Facility for storing and / or transporting liquefied gas

Abstract

The invention relates to a facility for storing and / or transporting and / or transferring a liquefied gas, preferably liquefied hydrogen, the facility comprising a sealed and thermally insulating container (1) comprising: a leak-tight outer wall, a secondary leak-tight membrane (4) located at a distance from an inner side of the outer wall and defining a secondary space between the outer wall and the secondary leak-tight membrane, the facility comprising an inerting device (11) connected to the secondary space in order to maintain the secondary gaseous phase in the form of a gaseous composition made up of one or more primary chemical species, and optionally one or more secondary chemical species, wherein the partial pressure of the or each primary chemical species is lower than the triple point of the primary chemical species, and wherein the partial pressure of the or each residual chemical species is lower than 0.14 kPa.

Description

Installation for the storage and / or transport of liquefied gas

[0001] The invention relates to the field of installations for the storage and / or transport of low-temperature liquefied gas. In particular, the invention relates to the field of installations comprising a sealed and thermally insulating tank for the storage and / or transport of low-temperature liquefied gas, such as a tank for the transport of liquid hydrogen, which is at approximately -253°C at atmospheric pressure but can also be stored under higher pressure. These installations can be installed at a fixed position or on any land or floating vehicle. Technological background

[0002] Installations comprising a membrane tank for the storage and / or transport of liquefied natural gas at atmospheric pressure are known. The tank comprises, for example, a tank wall having successively, in the direction of the thickness, from the inside to the outside of the tank, a primary sealing membrane intended to be in contact with the liquefied natural gas, a primary thermally insulating barrier, a secondary sealing membrane, a secondary thermally insulating barrier and a supporting structure defining the general shape of the tank.

[0003] The primary and secondary waterproofing membranes delimit between them a primary space which contains the primary insulating barrier and which is generally filled with nitrogen to avoid the risk of ignition in the event of a leak.

[0004] Nitrogen is also supplied to the secondary space defined by the spacing between the secondary waterproofing membrane and the supporting structure.

[0005] The sealing membranes of such a tank can leak, causing liquefied natural gas to pass from inside the tank to the primary and / or secondary thermally insulating barriers. However, when low-temperature liquefied gas invades the primary space, the primary and secondary spaces are cooled very quickly.

[0006] Document WO2015078972A1 defines a sampling method for gas composition analysis in the case of an insulation atmosphere of less than 10 kPa and preferably less than 1 kPa.

[0007] Document FR2502289A1 indicates a regulation of the pressure of the secondary space to remain higher than or equal to that of the LNG contained in the tank (i.e. approximately 100 kPa, or even 95 kPa). The LNG contained in the tank is at atmospheric pressure, which implies a continuous supply of condensable gas as soon as a cold condensation point appears. Leak detection is done by monitoring the quantities of gas injected. Summary

[0008] Certain aspects of the invention are based on the observation that, if the temperature of the primary or secondary space were to fall below the liquefaction point of nitrogen, namely -196°C at atmospheric pressure, the liquefaction of nitrogen could pose a major problem because the liquid nitrogen could flow by gravity, in particular in the secondary space onto the internal surface of the supporting structure. However, the supporting structure is generally not designed to reach such a low temperature and would risk unacceptable embrittlement.

[0009] Thus, there is a need to find a solution to avoid the formation of cold liquid in the primary or secondary space of an installation for the storage and / or transport of low-temperature liquefied gas such as hydrogen.

[0010] One idea behind the invention is to provide a facility that solves the above-mentioned problems.

[0011] Another idea underlying the invention is to use essentially carbon dioxide (CO2) as an inert gas in the secondary space of a sealed and thermally insulating tank containing liquefied gas, in particular when said tank contains liquid hydrogen.

[0012] Another idea underlying the invention is to carry out a process for inerting the secondary space of such a sealed and thermally insulating tank.

[0013] Another idea underlying the invention is to provide a method for detecting a leak in such a sealed and thermally insulating tank.

[0014] To this end, the invention proposes an installation for the storage and / or transport and / or transfer of a liquefied gas, preferably liquefied hydrogen, said installation comprising a sealed and thermally insulating container, the sealed and thermally insulating container comprising: a sealed outer wall, a secondary sealed membrane located at a distance from an inner side of the outer wall and defining a secondary space between the outer wall and the secondary sealed membrane, a secondary thermally insulating barrier and a secondary gas phase arranged in the secondary space, the secondary space being delimited by the outer wall, the secondary sealed membrane being carried by the secondary thermally insulating barrier, a primary sealed membrane located at a distance from an inner side of the secondary sealed membrane and defining a primary space between the secondary sealed membrane and the primary sealed membrane,the primary sealed membrane being intended to be in contact with the liquefied gas, preferably the liquefied hydrogen contained in the container,a primary thermally insulating barrier arranged in the primary space, the primary sealed membrane being carried by the primary thermally insulating barrier,said installation comprising an inerting device connected to the secondary space to maintain the secondary gas phase in the form of a gaseous composition consisting of one or more main chemical species, and possibly one or more residual chemical species,the inerting device being configured to maintain the secondary gas phase at an absolute pressure greater than 10 kPa, in which the partial pressure of the or each main chemical species is lower than the triple point of said main chemical species,and in which the partial pressure of the or each residual chemical species is lower than 0.14 kPa.,

