Equipment for storing and / or transporting liquefied gas

Abstract

The present invention relates to an installation for storing and / or transporting and / or transferring a liquefied gas, preferably liquefied hydrogen, comprising a sealed, insulated container (1) with a sealed outer wall and a secondary sealing membrane (4) located at a distance from the inside of the outer wall and defining a secondary space between the outer wall and the secondary sealing membrane, the installation comprising an inerting device (11) connected to the secondary space such that the secondary gas phase is maintained in the form of a gas composition composed of one or more main chemical species and optionally one or more residual chemical species, the partial pressure of the main chemical species being lower than the triple point of the main chemical species and the partial pressure of the residual chemical species being lower than 0.14 kPa.

Description

[Technical field]

[0001] The present invention relates to the field of installations for storing and / or transporting liquefied gases at low temperatures. In particular, the invention relates to the field of installations comprising sealed, insulated tanks for storing and / or transporting liquefied gases at low temperatures, such as tanks for transporting liquid hydrogen, which at atmospheric pressure is about -253°C, but which can also be stored at higher pressures. These installations can be installed at fixed stations or on land or floating vehicles. [Background technology]

[0002] Installations are known which comprise membrane-type tanks for storing and / or transporting liquefied natural gas at atmospheric pressure, which successively comprise, for example in the thickness direction 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 insulating barrier, a secondary sealing membrane, a secondary insulating barrier and a load-bearing structure which defines the overall shape of the tank.

[0003] The primary and secondary sealing membranes, between them, comprise the primary insulating barrier and define a primary space which is typically filled with nitrogen to avoid the risk of fire in the event of a leak.

[0004] Nitrogen is also provided to a secondary space defined by the space between the secondary sealing membrane and the load-bearing structure.

[0005] The sealing membrane of such a tank may have leaks that allow the passage of the liquefied natural gas from inside the tank towards the primary and / or secondary insulating barriers, whereby the primary and secondary spaces are cooled rapidly as liquefied gas at a lower temperature enters the primary space.

[0006] WO 2015 / 078972 defines a sampling method for the analysis of gas composition in the case of an adiabatic atmosphere below 10 kPa, preferably below 1 kPa.

[0007] FR 2 502 289 A1 indicates a regulation such that the pressure of the secondary space must be kept equal to or greater than the pressure of the LNG contained in the tank (i.e. approximately 100 kPa, or even 95 kPa), which is at atmospheric pressure, which is associated with a continuous supply of condensable gas as soon as the cold point of condensation occurs. Summary of the Invention

[0008] A particular aspect of the invention is that when the temperature of the primary or secondary space falls below the liquefaction point of nitrogen, i.e. -196°C at atmospheric pressure, liquefaction of nitrogen can cause major problems, since liquid nitrogen will flow under the influence of gravity, especially in the secondary space, to the inner surfaces of the load-bearing structures, which currently are not generally designed for situations where such low temperatures are reached, with the risk of unacceptable weakening.

[0009] There is therefore a need to find a solution that makes it possible to prevent the formation of cold liquids in primary and secondary spaces in installations for storing and / or transporting liquefied gases, such as hydrogen, at low temperatures.

[0010] One idea underlying the present invention is to provide a facility which solves the above mentioned problems.

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

[0012] Another idea underlying the present invention is to provide a method for inerting the secondary space of such a closed, insulated tank.

[0013] Another idea underlying the present invention is to provide a method for detecting leaks in such a closed, insulated tank.

[0014] In summary, the invention proposes an installation for storing and / or transporting and / or transferring a liquefied gas, preferably liquefied hydrogen, said installation comprising a sealed, insulated container, said container comprising a sealed outer wall, a secondary sealing membrane located at a distance from the inside of said outer wall, said secondary sealing membrane defining a secondary space between said outer wall and said secondary sealing membrane, a secondary insulating barrier and a secondary gas phase arranged in said secondary space bounded by said outer wall and supporting said secondary sealing membrane, and a primary sealing membrane located at a distance from the inside of said secondary sealing membrane, said secondary sealing membrane defining a secondary space between said secondary sealing membrane and said primary sealing membrane. a primary sealing membrane intended to be in contact with a liquefied gas, preferably liquefied hydrogen, contained in the sealed insulated container, defining a primary space within the sealed insulated container, and a primary insulating barrier arranged in the primary space and supporting the primary sealing membrane, the installation having an inerting device connected to the secondary space such that the secondary gas phase is maintained in the form of a gas composition composed of one or more main chemical species and optionally one or more residual chemical species, the inerting device being configured to maintain, for the secondary gas phase, a pressure of more than 10 kPa absolute, the partial pressure of the main chemical species being lower than the triple point of the main chemical species and the partial pressure of the residual chemical species being lower than 0.14 kPa.

