Facility and method for purifying a hydrogen gas stream and for filling tanks

Abstract

The invention relates to a facility and method for purifying a gas stream comprising hydrogen and carbon monoxide. The facility comprises a TSA adsorption unit (3) comprising an active material configured to adsorb at least some of the carbon monoxide, a first gas-stream flow path (4, 5) and a second gas-stream flow path (6, 7), and a heating system for heating the gas stream (8, 9), wherein the first flow path (4, 5) transfers the gas stream to the adsorption unit (3) and from the adsorption unit (3) to a first collector (10) for collecting the purified gas stream, and the second flow path (6, 7) transfers the gas stream to the heating system (8), then to the adsorption unit (3), and then to a second collector (100), in particular a vent. In the purification method, the adsorption unit (3) follows a cycle comprising a purification phase and a regeneration phase.

Description

Installation and process for purifying a hydrogen gas stream and filling tanks

[0001] The present invention relates to an installation and a method for purifying a hydrogen gas stream containing carbon monoxide, as well as to a hydrogen gas tank filling station incorporating said installation and to a method for filling hydrogen gas tanks using said method.

[0002] Large-scale hydrogen production is typically achieved through steam reforming of a methane-rich gas source (known as the SMR process). This process leads to the formation of a synthesis gas primarily rich in hydrogen and carbon monoxide. The synthesis gas must then be further processed, for example by purification or distillation processes, to obtain a gas stream with an increased hydrogen content.

[0003] Depending on the required purity level and target production cost, several solutions are available. Ultrapure hydrogen can be produced by cryogenic distillation of a gas mixture rich in hydrogen and carbon monoxide. The hydrogen-rich residual gas stream from a cryogenic carbon monoxide separation cold box contains approximately 97% hydrogen.

[0004] Alternatively, the hydrogen- and carbon monoxide-rich gas mixture from the steam reforming furnace, or after one or more water-gas shift (WGS) steps, can also be purified by adsorption in a pressure swing adsorption (PSA) unit. In this case, the contaminant removal efficiency is limited by the PSA adsorption process. The hydrogen-rich gas stream exiting the PSA unit may still contain carbon monoxide ranging from a few ppm to tens or hundreds of ppm.

[0005] For mobility applications, such as powering a fuel cell, or certain industrial applications, such as the manufacture of electronic products, the presence of carbon monoxide, even at low levels, is critical. This molecule can compromise the operation of a fuel cell if its concentration exceeds 200 ppb, or even 100 ppb or 2 ppb, depending on the fuel cell technology used.

[0006] A known technique for purifying a gas stream containing hydrogen and between 0.5 and 100 ppm of carbon monoxide to a carbon monoxide concentration of approximately 100 ppb involves passing the gas stream through an adsorbent, such as activated carbon or molecular sieves, at very low temperatures, typically that of liquid nitrogen. The main drawback of this technique is the high cost of the equipment and the high operating costs.

[0007] Another known purification technique involves passing the gas stream containing hydrogen and carbon monoxide through a palladium-coated metal membrane. Due to the cost of palladium, this technique is also expensive. Furthermore, the pressure drop caused by the membrane reduces the pressure of the purified gas stream, to the detriment of subsequent applications, which often require higher pressure.

[0008] Documents JP2011-167629 A2 and WO2019 / 025690 also describe the use of a TSA (Temperature Swing Adsorption) unit to further purify a gas stream containing hydrogen and carbon monoxide, in order to obtain a carbon monoxide content below 1 ppm. These solutions do not allow the carbon monoxide content to be reduced below 200 ppb, or even 100 ppb or 2 ppb. Furthermore, the regeneration of the adsorption units is carried out using mixtures of hydrogen and nitrogen, which can impair the proper functioning of the installations and introduce additional impurities into the purified hydrogen stream.

[0009] US2008 / 0108715 describes the purification of a hydrogen gas stream at near atmospheric pressure using a catalyst to facilitate the chemical reaction that transforms carbon monoxide into methane and water. This process requires additional steps to separate the water and methane and is not compatible with a high-pressure hydrogen gas stream.

[0010] Existing solutions use complex installations and are suited to purifying either very large quantities of hydrogen, for example, around 200 tons per day, or small quantities, around 2 tons per day or less. However, there is a need, particularly for mobility applications, to produce intermediate quantities, on the order of tens or several tens of tons per day, and at higher purity levels.

[0011] The present invention aims to effectively remedy these drawbacks by proposing a gas stream purification installation comprising hydrogen and carbon monoxide, the installation comprising a TSA type adsorption unit including an active material configured to adsorb at least a portion of the carbon monoxide, a first gas stream circulation path, a second gas stream circulation path, a set of flow control devices configured to selectively direct the gas stream into the first or second circulation path, and a gas stream heating system.

[0012] The first flow path is configured to transfer the gas stream to the adsorption unit, and to transfer the gas stream exiting the adsorption unit to a first purified gas stream collector.

[0013] The second flow path is configured to transfer the gas stream to the heating system, transfer the gas stream heated by the heating system to the adsorption unit, and transfer the gas stream exiting the adsorption unit to a second collecting device, including a vent.

[0014] The same gas stream is used in both adsorption and regeneration configurations. This eliminates the need for specific regeneration gas sources and results in a simpler installation compared to state-of-the-art systems. The risks of contamination, particularly by nitrogen, are also eliminated.

[0015] According to one embodiment, the second flow path is further configured to transfer the gas stream exiting the adsorption unit to the heating system, and to transfer the gas stream exiting the heating system to the second collecting unit.

[0016] According to one implementation, the first flow path includes a first purification line configured to transfer the gas stream directly to the adsorption unit.

[0017] In one embodiment, the second flow path comprises a first regeneration line configured to transfer the gas stream to the adsorption unit, and a first discharge line configured to transfer the gas stream exiting the adsorption unit to the second collector. The first regeneration line and / or the first discharge line are in heat exchange with the heating system.

[0018] According to one embodiment, the installation includes a bypass line configured to transfer the gas stream directly to the first collecting unit, without passing through the adsorption unit.

