Gas storage and / or transport tank comprising a projection

Abstract

The invention relates to a tank (1) for transporting and / or storing a first gas, the tank comprising a wall (2) defining a cavity (3), a lower volume (4) of which is intended to contain the first gas in liquid form and an upper volume (5) of which is intended to contain the first gas in gaseous form, wherein the wall (2) comprises an upper portion (9) which contributes to defining the upper volume (5) of the cavity (3), characterised in that the tank (1) comprises a projection (16) positioned outside the cavity (3) and provided with a partition (17) defining an internal space (18), wherein the upper portion (9) of the wall (2) comprises an opening (19) which opens, on the one hand, into the upper volume (5) of the cavity (3) and, on the other hand, into the internal space (18) of the projection (16), wherein the internal space (18) of the projection (16) at least partly contains a device (20) for liquefying the first gas containing a second gas different from the first gas.

Description

[0001]DESCRIPTION Title of the invention: Gas storage and / or transport tank comprising a protrusion. The present invention relates to the field of transporting and storing a liquefied gas, for example, hydrogen. It relates more particularly to installations for a sealed and thermally insulated tank for the storage and / or transport of the liquefied gas. The liquefied gas is transported by sea in sealed and thermally insulated storage tanks installed on transport vessels. The gas is kept in liquid form to increase the quantity of gas transported per tank, the volume occupied by one kilogram of gas in liquid form being much less than the volume occupied by one kilogram of gas in gaseous form.These tanks maintain the liquefied gas at very low temperatures, specifically for hydrogen, below -250°C, the temperature at which hydrogen is in liquid form at atmospheric pressure. The tank has a sealed wall that defines the storage volume of the liquefied gas. This wall is subject to a heat flow that tends to warm the tank's contents, resulting in the evaporation of the liquefied gas. The tank is considered thermally insulating because the structure of the sealed wall is designed to minimize this heat flow and the vaporization of the liquefied gas. The liquefied gas is thus present in the tank in a two-phase liquid-vapor equilibrium.A portion of the liquefied gas is in the vapor phase, forming boil-off gas (BOG) in the upper part of the tank volume. The liquefied gas is primarily in the liquid phase, which extends into the lower part of the tank volume. The goal is to minimize the presence of boil-off gas in the storage tank. Several systems are designed to condense this boil-off gas. Reliquefaction systems, for example, draw the boil-off gas from the tank, cool it using external heat exchangers, and then reintroduce it into the tank. This process requires a significant amount of energy because the boil-off gas heats up as it exits the tank.There are also subcooling systems that work by recovering liquid gas from the tank, subcooling it, and then spraying it onto the vapor gas inside the tank to cool and liquefy it. For example, the liquefied gas in liquid phase is pumped from the bottom of the tank, subcooled outside the tank, and then directed to spray nozzles located against the upper wall, which spray the gas into the upper part of the tank where the vapor gas resides. This system also requires high energy consumption because, during the extraction of the liquid gas by the pumps, a significant amount of heat is injected into the liquid gas, requiring a greater subcooling effort. The invention falls within this context and aims to offer an alternative to these systems by presenting a tank comprising a compartment for the transport and / or storage of a gas.This tank is equipped with a protrusion positioned outside the tank housing and in fluidic communication with said housing. The protrusion contains, in particular, a liquefaction device that liquefies the gas located in the upper part of the tank in gaseous form, while consuming less energy than traditional systems described in the prior art.The present invention thus has as its main object a tank for the transport and / or storage of a first gas, comprising a wall delimiting a compartment whose lower volume is intended to contain the first gas in liquid form and whose upper volume is intended to contain the first gas in gaseous form, the wall having an upper part participating in delimiting the upper volume of the compartment, characterized in that said tank includes a protrusion positioned outside the compartment and provided with a partition delimiting an internal space, the upper part of the wall comprising an opening leading on the one hand into the upper volume of the compartment and on the other hand into