[0015] According to a first object, the present invention proposes an installation for storing and / or transporting a liquefied gas, preferably liquefied hydrogen, said sealed and insulated container being a sealed and insulated tank, said sealed and insulated tank comprising a sealed outer wall, which is a sealed load-bearing structure, a secondary sealing membrane located at a distance from the inside of said load-bearing structure, said secondary sealing membrane defining a secondary space between said load-bearing structure and said secondary sealing membrane, a secondary insulating barrier and a secondary gas phase arranged in said secondary space, said secondary insulating barrier being anchored to said load-bearing structure and said secondary sealing membrane being supported by said secondary insulating barrier, and a primary sealing membrane located at a distance from the inside of said secondary sealing membrane, said secondary insulating barrier and a secondary gas phase defining a secondary space between said load-bearing structure and said secondary sealing membrane, said secondary insulating barrier being anchored to said load-bearing structure and said secondary sealing membrane being supported by said secondary insulating barrier, said primary sealing membrane being located at a distance from the inside of said secondary sealing membrane, The installation comprises a primary sealing membrane defining a primary space between the secondary sealing membrane and the primary sealing membrane and intended to be in contact with a liquefied gas, preferably liquefied hydrogen, contained in the tank, and a primary insulating barrier arranged in the primary space and supporting the primary sealing membrane, the installation having an inerting device connected to the secondary space such that the secondary gas phase is maintained in the form of a gas composition composed of one or more main chemical species and optionally one or more residual chemical species, the inerting device being configured to maintain, for the secondary gas phase, a pressure of more than 10 kPa absolute, the partial pressure of the main chemical species being lower than the triple point of the main chemical species and the partial pressure of the residual chemical species being lower than 0.14 kPa.

[0016] Due to these characteristics, the inventors have discovered that by using such a gas composition in the secondary gas phase, in the event of a liquid hydrogen leak, it is possible to prevent or strongly limit the formation of cold liquid in the secondary space. In particular, in response to a drop in temperature on the secondary membrane, one or more of the main chemical species that were initially in the gas phase can condense into a solid phase, for example in the form of a more or less porous solid, such as snow or ice, without passing through a liquid state. Moreover, such a solid phase tends to adhere to the location where it is formed, for example on the secondary membrane, and does not flow into the secondary space. Thus, the risk of it reaching the load-bearing structure and / or forming a thermal bridge through the secondary space is significantly reduced.

[0017] The total pressure of the secondary gas phase may be equal to atmospheric pressure or may be higher or lower, within the limits imposed by the mechanical strength of the sealed membrane. The threshold value is 0.14 kPa, the triple point of dioxygen, thus ensuring that residual dioxygen cannot condense into the liquid phase, if appropriate, thereby mitigating the hazards inherent in liquid oxygen, such as corrosion, oxidation, combustion and explosion.

[0018] Due to these features, the risk of damage to the load-bearing structure is significantly reduced.

[0019] Furthermore, in the event of a leak of liquid hydrogen in the primary space, one or more of the main species may convert from a gaseous state to a liquid state when in contact with the secondary membrane. This change of state is reflected by a drop in pressure, since the one or more main species in the solid state are much denser compared to their gaseous state. This phenomenon can be used to detect leaks.

[0020] According to various embodiments, the facility for storing and / or transporting liquefied hydrogen may have one or more of the following features:

[0021] According to embodiments, the inerting device is configured to maintain a pressure for the secondary gas phase strictly below 95 kPa absolute.

[0022] This range of absolute pressures of the secondary gas phase allows both to keep the gas composition in a gaseous state while maintaining turbulent to laminar flow properties so as not to increase the resistance to the free circulation of the gas composition in the insulating space, which may be caused by transient flow regimes with molecular flow, and to generate a negative pressure relative to the atmospheric pressure in the secondary insulating space, so as to make it possible to place a detection system for the tightness of the external sealing wall by monitoring whether the increase in pressure exceeds a certain criterion. This criterion may be a maximum pressure threshold that is not exceeded. The skilled person can define this criterion based on the detection level for the desired tightness to be generated, for example based on the derivative with respect to time of the pressure P in the secondary insulating space, i.e. ΔP / Δt, where ΔP represents the amount of change in the pressure in the secondary space during a time increment Δt, the duration of which can be combined to reach a sliding duration of at least 30 minutes and up to 48 hours or more. Preferably, the relevant criteria should also take into account degassing of materials present in the secondary space (e.g. reinforced polyurethane foam) and / or increased oxygen concentration, and the effect of the day-night cycle and / or weather on the average temperature in the secondary insulated space and therefore the pressure P in the secondary insulated space.

[0023] According to various embodiments, the gas composition includes at least one predominant species selected from the group consisting of dinitrogen, carbon dioxide, and argon.

[0024] According to embodiments, the primary species is selected from the group consisting of dinitrogen, carbon dioxide, and argon.

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

[0026] The primary insulating barrier must ensure that the service temperature of the secondary membrane is higher than the freezing point of one or more of the predominant chemical species at the service pressure, which, in particular when the predominant chemical species is carbon dioxide, is close to -80°C for service pressures close to atmospheric pressure. For example, the primary insulating barrier may be designed such that the service temperature of the secondary membrane is typically close to -50°C.

