Cryogenic fluid production facility

Abstract

The invention relates to an installation for producing a cryogenic fluid, comprising: a circuit of gas to be cooled, having an upstream end intended to be connected to a source of gas to be cooled and a downstream end intended to be connected to a receiving system, a set of heat exchangers in heat exchange with the circuit of gas to be cooled, a cooling circuit with a cooling gas cycle, arranged to cool the gas to be cooled by heat exchange with one of the heat exchangers, the cooling circuit comprising at least one cryogenic purifier arranged to purify at least the cooling gas, a conduit for conveying a vaporized gas mixed with impurities to the cooling circuit, the cryogenic purifier comprising a purification bottle, the regeneration circuit being arranged to regenerate the purification bottle. Figure for the abstract: Fig. 1

Description

Title of the invention: Installation for producing a cryogenic fluid

[0001] The field of the present invention is that of a plant for producing a cryogenic fluid, in particular liquefied hydrogen. The present invention also relates to a method for producing a cryogenic fluid, in particular liquefied hydrogen.

[0002] Hydrogen is an energy vector that plays an increasing role in the decarbonization of various sectors, particularly transport and industry. Hydrogen liquefaction makes it possible to store hydrogen and transport it over long distances.

[0003] It is known that the processes for producing a cryogenic fluid such as liquefied hydrogen are divided into two successive stages: 1) pre-cooling and 2) cooling ensuring liquefaction. Pre-cooling can be carried out with a pre-cooling device comprising a pre-cooling fluid cycle circuit (nitrogen or gas mixture), also called a pre-cooling circuit, and at least a first set of heat exchangers arranged in a first cold box so as to exchange heat with the hydrogen circuit to be liquefied.Cooling can be carried out by a cooling device comprising a cooling fluid cycle circuit, also called a cooling circuit, the cooling fluid being in particular hydrogen, helium or a mixture of gases as well as at least a second set of heat exchangers arranged in the first cold box and in a second cold box so as to exchange heat with the hydrogen circuit to be liquefied.

[0004] The liquefaction of hydrogen involves a logistics chain with stages of filling containers (trucks, boats, etc.), storage and transfer of liquefied hydrogen, inevitably leading to losses of hydrogen molecules by vaporization due to the significant heat inputs during these stages. Also, the desire to collect and reliquefy these hydrogen molecules, which are in the form of exhaust gas, is always present in the design of the installations.

[0005] However, the installation of networks for recovering these exhaust gases involves the direct connection of the installation for liquefying hydrogen (which is a pure hydrogen system) with systems such as loading bays, storage bays, trucks, etc. which are potentially polluted and include hydrogen and impurities.

[0006] Furthermore, during the connection / disconnection operations of these systems comprising impurities with the installation for the liquefaction of hydrogen, in particular during maintenance steps, the risks of contamination with air comprising in particular oxygen and nitrogen, exist and can cause safety risks.

[0007] More particularly, in installations for the liquefaction of hydrogen using one or more hydrogen cycle circuits (for example, the coolant cycle circuit), these operations of connecting / disconnecting the impure systems with the installation can lead to an entry of impurities, in particular air or oxygen, into the hydrogen cycle circuits. In operation, these impurities can freeze and accumulate in said circuits, in particular in the second cold box. In the case of oxygen, this accumulation can lead to safety risks in the presence of hydrogen.

[0008] The present invention thus aims to limit, or even prevent, the risk of pollution of the hydrogen cycle circuits of an installation for the production of a cryogenic gas, in particular for the liquefaction of hydrogen, mainly during the connection / disconnection steps with systems comprising impurities.

[0009] The subject of the invention thus relates to an installation for producing a cryogenic fluid, in particular liquefied hydrogen, comprising: - a circuit for gas to be cooled, in particular hydrogen, having an upstream end intended to be connected to a source of gas to be cooled and a downstream end intended to be connected to at least one receiving system arranged to receive the cooled gas, such as cryogenic storage and / or a means of transport, - a set of heat exchangers in thermal exchange with the gas circuit to be cooled, - a cooling circuit with a cooling gas cycle, in particular hydrogen gas, arranged to cool the gas to be cooled from the gas circuit to be cooled by heat exchange with at least one of the heat exchangers, the cooling circuit comprising at least one cryogenic purifier arranged to purify at least the cooling gas, - a conduit for conveying a vaporized gas mixed with impurities to the cooling circuit upstream of the cryogenic purifier so that this vaporized gas mixed with impurities is treated in the cooling circuit by passing through the cryogenic purifier, - The cryogenic purifier comprising at least one purification bottle arranged to retain the impurities mixed with the vaporized gas, and a regeneration circuit for said purification bottle, the regeneration circuit generation being arranged to regenerate the purification bottle.

[0010] According to one aspect of the invention, the conduit for conveying a vaporized gas mixed with impurities is connected by one of its ends to the cooling circuit and by its other end to a source of vaporized gas mixed with impurities.

[0011] Advantageously, the installation according to the invention makes it possible to recycle the vaporized gases, also called "boil-off gas" in English, generated by the connection / disconnection with a source of vaporized gas, in particular an external source of vaporized gas, when heat enters the source of vaporized gas, and to purify them so that they can be used in the cooling circuit.