[0015] According to a first object, the invention provides an installation for the storage and / or transport of a liquefied gas, preferably liquefied hydrogen, the sealed and thermally insulating container being a sealed and thermally insulating tank, the sealed and thermally insulating tank comprising:an external wall being a sealed supporting structure,a secondary sealed membrane located at a distance from an inner side of the supporting structure and defining a secondary space between the supporting structure and the secondary sealed membrane,a secondary thermally insulating barrier and a secondary gas phase arranged in the secondary space, the secondary thermally insulating barrier being anchored to the supporting structure, the secondary sealed membrane being carried by the secondary thermally insulating barrier,a primary sealed membrane located at a distance from an inner side of the secondary sealed membrane and defining a primary space between the secondary sealed membrane and the primary sealed membrane, the primary sealed membrane being intended to be in contact with a liquefied gas, preferably liquefied hydrogen contained in the tank, a primary thermally insulating barrier arranged in the primary space, the primary sealed membrane being carried by the primary thermally insulating barrier, said installation comprising an inerting device connected to the secondary space to maintain the secondary gaseous phase in the form of a gaseous composition consisting of one or more main chemical species, and possibly one or more residual chemical species, the inerting device being configured to maintain the secondary gaseous phase at an absolute pressure greater than 10 kPa,wherein the partial pressure of the or each principal chemical species is less than the triple point of said principal chemical species, and wherein the partial pressure of the or each residual chemical species is less than 0.14 kPa.,

[0016] Thanks to these characteristics, the inventors have discovered that using such a gaseous composition in the secondary gaseous phase makes it possible, in the event of a liquid hydrogen leak, to avoid or greatly limit the formation of cold liquid in the secondary space. Indeed, in response to a temperature drop at the secondary membrane, the main chemical species initially in the gaseous phase can condense into the solid phase, in the form of a more or less porous solid, for example in the form of snow or ice cubes, without passing through the liquid state. In addition, such a solid phase tends to adhere to the location where it forms, for example to the secondary membrane, and does not flow into the secondary space. The risk of reaching the supporting structure and / or creating a thermal bridge through the secondary space is therefore greatly reduced.

[0017] The total pressure of the secondary gas phase can be equal to atmospheric pressure or a higher or lower pressure, within the limits imposed by the mechanical strength of the waterproof membranes. The threshold of 0.14 kPa, which is the triple point of oxygen, ensures that residual oxygen, if present, cannot condense in the liquid phase, thus reducing hazards inherent to liquid oxygen, such as corrosion, oxidation, combustion or explosion.

[0018] Thanks to these characteristics, the risk of damage to the supporting structure is therefore significantly reduced.

[0019] Additionally, when a liquid hydrogen leak occurs in the primary space, the main chemical species can change from gaseous to solid state upon contact with the secondary membrane. This change of state results in a decrease in pressure because the main chemical species in the solid state are much denser than in the gaseous state. This phenomenon can be used to detect leaks.

[0020] According to embodiments, such an installation for the storage and / or transport of liquefied hydrogen may comprise one or more of the following characteristics.

[0021] According to embodiments, the inerting device is configured to maintain the secondary gas phase at an absolute pressure strictly less than 95 kPa.

[0022] This specific range of absolute pressure of the secondary gas phase makes it possible to:- maintain the gaseous composition in the gaseous state while retaining turbulent to laminar flow properties so as not to increase the resistance to the free circulation of the gaseous composition in the insulation space which would be induced by the transition to transient flow regimes with the molecular flow, and- establish a negative relative pressure in the secondary insulation space compared to atmospheric pressure in order to allow the establishment of a detection system concerning the tightness of the external tight wall by monitoring the rise in pressure beyond a criterion. This criterion could be a maximum threshold pressure not to be exceeded.A person skilled in the art may define this criterion according to the level of detection of the seal that he wishes to implement, for example based on the time derivative of the pressure P in the secondary insulation space, namely ΔP / Δt, where ΔP represents a variation in the pressure in the secondary space during a time step Δt, the duration of which is at least 30 min and cumulative up to a sliding duration of up to 48 h or more. Preferably, the criterion should take into account the degassing of the materials present in the secondary space (for example reinforced polyurethane foam) and / or an increase in the O2 concentration, as well as the influence of variations in external temperatures associated with day / night cycles and / or meteorology on the average temperature of the secondary insulation space and consequently on the pressure P in the secondary insulation space.

[0023] According to embodiments, the gaseous composition comprises at least one main chemical species selected from the group consisting of: nitrogen, carbon dioxide and argon.

[0024] According to embodiments, said or each main chemical species is selected from the group consisting of: nitrogen, carbon dioxide and argon.

[0025] The triple point of nitrogen is 12.5 kPa at 64K. The triple point of carbon dioxide is 519 kPa at 217K. The triple point of argon is 68.7 kPa at 83.75K.