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

[0028] Therefore, the higher the percentage by volume of carbon dioxide in the secondary gas phase, the lower the risk that other gases present in the secondary gas phase will condense into liquid phase in response to a drop in temperature.

[0029] According to one embodiment, the predominant species comprises argon, which occupies at least 50% by volume of the secondary gas phase, preferably at least 99% by volume of the secondary gas phase, meaning that argon occupies at least, for example, 60%, 70%, 80%, 90% or 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 predominant species comprises dinitrogen and the partial pressure of said dinitrogen is below its triple point, i.e. 12.5 kPa.

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

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

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

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

[0035] According to one embodiment, the source of carbon dioxide includes a carbon dioxide generator capable of producing carbon dioxide from atmospheric air and a source of hydrocarbons, or preferably a pressurized carbon dioxide reservoir.

[0036] According to one embodiment, the inactivation device comprises a first gas source having a gas reservoir filled with a first of the main chemical species or a gas generator capable of generating the first of the main chemical species, and a second gas source having a gas reservoir filled with a second of the main chemical species or a gas generator capable of generating the second of the main chemical species.

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

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

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

[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 with an absolute pressure of less than 1 Pa. By placing the primary space under vacuum in this way, it is possible to obtain very good insulating properties.

[0042] According to one embodiment, the equipment for storing and / or transporting liquefied hydrogen further comprises a pressure sensor capable of detecting the pressure in the secondary space, and an alarm device capable of generating an alarm in response to the pressure sensor detecting that the pressure of the secondary gas phase is lower than a pressure threshold.

[0043] These features make it possible to detect a drop in pressure in the secondary space, which would likely be caused by a liquid hydrogen leak.

[0044] According to one embodiment, the primary insulation barrier comprises a number of support pillars extending in the thickness direction of the primary insulation barrier to maintain a distance between the secondary sealing membrane and the primary sealing membrane, these features allowing the primary sealing membrane to be firmly supported to create an improved vacuum in the primary space without risking destruction of the primary sealing membrane.

[0045] The secondary sealing membrane can be manufactured by various methods. According to one embodiment, the secondary sealing membrane has a plurality of secondary undulations and a plurality of flat portions located between the secondary undulations, the flat portions resting on the secondary 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 undulations protrude on the inside of the secondary sealing membrane.

[0048] The secondary insulating barrier can be manufactured by a number of methods. According to one embodiment, the secondary insulating barrier comprises a number of juxtaposed insulating panels that support the secondary sealing membrane.

[0049] According to one embodiment, the insulation panel is self-supporting, i.e. it maintains a vacuum. According to one embodiment, one insulation panel comprises a box made of plywood containing an insulating material, for example 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 exhaust line opening into the secondary space, for example the supply line and / or the exhaust line passing through the load-bearing structure to open into the secondary space, and a vacuum pump can be connected to the exhaust line in a temporary manner for an initial purge phase, for example via a flexible connector, and later disconnected.

[0051] According to one embodiment, the facility for storing and / or transporting liquefied gas, preferably liquid hydrogen, further comprises a measuring device capable of measuring the amount of said main species injected into said secondary gas phase via at least one said supply line and the amount of gas exhausted from said secondary space via at least one said exhaust line, and capable of issuing an alarm upon detection that the difference between the amount of said main species injected and the amount of gas exhausted exceeds a positive amount threshold.

[0052] According to one embodiment, the tank may have a general shape that is spherical, cylindrical, polyhedral or prismatic.

[0053] According to one embodiment, the invention provides a method of operating the above-mentioned installation, comprising an injection step during which the main species is injected into the gas phase until the secondary gas phase has a pressure of more than 10 kPa absolute, the partial pressure of the main species being lower than the triple point of the main species and the partial pressure of the residual species being lower than 0.14 kPa.

[0054] According to one embodiment, said injecting step further comprises injecting said one or more primary species at a pressure strictly below 95 kPa absolute.

[0055] Said specific range of absolute pressure of the secondary gas phase makes it possible both to keep the gas composition in a gaseous state while maintaining turbulent versus laminar flow characteristics so as not to increase the resistance to the free circulation of the gas composition in the insulating space, which may be caused by unsteady flow conditions with molecular flow, and to generate a negative pressure relative to the atmospheric pressure in the secondary insulating space, so as to make it possible to place a detection system for the tightness of the external sealing wall by monitoring whether the increase in pressure exceeds a certain criterion, which may be a maximum pressure threshold that is not to be exceeded.

[0056] According to one embodiment, the operating method further comprises a step of evacuating the secondary gas phase by a vacuum pump being connected to the evacuation line and activated. Preferably, in this case, the vacuum pump is activated in the step of evacuating the secondary gas phase to bring the secondary space to a pressure of less than 10 kPa, preferably less than 1 kPa absolute, and the injection step is performed after the step of evacuating the secondary gas phase.