[0012] According to one aspect of the invention, the conveying conduit comprises two ends, one of its ends being connected to the source of vaporized gas mixed with impurities and its other end being connected to the cooling circuit upstream of the cryogenic purifier in the direction of circulation of the cooling gas.

[0013] According to one aspect of the invention, the vaporized gas comprises hydrogen gas.

[0014] According to one aspect of the invention, the vaporized gas source comprises the system receiver. Vaporized gas is produced, in particular, when cooled and liquefied gas is transferred to the receiver system and vaporized by a heat input into said receiver system.

[0015] According to one aspect of the invention, the source of vaporized gas comprises the source of gas to be cooled. The vaporized gas is notably produced when the gas to be cooled is transferred from the source of gas to be cooled to the cryogenic fluid production facility.

[0016] According to one aspect of the invention, the installation comprises a member for detecting at least one impurity, said detection member being arranged to measure the level of at least one impurity in the source of vaporized gas, in particular in the receiver system.

[0017] According to one aspect of the invention, the installation comprises a conveying valve arranged to control the flow rate of vaporized gas mixed with impurities passing through the conveying conduit as a function at least of the level of impurities measured in the source by the detection member, said conveying valve being arranged on the conveying conduit.

[0018] According to one aspect of the invention, when the level of impurities measured by the detection member in the source of vaporized gas is greater than a predetermined threshold value, the conveying valve is arranged to prevent the passage of the vaporized gas mixed with the impurities into the conveying conduit.

[0019] According to one aspect of the invention, when the level of impurities measured by the detection member in the source of vaporized gas is greater than 2 ppm, preferably su above 1.5 ppm, preferably above 1 ppm, the conveying valve is arranged to prevent the passage of vaporized gas mixed with impurities into the conveying conduit.

[0020] According to one aspect of the invention, the impurity detection member is arranged to measure an oxygen level in the vaporized gas source.

[0021] Thus, the vaporized gas entering the cooling circuit does not generate excessive pollution of said cooling circuit, in particular the cooling circuit does not receive a gas comprising an oxygen level that is too high for the cooling circuit.

[0022] According to one aspect of the invention, the at least one purification bottle comprises a member for retaining at least one impurity, said retaining member being arranged to retain at least one impurity circulating in the purification bottle.

[0023] According to one aspect of the invention, the retention member comprises at least one adsorbent configured to adsorb the impurities mixed with the vaporized gas.

[0024] According to one aspect of the invention, the adsorbent is configured to absorb at least one impurity chosen from oxygen, and / or carbon monoxide, and / or nitrogen, and / or argon.

[0025] According to one aspect of the invention, the cooling circuit comprises at least one analyzer arranged to measure the level of at least one impurity retained on the adsorbent of the purification bottle.

[0026] Indeed, when the adsorbent of the purification bottle is saturated with impurities, the purification bottle can no longer play its role. The presence of the analyzer makes it possible to control the saturation of the adsorbent with impurities and therefore at what point the purification bottle will no longer be able to effectively purify the gas passing through it.

[0027] According to one aspect of the invention, the analyzer is arranged to measure the level of oxygen and / or nitrogen and / or carbon monoxide and / or argon retained on the adsorbent.

[0028] According to one aspect of the invention, the conveying valve is arranged to control the flow rate of vaporized gas mixed with impurities passing through the conveying conduit as a function of the level of impurities retained on the adsorbent.

[0029] According to one aspect of the invention, the conveying valve is arranged to prevent the passage of vaporized gas mixed with impurities into the conveying conduit when the level of impurities on the adsorbent is greater than a predetermined threshold level, in particular a threshold level of 1 ppm.

[0030] In this way, the vaporized gas mixed with impurities does not enter the conveying conduit when the adsorbent is saturated with impurities and the purification bottle cannot treat said gas mixed with impurities.

[0031] According to one aspect of the invention, the conveying valve is arranged to control the flow rate of vaporized gas mixed with impurities in the conveying conduit as a function of the level of oxygen and / or nitrogen and / or carbon monoxide and / or argon retained on the adsorbent.

[0032] According to one aspect of the invention, the conveying valve is arranged to prevent the passage of vaporized gas mixed with impurities into the conveying conduit when the oxygen level on the adsorbent is greater than 30 ppb and / or the nitrogen level on the retention member is greater than 1 ppm.

[0033] Alternatively, the analyzer is arranged to emit an alarm signal depending on the level of impurities on the retention member. In this case, the user can manually stop the passage of the vaporized gas mixed with impurities in the conveying conduit when the level of impurities is higher than the threshold level.

[0034] According to one aspect of the invention, the analyzer is arranged in the purification bottle.

[0035] According to one aspect of the invention, the cooling circuit comprises at least one diverting valve configured to control the flow rate of the cooling gas passing into the purification bottle as a function of the level of impurities measured on the adsorbent.

[0036] According to one aspect of the invention, the diverting valve is arranged to prevent the circulation of the cooling gas in the purification bottle when the level of impurities on the retention member is higher than the threshold level.