[0019] According to one embodiment, the installation includes a bypass route of the heating system, in particular a bypass line of the first heating element, configured to transfer the gas stream to the adsorption unit without passing through the heating system.

[0020] According to one embodiment, the heating system includes a first heating element in heat exchange with the first regeneration line and / or a second heating element in heat exchange with the first exhaust line.

[0021] According to one embodiment, the second heating element is a heat exchanger configured to supply calories to the gas stream by exchange with a heat transfer fluid.

[0022] According to one embodiment, the heating system comprises a single heating element configured to heat the gas stream flowing in the second circulation path upstream of the adsorption unit, and to heat the gas stream flowing in the second circulation path downstream of the adsorption unit.

[0023] According to one embodiment, the active material configured to adsorb at least some of the carbon monoxide includes Nickel.

[0024] According to one embodiment, the active material configured to adsorb at least some of the carbon monoxide comprises more than 50% by mass of nickel.

[0025] According to one embodiment, the adsorption unit comprises a single adsorption volume consisting of one or more adsorbers fluidically connected to each other.

[0026] According to one embodiment, the first path includes the first purification line configured to bring the gas stream to the adsorption unit and the first recovery line configured to transfer the gas stream from the adsorption unit to the first collecting organ.

[0027] According to one embodiment, the flow control assembly includes one component, in particular a valve, configured to allow or prevent the passage of the gas stream into the first purification line, and one component, in particular a valve, configured to allow or prevent the passage of the gas stream into the first recovery line.

[0028] According to one embodiment, the second path includes the first regeneration line, configured to transfer the gas stream to the heating system and from the heating system to the adsorption unit, and the first exhaust line configured to transfer the gas stream from the adsorption unit to the heating system and from the heating system to the second collector.

[0029] According to one embodiment, the flow control assembly includes one element, in particular a valve, configured to permit or prevent the passage of gas stream into the first regeneration line, and one element, in particular a valve, configured to permit or prevent the passage of gas stream into the first discharge line.

[0030] According to one embodiment, the adsorption unit comprises at least two distinct adsorption volumes. The first and second flow paths each comprise a plurality of fluidic paths configured to allow portions of the gas stream to be distributed to each adsorption volume.

[0031] Each path in the plurality of fluidic paths of the first path is configured to transfer a portion of the gas stream to the adsorption unit and from the adsorption unit to the first collecting organ,

[0032] Each path of the plurality of fluidic paths of the second path is configured to transfer a portion of the gas stream to the heating system, then from the heating system to the adsorption unit, and from the adsorption unit to the second collecting organ.

[0033] According to one embodiment, the adsorption unit comprises or consists of a first and a second adsorption volume, each consisting of an adsorber or a plurality of adsorbers fluidically connected to each other.

[0034] According to one embodiment, the first flow path comprises a first and second purification line respectively configured to transfer the gas stream respectively to the first and second adsorption volume, and a first and second recovery line respectively configured to transfer the gas stream respectively from the first and second adsorption volume to the first collecting unit.

[0035] According to one embodiment, the flow control assembly comprises a first and second respective organ, including valves, configured to permit or prevent the passage of the gas stream respectively in the first and second purification lines, and a third and fourth respective organ, including valves, configured to permit or prevent the passage of the gas stream respectively in the first and second recovery lines.

[0036] According to one embodiment, the second path comprises a first and a second regeneration line configured to transfer the gas stream from the heating system respectively to the first and second adsorption volume, and a first and a second line configured to transfer the gas stream respectively from the first and second adsorption volume to the heating system.

[0037] According to one embodiment, the flow control assembly includes a fifth and sixth respective organs, including valves, configured to permit or prevent the passage of the gas stream in the first and second regeneration lines respectively, and a seventh and eighth respective organs, including valves, configured to permit or prevent the passage of the gas stream in the first and second discharge lines respectively.

[0038] According to one embodiment, the flow control assembly includes at least a ninth component, namely a pressure regulator, configured to reduce the pressure of the gas stream in the second flow path, upstream of the adsorption unit.

[0039] The invention further relates to a gaseous hydrogen tank filling station comprising a hydrogen source and a purification installation as described above or below.

[0040] The invention also relates to a method for purifying a gas stream comprising hydrogen and carbon monoxide, using a purification installation as described above or below. In the method, the adsorption unit follows a cycle comprising: a purification phase, in which at least a first portion of the gas stream is directed into the first circulation path to supply the first collecting unit with the first purified portion of the gas stream; and a regeneration phase, in which at least a second portion of the gas stream is directed into the second circulation path to regenerate at least a portion of the active material.

[0041] The gas stream comprising hydrogen and carbon monoxide typically has a hydrogen content greater than or equal to 97%, preferably greater than or equal to 99%.

[0042] The first portion of purified gas stream may have a carbon monoxide content of less than or equal to 2 ppb, preferably less than 0.5 ppb.

[0043] According to one embodiment, the purification phase includes: a step of supplying the first portion of the gas stream to the adsorption unit; a step of adsorbing the carbon monoxide contained in the first portion of the gas stream by the adsorption unit; a step of supplying the first collecting unit with the first portion of the purified gas stream with a carbon monoxide content less than or equal to 2 ppb.

[0044] According to one embodiment, the regeneration phase includes: a step of heating the second portion of the gas stream to a temperature between 120 °C and 300 °C, in particular between 170 °C and 200 °C; a step of supplying the second portion of the heated gas stream to the adsorption unit; a step of desorption of the carbon monoxide adsorbed during the purification phase by the adsorption unit; a step of supplying the second collecting unit with the second portion of the gas stream that has passed through the adsorption unit.

[0045] According to one embodiment, in the purification phase, the residence time of the first portion of gas stream in the adsorption unit is greater than or equal to five seconds, preferably greater than or equal to ten seconds.

[0046] According to one embodiment, in the regeneration phase, the second portion of gas stream having passed through the adsorption unit is heated to a temperature greater than or equal to 100 °C, in particular between 100 °C and 300 °C, preferably between 100 °C and 150 °C.

[0047] According to one implementation, the transition from the purification phase to the regeneration phase is carried out manually.

[0048] According to one implementation, the transition from the purification phase to the regeneration phase is carried out automatically.