the internal space of the protrusion, the internal space of the protrusion containing at least in part a device for liquefying the first gas containing a second gas different from the first gas.The first gas transported and / or stored in the tank is typically a gas with a very low boiling point, often at temperatures expressed in negative degrees Celsius, such as dihydrogen. During transport and / or storage, this first gas is predominantly in liquid form within the tank cavity. However, heat transfer occurs through the tank wall, which can warm the first gas and cause it to partially vaporize. It is therefore important to note that within the tank cavity, the first gas exists in both liquid and gaseous states. Due to gravity, the first gas in liquid form remains at the bottom of the cavity, referred to as the lower cavity volume, while the first gas in gaseous form occupies the top of the tank, designated as the upper cavity volume.It is understood that, depending on the quantity of gas in gaseous and liquid form, the lower and upper volumes fluctuate. As will become apparent from the description of the invention, the objective is to control the pressure rise in the tank, which cannot reach a high pressure (typically a maximum pressure of around 2 bar) through reliquefaction of the evaporated gas or its consumption, while simultaneously limiting the energy consumption associated with managing the evaporated gas, i.e., the gas in its gaseous form. In other words, the invention aims to enable the delivery of a maximum amount of gas in liquid form while ensuring minimal energy consumption for processing the gas in its gaseous form. When the tank is rectangular in shape, the tank wall comprises an upper partition, an opposing lower partition, and lateral partitions connecting the lower partition to the upper partition.It is thus understood that, depending on the upper volume of the housing, the upper part of the wall comprises the top partition and a more or less substantial upper portion of the side partitions. The same reasoning applies to a prismatic tank. The upper part of the wall includes an internal surface in contact with the first gas in its gaseous form, delimiting the upper volume of the housing. It also includes an external surface opposite the internal surface and at least partially in contact with the environment outside the tank. It is on this external surface that the protrusion is located; the protrusion is therefore outside the tank housing. The protrusion is positioned to encircle the opening in the upper part of the wall.More specifically, it is the bulkhead that covers the opening, thus allowing communication between the internal space of the protrusion and the tank housing via this opening. As a result, the first gas, in its gaseous form, can pass from the upper volume of the housing to the internal space of the protrusion. The liquefaction device, located within the internal space of the protrusion, contains a second gas whose boiling point is lower than or equal to that of the first gas. For example, if the first gas is dihydrogen, the second gas could be helium, as the normal boiling point of dihydrogen is -252.8°C and the boiling point of helium is -268.9°C. In this example, the liquefaction temperature of dihydrogen being between -250.24 °C and -252.83 °C, the temperature of the cold source can be between -252 °C and -259 °C, preferably between -255 °C and -259 °C.This liquefaction device cools and liquefies the first gas in its gaseous state within the protrusion, converting it into a liquid first gas. Once liquefied, the gas can return by gravity to the tank housing through the existing opening or another designated opening. The protrusion allows the first gas liquefaction process to be located outside the tank. This, for example, reduces the exposure of the heat exchange components involved in this liquefaction to the movement of the liquid first gas within the tank. It also provides a protected location, preventing the heat exchange components from being overly sensitive to ambient temperatures, thus helping to limit energy consumption related to managing the gaseous first gas within the tank.According to an optional feature of the invention, the liquefaction device comprises a heat exchange surface disposed within the internal space of the protrusion. This heat exchange surface allows heat exchange between the first gas and the second gas and therefore constitutes the part of the liquefaction device that enables the liquefaction of the first gas. The heat exchange surface is thus positioned within the internal space of the protrusion, which allows heat exchange when the first gas, in its gaseous form, occupies this internal space. The first gas, in its gaseous form, upon contacting the heat exchange surface, can thus transfer heat. The first gas, having released heat, liquefies and