reused within the treatment system as fuel for the reforming unit, for example, for the combustion device.

[0029] According to an optional feature of the invention, the treatment system includes a compression device on the return line of the decarbonized gases.

[0030] The compression device allows for an adjustment of the pressure of the decarbonized gases prior to their return to the reforming unit.

[0031] According to an optional feature of the invention, the carbon dioxide capture unit includes a means for heating the desublimation device and a carbon dioxide storage tank in liquid form connected to the desublimation device.

[0032] The heating system recovers carbon dioxide in liquid form, which was previously in solid form due to desublimation. The storage tank allows for the storage of carbon dioxide in liquid form at a pressure, for example, between 7 and 15 bar. The carbon dioxide is stored in the tank prior to being exported to a permanent storage site.

[0033] According to an optional feature of the invention, the drying unit includes a condensation device, one pass of the condensation device being formed by a diversion loop connected to the fluid loop.

[0034] The condensation device is configured to condense the water present in the carbon dioxide-laden gases from the reforming unit's reforming section. The condensation device includes a pass channeling the carbon dioxide-laden gases, which exchanges heat with another pass channeling the fluid from the fluid loop.

[0035] The invention further relates to a dihydrogen production installation, comprising the treatment system as previously mentioned and a connection terminal, the distribution line of the treatment system being connected to the connection terminal.

[0036] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and examples of embodiments given by way of illustration and not limitation with reference to the accompanying drawings on the other hand, on which: [Fig. 1] schematically illustrates a treatment system according to the invention in a first embodiment, in which a desublimation device of a carbon dioxide capture unit of the treatment system is cooled by a fluid loop exchanging heat with liquefied natural gas:

[0037] [Fig. 2] illustrates, schematically, a treatment system according to the invention in a second embodiment;

[0038] [Fig. 3] illustrates, schematically, a variant of the treatment system according to the first embodiment.

[0039] 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.

[0040] In the figures, elements common to several figures retain the same reference. Figures 1 to 3 thus schematically illustrate a dihydrogen production plant used in the production of so-called "blue dihydrogen," that is, dihydrogen that captures carbon dioxide during dihydrogen production. To this end, the dihydrogen production plant includes a carbon dioxide-laden gas treatment system (1).

[0041] The treatment system 1 includes a reforming unit 2. This reforming unit 2 is a steam reforming unit of methane, as shown in Figures 1 and 3, which illustrate a first embodiment, and an autothermal reforming unit, as shown in Figure 2, which illustrates a second embodiment. In the case of a reforming unit 2 corresponding to a steam reforming unit of methane, this reforming unit 2 consists of at least one combustion device 4, or combustion chamber, and a reforming device 6, or reforming reactor. In the case of a reforming unit 2 corresponding to an autothermal reforming unit, the reforming unit 2 lacks the separate combustion device 4, a combustion operation being associated with the reforming.

[0042] The reforming unit 2 is configured to form, from fuel, a gas stream containing, in particular, dihydrogen and carbon dioxide. The fuels used to power the reforming unit 2 are natural gas and steam. To supply the reforming unit 2, which is a steam reforming unit for methane, with water and air, the treatment system 1 includes a water supply line 8 and an air supply line 9. The water supply line 8 is specifically configured to supply the reforming device 6, while the air supply line 9 is configured to supply the combustion device 4. Alternatively, to supply the reforming unit 2, which is an autothermal reforming unit, the treatment system 1 can include an oxygen supply line instead of the air supply line 9.To supply the reforming unit 2 with natural gas, the treatment system 1 includes a liquefied natural gas storage tank 10. The storage tank 10 is connected here to a connection terminal 11 of the hydrogen production plant via a distribution line 13.