[0049] According to one embodiment, in the regeneration phase, the second portion of the gas stream is expanded, in the second circulation path upstream of the adsorption unit, to a regeneration pressure less than or equal to 5 bar, preferably less than or equal to 1-2 bar, even more preferably less than or equal to 1 bar.

[0050] According to one embodiment, a gas stream pressure at the inlet of the purification installation is greater than or equal to 10 bar, preferably greater than or equal to 20 bar.

[0051] According to one embodiment, a gas stream pressure at the inlet of the purification installation is greater than or equal to 100 bar, preferably greater than or equal to 200 bar.

[0052] According to one embodiment, in the purification phase the first portion of gas stream flows in the adsorption unit in a first direction of flow, and in the regeneration phase the second portion of gas stream flows in the adsorption unit in a second direction of flow opposite to the first direction of flow.

[0053] According to one embodiment, the second portion of gas stream having passed through the adsorption unit reaches, during the regeneration phase, a maximum carbon monoxide content greater than or equal to 100 ppm.

[0054] According to one embodiment, the cycle includes, between the regeneration phase and the adsorption phase, a cooling phase, in which at least a third portion of the gas stream is directed into the second circulation path without being heated, to cool at least a part of the regenerated active material.

[0055] According to one embodiment, the process uses an adsorption unit comprising at least two distinct adsorption volumes. The first and second adsorption volumes each follow, in staggered cycles, a purification phase and a regeneration phase.

[0056] The invention further relates to a method for filling gas tanks. This method comprises: a step of supplying a gas stream comprising hydrogen and carbon monoxide; a step of purifying the gas stream implementing a purification process as described above or below; a step of filling a tank with the purified gas stream.

[0057] The invention may also relate to any alternative installation or process comprising any combination of the above or below features, particularly within the scope of the claims.

[0058] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only to illustrate, but in no way limit, the invention.

[0059] is a schematic and partial representation of a purification installation according to a first embodiment of the invention.

[0060] is a schematic and partial representation of a purification installation according to a second embodiment of the invention.

[0061] is a schematic and partial representation of a filling station according to the invention.

[0062] is a schematic and partial representation of a filling station according to the invention.

[0063] With reference to the aforementioned, a gas stream purification installation 1 comprising hydrogen and carbon monoxide includes, according to a first embodiment of the invention, a TSA-type adsorption unit 3. The adsorption unit 3 comprises an active material configured to adsorb at least a portion of the carbon monoxide. This material may also be generically referred to as the adsorbent.

[0064] The term "configured to adsorb at least some of the carbon monoxide" means that the active material preferentially adsorbs carbon monoxide over other species with which it may come into contact, such as other impurities that may be present.

[0065] The active material is notably capable of adsorbing a substantial portion of the carbon monoxide contained in a gas stream with which it is brought into contact for a specified period. For example, the active material can be configured to adsorb at least 50% of the carbon monoxide contained in a gas stream when exposed to the gas stream for at least one hour.

[0066] The gas stream is typically supplied by a source 2, which is not part of the installation according to the invention, and which can be a pressurized hydrogen distribution network, for example between 30 bar and 250 bar, typically 100 bar, or a steam reforming reactor (SMR), or even a fixed or mobile tank.

[0067] Other examples of hydrogen sources 2 that can supply the gaseous feed 2 of an installation 1 according to the invention are, in a non-limiting manner: an electrolyzer, an autothermal steam reforming reactor (ATR), a partial oxidation reforming reactor (POX), an off-gas recovery unit equipped with a preliminary hydrogen purification system.

[0068] Of course, the gaseous feed stream 2 can be a mixture of gases from two or more of the sources listed above.

[0069] Installation 1 also includes a first gas flow path 4, 5, a second gas flow path 6, 7, and a set of flow control devices 400, 500, 610, 620, 700 configured to selectively direct the gas flow into the first 4, 5 or the second 6, 7 flow path. The flow control devices 400, 500, 610, 620, 700 may, for example, be on / off type valves, i.e., valves designed to be usable in two alternative configurations: fully closed or fully open; controlled valves, i.e., valves designed to be able to continuously vary the flow rate of the gas passing through them; calibrated orifices; or any other suitable flow control device.

[0070] Installation 1 also includes a gas stream heating system 8, 9, for example one or more electric heaters, or one or more heat transfer fluid exchangers.

[0071] The first flow path 4, 5 is configured to transfer the gas stream from the source 2 to the adsorption unit 3, and to transfer the gas stream exiting the adsorption unit 3 to a first collecting element 10 of the purified gas stream.

[0072] The second flow path 6, 7 is configured to transfer the gas stream from source 2 to the heating system 8, transfer the gas stream heated by the heating system 8 to the adsorption unit 3, and transfer the gas stream exiting the adsorption unit 3 to a second collecting element 100, including a vent.

[0073] The first 4, 5 and the second 6, 7 traffic lanes may be distinct or partially overlap. Thus, for example, there may be one or more pipes that are part of both traffic lanes.

[0074] In other words, the first flow path 4, 5 is configured to direct a purified gas stream to a first collector 10, while the second flow path is configured to direct a carbon monoxide-enriched gas stream to a second collector 100. The first collector 10 and the second collector 100 are therefore distinct.

[0075] When the installation is in operation, the same gas stream is used in both configurations, adsorption and regeneration, of the adsorption unit. In other words, the gas that is introduced into the adsorption unit 3 via the first circulation path 4 has the same nature, in particular the same composition, as the gas that is introduced into the adsorption unit 3 via the second circulation path 6, 7.

[0076] This eliminates the need for specific sources of regeneration gas and results in a simplified installation compared to state-of-the-art installations. The risks of contamination, particularly by nitrogen, are also eliminated.

[0077] According to other aspects, embodiments of the invention may include one or more of the following characteristics.

[0078] In one embodiment, the installation 1 may include a preliminary purification unit, for example a drying unit configured to remove or reduce the water content of the feed gas stream 2. Such a preliminary purification unit is then arranged in the first path 4, 5 upstream of the adsorption unit 3, and in the second path, upstream of the heating system 8.