[0037] According to one aspect of the invention, the diversion valve is arranged to divert the cooling gas towards a conduit for diverting said cooling gas when the level of impurities on the adsorbent is higher than the threshold level, the diversion conduit being connected by one of its ends to the cooling circuit upstream of the purification bottle and by its other end to the cooling circuit downstream of the purification bottle.

[0038] Alternatively, the cryogenic purifier comprises at least two purification bottles, each purification bottle comprising a member for retaining at least one impurity and a circuit for regenerating said purification bottle.

[0039] In this variant, according to one aspect of the invention, the diversion valve is arranged to divert the cycle gas to another purification bottle whose adsorbent comprises an impurity level lower than the threshold level.

[0040] In this variant, the two purification bottles are identical.

[0041] According to one aspect of the invention, the regeneration circuit is arranged to regenerate the purification bottle as a function of the level of impurities measured on the adsorbent of said purification bottle.

[0042] According to one aspect of the invention, the regeneration circuit comprises a regeneration fluid generation such as a gas selected from nitrogen, hydrogen, helium or a mixture of at least two of these gases or all of these gases.

[0043] According to one aspect of the invention, the pressure of the regeneration fluid is greater than the pressure of the cycle gas.

[0044] According to one aspect of the invention, the regeneration temperature is at least 100°C higher than the retention temperature, in particular the adsorption temperature.

[0045] According to one aspect of the invention, the purification bottle comprises cryogenic valves, making it possible to avoid exchanges between the cycle gas circuit (hydrogen to be liquefied) and the fluid of the regeneration circuit.

[0046] According to one aspect of the invention, the installation comprises a bypass pipe arranged to divert the cooling gas and the vaporized gas treated in the cryogenic purifier towards the gas circuit to be cooled.

[0047] According to one aspect of the invention, the bypass pipe comprises two ends, one of the ends being connected to the cooling circuit downstream of the cryogenic purifier in the direction of circulation of the cycle gas, and the other end being connected to the circuit of gas to be cooled.

[0048] According to one aspect of the invention, the installation comprises a bypass pipe arranged to control the flow rate of treated vaporized gas and possibly the cooling gas passing from the cooling circuit downstream of the cryogenic purifier to the gas circuit to be cooled.

[0049] According to one aspect of the invention, the regeneration circuit is arranged to circulate the regeneration fluid in the purification bottle in a direction opposite to the direction of circulation of the gas circuit to be cooled.

[0050] The present invention also relates to a method for producing a cryogenic fluid, in particular hydrogen, said method using a liquefied gas production plant, said method comprising the following steps: - Supply of a source of gas to be cooled into a circuit of gas to be cooled, - Cooling of the gas to be cooled by heat exchange with at least one cooling gas circulating in a cooling circuit with a cooling gas cycle, - Conveying a vaporized gas mixed with impurities from a source of vaporized gas to the cooling circuit by means of a conduit for conveying said vaporized gas mixed with impurities, said vaporized gas mixed with impurities being brought to the cooling circuit upstream of a cryogenic purifier arranged in the cooling circuit and arranged to purify at least the cycle gas, - Retention of impurities mixed with the vaporized gas by at least one purification bottle of the cryogenic purifier on a body of retention of said impurities, in particular at least one adsorbent, - Regeneration of said purification bottle according to a defined time and / or a defined frequency, and / or the rate of impurities retained in the purification bottle measured by the analyzer.

[0051] According to one aspect of the invention, the defined time and / or the defined frequency is estimated based on an estimate of the duration of use during which the adsorbent is capable of adsorbing at least one impurity.

[0052] According to one aspect of the invention, the method comprises a step of measuring the level of impurities in the source of vaporized gas mixed with impurities, the measuring step being carried out by a member for detecting at least one impurity in the source of vaporized gas.

[0053] According to one aspect of the invention, the method comprises a step of controlling the flow rate of vaporized gas mixed with impurities passing through the conveying conduit by at least one conveying valve as a function of the impurity level measured in the external source of vaporized gas.

[0054] According to one aspect of the invention, when the level of impurities in the source is greater than a predetermined threshold value, the conveying valve closes so as to prevent the passage of vaporized gas mixed with impurities into the conveying conduit.

[0055] According to one aspect of the invention, when the level of impurities in the source is greater than 2 ppm, preferably 1.5 ppm, preferably 1 ppm, the conveying valve closes so as to prevent the passage of the vaporized gas mixed with impurities into the conveying conduit.

[0056] According to one aspect of the invention, the measured impurity is chosen from oxygen and / or nitrogen and / or carbon monoxide and / or argon.

[0057] According to one aspect of the invention, the purification bottle comprises at least one member for retaining at least one impurity, the retention of said impurity being carried out by said retention member.

[0058] According to one aspect of the invention, the retention member is an adsorbent.

[0059] According to one aspect of the invention, the impurities mixed with the vaporized gas are adsorbed by the adsorbent.

