Facility and method for liquefying hydrogen

Abstract

The invention relates to a facility and a method for liquefying hydrogen, comprising a hydrogen supply circuit (2) feeding a cryogenic storage unit (8) provided with a draw-off line (11) for supplying hydrogen to a tank (12), wherein the facility (1) comprises a set of one or more heat exchangers (3, 4, 5) exchanging heat with the supply circuit (2) and with a cooling device comprising a cryogenic refrigerator (7) having a refrigeration cycle in which a cycle gas circulates through a cycle circuit (70), wherein the cycle gas comprises a mixture comprising at least 50 mol% of helium and less than 50 mol% of hydrogen, wherein the cycle circuit (70) of the refrigerator (7) comprises a compression member (17) having at least one centrifugal compressor, a cooling member (3, 4), an expansion member (27, 37) and a reheating member (5, 4, 3), wherein the facility (1) comprises at least one vaporisation-gas recovery line (9, 10) for recovering gaseous hydrogen, the vaporisation gas recovery line (9, 10) being connected to the cycle circuit (70) so as to reinject this vaporisation gas into the cycle circuit, and wherein the facility (1) further comprises a transfer line (13) connecting the cycle circuit (70) to the supply circuit (2) and configured so as to allow the cycle gas to be transferred into the supply circuit (2).

Description

Hydrogen liquefaction installation and process

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

[0002] The invention relates more particularly to a hydrogen liquefaction installation comprising a hydrogen supply circuit having an upstream end intended to be connected to a source of gaseous hydrogen and a downstream end connected to at least one cryogenic storage of liquefied hydrogen of the installation, the cryogenic storage being equipped with a withdrawal line configured to allow the supply of liquefied hydrogen to at least one tank to be filled, for example a mobile tank, the installation comprising a set of heat exchanger(s) in thermal exchange with the supply circuit and a cooling device in thermal exchange with at least part of the set of heat exchanger(s) configured to cool the supply circuit, the cooling device comprising a cryogenic refrigerator with a cycle refrigeration of a cycle gas in a cycle circuit,the cycle gas comprising a mixture comprising at least 50% by mole of helium and less than 50% by mole of hydrogen, the refrigerator cycle circuit comprising a cycle gas compression unit having at least one centrifugal type compressor, a cycle gas cooling unit, a cycle gas expansion unit and a cycle gas heating unit, the installation comprising at least one vaporization gas recovery line configured to recover gaseous hydrogen, for example, generated during the supply of liquefied hydrogen to at least one tank to be filled, the vaporization gas recovery line being connected to the cycle circuit to reinject this vaporization gas into the cycle circuit.

[0003] Hydrogen liquefaction is a known method using hydrogen cycle refrigerators. However, hydrogen's low molar mass makes its compression by centrifugal compressors inefficient. A known solution involves adding a heavier compound to the cycle circuit for compression; this heavier compound (neon or hydrocarbon) is separated before the final expansions of the refrigeration cycle. This adds complexity to the system.

[0004] Another known solution involves using a cycle gas containing or composed of helium. This requires a closed refrigeration cycle or presents problems with helium migration.

[0005] Furthermore, the recovery of hydrogen vaporization gas requires expensive or complex dedicated devices.

[0006] One aim of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0007] 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 the installation further comprises a transfer line connecting the cycle circuit to the supply circuit and configured to allow the transfer of cycle gas into the supply circuit.

[0008] Furthermore, embodiments of the invention may include one or more of the following features: the installation includes a first vaporization gas recovery line connecting the cryogenic storage to the cycle circuit configured to transfer vaporization gas from the cryogenic storage to the cycle circuit; the installation includes a second vaporization gas recovery line comprising a downstream end connected to the cryogenic storage and / or the cycle circuit and an upstream end configured to be connected to a tank to be filled and / or a tank filling circuit, the second recovery line being configured to transfer vaporization gas from a tank to be filled and / or a tank filling circuit to the cryogenic storage and / or the cycle circuit; the cycle circuit includes, downstream of an expansion device, a phase separator pot.At least one vaporization gas recovery line is connected to the phase separator pot; the supply circuit includes a final expansion device located between the heat exchanger assembly(ies) and the cryogenic storage.