[0079] That is to say, the gas stream 2 entering the installation 1 is directed to the preliminary purification unit; only after this preliminary purification is the gas stream 2 directed to the adsorption unit 3 via the first path 4, 5 or to the heating system 8 via the second path 6, 7.

[0080] When the preliminary purification unit includes a drying unit, the gas stream exiting this drying unit typically has a water content of less than or equal to 1 ppm.

[0081] In one embodiment, the second flow path 7 is further configured to transfer the gas stream exiting the adsorption unit 3 to the heating system 8, 9 and to transfer the gas stream exiting the heating system 8, 9 to the second collector organ 100.

[0082] Any toxic components produced when the adsorption unit 3 is regenerated can then be degraded through thermal treatment. The risks of supplying the second collecting unit 100, and in particular venting, with toxic components are significantly reduced.

[0083] In one embodiment, the first flow path 4, 5 includes a first purification line 4 configured to transfer the gas stream directly to the adsorption unit 3. That is, the first purification line 4 does not include any element or component configured to modify the composition or thermodynamic conditions of the gas stream. Thus, the gas stream from the source 2 is transferred to the adsorption unit 3 and arrives at the adsorption unit 3 with substantially the same composition and thermodynamic conditions as when it was drawn from the source 2.

[0084] In one embodiment, the second circulation path 6, 7 includes a first regeneration line 6 configured to transfer the gas stream to the adsorption unit 3, and a first discharge line 7 configured to transfer the gas stream exiting the adsorption unit 3 to the second collector 100. The first regeneration line 6 and / or the first discharge line 7 is in heat exchange with the heating system 8, 9. During operation of the installation, this allows for the efficient heating of the gas stream that will be used for the regeneration of the adsorbent, and / or the gas stream exiting the adsorption unit 3 during regeneration and circulating in the second circulation path 7, in particular in the first discharge line 7.

[0085] In one embodiment, the heating system 8, 9 includes a first heating element 8 in heat exchange with the first regeneration line 6 and / or a second heating element 9 in heat exchange with the first exhaust line 7. During the operation of the installation 1, this allows separate and independent control of the two temperatures and heating processes of, on the one hand, the gas stream used for regeneration, and on the other hand, the stream which has been used to regenerate the adsorbent and which exits the adsorption unit 3. This optimizes the efficiency and safety of the regeneration.

[0086] In one embodiment, the second heating element 9 is a heat exchanger configured to supply heat to the gas stream by exchange with a heat transfer fluid. This configuration is particularly advantageous when the regeneration of the adsorbent is preceded by a depressurization of the adsorption unit 3.

[0087] In one embodiment, the heating system 8, 9 comprises a single heating element configured to heat the gas stream flowing in the second circulation path 6 upstream of the adsorption unit, and to heat the gas stream flowing in the second circulation path 7 downstream of the adsorption unit 3. That is, the heating system consists of a single device configured to heat both the gas stream flowing in the first circulation path and the gas stream flowing in the second circulation path. The number of machines installed is reduced, and the installation is simplified.

[0088] For example, the heating system may be an electric heater associated with both the first regeneration line 6 and the first exhaust line 7. In another example, the heating system may be a heat exchanger configured to exchange heat between the first regeneration line 6 and the first exhaust line 7 and a heat source.

[0089] In one embodiment, the installation 1 includes a bypass of the heating system 8, in particular a bypass line of the first heating element 8. This bypass line, not shown in the figures, is configured to transfer the gas stream to the adsorption unit 3 without passing through the heating system 8, 9.

[0090] This allows the adsorbent to be cooled after it has been regenerated and before being used again for carbon monoxide adsorption. The adsorbent can thus be brought back, for example, to the temperature of source 2.

[0091] In an embodiment, the active material configured to adsorb at least some of the carbon monoxide can be an adsorbent material, or a catalyst used as an adsorbent, or a mixture of an adsorbent material and a catalyst.

[0092] In one embodiment, the active material configured to adsorb at least a portion of the carbon monoxide includes nickel. The efficiency of carbon monoxide adsorption is improved while maintaining a low risk of production and release of toxic compounds. Specifically, the installation limits the formation of Ni(CO)4 during regeneration and degrades any Ni(CO)4 that would otherwise have formed, thus obtaining and supplying a non-toxic gas stream to the second collector 100.

[0093] The nickel content in the active material can be chosen based on factors such as the purity of the incoming gas stream 2 and the available volume for the active material. For example, the volume of active material could be increased to reduce the nickel content, or an active material with a high nickel content could be used to reduce the required volume of adsorbent.

[0094] In one embodiment, the active material configured to adsorb at least some of the carbon monoxide contains nickel, preferably more than 50% nickel by mass. The adsorption performance is further improved.

[0095] In this design, the adsorption unit 3 comprises a single adsorption volume 3 consisting of one or more fluidically connected adsorbers. The installation is simplified while maintaining satisfactory purification and production performance.

[0096] In one embodiment, the first path 4, 5 comprises the first purification line 4, configured to bring the gas stream to the adsorption unit 3, and the first recovery line 5, configured to transfer the gas stream from the adsorption unit 3 to a first collector 10. Thus, the first path 4, 5 allows the gas stream supplied at the inlet of the installation to be transferred to the first collector 10, via the adsorption unit 3. The first path 4, 5 is, for example, made up of the first purification line 4, the adsorption unit 3 and the first recovery line 5; the lines can of course be equipped with flow control devices if necessary.

[0097] In one embodiment, the flow control assembly includes a device 400, in particular a valve, configured to permit or prevent the passage of the gas stream in the first purification line 4, and a device 500, in particular a valve, configured to permit or prevent the passage of the gas stream in the first recovery line 5.

[0098] In one embodiment, the second path 6, 7 comprises the first regeneration line 6, configured to transfer the gas stream to the heating system 8, 9 and from the heating system 8, 9 to the adsorption unit 3, and the first discharge line 7, configured to transfer the gas stream from the adsorption unit 3 to the heating system 8, 9 and from the heating system 8, 9 to the second collector 100. Thus, the second path 6, 7 allows the gas stream supplied at the inlet of the installation to be transferred to the second collector 100, passing through the heating system 8, 9 and the adsorption unit 3. The second path 6, 7 is, for example, made up of the first regeneration line 6, the heating system 8, 9, the adsorption unit 3, and the first discharge line. 7; the pipes can of course be fitted with flow control devices if necessary.