[0060] According to one aspect of the invention, the method comprises a step of measuring the level of impurities on the retention member, in particular a step of measuring the level of oxygen and / or nitrogen and / or carbon monoxide and / or argon on the retention member.

[0061] According to one aspect of the invention, this measuring step is carried out by at least one analyzer arranged in the purification bottle.

[0062] According to one aspect of the invention, the method comprises a flow rate control step vaporized gas mixed with impurities in the delivery pipe depending on the level of impurities retained on the retention device.

[0063] According to one aspect of the invention, when the level of impurities retained by the retention member is greater than a threshold level, in particular a threshold level of 1 ppm, the conveying valve closes so as to prevent the passage of the vaporized gas mixed with impurities into the conveying conduit.

[0064] According to one aspect of the invention, the method comprises a step of controlling the flow rate of the cooling gas in the purification bottle as a function of the level of impurities retained on the retention member.

[0065] According to one aspect of the invention, the step of controlling the flow rate of the cooling gas in the purification bottle is carried out by a diverting valve which, in the closed position, prevents the passage of the vaporized gas mixed with impurities into the purification bottle.

[0066] According to one aspect of the invention, when the level of impurities on the adsorbent is higher than the threshold level, the diverting valve prevents the passage of the cooling gas into the purification bottle.

[0067] According to one aspect of the invention, when the level of impurities in the adsorbent is greater than the threshold level, the diversion valve diverts the cooling gas towards a conduit for diverting said cooling gas, the diversion conduit being connected by one of its ends to the cooling circuit upstream of the purification bottle and by its other end to the cooling circuit downstream of the purification bottle.

[0068] Alternatively, when the impurity level of the retention member is higher than the threshold level, the control member diverts the cycle gas to another purification bottle whose impurity level is lower than the threshold level.

[0069] According to one aspect of the invention, the regeneration step takes place when the level of impurities in the retention member is higher than the threshold level.

[0070] According to one aspect of the invention, the threshold rate can vary depending on the impurity.

[0071] In one aspect according to the invention, the cooling circuit comprises at least one compressor, in particular a high pressure HPH2 compressor arranged to compress the cooling gas.

[0072] According to one aspect of the invention, the regeneration comprises the following steps: - isolation of the purification bottle by closing the diversion valve and diverting the cycle gas into the diversion conduit so as to prevent the passage of the vaporized gas to impurities in the cooling circuit, - depressurization of the isolated purification bottle until a regeneration pressure of at least 2 bar is obtained, in particular equal to 30 bar, by venting the gas via a vent, said venting being carried out by opening a vent valve allowing the gas to pass into a vent in the open position, - Heating of the insulated purification bottle by circulating a hot fluid in said bottle, in particular the compressed cycle gas from the cooling circuit or the hydrogen to be cooled from the source of gas to be cooled, the hot fluid circulating in the purification bottle at a flow rate less than or equal to 1% of the flow rate of the cycle gas circulating in the cooling circuit, - Desorption of impurities retained on the adsorbent of the isolated purification bottle, - Repressurization of the isolated purification bottle by closing the vent valve, - Cooling of the insulated bottle by circulation of hydrogen from the cooling circuit after heat exchange with the second set of heat exchangers at a flow rate less than or equal to 1% of the flow rate of the cycle gas in the cooling circuit, - Possibly, opening of the diverter valve to allow the passage of vaporized gas mixed with impurities into the cooling circuit, - Opening of the diverting valve to allow the passage of cycle gas possibly mixed with vaporized gas mixed with impurities into the regenerated and cooled purification bottle.

[0073] According to one aspect of the invention, the regeneration is triggered according to a given frequency over time, for example at least once a month. The frequency is chosen according to the time it takes for the adsorbent to become saturated.

[0074] According to one aspect of the invention, the regeneration is triggered manually by an operator or automatically by configuring the start time of the regeneration.

[0075] Thus the operator can anticipate and choose the regeneration period during a period when the installation is lightly loaded.

[0076] According to one aspect of the invention, regeneration is triggered automatically when the alarm of the oxygen and nitrogen detection thresholds is triggered.

[0077] According to one aspect of the invention, regeneration is triggered automatically in the event of an increase in the pressure drop (depressurization) of the retention member and / or the filters at the inlet of the turbines of the gas circuit to be cooled.

[0078] According to one aspect of the invention, the regeneration is triggered automatically after a hot restart of the installation.

[0079] Thus, regeneration allows the impurities absorbed by the retention member at cryogenic temperature not to be released into the gas circuit to be cooled when the temperature of the installation rises during restart.

[0080] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0081] [Fig-1] [Fig.l] is a schematic representation of a production facility liquefied hydrogen according to the invention;

[0082] [Fig.2] [Fig.2] is a schematic representation of a production facility liquefied hydrogen according to another embodiment according to the invention;

[0083] [Fig.3] [Fig.3] is a schematic representation of a cryogenic purifier according to [Fig.l];

[0084] [Fig.4] [Fig.4] is a block representation of the production process of liquefied hydrogen according to the invention

[0085] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0086] Figures 1 and 2 schematically show a liquefied hydrogen production plant 1, divided into two successive parts: 1) pre-cooling and 2) cooling ensuring liquefaction. Pre-cooling is carried out with a pre-cooling device 8 which uses a nitrogen cycle or a mixture composed of a mixed refrigerant of hydrocarbon type of crude formula CnHm, or a mixture of mixed refrigerant and nitrogen and / or argon in a first cold box 3. Cooling is carried out by a cooling device 9 which comprises a cooling circuit 59 with a hydrogen cycle circulating in the first cold box 3 and in a second cold box 4. These pre-cooling and cooling devices use heat exchangers 5, 6 and 7 to carry out the pre-cooling and cooling of the hydrogen circuit to be cooled 2.