[0043] The storage tank 10 is connected to the reforming unit 2 by a supply line 12, which channels the liquefied natural gas from the storage tank 10 to the reforming unit 2. The supply line 12 is connected to the distribution line 13 extending to the connection terminal 11, between the storage tank 10 and this connection terminal 11. Since the reforming unit 2 uses natural gas in the form of vapor as fuel, the distribution line 13 carries, between the storage tank 10 and a connection point of the supply line, a pump 14, a heat exchanger 15 and a vaporization device 16. The pump 14 is configured to increase the pressure of the liquefied natural gas so that it is compatible with the connection terminal. The pump allows, for example, the pressure of liquefied natural gas to be raised to between 70 and 110 bar abs.The heat exchanger 15 is a heat exchanger configured specifically to preheat the liquefied natural gas before it is delivered to the reforming unit 2, according to an operating mode that will be described later. The heat exchanger 15 also initiates the vaporization of the liquefied natural gas before it passes into the vaporization unit 16. This vaporization unit 16 is configured to complete the vaporization of the liquefied natural gas from the heat exchanger 15 before its use, for example, with seawater. The vaporization unit 16 allows, on the one hand, the vaporization of the liquefied natural gas prior to its delivery to the reforming unit 2, and on the other hand, its vaporization prior to its arrival at the connection terminal 11.The pump 14, the heat exchange device 15 and the vaporization device 16 are arranged in that order on the supply line 12 between the storage tank 10 and the connection point of the supply line 12.

[0044] As can be seen in Figures 1 and 3, in the case of the reforming unit 2, which corresponds to a steam reforming unit for methane, the combustion device 4 and the reforming device 6 are supplied separately with natural gas that has been vaporized within the vaporization device 16. Thus, downstream of its connection point to the distribution line 13, the supply line 12 is split into a first branch 18 dedicated to supplying the combustion device 4 and a second branch 20 dedicated to supplying the reforming device 6. The first branch 18 and the second branch 20 extend in parallel within the treatment system 1. The first branch 18 and the second branch 20 can be equipped with valves to regulate the flow of the natural gas that they channel.On the contrary, in Figure 2 the reforming device 6 of the reforming unit 2 corresponding to an autothermal reforming unit is supplied by a supply line 12 having a single branch; in other words, in the case of the autothermal reforming unit the supply line 12 is not split into two branches.

[0045] Within the reforming unit 2, a chemical reaction between natural gas from storage tank 10, water from water supply line 8, and air from air supply line 9 or oxygen from oxygen supply line leads to the formation of, among other gases, dihydrogen and carbon dioxide. More specifically, at the outlet of reforming unit 2, the reforming device 6 emits gases laden with carbon dioxide which also contain dihydrogen as well as residual quantities of methane, carbon monoxide, and water. The treatment system 1 according to the invention is designed to treat said gases, in particular to extract carbon dioxide and dihydrogen.

[0046] For this purpose, the treatment system 1 comprises, in this order, a drying unit 22, a carbon dioxide capture unit 24 and a dihydrogen separation unit 26. Here, "in this order" means that the carbon dioxide-laden gases emitted by the reforming device 6 of the reforming unit 2 pass successively through the drying unit 22, then the carbon dioxide capture unit 24, then the dihydrogen separation unit 26.

[0047] The drying unit 22 is configured to extract water from the carbon dioxide-laden gases exiting the reforming device 6 of the reforming unit 2. To achieve this, the drying unit 22 may optionally include a water condensation device 27, a separator (not shown), and at least one drying device. The drying device 28 is shown here as a molecular sieve, but could also be a membrane or a cryogenic scrubber. The drying device 28 is configured to retain the water present in the carbon dioxide-laden gases. The drying unit 22 may, for example, include two molecular sieves operating alternately. The water is then discharged from the molecular sieve and the drying unit 22 via a water discharge line 30 of the treatment system 1.At the outlet of the drying unit 22, the dried carbon dioxide-laden gases are directed to the carbon dioxide capture unit 24. The carbon dioxide capture unit 24 is configured to extract the carbon dioxide present in the carbon dioxide-laden gases emitted by the reforming device 6 of the reforming unit 2.

[0048] The carbon dioxide capture unit 24 includes a pre-cooling device 32. The pre-cooling device 32 is a heat exchanger which includes a primary pass 34 and a secondary pass 36. The primary pass 34 is configured to channel the carbon dioxide-laden gases and to cool them by heat exchange with the secondary pass 36 which will be described later.

[0049] According to the invention, the carbon dioxide capture unit 24 of the treatment system 1 comprises a desublimation device 38 configured to desublimate the carbon dioxide present in the carbon dioxide-laden gases. The desublimation device 38 is connected to the pre-cooling device 32 and disposed downstream of the latter in a direction of carbon dioxide-laden gas flow.