[0057] According to one embodiment, the absolute pressure of the secondary gas phase is lower than 40 kPa during the steps of evacuating and injecting the secondary gas phase.

[0058] According to one embodiment, the step of evacuating the secondary gas phase and the step of injecting are performed repeatedly.

[0059] Thus, the step of evacuating or injecting the secondary gas phase, e.g. carbon dioxide, can be performed as many times as necessary, e.g. depending on measurements provided by a gas analyzer connected to the secondary space.

[0060] According to one embodiment of the operating method, the injection step is performed to create a circulation of the secondary gas phase capable of renewing the secondary gas phase.

[0061] Such an operating method is carried out under temperature and pressure conditions for operating the installation, i.e. the tank containing a liquefied gas, preferably the tank containing liquefied hydrogen. According to one embodiment, the method is carried out when the liquid hydrogen fills at least 10% by volume of the tank, for example 50% by volume.

[0062] Such installations may form part of onshore or underwater storage facilities and may also be installed on floating, coastal or deep-sea structures, in particular ships, Floating Storage and Regasification Units (FSRUs) and Floating Production Storage and Offloading Units (FPSOs). Such installations may also be used as fuel storage for all kinds of land vehicles and ships.

[0063] According to one embodiment, a vessel used for transporting liquid gas, preferably liquid hydrogen, has a double hull and said equipment is arranged within said double hull.

[0064] According to one embodiment, the present invention also provides a transportation system for liquefied gas, preferably liquid hydrogen, comprising such a vessel, an insulated pipeline arranged to connect said sealed insulated tank installed in the hull of said vessel to an onshore or floating storage facility, and a pump for driving a flow of liquid gas, preferably liquid hydrogen, via said insulated pipeline from said onshore or floating storage facility to said sealed insulated tank installed in the hull of said vessel or from said sealed insulated tank installed in the hull to said onshore or floating storage facility.

[0065] According to one embodiment the invention provides a method for loading or unloading on board a ship, wherein said liquid gas, preferably liquid hydrogen, is transferred via an insulated pipeline from said onshore or floating storage facility to said sealed insulated tank installed in the hull of said ship or from said sealed insulated tank installed in the hull of said ship to said onshore or floating storage facility.

[0066] The invention can be better understood in the following detailed description of some specific embodiments of the invention, given by way of non-limiting example with reference to the accompanying drawings, in which further objects, details, features and advantages are more clearly indicated. [Brief description of the drawings]

[0067] [Figure 1] FIG. 1 is a schematic diagram of an installation according to one embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a multi-layer structure that can be used to manufacture the tank in the installation in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a ship having a tank for transporting liquefied gas and a terminal for loading and unloading the tank. [Figure 4] FIG. 4 is a phase diagram of carbon dioxide. [Diagram 5] FIG. 5 is a schematic diagram of an installation according to another embodiment. [Figure 6] FIG. 6 is a cross-sectional view of an installation according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0068] With reference to FIGS. 1 and 2, an installation for storing and / or transporting liquefied gas, preferably liquefied hydrogen, comprises a sealed, insulated tank 1.

[0069] The sealed, insulated tank 1 is a membrane type tank and is therefore capable of storing a liquefied gas, for example liquid hydrogen. The tank 1 has a multi-layer structure comprising, from the outside to the inside, an insulating element 20, for example as shown in FIG. 2, a secondary insulating barrier 3 resting against a load-bearing structure 2, a secondary sealing membrane 4 resting against said secondary insulating barrier 3, a primary insulating barrier 5 resting against said 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 interior space 21 intended to contain a liquefied gas, preferably liquid hydrogen.

[0070] As can be seen from FIG. 2, the primary membrane 6 and the secondary membrane 4 are corrugated and each have primary undulations 26 and secondary undulations 24 that project in the direction of the interior space 21 of the tank 1 .

[0071] The space located between the secondary sealing membrane 4 and the primary sealing membrane 6 defines a primary space. The primary space has a primary insulating barrier 5.

[0072] The primary insulating barrier 4 has a number of support pillars 25 extending in the thickness direction of the primary insulating barrier 5 to maintain the distance between the secondary sealing membrane 4 and the primary sealing membrane 6. Each support pillar 25 has a first flat end 27 in contact with the primary membrane 6 and between two primary undulations 26, and a second flat end 28 in contact with the secondary membrane 4 and between two secondary undulations 24. The first flat end 27 and the second flat end 28 are arranged opposite each other. The primary space is placed under enhanced vacuum, e.g. a pressure of less than 1 Pa, to improve the thermal insulation of the primary insulating barrier 5.

[0073] The tank 1 also has a secondary space defined by the space located between the load-bearing structure 2 and the secondary sealing membrane 4. The secondary space has a secondary insulating barrier 3 and a secondary gas phase, which will be described below.

[0074] The secondary insulation barrier 3 includes a plurality of free-standing insulation panels 20, such as reinforced polyurethane foam. For example, the free-standing insulation panels 20 include two rigid plywood panels with polyurethane foam sandwiched between them.

