Process for liquefying a feed fluid at a cryogenic temperature

Abstract

The invention relates to a feed fluid liquefaction installation at a cryogenic temperature comprising a feed circuit (2), a set of heat exchanger(s) (3, 4) in heat exchange with the feed circuit, a cooling device (6) for the set of heat exchanger(s) and comprising a cycle gas refrigerator comprising hydrogen and / or helium and at least one additional component having a molar mass greater than 15g / mol, the cycle circuit (60) comprising at least one cycle gas purification element (7) by adsorption disposed downstream of a compressor of the compression system (16) and upstream of an expansion element of the expansion system (26), the installation (1) comprising at least one regeneration line (8) for the cycle gas purification element (7) configured to inject a flow of regeneration gas into the cycle gas purification element (7) during a regeneration phase,at least one regeneration line (8) comprising an upstream end connected to the supply circuit (2) and / or the cycle circuit (60) and a downstream end connected to an inlet of the cycle gas purification unit (7). Abbreviated figure: Fig. 1,

Description

Title of the invention: Method for liquefying a feed fluid at a cryogenic temperature

[0001] The invention relates to an installation and a method for liquefying a feed fluid at a cryogenic temperature.

[0002] The invention relates in particular to the liquefaction of hydrogen.

[0003] The invention relates more particularly to an installation for liquefying a feed fluid at a cryogenic temperature, for example hydrogen, comprising a feed circuit for the feed fluid, a set of heat exchanger(s) in heat exchange with the feed circuit, a cooling device in heat exchange with at least part of the set of heat exchanger(s) configured to cool the feed fluid to a determined target temperature, the cooling device comprising a cycle gas refrigerator including, in a cycle circuit, a compression system, a cooling system and an expansion system for subjecting the cycle gas to a thermodynamic cycle to produce cold, wherein the cycle gas comprises hydrogen and / or helium and at least one additional component having a molar mass greater than 15g / mol,the cycle circuit comprising at least one cycle gas purification unit by adsorption, the cycle gas purification unit being located downstream of a compressor of the compression system and upstream of an expansion unit of the expansion system, the installation comprising at least one regeneration line for the cycle gas purification unit configured to inject a flow of regeneration gas into the cycle gas purification unit during a regeneration phase.. ,

[0004] Document FR2723183A describes a liquefaction process that uses hydrogen as the cycle gas, supplemented by a mixture of hydrocarbons. The hydrogen is compressed with the hydrocarbons, which are used for pre-cooling. Cooling to the hydrogen liquefaction temperature is achieved with the hydrogen purified of the hydrocarbons via separation obtained through successive expansions. These successive expansions allow condensation of the heavier compounds, and the remaining compounds are removed via a separation column to allow expansion at very low temperatures without the risk of solidifying impurities.

[0005] This solution still presents risks of solidification of compounds in the cycle.

[0006] Other documents provide for the separation of hydrocarbons after pre Adsorption cooling. However, these solutions require sources of pure gas at ambient temperature (hydrogen) for adsorbent regeneration. This is not always feasible.

[0007] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0008] To this end, the installation according to the invention, which also conforms to the generic definition given in the preamble above, is essentially characterized in that at least one regeneration line comprises an upstream end connected to the supply circuit and / or to the cycle circuit and a downstream end connected to an inlet of the cycle gas purification unit.

[0009] Furthermore, embodiments of the invention may include one or more of the following features: - the installation includes a pre-cooling device in heat exchange with at least part of the heat exchanger assembly(ies), the pre-cooling device being configured to cool the feed fluid to a pre-cooling temperature higher than the target temperature, - the feed circuit includes a feed gas adsorption purification unit, at least one regeneration line for the cycle gas purification unit including an upstream end connected to the feed circuit at an outlet to a feed gas adsorption purification unit, - the upstream end of the cycle gas purification unit regeneration line is connected to the downstream supply circuit of its cooling by the pre-cooling device, the cycle gas purification unit regeneration line comprising a heating element configured to heat the relevant gas flow before its supply to the cycle gas purification unit to a determined regeneration temperature, for example at ambient temperature, - The upstream end of the cycle gas purification unit's regeneration line is connected to the cycle circuit downstream of the cycle gas purification unit, at a portion of the cycle circuit which, in its operating configuration, is at a cryogenic temperature, for example around 80K. The regeneration line includes a heating element configured to heat the relevant gas stream to a predetermined regeneration temperature, for example ambient temperature. - The upstream end of the regeneration line is connected to the cycle circuit downstream of an expansion element of the expansion system at a portion of the cycle circuit which, in its operating configuration, is at a temperature equal to or close to the target temperature, - the regeneration line heating element comprises at least one of the following: at least one heating passage in at least one of the heat exchanger assembly(ies), a heater separate from the heat exchanger assembly(ies), for example an electric heater, - the installation comprising a system for regenerating the purification unit by adsorption of the feed gas, the regeneration system comprising circuitry and a heating element configured to sweep the purification unit by adsorption with a flow of regeneration gas at a determined regeneration temperature, the heating element of the regeneration system of the purification unit (9) by adsorption of the feed gas comprising or consisting of the heating element of the regeneration line, - the installation comprising at least one expansion turbine supported by a gas-type bearing, for example a cycle gas turbine, the bearing of said turbine being supplied with lift gas by at least one supply line, the supply line being connected to the regeneration line, - at least one supply line is a branch of the regeneration line.

