Facility and method for liquefying hydrogen

Abstract

The invention relates to a facility and a method for liquefying hydrogen, comprising a hydrogen supply circuit (3), a set of heat exchangers (4, 5, 6, 7), a cooling system (9) in heat exchange with at least a portion of the set of heat exchangers and comprising a refrigerator with refrigeration cycle of a first cycle gas comprising helium and / or hydrogen and / or neon, the supply circuit (3) comprising a device (13) for purifying hydrogen by adsorption configured to bring the concentration of at least one impurity, for example at least one of oxygen, nitrogen, argon or a hydrocarbon, below a determined threshold, the supply circuit (3) further comprising at least two isomeric conversion sections arranged in series and configured to ensure a conversion of orthohydrogen into parahydrogen with a final ratio determined at the downstream end (23), one of the conversion sections consisting of the device (13) for purifying hydrogen by adsorption, the purification device (13) being of the zeolite type.

Description

Hydrogen liquefaction plant and process

[0001] The invention relates to a plant and a method for liquefying hydrogen.

[0002] The invention relates more particularly to a hydrogen liquefaction installation comprising a hydrogen supply circuit to be cooled having an upstream end intended to be connected to a source of gaseous hydrogen and a downstream end intended to be connected to at least one member for collecting the liquefied hydrogen, the installation comprising a set of heat exchanger(s) in heat exchange with the supply circuit, the installation comprising a cooling system in heat exchange with at least part of the set of heat exchanger(s) and configured to lower the temperature of the hydrogen to a determined temperature, for example between 15 and 25K, the cooling system comprises a refrigerator with a refrigeration cycle of a first cycle gas comprising helium and / or hydrogen and / or neon,the supply circuit comprising a device for purifying hydrogen by adsorption configured to bring the concentration of at least one impurity, for example at least one of: oxygen, nitrogen, argon, a hydrocarbon, below a determined threshold, the supply circuit further comprising at least two isomeric conversion sections arranged in series and configured to ensure conversion of ortho hydrogen into para hydrogen with a determined final ratio at the downstream end.,

[0003] Hydrogen liquefaction is generally carried out from a feed stream of gaseous hydrogen at room temperature and at a pressure of, for example, between 15 and 30 bara.

[0004] In a first pre-cooling step, the feed gas is cooled by a first cooling device, for example a first refrigeration cycle (N2, "MR", etc.). The feed gas is then cooled by an H2 and / or He and / or Ne cycle refrigerator, with a view to liquefaction.

[0005] The hydrogen to be liquefied can come from various sources including impurities. A so-called "cold" purification is generally provided inside the liquefier (usually located where the feed gas is cooled to an intermediate temperature of approximately 80K). This adsorption-type purification is sized to achieve a nominal specification of contaminants at the outlet (for example, a limited number of ppb of oxygen and a limited number of ppm of nitrogen).

[0006] Purification generally uses at least two adsorption beds in parallel. When one is in adsorption, the other is in regeneration, and vice versa. Regeneration can be carried out with a hydrogen or other warmer stream (e.g., room temperature). Regeneration can also (alternatively or in combination) be carried out with a gas stream at relatively lower pressure.

[0007] Downstream of cryogenic purification, the liquefier generally includes catalysis sections designed to convert ortho hydrogen into para hydrogen (in one or more catalytic converters and / or from the catalyst directly to passages in the liquefier's cooling exchangers).

[0008] In addition to retaining residual impurities, the cryogenic purification step also helps protect the downstream catalyst from impurities, which cannot be easily regenerated.

[0009] Catalysis sections are relatively expensive and complicate the installation.

[0010] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0011] To this end, the installation according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that one of the conversion sections is constituted by the device for purifying hydrogen by adsorption, said purification device being of the zeolite type.

[0012] Furthermore, embodiments of the invention may comprise one or more of the following characteristics: the purification device is located upstream of one or more isomeric conversion sections of the catalyst type and located in at least a part of the set of exchangers and / or in one or more catalytic converters separate from the exchangers, the purification device is zeolite type 13X with a silica content greater than 1 and preferably between 1.2 and 1.3, the hydrogen purification device is configured to ensure a pre-conversion of ortho hydrogen into para hydrogen with a determined intermediate ratio of between 25% and 60%, preferably between 30% and 45%, the catalyst type catalysis sections are configured to ensure a conversion of ortho hydrogen into para hydrogen from the intermediate ratio to the final ratio,the feed circuit contains a total quantity of catalyst configured to ensure a conversion of ortho hydrogen into para hydrogen up to the level of the final ratio, the conversion of ortho hydrogen into para hydrogen at the level of the intermediate ratio being obtained by the pre-conversion carried out by the purification device, the purification device contains a quantity of zeolite in excess of the quantity required to bring the concentration of impurity(ies) below determined threshold(s), this quantity of excess zeolite being configured to ensure a pre-conversion of ortho hydrogen into para hydrogen at the level of the intermediate ratio, the installation comprises a pre-cooling system, for example a cryogenic refrigerator,in heat exchange with at least part of the heat exchanger assembly(s) and configured to lower the temperature of the hydrogen to be cooled from ambient temperature to a determined intermediate temperature, for example between 60 and 110K and preferably between 60 and 90K, the purification device is arranged at the level of the supply circuit cooled to the intermediate temperature.,