[0087] Installation 1, the first cold box 3 includes two heat exchangers 5 and 6, a purification stage 10, a catalytic device 20 and a cryogenic purifier 50. The second cold box 4, for its part, includes a heat exchanger 7, a final expansion organ 23 such as a Joule-Thompson valve, as well as a cooling cycle turbine.

[0088] The installation 1 comprises a circuit of gas to be cooled 2 in which hydrogen to be cooled circulates, and comprises an upstream end 21 intended to be connected to a source of hydrogen to be cooled. The circuit of gas to be cooled 2 comprises a downstream end 22 which is connected to a receiving system 40 such as cryogenic storage. Alternatively, the downstream end 22 is connected to a means of transport 40 of the liquefied gas.

[0089] The cooling circuit 59 comprises a high pressure compressor (HPH2) 29 arranged to compress at least the cycle gas of said cooling circuit. The cooling circuit 59 also comprises a cryogenic purifier 50 arranged to purify at least said cycle hydrogen.

[0090] The installation comprises a conveying conduit 54 having two ends, one of its ends is connected to the source 56 of vaporized hydrogen mixed with impurities and its other end is connected to the cooling circuit 59 upstream of the cryogenic purifier 50 in the direction of circulation of the hydrogen cycle 59. In this way, the vaporized gas mixed with impurities is treated in the cooling circuit 59 by passing through the cryogenic purifier 50. In this way, the installation 1 makes it possible to recycle vaporized hydrogen, also called "boil-off gas" in English, generated by the connection / disconnection with a source of vaporized gas, here vaporized hydrogen, mixed with impurities 56 when heat enters this source of vaporized hydrogen 56 and to purify this vaporized hydrogen by retaining these impurities. The vaporized hydrogen can then be used in the cooling circuit 59.

[0091] The installation 1 comprises a conveying valve 55 on the conveying conduit 54 to control the flow rate of vaporized hydrogen mixed with impurities circulating in said conveying conduit 54. When the level of impurities measured by the detection member 60 is greater than a predetermined threshold value, the conveying valve 55 prevents the passage of the vaporized hydrogen mixed with impurities into the conveying conduit 54. More specifically, when the measured oxygen level is greater than 1 ppm, the conveying valve 55 prevents the passage of the vaporized hydrogen mixed with impurities into the conveying conduit 54. Thus, the vaporized hydrogen which enters the cooling circuit does not generate excessive pollution of the cooling circuit.

[0092] As previously indicated, the vaporized gas comprising impurities is supplied to the cryogenic purifier through the conveying conduit 54. The cryogenic purifier 50 comprises a purification bottle 51 arranged to retain the impurities mixed with the vaporized hydrogen. More precisely, the puri 51 comprises a retention member, here an adsorbent, arranged to retain at least one impurity circulating in said bottle. The adsorbent is arranged to retain at least one impurity chosen from carbon monoxide and / or nitrogen and / or oxygen and / or argon. The cryogenic purifier 50 also comprises a regeneration circuit for the purification bottle, which allows it to be regenerated, that is to say to desorb the impurities retained by the adsorbent, in particular when the latter is saturated with impurities. Indeed, when the retention member of the purification bottle 51 is saturated with impurities, the purification bottle 51 can no longer play its role. The regeneration circuit will be described in more detail in [Fig. 3].

[0093] In the embodiment shown in [Fig. 1], the cooling circuit 59 comprises a diverting valve 52 which controls the cycle hydrogen flow rate of the cooling circuit circulating in the purification bottle 51 as a function of the impurity level measured on the adsorbent. This diverting valve 52 prevents the circulation of the hydrogen cycle 59 in the purification bottle 51 when the impurity level on the retention member is greater than a threshold level. This diverting valve 52 allows a diversion of the cycle hydrogen 59 towards a diverting conduit 53. The diverting conduit 53 is connected by one of its ends to the cooling circuit 59 upstream of the purification bottle 51 and by its other end to the cooling circuit 59 downstream of the purification bottle 51 in the direction of circulation of the cycle hydrogen.In this way, even when the purification bottle is being regenerated, the cooling circuit can operate in a closed loop and there is no need to pause the installation.

[0094] The purification bottle 51 here comprises an analyzer 61 present on the adsorbent in order to measure the level of impurities, in particular oxygen and / or nitrogen, retained on said adsorbent.