[0099] In one embodiment, the flow control assembly includes a device 610, in particular a valve, configured to permit or prevent the passage of gas stream into the first regeneration line 6, and a device 700, in particular a valve, configured to permit or prevent the passage of gas stream into the first discharge line 7.

[0100] In one embodiment, the flow control assembly includes at least a ninth component 620, in particular a pressure reducer, configured to reduce the pressure of the gas stream in the second circulation path 6, 7, upstream of the adsorption unit 3. This allows hydrogen to be saved and only the necessary amount of hydrogen to be used for the regeneration of the adsorbent.

[0101] In one embodiment, the installation includes a bypass line, not shown in the figures, configured to transfer the gas stream directly to the first collecting unit 10, without passing through the adsorption unit 3. This slows down the aging of the installation, particularly if for intervals of time the gas stream from the source 2 does not require purification.

[0102] This also allows the first collecting unit 10 to continue being supplied during the regeneration of unit 3, provided that the gas stream from source 2 does not require purification during this period. For example, it is possible to select a period of time during which the purity of the source is sufficient to perform the regeneration of adsorption unit 3.

[0103] In a second embodiment illustrated in Figure 3, the adsorption unit comprises at least two distinct adsorption volumes 31, 32. That is, each adsorption volume 31, 32 is fluidly separated from the other adsorption volumes, such that the gas inside one of these volumes cannot mix with the gas in another. Each adsorption volume 31, 32 can consist of one adsorber or a plurality of adsorbers fluidly connected to each other to form a single volume. Distinct adsorption volumes can also be obtained by providing sealed walls within an adsorber, thus creating two or more fluidly separated portions.

[0104] The first 4, 5 and the second 6, 7 flow paths each comprise a plurality of fluidic paths configured to distribute portions of the gas stream to each adsorption volume 31, 32. For example, a first fluidic path transfers a first portion of the gas stream to a first adsorption volume, a second fluidic path transfers a second portion of the gas stream to a second adsorption volume, and so on. Thus, each fluidic path transfers a portion of the gas stream to a different adsorption volume 31, 32.

[0105] Each path of the plurality of fluidic paths of the first path 4, 5 is configured to transfer a portion of the gas stream to the adsorption unit 3 and from the adsorption unit 3 to the first collector element 10. Each path of the plurality of fluidic paths of the second path 6, 7 is configured to transfer a portion of the gas stream to the heating system 8, 9, then from the heating system 8, 9 to the adsorption unit 3, and from the adsorption unit 3 to the second collector element 100.

[0106] Fluidic paths can be distinct or partially overlap, that is, one or more conduits can be part of one or more fluidic paths.

[0107] Such an arrangement with multiple adsorption volumes 31, 32 allows the installation to operate continuously, as the adsorbent in a first adsorption volume 31 can be regenerated while a second volume 32 is used for gas stream purification. Production at the installation is therefore never interrupted.

[0108] In one embodiment, the TSA type adsorption unit 3 comprises or consists of a first 31 and a second 32 adsorption volumes, each consisting of an adsorber or a plurality of adsorbers fluidically connected to each other.

[0109] In one embodiment, the first flow path includes a first 41 and a second 42 respective purification lines configured to transfer the gas stream respectively to the first 31 and to the second 32 adsorption volume, and a first 51 and a second 52 respective recovery lines configured to transfer the gas stream respectively from the first 31 and the second 32 adsorption volume to the first collecting organ 10.

[0110] In one embodiment, the flow control assembly includes a first 401 and a second 402 respective organs, including valves, configured to permit or prevent the passage of the gas stream respectively in the first 41 and in the second 42 purification line, and a third 501 and fourth 502 respective organs, including valves, configured to permit or prevent the passage of the gas stream respectively in the first 51 and second 52 recovery line.

[0111] In one embodiment, the second path comprises a first 61 and a second 62 regeneration lines respectively configured to transfer the gas stream from the heating system 8, 9 respectively to the first 31 and to the second 32 adsorption volume, and a first 71 and a second 72 lines respectively configured to transfer the gas stream from the first 31 and the second 32 adsorption volume respectively to the heating system 8, 9.

[0112] In one embodiment, the flow control assembly includes a fifth 611 and a sixth 612 respective devices, including valves, configured to permit or prevent the passage of the gas stream in the first 61 and second 62 regeneration line respectively, and a seventh 701 and eighth 702 respective devices, including valves, configured to permit or prevent the passage of the gas stream in the first 71 and second 72 discharge line respectively.

[0113] When the second path 6, 7 includes a plurality of fluidic paths, it is also conceivable to provide a plurality of ninth control devices 620, each associated with a fluidic path and configured to reduce a pressure of the gas stream in said fluidic path, upstream of the adsorption unit 3.

[0114] With reference to the, the invention also relates to a gaseous hydrogen tank filling station 10 comprising a hydrogen source 20 and a purification installation 1 as described above.

[0115] Source 20 can be, in particular, a mobile or fixed hydrogen gas tank, a semi-trailer or trailer, or a pipeline connected to a hydrogen gas distribution network. In such a configuration, purification is carried out as close as possible to the point of use, which improves the reliability of the supply chain.

[0116] As shown in Figure 1, the source 20 can include several of these, such as a semi-trailer 21, a trailer 22, or a pipeline 23 connected to a gaseous hydrogen distribution network. In this case, the supply gas stream 2 can be provided selectively by only one of these sources 21, 22, 23, or it can consist of a mixture of gases from at least two of these sources 21, 22, 23.

[0117] It is also possible to provide that a portion 200 of the gas supplied by the source(s) 20, 21, 22, 23 is withdrawn upstream of the purification installation 1 and intended for another use.

[0118] The invention further relates to a method for purifying a gas stream 2 comprising hydrogen and carbon monoxide. The method can use a purification installation 1 as described above.