can fall by gravity into the internal space of the protrusion before being discharged and falling back into the tank housing.To be evacuated from the internal space of the protrusion, the first gas can be guided by a manifold leading it to the opening or another opening provided for this purpose. The manifold can, for example, consist of an inclined plane. According to an optional feature of the invention, the liquefaction device includes a circulation duct for the second gas, the heat exchange surface being at least partially defined by an external peripheral surface of the circulation duct. The external peripheral surface is a surface opposite an internal area of ​​the circulation duct, this internal area, or peripheral surface, of the duct being the surface of the circulation duct in contact with the second gas circulating within this duct. The external peripheral surface, for its part, is in contact with the first gas in gaseous form present in the internal space of the protrusion.Thus, when the first gas is in contact with the outer peripheral surface and the second gas is in contact with the inner zone, heat transfer occurs between the first and second gases via these surfaces. The second gas then absorbs heat, tends to evaporate, and subsequently circulates through the liquefaction device, while the first gas liquefies. According to an optional feature of the invention, the outer peripheral surface area of ​​the circulation pipe is between 20 and 100 m². These values ​​for the outer peripheral surface area allow for efficient cooling and liquefaction of the first gas for a given flow rate of evaporated gas generated by the heat inputs into the tank. By way of non-limiting example, an outer peripheral surface area of ​​the circulation pipe between 20 m² and 100 m² is particularly effective for liquefying 90 kg / h of evaporated gas.To increase the heat exchange surface area between the first and second gases, the circulation duct can be designed with sinuous or spiral shapes. This increases the external peripheral surface area of ​​the circulation duct within the protrusion, thereby improving the liquefaction of the first gas. Alternatively or additionally, the heat exchange surface area between the first and second gases can be increased by internal or external fins positioned at the heat exchange surface. According to an optional feature of the invention, the opening forms a single means of communication between the protrusion's internal space and the tank housing.In other words, the opening allows the first gas, in its gaseous form, to pass from the upper volume of the housing to the internal space of the protrusion in one direction, and in the other direction, the first gas, in its liquid form following liquefaction within the protrusion, to pass from the internal space of the protrusion back to the upper volume of the housing. Thus, the first gas, once liquefied by the liquefaction device, can pass back through the same opening through which it previously passed in its gaseous state. This simplifies the protrusion's configuration, as only one opening is needed for these exchanges. Optionally, the opening includes a tube, which protrudes into the internal space of the protrusion. In this case, the first gas, liquefied by the liquefaction device, passes through the space formed between the opening and this tube.The first gas in gaseous form from the tank housing is not impeded by the flow of the first liquefied gas. In an alternative embodiment of the invention, the first gas liquefied by the liquefaction device is discharged from the internal space of the protrusion through a passage in the upper part other than the opening. According to an optional feature of the invention, the protrusion includes a first gas discharge pipe passing through the protrusion's partition. This discharge pipe manages the evacuation of excess first gas from the internal space of the protrusion, thus helping to maintain a certain pressure within the tank. The first gas discharged through this discharge pipe can then be used for other applications.It can, for example, be burned to recover energy or for other industrial processes, such as powering ship propulsion engines or electric generators. According to an optional feature of the invention, the tank includes a vacuum bell covering the protrusion and hermetically sealed to the upper part of the wall. By covering the protrusion, the vacuum bell helps prevent heat transfer between the environment outside the tank and the internal space of the protrusion, thus preventing the liquefaction of oxygen from the ambient air. This prevents the protrusion from heating up, thereby reducing the amount of energy required to cool and liquefy the second gas. Consequently, the presence of the vacuum bell improves the efficiency of the liquefaction device. According to an optional feature of