[0050] The desublimation device 38 includes at least one heat exchanger configured to indirectly cool the carbon dioxide-laden gases using liquefied natural gas. More specifically, and as shown in Figures 1 to 3, the desublimation device 38 comprises a first desublimator 38A and a second desublimator 38B that operate alternately. The first desublimator 38A operates, for example, in a capture or freezing mode while the second desublimator 38B operates in a regeneration or defrosting mode, and conversely, the first desublimator 38A operates in regeneration mode while the second desublimator 38B operates in capture mode.The alternating operation of the first desublimator 38A and the second desublimator 38B allows continuous capture of carbon dioxide within the desublimation device 38, the capture mode being constantly ensured by one or the other of the desublimators 38A, 38B.

[0051] Within the desublimation device 38, the desublimator 38A, 38B comprises a chamber 40 and a thermal management pass 42. The chamber 40 of the desublimation device 38 is configured to receive gases containing carbon dioxide. In the capture mode, this chamber 40 is cooled by heat exchange with the thermal management pass 42. Conversely, in the regeneration mode, the chamber 40 of the desublimator 38A, 38B is heated by heat exchange with the thermal management pass 42.

[0052] According to the invention, the treatment system 1 includes a fluid loop 44 that helps cool the carbon dioxide-laden gases emitted by the reforming device 6 of the reforming unit 2. This fluid loop 44 is configured to channel a fluid that exchanges heat with the carbon dioxide-laden gases, for example, butane. The fluid loop 44 extends between the distribution line 13 on one side and the desublimation device 38 on the other. More specifically, the fluid loop 44 includes the thermal management pass 42 of the desublimation device 38 when the latter is in capture mode.

[0053] The fluid loop 44 exchanges heat with the distribution line 13 via the heat exchanger 15. For this purpose, the heat exchanger 15 comprises a first layer 46 and a second layer 48. The first layer 46 forms a section of the distribution line 13 that carries liquefied natural gas from the storage tank 10. The second layer 48 is formed by a portion of the fluid loop 44 that carries the fluid intended to exchange heat with the carbon dioxide-rich gases. It is understood from the above that within the heat exchanger 15, the fluid intended to exchange heat with the carbon dioxide-rich gases, which circulates in the second layer 48, is cooled by heat exchange with the liquefied natural gas circulating in the first layer 46.

[0054] Once cooled by heat exchange with the liquefied natural gas, the fluid channeled in the fluid loop 44 circulates to the thermal management pass 42 of the desublimation device 38 in which it exchanges heat with the carbon dioxide-laden gases circulating within the enclosure 40 of the desublimarer 38A, 38B operating in capture mode, thus cooling the said gases in order to desublimate the carbon dioxide they contain.

[0055] It should be noted that in the desublimator 38A, 38B of the desublimation device 38 operating in regeneration mode, the thermal management passage 42 channels a thermal management fluid separate from the fluid in the fluid loop 44. This thermal management fluid is then a heating means 50 used to warm the chamber 40 of the desublimator 38A, 38B. Such heating of the chamber 40 by the heating means 50 allows the carbon dioxide that was desublimated during the operation of the capture mode to liquefy.

[0056] As previously mentioned, the drying unit 22 includes a condensation device 27 for the water present in the carbon dioxide-laden gases exiting the reforming unit 6 of the reforming unit 2. As can be seen in Figures 1 to 3, the condensation device 27 comprises a channeling pass 52 for the carbon dioxide-laden gases and a cooling pass 54 configured to cool the channeling pass 52. The cooling pass 54 of the condensation device 27 is more specifically formed by a diversion loop 56 of the fluid loop 44. It is understood here that a portion of the fluid circulating within the fluid loop 44 is diverted to exchange heat with the carbon dioxide-laden gases within the condensation device 27.The diversion loop 56 is more specifically connected to the fluid loop 44 between the desublimation device 38 and the heat exchange device 15 according to a direction of fluid circulation within the fluid loop 44. At the outlet of the desublimation device 38, and more precisely at the outlet of the desublimator 38A, 38B operating in regeneration mode, the carbon dioxide is in liquid form since it has been liquefied using the heating means 50. This carbon dioxide is thus stored in liquid form in a storage tank 58 of the treatment system 1. The carbon dioxide in liquid form is, for example, stored in the storage tank 58 at a pressure between 7 and 15 bar.