[0009] The invention also relates to a hydrogen liquefaction process using an installation according to any one of the preceding claims, the process comprising a step of recovering vaporization gas consisting mainly of hydrogen in the refrigerator cycle circuit, a step of transferring a determined quantity of cycle gas into the supply circuit and a step of recovering vaporization gas consisting mainly of helium from cryogenic storage to the cycle circuit.

[0010] Depending on other possible features, the installation is configured to maintain a helium level in the cycle circuit above a determined threshold.

[0011] 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.

[0012] Other features and advantages will become apparent upon reading the description below, which refers to the figures in which: Brief description of the figures

[0013] 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:

[0014] is a schematic and partial view illustrating an example of the structure and operation of an installation according to the invention. Detailed description

[0015] In all the figures, the same references refer to the same elements.

[0016] 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.

[0017] The illustrated hydrogen liquefaction installation 1 classically comprises a hydrogen supply circuit 2 having an upstream end intended to be connected to a source of gaseous hydrogen (for example at ambient temperature and at a pressure between a few bar and 40 bar) and a downstream end connected to at least one cryogenic storage 8 of the liquefied hydrogen.

[0018] As shown schematically, the cryogenic storage 8 can be equipped with at least one withdrawal line 11 configured to allow the supply of liquefied hydrogen to at least one tank 12 to be filled, for example mobile tanks.

[0019] Installation 1 includes, for example in at least one cold box, a set of heat exchangers 3, 4, 5 in heat exchange with the supply circuit 2 and a cooling device in heat exchange with at least part of the set of heat exchangers 3, 4, 5 configured to cool the supply circuit 2 for the purpose of hydrogen liquefaction.

[0020] Downstream of the set of exchangers 3, 4, 5n the supply circuit may include a final expansion device 6 (turbine and / or valve for example).

[0021] The cooling device may include at least one pre-cooling system 14 (e.g. nitrogen cycle or other) configured to pre-cool the hydrogen from the supply circuit 2 to a pre-cooling temperature (e.g. 80K).

[0022] The cooling device includes a cryogenic refrigerator 7 configured to further cool the hydrogen for liquefaction, for example to a temperature of 20K.

[0023] Refrigerator 7 is of the refrigeration cycle type of one cycle gas in a 70 cycle circuit.

[0024] The cycle gas comprises a mixture including at least 50 mole percent of helium and less than 50 mole percent of hydrogen, for example 80% helium and 20% hydrogen.

[0025] The mixture has a density at the compressor inlet that is compatible with centrifugal compression technology.

[0026] Classically, the refrigerator 7 cycle circuit 70 includes a cycle gas compression unit 17 comprising one or more centrifugal compressors, a cycle gas cooling unit 3, 4 (for example, the one or more counter-current multi-pass heat exchangers), a cycle gas expansion unit 27, 37 (one or more turbines and / or expansion valve(s)) and a cycle gas heating unit 5, 4, 3 (for example, the same counter-current heat exchangers).

[0027] As illustrated, the cycle circuit 70 may include, at its colder end, downstream of an expansion device 37, a phase separator pot 47. The phase separator pot 47 may form a thermosiphon, supplying cooling power to at least one heat exchanger 5 via the cycle gas flow. A gas outlet from the separator pot 47 may return a gas flow to the compression device 17.

[0028] The illustrated installation 1 includes a first vaporization gas recovery line 10 connecting the cryogenic storage 8 to the cycle circuit 70, for example at the separator pot 47. This first recovery line 10 is configured to transfer vaporization gas from the cryogenic storage 8 to the cycle circuit 70.

[0029] As illustrated, the installation 1 includes, in this example, a second vaporization gas recovery line 9 configured to recover vaporization gases (hydrogen) collected in the tanks 12 to be filled and / or in the circuitry intended for filling these tanks 12 (loading bay for example).

[0030] This second recovery line 9 includes an upstream end configured to be connected to a tank 12 to be filled and / or a filling circuit for a tank 12 to be filled and a downstream end connected to the installation 1. In this example, the downstream end of the second recovery line 9 is connected to the separator pot 47 (via the first recovery line 10).