[0013] The invention also relates to a method for liquefying hydrogen using a liquefaction installation conforming to any one of the characteristics above or below, comprising a step of cooling a hydrogen stream, a step of purifying the hydrogen stream, a step of converting ortho hydrogen into para hydrogen with a determined final ratio, in which part of the conversion step is carried out by the purification device and the other part is carried out by one or more catalyst catalysis sections.

[0014] According to other possible features, the conversion step carried out by the purification device is configured to carry out heating of the hydrogen flow which is added to the heating generated by the purification step.

[0015] 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.

[0016] Other features and advantages will appear on reading the description below, made with reference to the figures in which: Brief description of the figures

[0017] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0018] is a schematic and partial view illustrating an example of structure and operation of an installation according to a possible embodiment of the invention. Detailed description

[0019] In all figures, the same references refer to the same elements.

[0020] 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. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0021] The hydrogen liquefaction installation 1 illustrated schematically comprises a circuit 3 for supplying hydrogen to be cooled having an upstream end intended to be connected to a source 2 of gaseous hydrogen and a downstream end 23 intended to be connected to at least one member 8 for collecting the liquefied hydrogen.

[0022] Installation 1 comprising a set of heat exchanger(s) 4, 5, 6, 7 in thermal exchange with the supply circuit 3.

[0023] The installation 1 comprises a cooling system 9 in heat exchange with at least part of the heat exchanger assembly and configured to lower the temperature of the hydrogen to a determined temperature, for example between 15 and 25K. The cooling system 9 comprises a refrigerator with a refrigeration cycle of a first cycle gas comprising helium and / or hydrogen and / or neon.

[0024] In the example illustrated, several heat exchangers are arranged in series but of course a configuration with a single exchanger 6 can be envisaged.

[0025] As illustrated, the installation may also comprise at least one pre-cooling system 19, for example a cryogenic refrigerator, in heat exchange with at least part of the set of heat exchanger(s) and configured to lower the temperature of the hydrogen to be cooled from ambient temperature to a determined intermediate temperature, for example between 60 and 100K.

[0026] The supply circuit 3 comprises a device 13 for purifying hydrogen by adsorption configured to bring the concentration of at least one impurity contained in the hydrogen below a determined threshold. By impurity is meant, for example, at least one of: oxygen, nitrogen, argon, carbon monoxide, a hydrocarbon, etc.

[0027] The supply circuit 3 comprises at least two isomeric conversion sections arranged in series and configured to ensure conversion of ortho hydrogen into para hydrogen with a final ratio determined at the downstream end 23. The final ratio is for example greater than 70%, preferably greater than 90%, for example greater than 95%.

[0028] According to an advantageous feature, one of the conversion sections is constituted by the device 13 for purifying hydrogen by adsorption, said purification device 13 being of the zeolite type.

[0029] That is to say, the cryogenic molecular sieve type purification device 13 is configured to exhibit a catalytic activity for isomeric conversion of hydrogen (ortho to para). Thus, the purification device 13 ensures, simultaneously with the purification, a pre-conversion of hydrogen with a para hydrogen content greater than 25%, for example a content between 25.5% and 60%.

[0030] The purification device 13 is preferably a 13X type zeolite with a silica / aluminium ratio greater than 1 and preferably between 1.2 and 1.3, for example with a Li and / or Na and / or K structure and / or any other alkali or alkaline-earth type compound integrated in a binder, and / or of the Al2O3 type. The purification device 13 could, for example, contain a quantity of zeolite in excess of the quantity required to bring the impurity concentration below the determined threshold. This quantity of excess zeolite is configured to ensure pre-conversion of ortho hydrogen into para hydrogen at the intermediate ratio.

[0031] For example, the volume ratio of the amount of purification zeolite to the amount of isomeric conversion catalyst typically used to ensure the conversion during the pre-cooling of the hydrogen (down to approximately 80K) may be between three and thirty, for example between five and twenty, for example of the order of five to eight. To promote the isomeric conversion, preferably, the purification device is configured to operate at a cryogenic temperature, for example between 60 and 100K.

[0032] The purification device 13 is preferably located upstream of one or more catalyst-type isomeric conversion sections 14.

[0033] For example, the purification device 13 is arranged at the level of the supply circuit cooled to the intermediate temperature (around 80K for example between 100K and 60K).

[0034] These catalyst-type isomeric conversion sections 14 are located, for example, in the set of exchangers 6, 7 and / or in one or more catalytic converters separate from the exchangers.