[0057] At the outlet of the desublimation device 38, and more specifically at the outlet of the desublimator 38A, 38B operating in capture mode, the charged gases emitted by the reforming device 6 of the reforming unit 2, and freed of carbon dioxide, also called decarbonized gases, are sent to the secondary pass 36 of the pre-cooling device 32. The decarbonized gases circulating in the secondary pass 36 then exchange heat with the gases containing carbon dioxide circulating in the primary pass 34, thereby cooling said gases. It is thus understood that in the pre-cooling device 32, the decarbonized gases are used as a source of cooling to cool the gases containing carbon dioxide prior to their passage through the desublimation device 38.

[0058] At the outlet of the pre-cooling device 32 and the carbon dioxide capture unit 24, the decarbonized gases flow to the hydrogen separation unit 26. The hydrogen separation unit 26 is configured to extract the hydrogen present in the decarbonized gases. The hydrogen separation unit 26 includes, for example, at least one pressure swing adsorption (PSA) module 60. The hydrogen separation unit 26 includes, for example, two pressure swing adsorption modules 60 operating alternately. In alternative embodiments, the hydrogen separation unit 24 may include a different number of pressure swing adsorption modules 32, for example, four.As illustrated in the figures, the treatment system 1 includes a return line 62 configured to channel the dihydrogen produced within the reforming unit 2 and extracted from the decarbonized gases. This return line 62 connects the dihydrogen separation unit 26 to the reforming unit 2. More specifically, in the case of the reforming unit 2, which corresponds to a steam reforming unit for methane, the return line 62 connects the pressure reversal adsorption module 60 to the first branch 18 of the feed line 12, which, as a reminder, is dedicated to supplying the combustion device 4 of the reforming unit 2. It is understood here that the dihydrogen extracted from the decarbonized gases in the dihydrogen separation unit 26 is recycled to the reforming unit 2 as fuel, if necessary for the combustion device 4. The treatment system 1 also includes a branch line 64 connected to the line back 62.This branch line 64 is configured to convey the hydrogen separated from the decarbonized gases out of the treatment system 1, for example for use in other applications.

[0059] Notably, the treatment system 1 includes a return line 66 configured to channel the decarbonized gases from the hydrogen separation unit 26. More specifically, the return line 66 connects the hydrogen separation unit 26 to the reforming unit 2, optionally via the first branch 18 of the feed line 12 configured to supply fuel to the combustion device 4 of the reforming unit 2 when the reforming unit 2 is a steam reforming unit for methane. As can be seen in the figures, the return line 66 carries a compression device 68. When the reforming unit 2 is an autothermal reforming unit, this compression device 68 is a multi-stage compression device comprising alternating heat exchangers and compressors.When the reforming unit 2 corresponds to a steam reforming unit for methane, it is either a single-stage or a multi-stage compression device. The compression device 68 is configured to raise the pressure of the decarbonized gases to a pressure suitable for the operation of the reforming unit 2, and in particular for the operation of the combustion device 4 when the reforming unit 2 corresponds to a steam reforming unit for methane. Figure 3 shows an alternative embodiment of what has been described above. While this alternative will now be described with a reforming unit 2 corresponding to a steam reforming unit for methane, it could nevertheless be adapted to a self-heating reforming unit similar to that of Figure 2.

[0060] In this variant of Figure 3, the liquefied natural gas from the storage tank 10 and flowing in the distribution line 13 can, instead of successively passing through the pump 14, the heat exchanger 15, and the vaporization unit 16, take a bypass line 70. This bypass line 70 is connected to the distribution line 13 at one end and to the supply line 12 at the other. The flow of liquefied natural gas in the bypass line 70 and / or in the portion of the distribution line 13 carrying the pump 14, the heat exchanger 15, and the vaporization unit 16 is controlled by a regulating device 72.The control means 72 here comprises a plurality of valves, one of them being carried by bypass line 70 and the other being carried by the portion of the distribution line 13 carrying the pump 14, the heat exchange device 15 and the vaporization device 16. Alternatively, the control means 72 could correspond to a three-way valve disposed on the branch of the bypass line 70 on the distribution line 13.