[0026] The primary thermally insulating barrier must ensure that the operating temperature of the secondary membrane remains above the condensation point of the main chemical species(s) at the operating pressure. In particular, if the main chemical species is carbon dioxide, this condensation point is close to -80°C for an operating pressure close to atmospheric pressure. For example, the primary thermally insulating barrier may be designed so that the operating temperature of the secondary membrane is normally close to -50°C.

[0027] According to one embodiment, the main chemical species comprises carbon dioxide, wherein carbon dioxide constitutes at least 33% by volume of the secondary gas phase, preferably at least 89% by volume of the secondary gas phase, even more preferably at least 99.4% by volume of the secondary gas phase. For example, carbon dioxide constitutes 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% by volume of the secondary gas phase.

[0028] Thus, the greater the percentage of carbon dioxide by volume in the secondary gas phase, the greater the risk of condensation in the liquid phase of other gases present in the secondary gas phase in response to a decrease in temperature.

[0029] According to one embodiment, the main chemical species comprises argon, whereby argon may constitute at least 50% by volume of the secondary gas phase, preferably at least 99% by volume of the secondary gas phase. That is to say that argon constitutes, for example, at least 60%, 70%, 80%, 90%, 95% by volume of the secondary gas phase. In all cases, the partial pressure of argon in the secondary gas phase is lower than its triple point, i.e. 68.7 kPa.

[0030] According to one embodiment, the main chemical species comprises dinitrogen, the partial pressure of dinitrogen being lower than its triple point, i.e. 12.5 kPa.

[0031] According to one embodiment, the inerting device includes at least one gas source, the gas source comprising a gas reservoir filled with a said main species or a gas generator capable of generating a said main species.

[0032] According to one embodiment, the gas source is a nitrogen source.

[0033] According to one embodiment, the gas source is an argon source.

[0034] According to one embodiment, the gas source is a carbon dioxide source.

[0035] According to one embodiment, the carbon dioxide source comprises a carbon dioxide generator capable of generating carbon dioxide from atmospheric air and a hydrocarbon source, or preferably a pressurized carbon dioxide tank.

[0036] According to one embodiment, the inerting device includes a first gas source, the first gas source comprising a gas reservoir filled with a first said main species or a gas generator capable of generating a first said main species, and a second gas source, the second gas source comprising a gas reservoir filled with a second said main species or a gas generator capable of generating a second said main species.

[0037] According to one embodiment, the first gas source is the carbon dioxide source and the second gas source is the nitrogen source.

[0038] According to one embodiment, the first gas source is the carbon dioxide source and the second gas source is the argon source.

[0039] According to one embodiment, the first gas source is the nitrogen source and the second gas source is the argon source.

[0040] According to one embodiment, the primary space contains a primary gas phase having a pressure lower than the pressure of the secondary gas phase.

[0041] According to one embodiment, the primary space contains a primary gas phase having an absolute pressure of less than 1 Pa. By means of such evacuation of the primary space, very good thermal insulation properties can be obtained.

[0042] According to one embodiment, the installation for the storage and / or transport of liquefied hydrogen further comprises a pressure sensor capable of detecting a pressure in the secondary space and an alert device, the alert device being capable of generating an alert in response to detection by the pressure sensor that the pressure of the secondary gas phase is lower than a pressure threshold.

[0043] Thanks to these characteristics, it is possible to detect a drop in pressure in the secondary space which could be caused by a leak of liquid hydrogen.

[0044] According to one embodiment, the primary thermally insulating barrier comprises a plurality of support pillars extending along a direction of the thickness of the primary thermally insulating barrier in order to maintain a distance between the secondary waterproof membrane and the primary waterproof membrane. Thanks to these characteristics, it is possible to firmly support the primary waterproof membrane to create a high vacuum in the primary space without risking rupture of the primary waterproof membrane.

[0045] The secondary waterproof membrane can be made in various ways. According to one embodiment, the secondary membrane has a plurality of secondary corrugations and flat portions located between the secondary corrugations, the flat portions resting on the secondary thermally insulating barrier.

[0046] According to one embodiment, the secondary membrane has a first series of parallel undulations and a second series of undulations perpendicular to the first series of undulations.

[0047] According to one embodiment, the secondary corrugations protrude on the inner side of the secondary waterproof membrane.

[0048] The secondary thermally insulating barrier can be made in different ways. According to one embodiment, the secondary thermally insulating barrier comprises a plurality of juxtaposed insulating panels, the insulating panels carrying the secondary waterproof membrane.

[0049] According to one embodiment, the insulating panels are self-supporting, i.e. the insulating panels hold the vacuum. According to one embodiment, an insulating panel comprises a plywood box containing insulating material, for example a polyurethane (PU) foam, optionally reinforced with fibers.

[0050] According to one embodiment, the installation further comprises: at least one supply line connected to the gas source and opening into the secondary space, and at least one discharge line opening into the secondary space. For example, the supply line and / or the discharge line passes through the supporting structure to open into the secondary space. A vacuum pump may be connected to the discharge line temporarily for an initial purging phase, for example by a flexible connector, then disconnected.