[0010] The invention also relates to a method for liquefying a feed fluid at a cryogenic temperature, for example hydrogen, the method using an installation equipped with a feed circuit for the feed fluid, a set of heat exchanger(s) in heat exchange with the feed circuit, a cooling device in heat exchange with at least part of the set of heat exchanger(s), the cooling device comprising a cycle gas refrigerator including, in a cycle circuit, a compression system, a cooling system and an expansion system for subjecting the cycle gas to a thermodynamic cycle to produce cold, in which the cycle gas comprises hydrogen and / or helium and at least one additional component having a molar mass greater than 15g / mol, the cycle circuit comprising at least one cycle gas purification element by adsorption,The cycle gas purification unit being located downstream of a compressor in the compression system and upstream of an expansion unit in the expansion system, the process comprising a step of regenerating the cycle gas purification unit by purging with a regeneration gas flow, the regeneration gas flow being supplied by the supply circuit and / or the cycle circuit.

[0011] According to other possible features, the regeneration gas flow is taken from the supply circuit and / or cycle circuit downstream of a purification at a temperature between 100 and 70K and a determined purity, said flow being heated before being supplied to the cycle gas purification unit at a determined regeneration temperature, for example at ambient temperature.

[0012] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0013] Other features and advantages will become apparent from the following description, given with reference to the figures in which: Brief description of the figures

[0014] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0015] [Fig. 1] is a schematic and partial view illustrating the structure and function of a first example of the implementation of an installation according to the invention,

[0016] [Fig.2] is a schematic and partial view illustrating the structure and function of a second example of the implementation of an installation according to the invention,

[0017] [Fig.3] is a schematic and partial view illustrating the structure and function of a third example of the implementation of an installation according to the invention. Detailed description

[0018] In all figures, the same references refer to the same elements.

[0019] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Simple features from different embodiments can also be combined and / or interchanged to provide other embodiments.

[0020] The installation 1 for liquefying a feed fluid at a cryogenic temperature illustrated in [Fig.1] can in particular liquefy hydrogen.

[0021] The installation 1 includes a supply circuit 2 for the supply fluid (typically a more or less pure hydrogen stream), a set of heat exchanger(s) 3, 4 in heat exchange with the supply circuit.

[0022] Installation 1 further includes a heat exchange cooling device 6 with at least part of the heat exchanger assembly(ies) configured to cool the feed fluid to a predetermined target temperature, for example 20K or a temperature close to it, with a view to its liquefaction.

[0023] As schematically shown, the installation 1 may include at least one pre-cooling device 5 configured to pre-cool the feed gas flow between the initial temperature (ambient temperature for example) and an intermediate temperature pre-cooling (e.g. 80K).

[0024] The pre-cooling device 5 may include a cycle refrigerator (e.g., nitrogen) comprising, for example, a compression 15 and an expansion 25 for producing cold. Any other pre-cooling device may be considered.

[0025] The cooling device 6 comprises a cycle gas refrigerator including, in a cycle circuit 60, a compression system 16, a cooling system, and an expansion system 26 for subjecting the cycle gas to a thermodynamic cycle to produce cold. The cycle gas comprises hydrogen and at least one additional component having a molar mass greater than 15 g / mol, for example, at least one hydrocarbon, for example, a mixture of refrigerants.