[0095] The conveying valve 55 described above is also arranged to control the flow rate of vaporized hydrogen mixed with impurities in the conveying conduit 54 as a function of the level of impurities retained on the adsorbent, in particular the level of oxygen and / or nitrogen and / or carbon monoxide, and / or argon, measured by the analyzer 61. For example, the conveying valve 55 is arranged to prevent the passage of vaporized hydrogen mixed with impurities in the conveying conduit 54 when the level of oxygen on the retention member is greater than 30 ppb and / or the level of nitrogen on the retention member is greater than 1 ppm. In this way, the vaporized hydrogen mixed with the impurities does not enter the conveying conduit 54 when the adsorbent is saturated with oxygen and the purification bottle 51 cannot treat this hydrogen mixed with the impurities.

[0096] In a variant not shown here, the conveying valve 55 is arranged to control the flow rate of vaporized hydrogen mixed with impurities in the conveying conduit 54 as a function of time. Indeed, it is possible to program the regeneration of the purification bottle as a function of a predefined frequency or a time of use of said bottle. This is particularly useful when the time to reach saturation of the adsorbent can be estimated by a user.

[0097] It emits an alarm signal depending on the level of impurities on the retention member. In this case, the user manually stops the passage of vaporized hydrogen mixed with impurities in the conveying conduit 54 when the level of impurities is higher than a threshold level.

[0098] The purification bottle 51 comprises cryogenic valves, which prevent exchanges between the hydrogen cycle circuit 59 and the hot hydrogen.

[0099] In the embodiment described in [Fig.2], the cryogenic purifier 50 comprises two purification bottles 51, each purification bottle 51 comprises an impurity retention member, here an adsorbent, and a regeneration circuit for said purification bottle 51. In this variant, when one of the two purification bottles is saturated with impurities, that is to say the adsorbent can no longer adsorb impurities, the diversion valve 52 diverts the hydrogen cycle 59 to the other purification bottle 51 whose adsorbent has an impurity level below the threshold level. In this way, the cycle hydrogen of the cooling circuit 59, and possibly the vaporized hydrogen mixed with impurities coming from the source 56 of vaporized hydrogen can continue to be treated by the cryogenic purifier 51 during the regeneration of the purification bottle which had reached saturation.When two purification bottles 51 are present in the cryogenic purifier 50 as shown in [Fig.2], each purification bottle 51 comprises its retention member (adsorbent) and possibly its analyzer 61.

[0100] In these two embodiments, the installation 1 comprises a bypass pipe 57 which diverts the hydrogen cycle 59 and the vaporized hydrogen treated in the cryogenic purifier 50 towards the hydrogen circuit to be cooled 2. This bypass pipe 57 comprises two ends, one of the ends is connected to the cooling circuit downstream of the cryogenic purifier 50 in the direction of circulation of the hydrogen cycle 59. The other end is connected to the hydrogen circuit to be cooled 2.

[0101] [Fig. 3] represents a cryogenic purifier according to the embodiment of [Fig. 1]. In [Fig. 3], the lines shown in bold are the circuit portions in which a gas circulates during the regeneration of the purification bottle, while the other lines are the circuit portions in which a gas circulates during the adsorption of at least one impurity by the adsorbent of the purification bottle. The cryogenic purifier here comprises a purification bottle 51 and an analyzer 61 arranged in the bottle. The analyzer 61 is arranged to measure the level of impurity in the purification bottle, and more precisely the level of impurities retained on the adsorbent in the purification bottle. The cryogenic purifier comprises a regeneration circuit 62. The regeneration circuit 62 comprises a hot and compressed hydrogen gas coming from the outlet of the compressor 29 of the cooling circuit or coming from the upstream end 21 of the hydrogen circuit to be cooled 2. The hydrogen circulating in the regeneration circuit has a pressure higher than the pressure of the hydrogen cycle 59 and its temperature is at least 100°C higher than the retention temperature of the adsorbent which is adsorption.In addition, it allows the hot hydrogen to circulate in the opposite direction in the purification bottle 51, relative to the direction of circulation of the circuit of the hydrogen to be cooled 2. Its pressure is greater than or equal to 2 bar, in particular equal to 30 bar.

[0102] The regeneration circuit 62 comprises at least one vent valve 63 allowing the passage of gas into a vent in the open position and therefore allowing the depressurization of the purification bottle during the regeneration thereof.

[0103] Installation 1 can be used in a cryogenic hydrogen production process, according to the following steps visible in [Fig.4]: - step 100: supply of the hydrogen source to be cooled into the hydrogen circuit to be cooled 2, - step 200: cooling of the hydrogen to be cooled 2 by heat exchange with the hydrogen of the cycle present in a cooling circuit 59, - step 300: conveying the vaporized hydrogen mixed with impurities from the vaporized hydrogen source 56 to the cooling circuit 59 by means of the conveying conduit 54 which is brought to the cooling circuit upstream of the cryogenic purifier 50 arranged in the cooling circuit and arranged to purify at least the hydrogen cycle 59, - step 400: retention of impurities mixed with hydrogen vaporized by a purification bottle 51 of the cryogenic purifier 50, - step 500: regeneration of the purification bottle 51 as a function of a defined time and / or the level of impurities retained in the purification bottle 51, - step 600: routing of cycle hydrogen purified by the cryogenic purifier (cycle hydrogen mixed with vaporized hydrogen whose impurities have been retained by the cryogenic purifier) ​​into the circuit of hydrogen to be cooled 2 through bypass line 57 via a bypass valve.