[0051] According to one embodiment, the installation for the storage and / or transport of a liquefied gas, preferably liquefied hydrogen, further comprises a measuring device capable of measuring: a quantity of the or each main chemical species injected into the secondary gas phase by the at least one supply line, a quantity of gas extracted from the secondary space by the at least one discharge line, and capable of issuing an alert in response to the detection that a difference between the quantity of the or each main chemical species injected and the quantity of gas extracted exceeds a positive quantity threshold.

[0052] According to embodiments, the tank may have a general spherical, cylindrical, polyhedral or prismatic shape.

[0053] According to a second object, the invention provides a method for operating an installation as described above, comprising: an injection step in which the or each main chemical species is injected in the gas phase until the secondary gas phase is at an absolute pressure greater than 10 kPa, in which the partial pressure of the or each main chemical species is lower than the triple point of said main chemical species, and in which the partial pressure of the or each residual chemical species is lower than 0.14 kPa.

[0054] According to one embodiment, the injection step further comprises the injection of the main chemical species(s) at an absolute pressure strictly less than 95 kPa.

[0055] This specific range of absolute pressure of the secondary gas phase makes it possible to:- maintain the gaseous composition in the gaseous state while retaining turbulent to laminar flow properties so as not to increase the resistance to the free circulation of the gaseous composition in the insulation space which would be induced by the transition to transient flow regimes with the molecular flow, and- establish a negative relative pressure in the secondary insulation space in order to detect leaks in the external sealed wall by monitoring the rise in pressure beyond a criterion. This criterion could be a maximum threshold pressure not to be exceeded.

[0056] According to one embodiment, the operating method further comprises a step of evacuating the secondary gas phase during which a vacuum pump connected to the evacuation line is activated. Preferably in this case, the vacuum pump is activated in order to place the secondary space at an absolute pressure of less than 10 kPa, preferably less than 1 kPa, in the step of evacuating the secondary gas phase, the injection step being carried out after the step of evacuating the secondary gas phase.

[0057] According to one embodiment of the operating method, the absolute pressure of the secondary gas phase is less than 40 kPa during the steps of suction of the secondary gas phase and injection.

[0058] According to one embodiment of the operating method, the steps of evacuating the secondary gas phase and of injection are carried out repeatedly.

[0059] Thus, the steps of evacuation of the secondary gas phase and injection, for example of carbon dioxide, can be carried out as often as necessary, for example based on the measurements provided by a gas analyzer connected to the secondary space.

[0060] According to one embodiment of the operating method, the injection step is carried out in such a way as to create a circulation of the secondary gas phase making it possible to renew the secondary gas phase.

[0061] Such an operating method can be carried out under operating pressure and temperature conditions of the installation, that is to say that the tank contains the liquefied gas and preferably the tank contains liquefied hydrogen. According to one embodiment, the method is carried out when the liquid hydrogen fills at least 10% of the volume of the tank, for example 50% of this volume.

[0062] Such a facility may be part of a land-based or submerged storage facility, or may be installed in a floating, coastal, or deep-water structure, including a ship, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO), and others. Such a facility may also serve as a fuel tank in any type of land vehicle or vessel.

[0063] According to one embodiment, a ship for transporting a liquid gas, preferably liquid hydrogen, comprises a double hull and a aforementioned installation arranged in the double hull.

[0064] According to one embodiment, the invention also provides a system for transferring a liquid gas, preferably liquid hydrogen, the system comprising such a ship, insulated pipes arranged so as to connect the sealed and thermally insulating tank arranged in the hull of the ship to a floating or land-based storage facility and a pump for driving a flow of liquid gas, preferably liquid hydrogen, through the insulated pipes from or to the floating or land-based storage facility to or from the sealed and thermally insulating tank arranged in the hull of the ship.

[0065] According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which the liquid gas, preferably liquid hydrogen, is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the sealed and thermally insulating tank arranged in the hull of the ship. Brief description of the figures

[0066] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0067] It represents a schematic view of an installation according to one embodiment.

[0068] This is a sectional view of a multi-layer structure that can be used to make a tank wall in the installation of the.

[0069] This is a schematic cutaway representation of a ship with a liquefied gas transport tank and a terminal for loading / unloading this tank.

[0070] Illustrates a phase diagram of carbon dioxide.

[0071] Illustrates a schematic view of an installation according to another embodiment.

[0072] The figure represents a sectional view of another embodiment of an installation according to the invention.

[0073] With reference to figures 1 and 2, an installation for the storage and / or transport of liquefied gas, preferably liquefied hydrogen, comprises a sealed and thermally insulating tank 1.

[0074] The sealed and thermally insulating tank 1 is a membrane tank for storing a liquefied gas, for example liquid hydrogen. The tank 1 has a multi-layer structure comprising, from the outside to the inside, a secondary thermally insulating barrier 3, comprising for example insulating elements 20 shown in the, resting against a supporting structure 2, a secondary sealing membrane 4 resting against the secondary thermally insulating barrier 3, a primary thermally insulating barrier 5, resting against the secondary sealing membrane 4 and a primary sealing membrane 6 in contact with the liquefied gas contained in the tank 1. The primary sealing membrane 6 defines an internal space 21 intended to contain the liquefied gas, preferably intended to contain liquid hydrogen.