[0026] After purification and pre-cooling of the cycle gas, the cycle circuit 60 includes at least one cycle gas purification device 7 by adsorption (for example, of the TSA type). This cycle gas purification device 7 is located downstream of a compressor of the compression system 16 and upstream of an expansion device of the expansion system 26 to remove heavy components before expansion and cooling to temperatures below 80K.

[0027] This purification stage 7 is configured in particular to produce a regeneration gas with a determined degree of purity, specifically free from compound(s) having a molar mass greater than 2 g / mol, from a mixture of hydrogen and / or helium and CnHm-type compounds (for example, at least one CnHm-type compound other than CH4 and, for example, without nitrogen). For example, upstream of the purification stage 7, the hydrogen cycle gas contains a few ppm of C2H6 and C3H8.

[0028] The gas purification unit 7 may, in particular, comprise several separation vessels arranged in parallel and alternating between purification phases (adsorption of impurities) and regeneration phases (removal of impurities). The purification unit 7 may be of the molecular sieve type (13X zeolite, for example).

[0029] For this purpose, the installation 1 includes at least one regeneration line 8 for the cycle gas purification unit 7 configured to periodically inject a flow of regeneration gas into the cycle gas purification unit 7 during a regeneration phase.

[0030] According to an advantageous feature, at least one regeneration line 8 comprises an upstream end connected to the supply circuit 2 and / or the cycle circuit 60 and a downstream end connected to an inlet of the cycle gas purification unit 7. That is to say, supply gas (pure hydrogen) and / or cycle gas (pure hydrogen) is used as the regeneration gas.

[0031] As illustrated, the supply circuit 2 may include, for example downstream of a portion pre-cooled to the pre-cooling temperature, a pumping element 9 verification by adsorption of the feed gas (for example of the TSA type).

[0032] The regeneration line 8 of the cycle gas purification unit 7 may include an upstream end connected to the supply circuit 2 to an outlet of the feed gas purification unit 9 by adsorption. The feed gas is, for example, purified to a predetermined level of purity, for example so as to be free of compounds having a molar mass greater than 2 g / mol.

[0033] For this purpose, the regeneration line 8 of the cycle gas purification unit 7 may include a heating unit 10 configured to heat the relevant gas stream before it is supplied to the cycle gas purification unit 7 to a determined regeneration temperature, for example at ambient temperature.

[0034] That is to say, purified and cold feed gas (for example 80K) can be heated before being used for regeneration of the cycle gas purification organ 7.

[0035] The heating element 10 may include a heating passage in at least one of the heat exchanger assembly(ies) 3, 4. That is to say, this gas flow is heated by transferring cold to the installation to cool the supply circuit and / or the cycle circuit.

[0036] The heating element 10 may also include a heater separate from the heat exchanger assembly(ies) 3, 4, for example an electric heater.

[0037] As illustrated, this heating organ 10 can ensure both the heating of the regeneration gas of the feed gas purification organ 9 and the heating of the regeneration gas of the cycle gas purification organ 7.

[0038] Thus the extraction of this regeneration gas (withdrawal from the supply circuit 2) and its heating can be shared for these two purification components 7, 9 of the two circuits 2, 60. These common equipment can be used in particular successively for these two functions and / or simultaneously.

[0039] As illustrated, after purifying the regeneration gas 7, the impurity-laden gas can be returned, via a recycling line 18, to the cycle circuit 60, for example to the compression system 16, particularly at an intermediate pressure level between two compression stages. As illustrated, a heating element 12 can be provided in this return line 18 to bring the recycled gas back to ambient temperature, for example.

[0040] The embodiment of [Fig.2] differs from that of [Fig.1] in that the regeneration gas used for the regeneration of the cycle gas purification organ 7 is taken from the cycle circuit 60.

[0041] For example, the upstream end of the regeneration line 8 is connected to the cycle circuit 60 downstream of the cycle gas purification unit 7, at a portion of the cycle circuit which, in operating configuration, is at a temperature cryogenic, for example around or below 80K.

[0042] As illustrated, the upstream end of the regeneration line 8 can be connected to the cycle circuit 60 downstream of a cycle gas element 26, and to the cycle gas purification element 7, to draw a stream of pure cycle gas at an intermediate pressure (for example, between 5 and 20 bar) and which returns at a temperature, for example, of 40 K or lower. The regeneration line 8 similarly includes a heating element 10 to heat the relevant gas stream to a predetermined regeneration temperature, for example, ambient temperature.