the invention, the vacuum bell is welded to the upper part of the wall.This weld ensures a seal between the vacuum bell and the wall. In other words, this weld prevents exchanges between the interior and exterior spaces of the bell, thus isolating the protrusion from the external environment. The vacuum bell can be equipped with means to reinforce the weld, such as a welding collar. This welding collar strengthens the joint between the vacuum bell and the upper part of the wall. According to an optional feature of the invention, the drain pipe passes through the vacuum bell. When a vacuum bell is used, the drain pipe therefore passes through the protrusion's partition and through the vacuum bell. This configuration thus allows for the evacuation of excess first gas and the regulation of excessive pressure in the internal space of the protrusion, even when a vacuum vessel covers the protrusion.According to an alternative embodiment of the invention, the liquefaction device is at least partially integrated into the bulkhead of the protrusion. According to an optional feature of the invention, the liquefaction device includes a means for cooling the second gas, the cooling means being positioned outside the protrusion. The cooling means may, for example, be part of a refrigeration cycle for the second gas. In the case of a reverse Brayton cycle, the cooling means may, for example, include an expansion valve, a compressor, and piping. According to an alternative embodiment of the invention, the cooling means is at least partially integrated into the bulkhead of the protrusion. According to an optional feature, the liquefaction device includes an additional heat exchanger disposed within the internal space of the protrusion.According to an optional feature of the invention, the opening and the discharge pipe are aligned to form a flow path for the first gas within the protrusion. In this case, the liquefaction device is positioned away from this flow path. It should be noted that the protrusion allows for three operating modes: a BOG subtraction mode in which all of the first gas passing through the protrusion is discharged through the discharge pipe; a liquefaction mode in which all of the first gas is liquefied; and a hybrid mode in which part of the first gas is liquefied by the liquefaction device and another part is discharged through the discharge pipe. The flow path corresponds to the path of the first gas when the protrusion is in BOG subtraction mode.When the protrusion is in hybrid or liquefaction mode, all or part of the first gas is diverted from the gas flow path by cryopumping the first gas using the liquefaction device. It is important to understand here that the term "off-center" means that the liquefaction device is located at a distance from the first gas flow path. In other words, the liquefaction device is not positioned directly in line with this flow path, but rather offset from it. This flow path can be represented by an axis passing approximately through the opening and the discharge pipe. The liquefaction device is therefore positioned near this axis, but without being interposed between the opening and the discharge pipe.In other words, the liquefaction device is positioned at the periphery of the flow path, that is, at the periphery of the axis passing through the opening and the discharge pipe. As a non-limiting example, the protrusion may extend laterally relative to the flow path of the first gas. The protrusion then extends primarily in at least one direction perpendicular to the axis passing through the opening and the discharge pipe, thus forming a peripheral zone of the protrusion's internal space that is offset from the axis. The flow path does not pass through this peripheral zone, and the liquefaction device is therefore positioned within this peripheral zone, so as to be offset from the flow path.In another example, the liquefaction device can be arranged in an annular fashion around the axis passing through the opening and the discharge pipe, thus keeping it clear of the flow path. In each of these examples, it should be noted that the flow path can be at least partially calendered to optimize gas guidance within it. Because of this clear arrangement, the liquefaction device does not disrupt gas flow when the protrusion is operating in BOG subtraction mode. Therefore, the discharge pipe can extract the evaporation gas from the tank without constraint. In hybrid or liquefaction mode, all or part of the initial gas flow is diverted to the liquefaction device.For example, the first gas can be diverted annularly when the liquefaction device is arranged in an annular configuration, or it can be diverted to a peripheral area when the liquefaction device is located in such a peripheral area within the internal space of the protrusion. As a non-limiting example, the liquefaction device