[0075] In service, the secondary gas phase is essentially composed of carbon dioxide or other gas compositions as described in the examples. To generate and maintain the secondary gas phase, an inerting device 11, shown diagrammatically in Figure 1, can be provided. The secondary gas phase is maintained at a pressure close to atmospheric pressure, for example.

[0076] The inerting device 11 has a carbon dioxide source 12, for example a pressurised reservoir, connected to a supply line 14 which passes through the load-bearing structure 2 and opens into the secondary space. A compressor 13 may be provided to force carbon dioxide from the carbon dioxide source 12 into the secondary space.

[0077] The inerting device 11 further comprises an exhaust line 8 which passes through the load-bearing structure 2 and opens into the secondary space. Optionally, a vacuum pump 7 is connected to the exhaust line 8. The vacuum pump 7 can be connected to a gas analyzer 15 arranged for detecting the composition of the secondary gas phase. In this case, the gas analyzer 15 is arranged external to the vacuum pump 7. The gas analyzer 15 can in particular comprise a mass spectrometer.

[0078] Additionally, flow meter 9 and flow meter 16 may be provided to measure the flow rate of gas leaving the secondary space via exhaust line 8 and the flow rate of gas entering the secondary space via supply line 14, respectively.

[0079] 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.

[0080] The control unit 10 can be used to control the actuators of the inactivation device 11, in particular the compressor 13, the carbon dioxide source 12, and the vacuum pump 7, and to receive measurement signals from the sensors, in particular the gas analyzer 15, the flow meters 9, 16, the pressure sensor 18, and the temperature sensor 19.

[0081] Other aspects of the inerting device 11 are believed to be similar to the nitrogen distribution system described in WO 2015 / 155377.

[0082] Filling the inner space 21 with liquid hydrogen leads to a temperature drop in the primary membrane 6, the primary space, the secondary membrane 4 and finally in the secondary space. The temperature of the secondary membrane 4 is therefore between about -30°C and -70°C. At this temperature, carbon dioxide does not condense.

[0083] If a liquid hydrogen leak occurs in the primary membrane 6, the temperature of the secondary membrane 4 drops to a cold point below −80° C., which corresponds to the area through which the liquid hydrogen flows. Thus, in the secondary space, at this cold point, the carbon dioxide condenses into a solid phase without passing through a liquid phase, forming ice that adheres to the secondary membrane 4, for example the inside of the secondary undulations 24.

[0084] This phenomenon is explained in relation to Figure 4, where the phase diagram of CO2 is shown. CO2 in gas phase G is maintained at a pressure P below its triple point 40. Thus, in the event that the temperature T falls below a certain threshold, CO2 condenses into solid phase S without passing through liquid phase L.

[0085] The flow meters 9, 16 enable the control unit 10 to determine the amount of gas being exhausted from the secondary space via the exhaust line 8 and the amount of carbon dioxide being injected into the secondary space via the supply line 14.

[0086] To generate the secondary gas phase and renew it over time, intermittent or continuous inerting methods can be applied, for example under the direction of the control unit 10 .

[0087] The first inactivation method comprises the following steps: Discharging the secondary gas phase, which may initially consist of ambient air, via the discharge line 8 by means of the vacuum pump 7; Next, the secondary gas phase is exhausted, and once a sufficiently low pressure, for example a pressure of 1 kPa, is reached, the vacuum pump is stopped; Carbon dioxide is then injected via a carbon dioxide source 12, and if appropriate also via a compressor 13, until a service pressure is reached, for example a pressure equal to atmospheric pressure.

[0088] This process can be repeated multiple times until the secondary gas phase is composed of at least 99.4% carbon dioxide by volume, the remainder being ambient air, particularly residual oxygen, at very low partial pressures, thus reducing the risk of explosion. Over time, the process may need to be repeated multiple times as gas is released by materials present in the secondary insulating barrier 3.

[0089] Another possible inerting method is to renew the secondary gas phase by flushing. This method comprises the following steps: injecting carbon dioxide into the secondary space, via a carbon dioxide source 12 and, if appropriate, a compressor 13, so as to create a circulation of the secondary gas phase. The carbon dioxide source 12 pushes the secondary gas phase present in the secondary space towards a discharge line, in order to discharge it towards the outside of the secondary space and to replace it. In this method, it is not necessary to connect a vacuum pump to the discharge line 8.

[0090] The inactivation by washing method can be automated and implemented by an automatic device which automatically triggers the injection of carbon dioxide into the secondary space based on a pressure measurement made in the secondary space. Thus, the secondary space can be supplied with carbon dioxide with a limit of ±0.5 kPa relative to a fixed pressure installation point.