[0043] As schematically illustrated with dashed lines in [Fig. 1] and [Fig. 2], at least one turbine 15 of the pre-cooling cycle can be coupled to a compressor 25 of the same cycle to form a turbo-compressor. The same applies to the refrigeration cycle 60.

[0044] As schematically shown in [Fig. 3], the cycle circuit may in particular include at least one expansion turbine 26 supported by a gas-type bearing, for example, a cycle gas turbine. As illustrated, the turbine 26 may be coupled to a compressor 16 of the cycle circuit 60 on the same shaft. It should be noted that this turbo-compressor arrangement (turbine coupled to a compressor) may also be applied to one or more compressors of the supply circuit, if applicable.

[0045] The bearing of said turbine 26 can be supplied with lift gas by at least one supply line 11. This supply line 11 can be connected to the regeneration line 8. That is to say, the pure gas used for the regeneration of a purification unit can also be used to supply a bearing.

[0046] For example, at least one supply line 11 is a branch of the regeneration line 8 (or vice versa).

[0047] In the non-limiting example of [Fig. 3], purified gas for regeneration can be drawn from the outlet of a cycle gas purification unit 7. This cycle gas is heated, for example, in a section 3 of the heat exchanger assembly. A first portion of this heated gas can be distributed (after an optional valve 17) via a first supply line 11 to support the bearing of at least one compressor 16. The regeneration gas is sent via line 8 to the purification unit(s) 7 to be regenerated. A second portion of this gas can be distributed via a second supply line 11 to support the bearing of at least one turbine 26. As illustrated, a gas flow can also be sent (line 80) for the regeneration of a feed gas purification unit 9.

[0048] The distribution of the different pure gas flows can be ensured by a set of valves 17.

[0049] In the illustrated example, after the purification unit 7 has been scanned, the impurity-laden regeneration gas can be returned to the cycle circuit 60, for example to the compression input 16.

[0050] The invention makes it possible to ensure, when necessary, the regeneration of adsorbents with a purified gas stream from the installation. Despite the heating of a cold gas to obtain a regeneration gas at a non-cryogenic temperature, the impact on the energy efficiency of the installation is minor and, in particular, more advantageous overall than known solutions.

[0051] In particular, the installation uses a feed gas flow at a pressure, for example, between 10 and 60 bara and / or a cycle gas flow at a pressure between 1 and 70 bara (for example, a low-pressure section between 1 and 3 bar, a medium-pressure section between 5 and 10 bara, and a high-pressure section between 50 and 70 bara). Regeneration can be carried out with a flow at one of these pressures, preferably at the medium pressure. These pure gas flows under pressure allow for the regeneration of the adsorbents and can be shared and even recycled within the installation after use.

[0052] The gas flow for the bearing(s) (if applicable) is preferably at a pressure between 20 and 50 bara.

[0053] The regenerations of the feed gas and cycle gas purification units may or may not be synchronized.

Claims

1.

2.

3. Demands Installation for liquefying a feed fluid at a cryogenic temperature, for example hydrogen, comprising a feed circuit (2) for the feed fluid, a set of heat exchanger(s) (3, 4) in heat exchange with the feed circuit, a cooling device (6) in heat exchange with at least a part of the set of heat exchanger(s) configured to cool the feed fluid to a predetermined target temperature, the cooling device (6) comprising a cycle gas refrigerator including, in a cycle circuit (60), a compression system (16), a cooling system and an expansion system (26) for subjecting the cycle gas to a thermodynamic cycle to produce cold, wherein the cycle gas comprises hydrogen and / or helium and at least one additional component having a molar mass greater than 15g / mol,the cycle circuit (60) comprising at least one cycle gas purification unit (7) by adsorption, the cycle gas purification unit (7) being disposed downstream of a compressor of the compression system (16) and upstream of an expansion unit of the expansion system (26), the installation (1) comprising at least one regeneration line (8) for the cycle gas purification unit (7) configured to inject a flow of regeneration gas into the cycle gas purification unit (7) during a regeneration phase, characterized in that the at least one regeneration line (8) comprises an upstream end connected to the supply circuit (2) and / or to the cycle circuit (60) and a downstream end connected to an inlet of the cycle gas purification unit (7). Installation according to claim 1, characterized in that it comprises a pre-cooling device (5) in heat exchange with at least part of the heat exchanger assembly (3, 4), the pre-cooling device (5) being configured to cool the feed fluid to a pre-cooling temperature higher than the target temperature. An installation according to claim 1 or 2, characterized in that the supply circuit (2) comprises a feed gas adsorption purification unit (9), and at least one regeneration line (8) for the cycle gas purification unit (7), comprising a upstream end connected to the supply circuit (2) to an outlet an element (9) for purification by adsorption of the supply gas.