[0104] Step 500 of the method comprises the following sub-steps (not visible in the figures): 1. isolation of the purification bottle by closing the diversion valve and diverting the cycle gas into the diversion pipe to prevent the passage of vaporized gas to impurities in the cooling circuit, 2. depressurization of the isolated purification bottle until a regeneration pressure of at least 2 bar is obtained, in particular equal to 30 bar, by venting the gas via a vent, said venting being carried out by opening a vent valve allowing the gas to pass into a vent in the open position, 3. Heating the insulated purification bottle by circulating a hot fluid in said bottle, in particular the compressed cycle gas from the cooling circuit or the hydrogen to be cooled from the source of gas to be cooled, the hot fluid circulating in the purification bottle at a flow rate less than or equal to 1% of the flow rate of the cycle gas circulating in the cooling circuit, 4. Desorption of impurities retained on the adsorbent of the isolated purification bottle, 5. Repressurization of the isolated purification bottle by closing the vent valve, 6. Cooling of the insulated bottle by circulation of hydrogen from the cooling circuit after heat exchange with the second set of heat exchangers at a flow rate less than or equal to 1% of the flow rate of the cycle gas in the cooling circuit, 7. Optionally, open the diverter valve to allow the passage of vaporized gas mixed with impurities into the cooling circuit. 8. Opening of the diverting valve to allow the passage of cycle gas possibly mixed with vaporized gas mixed with impurities into the regenerated and cooled purification bottle.

[0105] Step 300 of the method comprises the following sub-steps: - step 301: measurement of the level of impurities, such as oxygen and / or nitrogen and / or carbon monoxide and / or argon in the source of vaporized hydrogen mixed with impurities 56, carried out by the impurity detection member 60 located in the source of vaporized hydrogen 56, - step 302: control of the flow rate of vaporized gas mixed with impurities passing through the conveying conduit by at least one conveying valve as a function of the impurity level measured in the external source of vaporized gas: • if the measurement of the impurity level in the source of vaporized hydrogen is greater than a predetermined threshold value, in particular 1 ppm, represented by the arrow “Y” in FIG. 4, then the triggering of step 303 takes place, namely closing of the conveying valve 55 arranged on the conveying conduit 54 of the vaporized gas mixed with the impurities so as to avoid the circulation of too high an impurity level in the cooling circuit, • otherwise return to step 301, represented by the arrow “N”,

[0106] Thus, the method comprises this step 300 of controlling the flow rate of vaporized hydrogen mixed with impurities passing into the conveying conduit 54 via the conveying valve 55 as a function of the impurity level measured in the source of vaporized gas 56.

[0107] Step 400 of the method comprises the following sub-steps: - step 401: measurement of the level of impurities, such as oxygen and / or nitrogen and / or carbon monoxide and / or argon on the retention member (here an adsorbent) using the analyzer 61 of the purification bottle 51, - step 402: • If the measurement of the rate of impurities retained by the retention member is greater than the threshold rate represented by the arrow “Y” in Figure 4, then step 303 is triggered. Otherwise, arrow represented by the arrow “N” in Figure 4, return to step 401. • If the measurement of the level of impurities retained by the adsorbent is higher than the threshold level represented by the arrow “Y” in Figure 4, then the triggering of step 500 is carried out by the diversion valve 52 which, in the closed position, prevents the passage of vaporized hydrogen mixed with the impurities into the purification bottle 51. Otherwise, represented by the arrow “N” in Figure 4, return to step 401.

[0108] Thus, step 400 allows the flow rate of vaporized hydrogen mixed with impurities to be controlled in the conveying conduit 54 as a function of the level of impurities retained on the retention member. This step 400 also allows the flow rate of the hydrogen cycle 59 to be controlled in the purification bottle 51 as a function of the level of impurities retained on the adsorbent.

[0109] Alternatively, the method is used in an installation 1 which comprises two 51 purification bottles in the 50 cryogenic purifier.

[0110] The regeneration can be triggered according to a given frequency in time, for example at least once a month. It can also be triggered manually by an operator or automatically by configuring the start time of the regeneration. Thus the operator can anticipate and choose the regeneration period during a period during which the installation 1 is lightly loaded. Other triggering methods are possible. For example, the regeneration is triggered automatically when the alarm of the oxygen and nitrogen detection thresholds are triggered. It can also be triggered in the event of an increase in the pressure drop, that is to say depressurization of the filters at the inlet of the turbines of the hydrogen circuit to be cooled 2. Finally, it can also be triggered automatically after a hot restart of the installation 1.Thus, regeneration allows the impurities absorbed by the retention device at cryogenic temperature not to be released into the hydrogen circuit to be cooled 2 when the temperature of the installation 1 rises during restart.