[0075] As seen in the, the primary membrane 6 and the secondary membrane 4 are corrugated and respectively have primary corrugations 26 and secondary corrugations 24 projecting towards the internal space 21 of the tank 1.

[0076] A primary space is defined by the space between the secondary waterproof membrane 4 and the primary waterproof membrane 6. The primary space includes the primary thermally insulating barrier 5.

[0077] The primary insulating barrier 4 comprises a plurality of support pillars 25 extending along a direction of the thickness of the primary thermally insulating barrier 5 in order to maintain a distance between the secondary waterproof membrane 4 and the primary waterproof membrane 6. Each support pillar 25 comprises a first flat end 27 which is in contact with the primary membrane 6, between two primary waves 26 and a second flat end 28 which is in contact with the secondary membrane 4, between two secondary waves 24. The first and second flat ends 27, 28 being located opposite each other. The primary space is placed under a high vacuum, for example at a pressure of less than 1 Pa, in order to increase the thermal insulation of the primary thermally insulating barrier 5.

[0078] The tank 1 further comprises a secondary space which is defined by the space located between the supporting structure 2 and the secondary waterproof membrane 4. The secondary space comprises the secondary thermally insulating barrier 3 and a secondary gas phase which will be described below.

[0079] The secondary thermally insulating barrier 3 comprises self-supporting insulating panels 20, for example reinforced polyurethane foam. For example, the self-supporting insulating panels 20 comprise two rigid plywood plates sandwiching polyurethane foam.

[0080] In use, the secondary gas phase is composed essentially of carbon dioxide or other gaseous compositions described in the examples. To produce and maintain the secondary gas phase, an inerting device 11 shown schematically in the can be used. The secondary gas phase is maintained for example at a pressure close to atmospheric pressure.

[0081] The inerting device 11 comprises a source of carbon dioxide 12, for example a pressure tank, connected to a supply line 14 passing through the supporting structure 2 and opening into the secondary space. A compressor 13 may be provided to carry out a forced injection of carbon dioxide from the source of carbon dioxide 12 into the secondary space.

[0082] The inerting device 11 further comprises an evacuation line 8 passing through the supporting structure 2 and opening into the secondary space. Optionally, a vacuum pump 7 is connected to the evacuation line 8. The vacuum pump 7 may be connected to a gas analyzer 15 configured to detect the composition of the secondary gas phase. The gas analyzer 15 is here placed at the outlet of the vacuum pump 7. The gas analyzer 15 may in particular comprise a mass spectrometer.

[0083] In addition, flow meters 9 and 16 may be provided to respectively measure a flow rate of gas leaving the secondary space via the discharge line 8 and a flow rate of gas entering the secondary space via the supply line 14.

[0084] A pressure sensor 18 is provided for measuring the pressure in the secondary space and a temperature sensor 19 is provided for measuring the temperature in the secondary space.

[0085] A control unit 10 can be used to control the various actuators of the inerting device 11, namely the compressor 13, the carbon dioxide source 12 and the vacuum pump 7 and receive the measurement signals from the various sensors, namely the gas analyzer 15, the flow meters 9 and 16, and the pressure 18 and temperature 19 sensors.

[0086] Other aspects of the inerting device 11 may be implemented in a manner analogous to the nitrogen distribution system described in document WO2015155377A1.

[0087] Filling the internal space 21 with liquid hydrogen causes a decrease in the temperature of the primary membrane 6, the primary space, the secondary membrane 4 and finally the secondary space. Thus, the temperature of the secondary membrane 4 is approximately -30°C to -70°C. At this temperature, carbon dioxide does not condense.

[0088] If a leak of liquid hydrogen appears in the primary membrane 6, the temperature of the secondary membrane 4 will drop below -80°C at a cold point corresponding to the area where the liquid hydrogen has flowed. Thus, in the secondary space, at this cold point, the carbon dioxide will condense into the solid phase without passing through the liquid phase and form an ice cube attached to the secondary membrane 4, for example inside the secondary corrugations 24.

[0089] This phenomenon is explained in relation to illustrating a phase diagram of CO2. CO2 in the gas phase G is maintained at a pressure P lower than its triple point 40. Thus, in the event of a decrease in temperature T beyond a certain threshold, the CO2 will condense into the solid phase S without passing through the liquid phase L.

[0090] By means of the flow meters 9 and 16, the control unit 10 can determine the quantity of gas discharged from the secondary space via the discharge line 8 and the quantity of carbon dioxide injected into the secondary space via the supply line 14.

[0091] To produce the secondary gas phase and then renew it over time, intermittent or continuous inerting processes can be used, for example under the control of the control unit 10.

[0092] A first inerting process comprises the following steps: evacuating the secondary gas phase, which may initially consist of ambient air, via the evacuation line 8 with the vacuum pump 7, then once the secondary gas phase has been evacuated to a sufficiently low pressure, for example 1 kPa, stopping the vacuum pump then injecting carbon dioxide via the carbon dioxide source 12 and, if necessary, the compressor 13 until the operating pressure is reached, for example equal to atmospheric pressure.