[0091] The control unit 10 may have an alarm function, for example the control unit 10 will issue an alarm in the following situations, including the possible case of liquid hydrogen leakage:

[0092] The pressure detector 18 indicates that the pressure in the secondary space is below a pressure threshold. In particular, condensation of carbon dioxide into a solid phase causes a drop in pressure in the secondary space. As an example, if the secondary space is adiabatic and is 68 m 3 free unpartitioned space and under normal operating conditions of the tank has a gas composition including a CO2 partial pressure of 100 kPa and an average temperature of 0° C., then, on equilibration of 3 liters of CO2 to the solid phase, in the event of the formation of a cold spot on condensation, the drop in pressure in the secondary space provided by this mechanism alone is 2.5 kPa. Thus, in this example, when the pressure sensor 18 detects a 2.5 kPa drop in pressure, the control unit 10 generates an alarm.

[0093] The amount of gas injected into the secondary space over a period of time exceeds a predetermined threshold amount of gas exhausted over the same period of time. In particular, the buildup of carbon dioxide in the secondary space may be due to the presence of an abnormal cold spot.

[0094] According to various embodiments, examples of preferred gas compositions that may be used to inerte the secondary space are set forth below.

[0095] [Table 1]

[0096] In example 1, the residual species can include atmospheric dioxygen.

[0097] [Table 2]

[0098] In Example 2, the total pressure is below the triple point of argon at 68.7 kPa.

[0099] [Table 3]

[0100] In Example 3, the total pressure is below 13 kPa, which is the triple point of dinitrogen.

[0101] For the gas compositions of Examples 1 to 3, the inerting device with a gas source can be applied in the same manner as the embodiment shown in Figure 1. The gas source needs to be adjusted appropriately based on the desired gas composition. In Example 1, the gas source is a carbon dioxide source, in Example 2, the gas source is an argon source, and in Example 3, the gas source is a dinitrogen source.

[0102] [Table 4]

[0103] In Example 4, the total pressure is subatmospheric.

[0104] [Table 5]

[0105] For the gas compositions in Examples 4 and 5, the inerting apparatus 110 shown in Figure 5 can be used. The same or similar elements are given the same reference numerals as those shown in Figure 1. The inerting apparatus 110 differs from the inerting apparatus 11 shown in Figure 1 in that the gas source 12 is the first gas source, and the inerting apparatus 110 further includes a second gas source 120.

[0106] In Example 4, the first gas source 12 is a carbon dioxide source and the second gas source 120 is a dinitrogen source.

[0107] In Example 5, the first gas source 12 is an argon source and the second gas source 120 is a carbon dioxide source.

[0108] The first main species contained in a first reservoir of the first gas source 12 and the second main species contained in a second reservoir of the second gas source 120 can be injected into the secondary space via one or more supply lines. Furthermore, one or more valves can be arranged in the supply lines 14, for example at the gas outlets of the first gas source 12 and / or the second gas source 120. The flow rate or amount of gas injected via the first gas source 12 or the second gas source 120 can be controlled by the control unit 10, which controls, for example, the valves arranged at the gas outlets of the first gas source 12 or the second gas source 120.

[0109] 3, a cross-section of a vessel 70 shows a sealed, insulated tank 71 having a prismatic overall shape incorporated into the vessel's double hull 72. The wall of the tank 71 has a primary sealing membrane in contact with the liquid hydrogen contained within the tank, a secondary sealing membrane disposed between the primary sealing membrane and the vessel's double hull 72, and two insulating barriers disposed respectively between the primary and secondary sealing membranes, and between the secondary sealing membrane and the double hull 72.

[0110] In a manner known per se, a loading / unloading pipeline 73 installed up deck of the ship can be connected by suitable connectors to an offshore or port terminal for transferring cargoes of hydrogen to and from the tanks 71.

[0111] FIG. 3 shows an example of a marine terminal with a loading / unloading station 75, an underwater pipe 76, and an onshore facility 77. The loading / unloading station 75 is a fixed marine facility including a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 supports a bundle of insulated flexible hoses 79 that can be connected to a loading / unloading pipeline 73. The orientable movable arm 74 is adjustable for any vessel size. Pipes, not shown, extend into the tower 78. The loading / unloading station 75 allows loading and unloading of the vessel 70 from the onshore facility 77 and from the vessel 70 to the onshore facility 77. The onshore facility 77 has a liquid hydrogen storage tank 80 and a connecting pipe 81 that is connected to the loading / unloading station 75 via the underwater pipe 76. The underwater pipe 76 allows the transfer of liquid hydrogen between the unloading station 75 and the onshore facility 77 over long distances, such as 5 km, and enables the tanker 70 to travel far from shore during unloading operations.

[0112] To generate the pressure required for the transfer of liquid hydrogen, pumps on board the vessel 70 and / or pumps provided at the shore facility 77 and / or pumps provided at the loading and unloading station 75 are used.