Claims

Claims

1. Installation (1) for producing a cryogenic fluid, in particular liquefied hydrogen, comprising: - a circuit of gas to be cooled (2), in particular hydrogen, having an upstream end (21) intended to be connected to a source of gas to be cooled and a downstream end (22) intended to be connected to at least one receiving system (40) arranged to receive the cooled gas, such as cryogenic storage and / or a means of transport, - a set of heat exchangers (5, 6, 7) in heat exchange with the circuit of gas to be cooled (1), - a cooling circuit (59) with a cooling gas cycle, in particular hydrogen gas, arranged to cool the gas to be cooled from the circuit of gas to be cooled by heat exchange with at least one of the heat exchangers (5, 6, 7), the cooling circuit comprising at least one cryogenic purifier (50) arranged to purify at least the cooling gas,- a conduit (54) for conveying a vaporized gas mixed with impurities, said vaporized gas comprising in particular hydrogen, to the cooling circuit (59) upstream of the cryogenic purifier (50) so that this vaporized gas mixed with impurities is treated in the cooling circuit by passing through the cryogenic purifier (50), - The cryogenic purifier (50) comprising at least one purification bottle (51) arranged to retain the impurities mixed with the vaporized gas, and a regeneration circuit for said purification bottle, the regeneration circuit (62) being arranged to regenerate the purification bottle (51).,

2. Installation (1) according to claim 1, characterized in that the conveying conduit (54) of a vaporized gas mixed with impurities is connected by one of its ends to a source of vaporized gas mixed with impurities (56) and by its other end to the cooling circuit (59) upstream of the cryogenic purifier (50) in the direction of circulation of the cooling gas.

3. Installation (1) according to the preceding claim, characterized in that said installation comprises a detection member (50) of at least one impurity, said detection member (50) being arranged to measure the level of at least one impurity in the source (56) of vaporized gas.

4. Installation (1) according to the preceding claim, characterized in that the purification bottle (51) comprises a retention member (60) for at least one impurity, in particular at least one adsorbent, said retention member (60) being arranged to retain at least one impurity circulating in the purification bottle (51), and the cooling circuit (59) comprises at least one analyzer (61) arranged to measure the level of at least one impurity retained on the retention member (60) of the purification bottle (51).

5. Installation (1) according to the preceding claim, characterized in that it comprises a conveying valve (55) arranged to control the flow rate of vaporized gas mixed with impurities passing through the conveying conduit (54) as a function at least of the level of impurities measured in the source of vaporized gas (56) by the detection member (50) and / or of the level of impurities retained on the retention member (60), said conveying valve (55) being arranged on the conveying conduit (54).

6. Installation (1) according to one of the preceding claims, characterized in that said installation (1) comprises a bypass pipe (57) arranged to divert the cooling gas and the vaporized gas treated in the cryogenic purifier (50) towards the gas circuit to be cooled (2).

7. Method for producing a cryogenic fluid (700), in particular hydrogen, said method using a liquefied gas production plant, said method comprising the following steps: - Supply (100) of a source of gas to be cooled into a circuit of gas to be cooled, - Cooling (200) of the gas to be cooled by heat exchange with at least one cooling gas circulating in a cooling circuit with a cooling gas cycle, - Conveying (300) of a vaporized gas mixed with impurities from a source of vaporized gas to the cooling circuit by means of a conduit for conveying said vaporized gas mixed with impurities, said vaporized gas mixed with impurities being brought to the cooling circuit upstream of a cryogenic purifier arranged in the cooling circuit and arranged to purify at least the cycle gas, - Retention (400) of the impurities mixed with the vaporized gas by at least one purification bottle of the cryogenic purifier on a member for retaining said impurities, in particular at least one adsorbent, - Regeneration (500) of said purification bottle as a function of a defined time and / or a defined frequency, and / or the level of impurities retained in the purification bottle measured by the analyzer.

8. Method (700) according to the preceding claim, characterized in that it comprises a step of measuring the level of impurities in the source of vaporized gas mixed with impurities (301), the measuring step being carried out by a member for detecting at least one impurity in the source of vaporized gas.

9. Method (700) according to the preceding claim, characterized in that the method comprises a step of controlling the flow rate of vaporized gas mixed with impurities passing through the conveying conduit by at least one conveying valve as a function of the impurity level measured in the external source of vaporized gas (302), and when the impurity level in the source is greater than a predetermined threshold value, the valve closes (303) so as to prevent the passage of the vaporized gas mixed with impurities into the conveying conduit.

10. Method (700) according to one of claims 7 to 9, characterized in that the method comprises a step of measuring the level of impurities on the retention member (401), in particular a step of measuring the level of oxygen and / or nitrogen and / or carbon monoxide and / or argon on the retention member, and a step of controlling the flow rate of the cooling gas in the purification bottle as a function of the level of impurities retained on the retention member (402), said step of controlling the flow rate of the cooling gas in the purification bottle This is achieved by a diverting valve which, in the closed position, prevents the passage of vaporized gas mixed with impurities into the purification bottle, and when the level of impurities on the retention member is higher than the threshold level, the diverting valve prevents the passage of cooling gas into the purification bottle (500).

Images