[0119] At the inlet of installation 1, the gas stream 2 has in particular a pressure between 5 bar and 700 bar, and a carbon monoxide content less than or equal to 100 ppm, preferably less than or equal to 20 ppm, preferably less than or equal to 5 ppm, even more preferably less than or equal to 1 ppm.

[0120] In other examples, the gas stream 2 may have a variable carbon monoxide content depending on the application context: for example, between 0.2 ppm and 100 ppm, or between 0.5 ppm and 50 ppm, or even between 0.5 ppm and 10 ppm. A carbon monoxide content between 0.5 ppm and 10 ppm is typical when the gas stream containing hydrogen and carbon monoxide is supplied by a pressure swing adsorption (PSA) process fed with a synthesis gas obtained by methane reforming.

[0121] It should be noted that a concentration of 0 ppm, or undetectable, could, for example, occur for a limited time, during which the hydrogen originates from a process that does not produce carbon monoxide, such as water electrolysis. In this case, the already pure gas stream 2 still flows through the adsorption unit 3. Alternatively, the already pure gas stream can bypass the adsorption unit 3 via a bypass line as described above.

[0122] When the process is executed, the adsorption unit 3 follows a cycle comprising a purification phase and a regeneration phase.

[0123] In the purification phase, at least a first portion of the gas stream is directed into the first flow path 4, 5 to supply the first collecting unit 10 with the first purified portion of the gas stream. During the purification phase, the active material, or adsorbent, adsorbs the carbon monoxide contained in the gas stream 2.

[0124] The first purified portion of gas stream has a lower carbon monoxide content than gas stream 2. In particular, the first purified portion of gas stream may have a carbon monoxide content less than or equal to 2 ppb.

[0125] The purification phase is notably followed or preceded by the regeneration phase.

[0126] In the regeneration phase, at least a second portion of the gas stream is directed into the second flow path 6, 7 to regenerate at least part of the active material. During the regeneration phase, the carbon monoxide adsorbed in the purification phase is released by the active material, or adsorbent.

[0127] The ratio between the gas flow rate of the first and second portion can vary depending on the carbon monoxide content of source 2.

[0128] If installation 1 includes a single adsorption volume 3, the second portion may, for example, have a flow rate of between 5% and approximately 45% of the flow rate of the first portion.

[0129] If the installation 1 includes two adsorption volumes 31, 32, the flow rate of the first portion can be between 70% and 100% of the flow rate of the gas stream 2, preferably between 90% and 100%, for example about 95%; the flow rate of the second portion is then between 0% and 30% of the flow rate of the gas stream 2, preferably between 0% and 10%, for example about 5%.

[0130] If a portion of gas stream 2 is unused, it can bypass the adsorption unit 3 by means of a bypass line as described above and be transferred directly to the first collecting unit 10, provided that its purity is sufficient.

[0131] In one embodiment, the purification phase includes: a step of supplying the first portion of the gas stream 2 to the adsorption unit 3; a step of adsorbing the carbon monoxide contained in the first portion of the gas stream 2 by the adsorption unit 3; and a step of supplying the first collecting unit 10 with the first portion of the purified gas stream with a carbon monoxide content less than or equal to 2 ppb.

[0132] In one embodiment, the regeneration phase includes: a step of heating the second portion of the gas stream 2 to a temperature between 120 °C and 300 °C, in particular between 170 °C and 200 °C; a step of supplying the second portion of the heated gas stream to the adsorption unit 3; a step of desorption of the carbon monoxide adsorbed during the purification phase by the adsorption unit 3; and a step of supplying the second collecting unit 100 with the second portion of the gas stream that has passed through the adsorption unit 3.

[0133] During the step of supplying the second portion of gas stream, which has passed through the adsorption unit 3, to the second collecting unit 100, the composition of this portion of gas stream may vary. Under the influence of temperature, a chemical reaction may occur, converting at least some of the carbon monoxide into methane and water through reaction with hydrogen. The gas stream will then become enriched in methane to the extent that the reaction takes place.

[0134] After passing through adsorption unit 3, in the initial part of the regeneration phase, the second portion of the gas stream may, for example, have a carbon monoxide content greater than or equal to 100 ppm. The carbon monoxide content will change during the regeneration phase. At the end of the regeneration phase, the carbon monoxide content will be less than or equal to the carbon monoxide content of gas stream 2. Thus, between the beginning and the end of the regeneration phase, the carbon monoxide content may reach a maximum, or peak, greater than or equal to 100 ppm.

[0135] In one embodiment, during the purification phase, the residence time of the first portion of the gas stream in the adsorption unit 3, also known as the contact time between the gas stream and the adsorbent material, is greater than or equal to five seconds, preferably greater than or equal to ten seconds. The performance of the adsorption process is optimized and improved.

[0136] Residence time, or contact time, typically refers to the period of time a gas molecule remains within the adsorption unit or volume. This contact time can be calculated by considering the ratio between the volume of adsorbent material in cubic meters and the actual gas flow rate in cubic meters per second, also known as the volumetric flow rate.

[0137] In one embodiment, during the regeneration phase, after passing through the adsorption unit 3, the second portion of the gas stream is heated to a temperature greater than or equal to 100 °C, in particular between 100 °C and 300 °C, preferably between 100 °C and 150 °C. That is to say, the regeneration phase includes, after the desorption step, an additional step of heating the gas stream that has passed through the adsorption unit 3.

[0138] The gas stream that has passed through the adsorption unit 3 may contain undesirable and / or toxic compounds which are degraded under the effect of temperature.

[0139] In particular, when the adsorbent contains nickel, the gas stream passing through adsorption unit 3 may contain nickel tetracarbonyl or Ni(CO)4, which is highly toxic. The additional heating step then allows for the decomposition and / or removal of all or part of the Ni(CO)4. Typically, a Ni(CO)4 content of 50 ppb or less is obtained, preferably 40 ppb or less, and even more preferably 1 ppb or less.

[0140] In one implementation, the transition from the purification phase to the regeneration phase is carried out manually.

[0141] In a given process, the transition from the purification phase to the regeneration phase is carried out automatically.