[0061] The bypass line 70 carries a pump and a heat exchange device 74. More specifically, the bypass line 70 forms a first layer of the heat exchange device 74. The heat exchange device 74 also includes a second layer formed by a bypass conduit 76 extending from the fluid loop 44. The bypass conduit 76 is connected at both ends to the fluid loop 44. The bypass conduit 76 allows a portion of the fluid channeled by the fluid loop 44 to circulate within the heat exchange device 74. It is understood here that the heat exchange device 74 is configured to perform a heat exchange between the liquefied natural gas circulating in its first layer, which is heated, and the fluid from the fluid loop 44 circulating in its second layer, which is cooled.The heat exchange device 74 thus makes it possible to vaporize the natural gas circulating in the bypass line 70 in order to deliver it to the reforming unit 2 while cooling the fluid from the fluid loop 44 prior to the capture of carbon dioxide in the desublimation device 38.

[0062] The present invention thus proposes a system for treating carbon dioxide-laden gases from a reforming unit, the treatment system using liquefied natural gas both to power the reforming unit and to participate in the capture of carbon dioxide by desublimation.

[0063] 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. Carbon dioxide-laden gas treatment system (1), comprising a liquefied natural gas storage tank (10), a distribution line (13) configured to connect the storage tank (10) to a natural gas connection terminal (11), the treatment system (1) comprising a reforming unit (2) comprising at least one reforming device (6) emitting carbon dioxide-laden gases, the treatment system (1) comprising a feed line (12) connecting the distribution line (13) to the reforming unit (2), the treatment system (1) comprising at least one carbon dioxide capture unit (24) comprising at least one carbon dioxide desublimation device (38, 38A, 38B), the treatment system (1) comprising a fluid loop (44) extending between the distribution line (13) and the desublimation device (38, 38A, 38B),the fluid loop (44) being configured to exchange heat between the carbon dioxide-laden gases circulating within the desublimation device (38, 38A, 38B) and the liquefied natural gas circulating within the distribution line (13).

2. A treatment system (1) according to claim 1, comprising a drying unit (22) and a dihydrogen separation unit (26) present in the gases emitted by the reforming device (6), the carbon dioxide capture unit (24) being disposed between the drying unit (22) and the dihydrogen separation unit (26).

3. A treatment system (1) according to claim 2, comprising a return line (62) connecting the dihydrogen separation unit (26) to the reforming unit (2).

4. Treatment system (1) according to any one of claims 1 to 3, wherein the fluid loop (44) includes a heat exchanger (15) of which a layer (46) is constituted by the distribution line (13).

5. Processing system (1) according to claim 4, wherein the supply line (12) is connected to the distribution line (13) downstream of the heat exchanger (15).

6. Treatment system (1) according to any one of claims 1 to 5, comprising a vaporization device (16) disposed on the distribution line (13) between the storage tank (10) and the feed line (12).

7. Treatment system (1) according to claim 6 in combination with claim 4, wherein the vaporization device (16) is disposed between the heat exchanger (15) and the feed line (12).

8. Processing system (1) according to any one of claims 1 to 7, wherein the reforming unit (2) comprises a combustion device (4), the feed line (12) comprising a first branch (18) connected to the combustion device (4) and a second branch (20) parallel to the first branch (18) and connected to the reforming device (6).

9. Processing system (1) according to any one of claims 1 to 8, wherein the carbon dioxide capture unit (24) includes a pre-cooling device (32).

10. Processing system (1) according to claim 9, wherein the pre-cooling device (32) comprises at least one primary pass (34) configured for the circulation of gases loaded with carbon dioxide and a secondary pass (36) configured for the circulation of decarbonized gases.

11. Processing system (1) according to any one of claims 1 to 10 in combination with claim 2, comprising a decarbonized gas return line (66) connecting the dihydrogen separation unit (26) to the reforming unit (2).

12. Treatment system (1) according to claim 11, comprising a compression device (68) on the return line of decarbonized gases.

13. Processing system (1) according to any one of claims 1 to 12, wherein the carbon dioxide capture unit (24) comprises a heating means (50) for the desublimation device (38, 38A, 38B) and a storage tank (58) for carbon dioxide in liquid form connected to the desublimation device.

14. Processing system (1) according to any one of claims 1 to 13 in combination with claim 2, wherein the drying unit (22) comprises a condensation device (27), a pass (54) of the condensation device (27) being formed by a deflection loop (56) connected to the fluid loop (44).

15. Hydrogen production installation, comprising the treatment system (1) according to any one of claims 1 to 14 and a connection terminal (11), the distribution line (13) of the treatment system (1) being connected to the connection terminal (11).

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