[0031] Of course, the downstream end of the second recovery line 9 could be connected directly to the separator pot 47 or to the cryogenic storage 8 or to another location in the cycle circuit 70.

[0032] This second recovery line 9 is configured to allow the recovery of vaporized hydrogen in tanks 12 to be filled and / or in the filling circuitry of these in the installation and in particular in the cycle circuit 70.

[0033] Installation 1 further includes a transfer line 13 connecting the cycle circuit 70 to the supply circuit 2 and configured to allow the transfer of cycle gas into the supply circuit 2. For example, the transfer line 13 draws the cycle gas after pre-cooling and is connected to the already pre-cooled supply circuit 2.

[0034] Thus, in operating configuration, the helium and hydrogen mixture of the cycle gas can be compressed in the centrifugal compressor(s) 17 offering better efficiency compared to a cycle gas consisting solely of hydrogen (due to the relatively higher molar mass of helium).

[0035] Vaporized hydrogen can be recovered from tank 12 or the loading bay via the second recovery line 9. This gas, consisting primarily of hydrogen, can be admitted into the cycle circuit 70 without requiring a separate, dedicated recovery system (the same applies to the vaporization gas from the cryogenic storage 8).

[0036] Adding hydrogen to the 70 cycle circuit may eventually decrease the relative proportion of helium in the 70 cycle circuit.

[0037] However, installation 1 allows the transfer of cycle gas into the feed circuit 2 via the transfer line 13. This feed gas 2 therefore receives a fraction of helium. This feed gas, which contains helium, after a final expansion 6, can produce liquid hydrogen and, in particular, subcooled liquid hydrogen (liquid hydrogen at a temperature below its saturation temperature).

[0038] The cooled and at least partially liquefied fluid is poured into cryogenic storage 8. The gaseous or vaporized portion in storage contains proportionally more helium. This helium-rich vaporized gas can be supplied to the cycle circuit 70 via the first recovery line 10. This allows the proportion of helium in the cycle gas to be maintained above a minimum threshold, for example, 50%.

[0039] Thus, the installation can be configured to maintain a helium concentration in the cycle circuit 70 above a predetermined threshold by controlling the gas flow in the transfer line 13 and in at least one recovery line. This control can be performed automatically via a set of valve(s) located on all or part of the aforementioned lines.

[0040] All or part of the pipes 13, 9, 10 or circuits may include one or more valves to control the circulation or flow rate of fluid. The entire system may be controlled by an electronic device including a microprocessor.

[0041] Compared to a system using a refrigerator with a closed refrigeration cycle, the liquid hydrogen produced by the open-cycle system according to the invention may contain a small proportion of residual helium. For example, 0.5% by mole in the liquid hydrogen produced at 20 K. However, this helium fraction can be easily separated if necessary.