[0093] This process may be repeated several times until the secondary gas phase is composed of at least 99.4% carbon dioxide by volume, the remainder being residual ambient air whose partial pressure, in particular that of residual oxygen, will be so low that an explosive risk is reduced. If gases are released over time from the materials present in the secondary thermally insulating barrier 3, it may be necessary to repeat this process several times.

[0094] In another inerting method that can be used, the secondary gas phase is renewed by sweeping. The method then comprises the following steps: injecting carbon dioxide into the secondary space via the carbon dioxide source 12, and if necessary the compressor 13, in order to create a circulation of the secondary gas phase. The carbon dioxide 12 will push the secondary gas phase present in the secondary space towards the discharge line in order to evacuate the gas phase towards the outside of the secondary space and in order to replace said secondary gas phase. In this method, it is not necessary for a vacuum pump to be connected to the discharge line 8.

[0095] This scanning inerting process can be automated and implemented by a controller that automatically triggers the injection of carbon dioxide into the secondary space based on a pressure measurement taken in the secondary space. Thus, the secondary space can be supplied with carbon dioxide with regulation at + / - 0.5 kPa around a fixed pressure setpoint.

[0096] The control unit 10 may also perform alert functions. For example, the control unit 10 issues alerts in the following cases, constituting probable cases of liquid hydrogen leakage:

[0097] - the pressure detector 18 indicates that the pressure in the secondary space has fallen below a pressure threshold. In fact, the condensation of carbon dioxide in the solid phase will cause a reduction in the pressure in the secondary space. For example, assuming that the secondary space is isolated, it has a volume of 68 m3 of unpartitioned free volume and has a gaseous composition containing a partial pressure of CO2 of 100 kPa and an average temperature of 0°C under normal operating conditions of the tank, then in the case of the formation of a cold spot involving the condensation in equilibrium of 3 liters of CO2 in solid phase, the pressure drop attributed by this mechanism alone is 2.5 kPa in the secondary space. Thus, in this example, if the pressure sensor 18 detects a pressure drop of 2.5 kPa, then the control unit 10 can generate an alert.

[0098] - the amount of gas injected into the secondary space over a period of time has exceeded by a certain threshold the amount of gas evacuated over the same period of time. Indeed, an accumulation of carbon dioxide in the secondary space can be caused by the presence of an abnormal cold spot.

[0099] Described below are examples of preferred gaseous compositions that may be used to inert the secondary space according to embodiments.

[0100] Example 1Chemical speciesvolume carbon dioxide89% nitrogen11% secondary? %

[0101] In Example 1, residual chemical species may include atmospheric oxygen.

[0102] Example 2Chemical species by volume argon>99% other<1%

[0103] In Example 2, the total pressure is below the triple point of argon, which is 68.7 kPa.

[0104] Example 3Chemical species by volume nitrogen>99% other<1%

[0105] In Example 3, the total pressure is less than 13 kPa, which is the triple point of nitrogen.

[0106] For the gaseous compositions of Examples 1 to 3, an inerting device comprising a gas source may be used in a manner analogous to the embodiment illustrated in FIG. The gas source must be adapted according to the gaseous composition that it is desired to obtain. For Example 1, the gas source is a carbon dioxide source, for Example 2, the gas source is an argon source and for Example 3, the gas source is a nitrogen source.

[0107] Example 4Chemical species by volume carbon dioxide 89% nitrogen 11%

[0108] In example 4, the total pressure is less than or equal to atmospheric pressure.

[0109] Example 5Chemical species by volume Argon 59.7% carbon dioxide 39.8% other 0.5%

[0110] For the gaseous compositions of Examples 4 and 5, an inerting device 110 as illustrated in the can be used. Identical or similar elements have the same reference numeral as the. The inerting device 110 differs from the inerting device 11 of the in that the gas source 12 is a first gas source and the inerting device 110 further comprises a second gas source 120.

[0111] For example 4, the first gas source 12 is a carbon dioxide source and the second gas source 120 is a nitrogen source.

[0112] For example 5, the first gas source 12 is an argon source and the second gas source 120 is a carbon dioxide source.

[0113] The first main species contained in the first reservoir of the first gas source 12 and the second main species contained in the second reservoir of the second gas source 120 may be injected into the secondary space via one or more supply lines. Furthermore, one or more valves may be placed on the supply line 14, for example at the gas outlet of the first gas source 12 and / or the second gas source 120. The flow rate or quantity of gas injected by the first gas source 12 or the second gas source 120 may be controlled via the control unit 10, which for example controls the valves located at the gas outlet of the first gas source 12 or the second gas source 120.

[0114] With reference to the, a cutaway view of a ship 70 shows an installation comprising a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealing membrane being in contact with the liquid hydrogen contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, and two thermally insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72.

[0115] In a manner known per se, loading / unloading pipes 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer a cargo of hydrogen from or to the tank 71.

[0116] The figure represents an example of a maritime terminal comprising a loading and unloading station 75, a subsea pipeline 76 and a shore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipes 73. The orientable mobile arm 74 adapts to all ship sizes. A connecting pipeline (not shown) extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the ship 70 from or to the shore installation 77. The latter comprises liquid hydrogen storage tanks 80 and connecting pipelines 81 connected by the subsea pipeline 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquid hydrogen between the loading or unloading station 75 and the shore installation 77 over a long distance, for example 5 km, which makes it possible to keep the vessel 70 at a great distance from the coast during loading and unloading operations.