4. Installation according to claims 2 and 3, characterized in that the upstream end of the regeneration line (8) of the cycle gas purification unit (7) is connected to the downstream supply circuit (2) of its cooling by the pre-cooling device (5), the regeneration line (8) of the cycle gas purification unit (7) comprising a heating unit (10) configured to heat the relevant gas stream before its supply to the cycle gas purification unit (7) to a determined regeneration temperature, for example at ambient temperature.

5. Installation according to any one of claims 1 to 4, characterized in that the upstream end of the regeneration line (8) of the cycle gas purification unit (7) is connected to the cycle circuit (60) downstream of the cycle gas purification unit (7), at a portion of the cycle circuit which, in operating configuration, is at a cryogenic temperature, for example around 80K, the regeneration line (8) comprising a heating unit (10) configured to heat the relevant gas stream to a determined regeneration temperature, for example ambient temperature.

6. Installation according to claim 5, characterized in that the upstream end of the regeneration line (8) is connected to the cycle circuit (60) downstream of a decompression member of the decompression system (26) at a portion of the cycle circuit which, in operating configuration, is at a temperature equal to or close to the target temperature.

7. Installation according to any one of claims 4 to 6, characterized in that the heating element (10) of the regeneration line (8) comprises at least one of: at least one heating passage in at least one of the heat exchanger assembly(ies) (3, 4), a heater separate from the heat exchanger assembly(ies) (3, 4), for example an electric heater.

8. An installation according to claim 4 combined with any one of claims 5 to 7, comprising a system for regenerating the purification element (9) by adsorption of the feed gas, the regeneration system comprising circuitry and a heating element configured to sweep the purification element (9) by adsorption with a flow of regeneration gas at a regeneration temperature. determined regeneration, characterized in that the heating element of the regeneration system of the feed gas adsorption purification element (9) comprises or is made up of the heating element (10) of the regeneration line (8).

9. Installation according to any one of claims 1 to 8, characterized in that it comprises at least one expansion turbine (26) supported by a gas-type bearing, for example a cycle gas turbine, the bearing of said turbine (26) being supplied with lift gas by at least one supply line (11), the supply line (11) being connected to the regeneration line (8).

10. An installation according to any one of claims 1 to 8, characterized in that it comprises at least one expansion turbine (26) coupled to a compressor (26) forming a turbo-compressor, the common axis of the turbine and the compressor being supported by a gas-type bearing supplied with lift gas by the supply line (11).

11. Installation according to claim 9 or 10, characterized in that at least one supply line (11) is a branch of the regeneration line (8).

12. A process for liquefying a feed fluid at a cryogenic temperature, for example hydrogen, the process using an installation equipped with a feed circuit (2) for the feed fluid, a set of heat exchanger(s) (3, 4) in heat exchange with the feed circuit, a cooling device (6) in heat exchange with at least a part of the set of heat exchanger(s) (3, 4), the cooling device (6) comprising a cycle gas refrigerator including, in a cycle circuit (60), a compression system (16), a cooling system and an expansion system (26) for subjecting the cycle gas to a thermodynamic cycle to produce cold, wherein the cycle gas comprises hydrogen and / or helium and at least one additional component having a molar mass greater than 15g / mol,the cycle circuit (60) comprising at least one cycle gas purification unit (7) by adsorption, the cycle gas purification unit (7) being disposed downstream of a compressor of the compression system (16) and upstream of an expansion unit of the expansion system (26), the process comprising a step of regenerating the cycle gas purification unit (7) by purging with a gas flow of, regeneration, the regeneration gas flow being supplied by the supply circuit (2) and / or the cycle circuit (60).

13. A method according to claim 12, characterized in that the regeneration gas stream is taken from the supply circuit (2) and / or the cycle circuit (60) downstream of a purification at a temperature between 100 and 70K and a determined purity, said stream being heated before being supplied to the cycle gas purification unit (7) at a determined regeneration temperature, for example at ambient temperature.

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