can be positioned at a distance of between 10 centimeters and several tens of centimeters, for example, one meter, from the traffic lane. The minimum value within this range is determined so that the main gas flow lines do not pass through the liquefaction device, and the maximum value within this range is determined so that the return of the liquid to the tank after liquefaction is straightforward. It should be noted that the distance value can be advantageously chosen, particularly within this range, depending on the height of the protrusion.According to an optional feature of the invention, the upper part of the wall comprises a gas dome with a passage defining an escape route for the first gas in vapor form. The internal space of the protrusion is configured so that the heat exchange surface of the liquefaction device is positioned away from the first gas escape route. The gas dome can also be equipped with a tube for transferring the first gas, in liquid form, to or from the tank housing. By defining an escape route for the first gas in vapor form, the passage facilitates the evacuation of this first gas in the event of overpressure in the tank housing. It should be understood that the first gas escape route corresponds to the path the gas follows when it is evacuated through the passage.Regarding the protrusion's arrangement, it can be positioned to cover the gas dome passage; in this case, the opening in the upper part of the wall coincides with the passage. Thus, the first gas's exhaust path extends between the exhaust pipe and this passage, which corresponds to the first gas's flow path within the protrusion. The heat exchange surface of the liquefaction device is then positioned so as not to obstruct this exhaust path. The protrusion can also be installed away from the gas dome. If this is the case, the passage and the opening are two separate openings. The protrusion's arrangement thus ensures that the liquefaction device is positioned away from the gas exhaust path. According to an optional feature of the invention, the protrusion is welded to the upper part of the wall.The weld then allows the protrusion's partition to be hermetically sealed to the upper part of the wall. According to an optional feature of the invention, the protrusion includes a welding flange. The welding flange thus reinforces the weld of the protrusion to the upper part of the wall. According to another optional feature of the invention, the first gas discharge pipe and the second gas circulation pipe pass through the protrusion's partition on the same portion of the partition. Other features, details, and advantages of the invention will become clearer upon reading the following description, on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings, on the other hand, in which: [Fig. 1] is a cross-sectional view of a tank used for the transport and / or storage of a first gas and comprising a first embodiment of a protrusion. [Fig.[Fig. 2] is a cross-sectional view of the protrusion according to the first embodiment. [Fig. 3] is a cross-sectional view of a second embodiment of the protrusion. [Fig. 4] is a cross-sectional view of a third embodiment of the protrusion. [Fig. 5] is a cross-sectional view of a fourth embodiment of the protrusion. [Fig. 6] is a cross-sectional view of a fifth embodiment of the protrusion. The features and variants of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive.Variants of the invention may include only a selection of the features described below, isolated from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art. In the figures, elements common to several figures retain the same reference numeral. Figure 1 is a cross-sectional view of a tank 1 used for the transport and / or storage of a first gas and comprising a first embodiment of a protrusion 16. The first gas may be of any type that exists in gaseous and liquid forms. Dihydrogen is particularly used as the first gas, although other applications of the tank, for example with liquefied natural gas, are also conceivable. The tank 1 includes a wall 2 that delimits a compartment 3.It is important to understand that compartment 3 corresponds to an internal void within tank 1, designed to contain the first gas. Wall 2 therefore serves to form this internal void by delimiting compartment 3. Within this compartment 3, the first gas can be present in different states. It is initially stored in tank 1 in liquid form, but due to a heat flow at wall 2 that tends to cause the first gas to evaporate, the first gas is present in compartment 3 in both liquid and gaseous forms. Compartment 3 comprises a lower volume 4, where the first gas is in liquid form, and an upper volume 5, where the first gas is in gaseous form. Indeed, under the effect of gravity, the first gas in liquid form naturally remains in the lower volume 4, which can be considered