[0117] To generate the pressure necessary for the transfer of liquid hydrogen, pumps on board the ship 70 and / or pumps equipping the onshore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0118] Similarly, the invention also relates to an installation for transferring a liquefied gas, preferably liquefied hydrogen. Such an installation can be seen as a liquefied gas transfer pipe and is also known by the English term "Pipe in Pipe". The figure represents a sectional view of such an installation (the inerting device is not shown). Said installation comprises a container in the form of a transfer pipe 201, the transfer pipe 201 comprises, going from the inside of the installation to the outside of the installation: - a primary sealed pipe 202, the primary sealed pipe 202 being intended to be in contact with the liquefied gas, preferably the liquefied hydrogen, contained in the interior space of the primary sealed pipe 202 to ensure its transfer,a secondary sealed wall 204 located at a distance from an outer side of the primary sealed pipe 202 and defining a primary space between the primary sealed pipe 202 and the secondary sealed membrane 204, a primary thermally insulating barrier 203 arranged in the primary space, an external sealed wall 206 located at a distance from the secondary sealed wall 204, and defining a secondary space between the external sealed wall 206 and the secondary sealed wall 204, a secondary thermally insulating barrier 205 and a secondary gas phase, arranged in the secondary space (defined between the secondary sealed wall 204 and the external sealed wall 206), the external wall 206 being carried by the secondary thermally insulating barrier 205, said installation comprising an inerting device 11, 110 connected, at least temporarily,to the secondary space for maintaining and / or putting the secondary gas phase in the form of a gaseous composition consisting of one or more main chemical species, and possibly one or more residual chemical species, the inerting device being configured to maintain the secondary gas phase at an absolute pressure greater than 10 kPa, in which the partial pressure of the or each main chemical species is less than the triple point of said main chemical species, and in which the partial pressure of the or each residual chemical species is less than 0.14 kPa.,

[0119] The inerting device 11, 110 is further configured to maintain the secondary gas phase at an absolute pressure strictly less than 95 kPa.

[0120] The transfer pipe 201 extends over a length L and is open at its ends for the transfer of the liquefied gas along the transfer pipe 201, inside the pipe 202. The pipe 202 is intended to transport the liquefied gas from one end of the transfer pipe 201 to another end of the transfer pipe 201.

[0121] The same principle of the invention in connection with inerting described in detail in an embodiment with a tank applies to a “Pipe in Pipe” type pipe. Inerting is advantageously carried out temporarily to place the secondary gas phase at the correct pressure level.

[0122] Advantageously, the secondary space is under overpressure compared to atmospheric pressure. This embodiment is made possible by the fact that the walls of the "Pipe in pipe" installation have a certain rigidity allowing this overpressure to be maintained.

[0123] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0124] The use of the verb "comprise", "comprise" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