[0113] The invention also relates to an installation for transferring liquefied gas, preferably liquefied hydrogen. Such an installation can also be considered as a liquefied gas transfer pipe and is known by the so-called term "pipe-in-pipe". Figure 6 shows a cross-section of such an installation (the inerting device is not shown here). Said installation has a vessel formed in the form of a transfer pipe 201, which comprises, from the inside of the installation to the outside of the installation, a primary sealed pipeline 202 intended to contact a liquefied gas, preferably liquefied hydrogen, contained in an internal space of said primary sealed pipeline 202 for transfer, a secondary seal wall 204 located at a certain distance from the outside of said primary sealed pipeline 202 and defining a primary space between said primary sealed pipeline 202 and said secondary seal wall 204, a primary insulating barrier 203 arranged in said primary space, and an outer seal wall 206 located at a certain distance from said secondary seal wall 204 and defining a secondary space between said outer seal wall 206 and said secondary seal wall 204. The installation comprises a wall 206, a secondary insulating barrier 205 and a secondary gas phase disposed in the secondary space (defined between the secondary containment wall 204 and the outer containment wall 206), the outer containment wall 206 being supported by the secondary insulating barrier 205, the installation having an inerting device 11,110 at least temporarily connected to the secondary space so as to maintain and / or arrange the secondary gas phase in the form of a gas composition composed of one or more main chemical species and optionally one or more residual chemical species, the inerting device being configured to maintain the secondary gas phase at a pressure greater than 10 kPa absolute, the partial pressure of each of the main chemical species being lower than the triple point of the main chemical species and the partial pressure of each of the residual chemical species being lower than 0.14 kPa.

[0114] The inerting device 11, 110 is configured to maintain a pressure for the secondary gas phase strictly below 95 kPa absolute.

[0115] The transfer pipe 201 extends over a length L and opens at its end for the transfer of said liquefied gas into the interior of the pipeline 202 and along the transfer pipe 201. The pipeline 202 is intended to transfer the liquefied gas from one end of the transfer pipe 201 to the other end of the transfer pipe 201.

[0116] The inventive principles regarding inerting, as detailed in the embodiment with the tank, apply equally to pipes of the "pipe-in-pipe" type. Inerting is advantageously performed temporarily to bring the secondary gas phase to an appropriate pressure level.

[0117] Advantageously, the secondary space is at an elevated pressure relative to atmospheric pressure. This embodiment is possible due to the fact that the walls of a "pipe-in-pipe" installation have a certain stiffness that allows an elevated pressure to be maintained.

[0118] Although the present invention has been described with reference to some specific embodiments, it is clear that the invention is in no way limited thereto, and that all technical equivalents of the described means and combinations thereof, provided that the conditions are met, are encompassed within the scope of the present invention.

[0119] The use of the terms "to have", "to comprise" or "to include" and their conjugations does not exclude the presence of other elements or steps in addition to those stated in a claim.

[0120] In the claims, any reference signs placed between parentheses shall not be construed as construing as limiting the claim.

Claims

1. Equipment for storing and / or transporting and / or transferring liquefied gas, preferably liquefied hydrogen, wherein the equipment includes a sealed insulated container (1,201), The aforementioned container is A sealed outer wall (2,206) and A secondary sealing membrane (4,204) is located at a distance from the inside of the outer wall (2,206), and the secondary sealing membrane (4,204) defines a secondary space between the outer wall (2,206) and the secondary sealing membrane (4,204), A secondary insulating barrier (3,205) and a secondary gas phase are arranged in the secondary space separated by the outer wall (2,206) and support the secondary sealing membrane (4,204), A primary sealing membrane (6,202) is positioned at a distance from the inside of the secondary sealing membrane (4,204), and is intended to define a primary space between the secondary sealing membrane (4,204) and the primary sealing membrane, and to come into contact with the liquefied gas, preferably liquefied hydrogen, contained in the sealed insulated container. A primary insulating barrier (5,203) is disposed within the primary space and supports the primary sealing membrane (6,202), Equipped with, The apparatus includes deactivators (11, 110) connected to the secondary space such that the secondary gas phase is maintained in the form of a gas composition composed of one or more main chemical species and optionally one or more residual chemical species. The deactivation device is configured to maintain the pressure of the secondary gas phase at an absolute value greater than 10 kPa and strictly less than 95 kPa. The partial pressure of the main chemical species is lower than the triple point of the main chemical species. The partial pressure of the aforementioned residual chemical species is lower than 0.14 kPa. The deactivation device includes at least one gas source (12), the gas source having a gas storage container filled with the main chemical species, or a gas generator capable of producing the main chemical species. The aforementioned equipment further includes, A supply line (14) connected to the gas source (12, 120) and opening into the secondary space, At least one discharge line (8) opening into the secondary space, The apparatus comprises measuring devices (9, 16, 10) capable of measuring the amount of the main chemical species injected into the secondary gas phase through at least one of the supply lines, and the amount of gas discharged from the secondary space through at least one of the discharge lines, and capable of issuing an alarm in response to the detection that the difference between the amount of the main chemical species injected and the amount of gas discharged exceeds a positive threshold.

2. The aforementioned sealed insulated container is a sealed insulated tank, The aforementioned outer wall is a load-bearing structure (2), The secondary thermal barrier (3) is anchored to the load-bearing structure (2). The apparatus according to claim 1.