[0142] In one embodiment, during the regeneration phase, the second portion of gas stream is expanded, in the second circulation path 6 upstream of the adsorption unit 3, to a regeneration pressure less than or equal to 5 bar, preferably less than or equal to 1-2 bar, even more preferably less than or equal to 1 bar.

[0143] A flow meter can be used to measure the flow rate in the second channel. The flow meter can also be used in a control loop of the ninth control unit(s) 620.

[0144] In one embodiment, the pressure of the gas stream 2 at the inlet of the purification installation 1 is greater than or equal to 10 bar, preferably greater than or equal to 20 bar. This occurs in particular when the gas stream 2 originates from the outlet of an SMR.

[0145] In one embodiment, the pressure of the gas stream 2 at the inlet of the purification installation 1 is greater than or equal to 100 bar, preferably greater than or equal to 200 bar. This occurs in particular when the gas stream 2 originates from a distribution network or pipeline.

[0146] In one embodiment, during the purification phase the first portion of gas stream flows in the adsorption unit 3 in a first direction of flow, and in the regeneration phase the second portion of gas stream flows in the adsorption unit 3 in a second direction of flow opposite to the first direction of flow.

[0147] For example, the second portion of gas stream can enter the adsorption unit 3 on the side where the exit of the first portion of gas stream is located and exit the adsorption unit 3 on the side where the entry of the first portion of gas stream is located.

[0148] In one embodiment, the cycle includes, between the regeneration phase and the adsorption phase, a cooling phase, in which at least a third portion of the gas stream is directed into the second circulation path 6, 7 without being reheated, to cool at least a portion of the regenerated active material. At the end of the cooling phase, the active material is preferably at the same temperature as the gas stream from source 2.

[0149] For example, the heating system 8, 9 can be switched off or deactivated, so that the third portion of the gas stream passes through it without being heated. Alternatively, the third portion of the gas stream can bypass the heating system 8, 9 via a bypass pipe provided for this purpose.

[0150] In one embodiment, the process may use an installation according to the second embodiment described above and illustrated schematically in Figure 1. The first adsorption volume 31 and the second adsorption volume 32 each follow, in staggered sequences, a cycle comprising a purification phase and a regeneration phase.

[0151] That is to say, the first portion of the gas stream is directed via a first fluidic path 41 to the first adsorption volume 31, to supply the first collecting element 10 with a first portion of purified gas stream. At the same time, the second portion of the gas stream is directed via a second fluidic path 42 to the second adsorption volume 32, in order to regenerate the adsorbent contained in the second adsorption volume.

[0152] When a configuration like the one shown is used, it is also possible, during the regeneration step, to use, instead of the second portion of the gas stream 2, all or part of the purified first portion of the gas stream. This can be achieved by directing all or part of the purified first portion of the gas stream to a bypass line, not shown in the figures, which connects an outlet of the first adsorption volume 31 to an inlet of the second adsorption volume 32.

[0153] The purification process was described under "steady-state conditions," that is, after the installation has been started. Start-up procedures for the installation and the purification process are well-established. During start-up, it is preferable to circulate a stream containing hydrogen through the adsorption unit 3, while heating this hydrogen stream to a temperature close to, for example, equal to, the temperature used for the regeneration phase. It is advantageous to use a pure hydrogen stream for start-up, i.e., one with a carbon monoxide content close to that of the first purified gas stream. However, less pure hydrogen, even one with a carbon monoxide content close to or equal to that of the gas stream to be purified, can also be used. The hydrogen stream used may also contain other impurities such as nitrogen, methane, and argon.

[0154] We will now describe an example of implementing the process according to the invention in an installation such as the one shown in Figure 1, where the feed gas stream 2 comes from a steam reformer (SMR). In an installation such as the one shown in Figure 2, the following description applies to one of the adsorption volumes 31, 32, while the other adsorption volume 32, 31 will be operated in a similar manner, but with a phase shift.

[0155] Although steam reforming is not part of the claimed process, its operation is briefly described, as it influences the composition of the feed gas stream 2. A hydrocarbon stream is introduced with steam into a steam reforming reactor (SMR). Since the reaction is endothermic, heat is produced by the combustion of a fuel composed of off-gas and / or hydrocarbons. In the SMR, the hydrocarbon and steam mixture is introduced into reforming tubes where the steam reforming reaction takes place. The product of this reaction is a gaseous mixture comprising hydrogen, carbon monoxide, carbon dioxide, water, methane, and possibly nitrogen and / or argon, depending on the specific composition of the fluids supplied to the SMR inlet. The carbon monoxide present at the SMR outlet is converted by a shift reaction with water into hydrogen and carbon dioxide.

[0156] At this stage, the gas produced by the SMR has a hydrogen content of 70% or higher. This gas is further purified by pressure swing adsorption (PSA). The off-gases can be used in the SMR burners to provide heat for the endothermic steam reforming reaction as described in the previous paragraph. The carbon monoxide content of the gas exiting the PSA process is around 2 ppm, but can vary between 0.5 ppm and 50 ppm depending on the PSA settings and parameters.

[0157] However, to achieve a carbon monoxide concentration between 0.5 ppm and 50 ppm, a significant decrease in PSA yield must be accepted. Therefore, the purification by adsorption (PSA) process cannot achieve a carbon monoxide concentration below 500 ppb at an acceptable cost. It is thus preferable to operate the PSA for production with a "standard" carbon monoxide concentration, i.e., around 2 ppm, and to purify only the amount of hydrogen required by the user.

[0158] This outgoing hydrogen stream, produced by the SMR and purified by the PSA, then constitutes the gas stream 2 supplying the process (or installation) according to the present invention. In this example, this gas stream 2 comprises approximately 99.95% hydrogen, 2 ppm carbon monoxide, less than 1 ppm water, and approximately 500 ppm nitrogen. For example, an active material is used that comprises 60% nickel by mass and 40% silica by mass.

[0159] During the purification phase, the feed gas stream 2 is directed into the first circulation channel 4, 5. This phase typically lasts 48 hours. At the end of the purification phase, the first portion of purified gas stream supplied to the first collecting unit 10 comprises approximately 99.95% hydrogen, approximately 500 ppm nitrogen, and 2 ppb carbon monoxide.