[0035] The hydrogen purification device 13 may be configured to ensure pre-conversion of ortho hydrogen into para hydrogen with a determined intermediate ratio of between 25% and 60%, preferably between 30% and 45%. By “ratio” is meant the molar fraction of para hydrogen, i.e.: the number of moles of para hydrogen divided by the sum of moles of ortho hydrogen and moles of para hydrogen.

[0036] The following catalyst type catalysis sections 14 are configured to provide conversion of ortho hydrogen to para hydrogen from the intermediate ratio to the final ratio.

[0037] Thus, the feed circuit 3 contains a total quantity of catalyst configured to ensure a conversion of ortho hydrogen into para hydrogen at the final ratio, the conversion of ortho hydrogen into para hydrogen at the intermediate ratio being obtained by the pre-conversion carried out by the purification device 13.

[0038] The equilibrium between the ortho and para forms of hydrogen is only a function of the hydrogen temperature and the reaction kinetics (spontaneous conversion) is accelerated by a significant deviation from equilibrium. The purification zeolite still allows significant participation in the conversion effort.

[0039] This makes it possible, for example, to reduce the quantity of catalysis section(s) 14 required downstream.

Claims

Hydrogen liquefaction installation comprising a circuit (3) for supplying hydrogen to be cooled having an upstream end intended to be connected to a source (2) of gaseous hydrogen and a downstream end (23) intended to be connected to at least one member (8) for collecting liquefied hydrogen, the installation (1) comprising a set of heat exchanger(s) (4, 5, 6, 7) in heat exchange with the supply circuit (3), the installation (1) comprising a cooling system (9) in heat exchange with at least part of the set of heat exchanger(s) and configured to lower the temperature of the hydrogen to a determined temperature, for example between 15 and 25K, the cooling system (9) comprises a refrigerator with a refrigeration cycle of a first cycle gas comprising helium and / or hydrogen and / or neon,the supply circuit (3) comprising a device (13) for purifying hydrogen by adsorption configured to bring the concentration of at least one impurity, for example at least one of: oxygen, nitrogen, argon, a hydrocarbon, below a determined threshold, the supply circuit (3) further comprising at least two isomeric conversion sections arranged in series and configured to ensure conversion of ortho hydrogen into para hydrogen with a determined final ratio at the downstream end (23), characterized in that one of the conversion sections is constituted by the device (13) for purifying hydrogen by adsorption, said purification device (13) being of the zeolite type., Installation according to claim 1, characterized in that the purification device (13) is located upstream of one or more catalyst-type isomeric conversion sections (14) and located in at least part of the set of exchangers (6, 7) and / or in one or more catalytic converters separate from the exchangers (6, 7). Installation according to any one of claims 1 or 2, characterized in that the purification device (13) is a 13X type zeolite with a silica content greater than 1 and preferably between 1.2 and 1.

3. Installation according to any one of claims 1 to 3, characterized in that the hydrogen purification device (13) is configured to ensure pre-conversion of ortho hydrogen into para hydrogen with a determined intermediate ratio of between 25% and 60%, preferably between 30% and 45%. Plant according to claims 2 and 4 taken in combination, characterized in that the catalyst-type catalysis sections (14) are configured to ensure conversion of ortho hydrogen into para hydrogen from the intermediate ratio to the final ratio. Installation according to claim 5, characterized in that the supply circuit (3) contains a total quantity of catalyst configured to ensure a conversion of ortho hydrogen into para hydrogen up to the level of the final ratio, the conversion of ortho hydrogen into para hydrogen at the level of the intermediate ratio being obtained by the pre-conversion carried out by the purification device (13). Installation according to claim 5 or 6, characterized in that the purification device (13) contains a quantity of zeolite in excess compared to the quantity required to bring the concentration of impurity(ies) below determined threshold(s), this quantity of excess zeolite being configured to ensure a pre-conversion of ortho hydrogen into para hydrogen at the level of the intermediate ratio. Installation according to any one of claims 1 to 7, characterized in that it comprises a pre-cooling system (19), for example a cryogenic refrigerator, in heat exchange with at least part of the set of heat exchanger(s) and configured to lower the temperature of the hydrogen to be cooled from ambient temperature to a determined intermediate temperature, for example between 60 and 110K and preferably between 60 and 90K. Installation according to claim 8, characterized in that the purification device (13) is arranged at the level of the supply circuit cooled to the intermediate temperature. A method of liquefying hydrogen using a liquefaction installation according to claim 2 and optionally also to any one of claims 3 to 9, comprising a step of cooling a hydrogen stream, a step of purifying the hydrogen stream, a step of converting ortho hydrogen into para hydrogen with a determined final ratio, in which part of the conversion step is carried out by the purification device (13) and the other part is carried out by one or more catalyst catalysis sections (14). Liquefaction method according to claim 10, characterized in that the conversion step carried out by the purification device (13) is configured to carry out heating of the hydrogen flow which is added to the heating generated by the purification step.

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