the lower part of compartment 3.Simultaneously, the first gas in its gaseous form will occupy the portion of housing 3 not filled by the liquid gas and therefore naturally remains in the upper volume 5, which can be considered the upper part of tank 1. The dimensions, and in particular the height of each volume, vary according to the quantity of first gas in its liquid form and thus the additional quantity of first gas in its vapor form. Within the wall, we can therefore distinguish an upper part 9 and a lower part 10, separated from each other by the liquid gas's flotation surface. More specifically, the wall 2 comprises an upper partition 6, a bottom partition 7, and side partitions 8. The bottom partition 7, located opposite the upper partition 6, forms the floor of tank 1. The upper partition 6, in turn, forms the ceiling of tank 1. The side partitions 8 connect the upper partition 6 to the bottom partition 7.Thus, when tank 1 is placed on a flat, horizontal surface, the bottom partition 7 and the top partition 6 are substantially horizontal, while the side partitions 8 are substantially vertical. It should therefore be understood that the upper part 9 of wall 2 comprises the top partition 6 and an upper portion of the side partitions 8, in contact with the first gas in its gaseous form. Similarly, the lower part 10 of wall 2 comprises the bottom partition 7 and another portion of the side partitions 8, the bottom partition 7 and this other portion of the side partitions 8 being in contact with the first gas in its liquid form. Wall 2 of tank 1 comprises an internal surface 11 and an external surface 12. The internal surface 11 is the one that delimits the housing 3; it is thus located inside tank 1. The external surface 12 is the one that delimits the exterior of tank 1 and is therefore in contact with an environment external to tank 1.It is therefore important to understand that the upper part 9 and the lower part 10 of the wall 2 each comprise a portion of the inner surface 11 and a portion of the outer surface 12. Thus, the upper part 9 of the wall 2 is in contact with the first gas, when it is in its gaseous phase, via the inner surface 11, and the lower part 10 is also in contact with the first gas, when it is in its liquid form, via the inner surface 11. The tank 1 is equipped with a gas dome 13 located in the upper part 9 of the wall 2 of the tank 1, more precisely in the ceiling 6 of the wall 2. This gas dome 13 contains a passage 15 allowing the first gas in gaseous form to be discharged from the housing 3 of the tank 1. The gas dome 13 also includes a pipe 14 allowing the first gas in liquid form to be supplied to or discharged from the housing 3 of the tank 1.This tube 14 extends from the outside of the tank 1 to the lower volume 4 of the housing 3, passing through the gas dome 13. The tank 1 according to the invention has a protrusion 16, which is disposed in contact with the external surface 12 of the upper part 9. The protrusion 16 is therefore not located inside the housing 3 but outside of it. Since it is positioned on the external surface 12 of the upper part 9, the protrusion 16 can be located either on the upper partition 6 or on the upper portion of the side partitions 8 in contact with the first gas in gaseous form. In the embodiment illustrated in Figure 1, the protrusion 16 is arranged on the upper partition 6. The protrusion 16 is hollow and includes a partition 17 which defines an internal space 18. The internal space 18 of the protrusion 16 is in fluidic communication with the housing 3 of the tank 1.For this purpose, the upper part 9 includes an opening 19, the partition 17 of the protrusion 16 being arranged so that the protrusion 16 covers this opening 19. "Fluidic communication" is understood to mean that the first gas can flow between the upper volume 5 of the housing 3 of the tank 1 and the internal space 18 of the protrusion 16 (in gaseous form) and between the internal space 18 of the protrusion 16 and the housing 3 of the tank 1 (in liquid form). Further details will be provided in the description of the following figures. The tank 1 also includes a liquefaction device 20 for the first gas, which is positioned at least partially within the internal space 18 of the protrusion 16.The role of this liquefaction device 20 is to liquefy the first gas in its gaseous form present in the internal space 18 of the protrusion 16, so that it becomes liquid again and returns, by gravity, to the lower volume 4 of the housing 3 via the opening 19. Liquefaction occurs through heat exchange with the portion of the liquefaction device 20 located in the internal space 18 of the protrusion 16, that is, the portion of the device 20 in direct contact with the first gas in its vapor form. Figure 2 is a cross-sectional view of the protrusion 16 according to the first embodiment. In this embodiment, the