[0160] During the regeneration phase, the feed stream is directed into the second flow path 6, 7, where it is heated to a temperature between 120 °C and 300 °C, specifically between 170 °C and 200 °C, before being introduced into the adsorption unit 3. This phase typically lasts 12 hours. At the beginning of the regeneration phase, the second portion of the gas stream supplied to the second collector contains approximately 500 ppm of nitrogen and up to 300 ppm of carbon monoxide, with the remainder being hydrogen. As the temperature of the active material increases, a methanation reaction of carbon monoxide occurs. The carbon monoxide content of the second portion of the gas stream decreases, and its methane content increases. At the end of the regeneration phase, the second portion of gas stream supplied to the second collecting organ comprises approximately 99.95% hydrogen, approximately 500 ppm nitrogen, and less than 2 ppb carbon monoxide.

[0161] The invention further relates to a method for filling hydrogen tanks 10. The method comprises: a step of supplying a gas stream 2 comprising hydrogen and carbon monoxide; a step of purifying the gas stream 2 implementing a purification process as described above; a step of filling a tank 10 with the purified gas stream.

Claims

A gas stream purification installation comprising hydrogen and carbon monoxide, the installation comprising a TSA-type adsorption unit (3) including an active material configured to adsorb at least a portion of the carbon monoxide, a first gas stream flow path (4, 5), a second gas stream flow path (6, 7), a set of flow control devices (400, 500, 610, 620, 700) configured to selectively direct the gas stream into the first (4, 5) or the second (6, 7) flow path, and a gas stream heating system (8, 9), the first flow path (4, 5) being configured to transfer the gas stream to the adsorption unit (3), and to transfer the gas stream exiting the adsorption unit (3) to a first collector (10) of the purified gas stream, the second traffic lane (6,7) being configured to transfer the gas stream to the heating system (8), transfer the gas stream heated by the heating system (8) to the adsorption unit (3), transfer the gas stream exiting the adsorption unit (3) to a second collecting element (100), in particular a vent. Installation according to claim 1, characterized in that the second flow path is further configured to transfer the gas stream exiting the adsorption unit (3) to the heating system (8, 9) and to transfer the gas stream exiting the heating system (8, 9) to the second collector element (100). Installation according to any one of claims 1 or 2, characterized in that the first flow path comprises a first purification line (4) configured to transfer the gas stream directly to the adsorption unit (3). Installation according to any one of claims 1 to 3, characterized in that the second flow path comprises a first regeneration line (6) configured to transfer the gas stream to the adsorption unit (3), and a first exhaust line (7) configured to transfer the gas stream exiting the adsorption unit (3) to the second collector element (100), the first regeneration line (6) and / or the first exhaust line (7) being in heat exchange with the heating system (8, 9). Installation according to claim 4, characterized in that the heating system comprises a first heating element (8) in heat exchange with the first regeneration line (6) and / or a second heating element (9) in heat exchange with the first exhaust line (7). Installation according to any one of claims 1 to 5, characterized in that the active material configured to adsorb at least a portion of the carbon monoxide comprises Nickel. An installation according to any one of claims 1 to 6, characterized in that the adsorption unit (3) comprises at least two distinct adsorption volumes (31, 32), and in that the first and second flow paths each comprise a plurality of fluidic paths configured to allow portions of the gas stream to be distributed to each adsorption volume (31, 32), each path of the plurality of fluidic paths of the first path being configured to transfer a portion of the gas stream to the adsorption unit (3) and from the adsorption unit (3) to the first collector element (10); each path of the plurality of fluidic paths of the second path being configured to transfer a portion of the gas stream to the heating system (8, 9), then from the heating system (8, 9) to the adsorption unit (3), and from the adsorption unit (3) to the second collector element (100). Gaseous hydrogen tank filling station comprising a hydrogen source and a purification installation according to any one of claims 1 to 7. A method for purifying a gas stream (2) comprising hydrogen and carbon monoxide, using an installation (1) according to any one of claims 1 to 7, wherein the adsorption unit (3) follows a cycle comprising: a purification phase, in which at least a first portion of the gas stream is directed into the first circulation path (4, 5) to supply the first collecting unit (10) with the first purified portion of the gas stream, a regeneration phase, in which at least a second portion of the gas stream is directed into the second circulation path (6, 7) to regenerate at least a portion of the active material. A process according to claim 9, characterized in that the purification phase comprises: a step of supplying the first portion of the gas stream (2) to the adsorption unit (3), a step of adsorbing the carbon monoxide contained in the first portion of the gas stream (2) by the adsorption unit (3), a step of supplying the first collecting unit (10) with the first portion of the purified gas stream with a carbon monoxide content less than or equal to 2 ppb. A process according to any one of claims 9 or 10, characterized in that the regeneration phase comprises: a step of heating the second portion of the gas stream (2) to a temperature between 120 °C and 300 °C, in particular between 170 °C and 200 °C, a step of supplying the second portion of the heated gas stream to the adsorption unit (3), a step of desorption of the carbon monoxide adsorbed during the purification phase by the adsorption unit (3), a step of supplying to the second collecting unit (100) the second portion of the gas stream having passed through the adsorption unit (3). A method according to any one of claims 9 to 11, characterized in that, in the purification phase, a residence time of the first portion of gas stream in the adsorption unit (3) is greater than or equal to five seconds, preferably greater than or equal to ten seconds. A method according to any one of claims 9 to 12, characterized in that, in the regeneration phase, the second portion of gas stream having passed through the adsorption unit (3) is heated to a temperature greater than or equal to 100 °C, in particular between 100 °C and 300 °C, preferably between 100 °C and 150 °C. A method according to any one of claims 9 to 13, using an installation according to claim 7, characterized in that the first adsorption volume (31) and the second adsorption volume (32) each follow, in a staggered fashion, a cycle comprising a purification phase and a regeneration phase. Method for filling gas tanks, said method comprising: a step of supplying a gas stream comprising hydrogen and carbon monoxide, a step of purifying the gas stream implementing a purification process according to any one of claims 9 to 14, a step of filling a tank with the purified gas stream.

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