Claims

A hydrogen liquefaction process using a hydrogen liquefaction plant comprising a hydrogen supply circuit (2) having an upstream end connected to a source of gaseous hydrogen and a downstream end connected to at least one cryogenic liquefied hydrogen storage (8) of the plant, the cryogenic storage (8) being equipped with a withdrawal line (11) configured to allow the supply of liquefied hydrogen to at least one tank (12) to be filled, for example, a mobile tank, the plant (1) comprising an assembly of heat exchanger(s) (3, 4, 5) in heat exchange with the supply circuit (2) and a cooling device in heat exchange with at least a portion of the assembly of heat exchanger(s) (3, 4, 5) configured to cool the supply circuit (2), the cooling device comprising a cryogenic refrigerator (7) with a cycle refrigeration of a cycle gas in a circuit (70) of cycle,the cycle gas comprising a mixture comprising at least 50% by mole of helium and less than 50% by mole of hydrogen, the refrigerator (7) cycle circuit (70) comprising a cycle gas compression unit (17) having at least one centrifugal compressor, a cycle gas cooling unit (3, 4), a cycle gas expansion unit (27, 37) and a cycle gas heating unit (5, 4, 3), the installation (1) comprising at least one vaporization gas recovery line (9, 10) configured to recover gaseous hydrogen generated during the supply of liquefied hydrogen to at least one tank (12) to be filled, the vaporization gas recovery line (9, 10) being connected to the cycle circuit (70) to reinject this vaporization gas into the cycle circuit,the installation (1) further comprising a transfer line (13) connecting the cycle circuit (70) to the supply circuit (2) and configured to allow the transfer of cycle gas into the supply circuit (2), the installation comprising a first vaporization gas recovery line (10) connecting the cryogenic storage (8) to the cycle circuit (70) configured to transfer vaporization gas from the cryogenic storage (8) to the cycle circuit (70), the process comprising a step of recovering vaporization gas consisting mainly of hydrogen in the cycle circuit (70) of the refrigerator (7), a step of transferring a determined quantity of cycle gas into the supply circuit (2) and a step of recovering vaporization gas consisting mainly of helium from the cryogenic storage to the cycle circuit (70),the process comprising a step of maintaining a helium concentration in the cycle circuit (70) above a predetermined threshold. A method according to claim 1, characterized in that the installation comprises a second vaporization gas recovery line (9) including a downstream end connected to the cryogenic storage (8) and / or the cycle circuit (70) and an upstream end configured to be connected to a tank (12) to be filled and / or a tank filling circuit (12) to be filled, the second recovery line (9) being configured to transfer vaporization gas from a tank (12) to be filled and / or a tank filling circuit (12) to be filled to the cryogenic storage (8) and / or the cycle circuit (70). Method according to any one of the preceding claims, characterized in that the cycle circuit (70) comprises, downstream of a decompression member (37), a phase separator pot (47). Method according to claim 3, characterized in that at least one vaporization gas recovery line (9, 10) is connected to the phase separator pot (47). A method according to any one of the preceding claims, characterized in that the supply circuit (2) comprises a final expansion element (6) located between the heat exchanger assembly (3, 4, 5) and the cryogenic storage (8). A method according to the preceding claim, characterized in that the installation is configured to maintain a helium level in the cycle circuit (70) above a determined threshold. Hydrogen liquefaction installation comprising a hydrogen supply circuit (2) having an upstream end intended to be connected to a source of gaseous hydrogen and a downstream end connected to at least one cryogenic liquefied hydrogen storage (8) of the installation, the cryogenic storage (8) being equipped with a withdrawal line (11) configured to allow the supply of liquefied hydrogen to at least one tank (12) to be filled, for example a mobile tank, the installation (1) comprising an assembly of heat exchanger(s) (3, 4, 5) in heat exchange with the supply circuit (2) and a cooling device in heat exchange with at least part of the assembly of heat exchanger(s) (3, 4, 5) configured to cool the supply circuit (2), the cooling device comprising a cryogenic refrigerator (7) with a cycle refrigeration of a cycle gas in a cycle circuit (70),the cycle gas comprising a mixture comprising at least 50% by mole of helium and less than 50% by mole of hydrogen, the refrigerator (7) cycle circuit (70) comprising a cycle gas compression unit (17) having at least one centrifugal compressor, a cycle gas cooling unit (3, 4), a cycle gas expansion unit (27, 37) and a cycle gas heating unit (5, 4, 3), the installation (1) comprising at least one vaporization gas recovery line (9, 10) configured to recover gaseous hydrogen generated during the supply of liquefied hydrogen to at least one tank (12) to be filled, the vaporization gas recovery line (9, 10) being connected to the cycle circuit (70) to reinject this vaporization gas into the cycle circuit,the installation (1) further comprising a transfer line (13) connecting the cycle circuit (70) to the supply circuit (2) and configured to allow the transfer of cycle gas into the supply circuit (2), the installation comprising a first vaporization gas recovery line (10) connecting the cryogenic storage (8) to the cycle circuit (70) configured to transfer vaporization gas from the cryogenic storage (8) to the cycle circuit (70), the installation being configured to recover vaporization gas consisting mainly of hydrogen in the cycle circuit (70) of the refrigerator (7) via at least one recovery line (9, 10), to transfer a determined quantity of cycle gas into the supply circuit (2), to recover vaporization gas consisting mainly of helium from the cryogenic storage to the cycle circuit (70) via the gas recovery line (10),the installation being further configured to maintain a helium level in the cycle circuit (70) above a predetermined threshold by controlling the gas flows in the transfer line (13) and in at least one recovery line (9, 10).

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