3. The apparatus according to claim 1 or 2, wherein the gas composition comprises at least one main chemical species selected from the group consisting of dinitrogen, carbon dioxide, and argon.

4. The apparatus according to claim 3, wherein the main chemical species is selected from the group consisting of dinitrogen, carbon dioxide, and argon.

5. The main chemical species includes carbon dioxide, The carbon dioxide comprises at least 33% of the secondary gas phase by volume, preferably at least 89% by volume, and more preferably at least 99.4% by volume. The apparatus according to claim 1 or claim 2.

6. The main chemical species includes argon, The apparatus according to claim 1 or claim 2, wherein the partial pressure of the argon is lower than its triple point, i.e., 68.7 kPa.

7. The apparatus according to claim 6, wherein the argon accounts for at least 50%, preferably at least 99%, of the volume ratio of the secondary gas phase.

8. The main chemical species includes dinitrogen, The apparatus according to claim 1 or claim 2, wherein the partial pressure of the dinitrogen is lower than its triple point, i.e., 12.5 kPa.

9. The apparatus according to claim 1 or 2, wherein the primary space contains a primary gas phase having a pressure lower than the pressure of the secondary gas phase.

10. The apparatus according to claim 1 or 2, wherein the primary space contains a primary gas phase having an absolute pressure lower than 1 Pa.

11. A pressure sensor (18) capable of detecting the pressure in the secondary space, The apparatus according to claim 1 or claim 2, further comprising: an alarm device (10) capable of generating an alarm in response to the detection by the pressure sensor that the pressure of the secondary gas phase is lower than a pressure threshold.

12. The apparatus according to claim 1 or 2, wherein the primary insulating barrier (5) has a plurality of support pillars (25) extending in the thickness direction of the primary insulating barrier (5) to maintain a distance between the secondary sealing membrane (4) and the primary sealing membrane (6).

13. The secondary sealing membrane (4) has a plurality of secondary undulations (24) and a plurality of flat portions located between the secondary undulations. The flat portion is placed on the secondary heat insulating barrier (3), The secondary undulations protrude inside the secondary sealing membrane (4). The apparatus according to claim 1 or claim 2.

14. The deactivation device is A first gas source (12) having a gas storage container filled with the first main chemical species, or a gas generator capable of producing the first main chemical species, A second gas source (120) having a gas storage container filled with a second main chemical species, or a gas generator capable of producing a second main chemical species, The apparatus according to claim 1, having the following features.

15. A method for operating the equipment described in claim 1, The process includes an injection step in which the main chemical species is injected into the gas phase until the secondary gas phase is at a pressure exceeding 10 kPa and strictly below 95 kPa in absolute value. The partial pressure of the main chemical species is lower than the triple point of the main chemical species. An operating method wherein the partial pressure of the residual chemical species is lower than 0.14 kPa.

16. The process further includes the step of discharging the secondary gas phase by connecting a vacuum pump (7) to the discharge line (8) and activating it, The vacuum pump (7) is activated in the step of discharging the secondary gas phase to bring the secondary space to an absolute pressure lower than 10 kPa, preferably lower than 1 kPa. The injection step is performed after the step of discharging the secondary gas phase. The operating method according to claim 15.

17. The operating method according to claim 16, wherein the step of discharging the secondary gas phase and the injection step are repeated.

18. The operating method according to claim 15, wherein the injection step is performed to create a circulation of the secondary gas phase that can renew the secondary gas phase.

19. The operating method according to claim 16, wherein the absolute pressure of the secondary gas phase is lower than 40 kPa in the step of discharging the secondary gas phase and the step of injection.

20. A vessel (70) for transporting liquid gas, preferably hydrogen, The vessel has a double hull (72) and equipment according to claim 1 or claim 2 arranged within the double hull, The aforementioned sealed insulated container is a sealed insulated tank, The aforementioned outer wall is a load-bearing structure (2), The secondary thermal barrier (3) is a vessel (70) moored to the load-bearing structure (2).

21. A system for transferring liquefied gas, preferably liquid hydrogen, The system includes the vessel (70) described in claim 20, Insulated pipelines (73, 79, 76, 81) are arranged to connect the sealed insulated tank (71) installed inside the hull of the ship to a land-based or floating storage facility (77), A pump for driving the flow of liquefied gas, preferably liquid hydrogen, via the insulated pipeline from the onshore or floating storage facility to the sealed insulated tank installed in the hull of the vessel, or from the sealed insulated tank installed in the hull of the vessel to the onshore or floating storage facility, A system equipped with these features.

22. A method for loading onto or unloading a vessel (70) according to claim 20, wherein liquefied gas, preferably liquid hydrogen, is transferred via an insulated pipeline (73, 79, 76, 81) from an onshore or floating storage facility (77) to a sealed insulated tank (71) located within the hull of the vessel, or from the sealed insulated tank (71) located within the hull of the vessel to the onshore or floating storage facility (77).

Images