[0125] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Installation for the storage and / or transport and / or transfer of a liquefied gas, preferably liquefied hydrogen, said installation comprising a sealed and thermally insulated container (1, 201), the sealed and thermally insulated container comprising: a sealed outer wall (2; 206), a secondary sealed membrane (4; 204) located at a distance from an inner side of the outer wall (2; 206) and defining a secondary space between the outer wall (2; 206) and the secondary sealed membrane (4; 204), a secondary thermally insulating barrier (3; 205) and a secondary gaseous phase disposed in the secondary space, the secondary space being delimited by the outer wall (2; 206), the secondary sealed membrane (4; 204) being supported by the secondary thermally insulating barrier (3; 205),a primary airtight membrane (6; 202) located at a distance from an inner side of the secondary airtight membrane (4; 204) and defining a primary space between the secondary airtight membrane (4; 204) and the primary airtight membrane, the primary airtight membrane being intended to be in contact with the liquefied gas, preferably the liquefied hydrogen contained in the airtight and thermally insulated container, a primary thermally insulating barrier (5; 203) disposed in the primary space, the primary airtight membrane (6; 202) being supported by the primary thermally insulating barrier (5; 203), said installation comprising an inerting device (11, 110) connected to the secondary space to maintain the secondary gaseous phase in the form of a gaseous composition consisting of one or more principal chemical species, and optionally one or more residual chemical species,the inerting device being configured to maintain the secondary gas phase at an absolute pressure greater than 10 kPa and strictly less than 95 kPa, wherein the partial pressure of the principal chemical species or species is less than the triple point of said principal chemical species, and wherein the partial pressure of the residual chemical species or species is less than 0.14 kPa, wherein the inerting device includes at least one gas source (12), the gas source comprising a gas tank filled with said principal species or a gas generator capable of generating said principal species, the installation further comprising: at least one supply line (14) connected to the gas source (12, 120) and opening into the secondary space, and at least one discharge line (8) opening into the secondary space, and a measuring device (9, 16,10) Capable of measuring: a quantity of the principal chemical species injected into the secondary gas phase via at least one feed line, a quantity of gas extracted from the secondary space via at least one discharge line, and capable of issuing an alert in response to the detection that a difference between the quantity of the principal chemical species injected and the quantity of gas extracted exceeds a positive quantity threshold. Installation according to claim 1, wherein the sealed and thermally insulating container is a sealed and thermally insulating tank, the outer wall being a load-bearing structure (2) and the secondary thermally insulating barrier (3) being anchored to the load-bearing structure (2). Installation according to claim 1 or 2, wherein said gaseous composition comprises at least one principal chemical species selected from the group consisting of: nitrogen, carbon dioxide and argon. Installation according to claim 3, wherein said or each principal chemical species is selected from the group consisting of: nitrogen, carbon dioxide and argon. An installation according to any one of claims 1 to 4, wherein said principal chemical species comprises carbon dioxide, carbon dioxide constituting at least 33% by volume of the secondary gaseous phase, preferably at least 89% by volume of the secondary gaseous phase, even more preferably at least 99.4% by volume of the secondary gaseous phase. Installation according to any one of claims 1 to 5, wherein said principal chemical species comprises argon, the partial pressure of argon being less than its triple point, i.e. 68.7 kPa. Installation according to claim 6, wherein argon constitutes at least 50% by volume of the secondary gaseous phase, preferably at least 99% by volume of the secondary gaseous phase. Installation according to any one of claims 1 to 7, wherein said principal chemical species comprises dinitrogen, the partial pressure of dinitrogen being less than its triple point, i.e. 12.5 kPa. An installation according to any one of claims 1 to 8, wherein the primary space contains a primary gaseous phase having a pressure lower than the pressure of the secondary gaseous phase. An installation according to any one of claims 1 to 9, wherein the primary space contains a primary gaseous phase having an absolute pressure of less than 1 Pa. An installation according to any one of claims 1 to 10, further comprising a pressure sensor (18) capable of detecting pressure in the secondary space and an alerting device (10), the alerting device being capable of generating an alert in response to a detection by the pressure sensor that the pressure of the secondary gas phase is below a pressure threshold. An installation according to any one of claims 1 to 11, wherein the primary thermally insulating barrier (5) comprises a plurality of support pillars (25) extending in a direction of the thickness of the primary thermally insulating barrier (5) in order to maintain a distance between the secondary waterproof membrane (4) and the primary waterproof membrane (6). An installation according to any one of claims 1 to 12, wherein the secondary waterproof membrane (4) has a plurality of secondary corrugations (24) and flat portions situated between the secondary corrugations, the flat portions resting on the secondary thermally insulating barrier (3), wherein the secondary corrugations protrude on the inner side of the secondary waterproof membrane (4). Installation according to claim 1, wherein the inerting device includes a first gas source (12), the first gas source (12) comprising a gas reservoir filled with a first said main species or a gas generator capable of generating a first said main species, and a second gas source (120), the second gas source (120) comprising a gas reservoir filled with a second said main species or a gas generator capable of generating a second said main species. A method of operating an installation according to claim 1, comprising: an injection step in which the main chemical species or each main chemical species is injected in the gaseous phase until the secondary gaseous phase is at an absolute pressure greater than 10 kPa and strictly less than 95 kPa, in which the partial pressure of the main chemical species or each main chemical species is less than the triple point of said main chemical species, and in which the partial pressure of the residual chemical species or each residual chemical species is less than 0.14 kPa. A method of operation according to claim 15, further comprising a secondary gas phase evacuation step during which a vacuum pump (7) is connected to the evacuation line (8) and activated, wherein the vacuum pump (7) is activated in order to place the secondary space at an absolute pressure of less than 10 kPa, preferably less than 1 kPa, in the secondary gas phase evacuation step, the injection step being carried out after the secondary gas phase evacuation step. A method of operation according to claim 16, wherein the steps of evacuating the secondary gaseous phase and injection are carried out repeatedly. A method of operation according to claim 15, wherein the injection step is carried out in such a way as to create a circulation of the secondary gaseous phase allowing the secondary gaseous phase to be renewed. A method of operation according to claim 16, wherein the absolute pressure of the secondary gas phase is less than 40 kPa during the secondary gas phase aspiration and injection steps. Vessel (70) for the transport of a liquid gas, preferably hydrogen, the vessel comprising a double hull (72) and an installation according to any one of claims 1 to 14 disposed in the double hull, and in which the sealed and thermally insulating container is a sealed and thermally insulating tank, the outer wall being a load-bearing structure (2) and the secondary thermally insulating barrier (3) being anchored to the load-bearing structure (2). A liquefied gas transfer system, preferably liquid hydrogen, the system comprising a vessel (70) according to claim 20, insulated pipes (73, 79, 76, 81) arranged to connect the sealed and thermally insulated tank (71) located in the hull of the vessel to a floating or land-based storage facility (77) and a pump for driving a flow of a liquefied gas, preferably liquid hydrogen, through the insulated pipes from or to the floating or land-based storage facility to or from the sealed and thermally insulated tank located in the hull of the vessel. Method of loading or unloading a ship (70) according to claim 20, in which a liquefied gas, preferably liquid hydrogen, is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the sealed and thermally insulated tank (71) disposed in the hull of the ship.

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