protrusion 16 is parallelepiped-shaped. The partition 17 of the protrusion 16 thus comprises an upper panel 21, a lower panel 37, and side panels 22.When the tank 1 is positioned on a flat, level surface, the upper panel 21 is horizontal and the side panels 22 are arranged vertically. The upper panel 21 and the lower panel 37 constitute the upper and lower faces, respectively, while the side panels 22 form the lateral faces of the parallelepiped. It should be noted that this configuration of the protrusion 16 is not limiting and that other shapes are also possible, for example, a cylindrical protrusion incorporating at least part of the liquefaction device 20 arranged in an annular fashion within said protrusion. The side panels 22 are in contact with the external surface 12 of the upper part 9 of the wall 2. These side panels 22 are arranged all around the opening 19 so that the entire partition 17 of the protrusion 16 surrounds said opening 19.To ensure a secure attachment, these side panels 22 can be welded to the external surface 12 and fitted with flanges 23 that form a base for the side panels 22 and reinforce the weld with the wall 2. However, the protrusion is not necessarily fixed or welded to the upper part 9 of the wall 2. Only a fluid connection between the protrusion and the tank is required. For example, the protrusion can be arranged around a flow channel extending hermetically from the opening 19 without forming physical contact with the upper part 9 of the wall 2. Indeed, the function of the protrusion is to protect the liquefaction device 20 from sloshing (charge sloshing) in the tank while ensuring vapor circulation and liquid return to the tank without an additional circulation system (such as a compressor or pump).The lower panel 37 includes an opening 38 positioned to correspond with the opening 19 in the upper part 9 of the wall 2, thus forming a common passage from the internal space 18 of the protrusion 16 to the upper volume 5 of the housing 3 of the tank 1. In this embodiment, the protrusion 16 is covered by a vacuum bell 25. The vacuum bell 25 here comprises an upper enclosure wall 261 and side enclosure walls 262 including flanges 263 by which said bell 25 is brought into contact with the external surface 12 of the upper part 9 of the wall 2. These side enclosure walls 262 are arranged parallel to and at a distance from the side panels 22 of the partition 17 of the protrusion 16, and the upper enclosure wall 261 is arranged parallel to and at a distance from the upper panel 21 of the partition 17 of the vacuum bell. of this one.In this way, the vacuum bell 25 covers the protrusion 16. The vacuum bell 25 is hermetically sealed to the upper part 9 of the wall 2 by welding its flanges 263 to the external surface 12 of the upper part 9. The vacuum bell 25 thus delimits a vacuum space around the protrusion 16, isolating it from the external environment and allowing for more efficient liquefaction of the first gas by preventing ambient air from heating the side panels 22 and the upper panel 21 of the partition 17. The protrusion 16 includes a first gas vent 27, allowing the first gas not liquefied by the liquefaction device 20 to escape from the internal space 18 of the protrusion 16. This first gas can then be used for various applications.The exhaust pipe 27 is positioned to pass through the upper panel 21 of the partition 17 of the protrusion 16 and the upper enclosure wall 261 of the vacuum bell 25, in order to allow the first gas to be exhausted in gaseous form beyond the vacuum bell. The liquefaction device 20 includes a circulation duct 28 for a second gas. This second gas is preferably a gas having a lower liquefaction point than the first gas, for example, helium when the first gas is dihydrogen. Through the circulation of the second gas within the liquefaction device 20, the circulation duct 28 of the liquefaction device 20 helps to form a heat exchange surface 29 between the first and second gases. It is thus understood that the heat exchange surface 29 is composed of parts of the liquefaction device 20 which are arranged in the internal space 18 of the protuberance 16.The circulation pipe 28 is partially located within the internal space 18 of the protrusion 16. The remainder of the liquefaction device 20 is positioned outside the internal space 18 of the protrusion 16. Since the circulation pipe 28 is, in this embodiment, the only part of the liquefaction device 20 located within the internal space 18 of the protrusion 16, it should be understood that the circulation pipe 28 alone forms the heat exchange surface 29. More precisely, the circulation pipe 28 has a cylindrical shape and thus comprises an external peripheral surface opposite an internal peripheral surface. The external peripheral surface is in contact with the first gas, while the internal peripheral surface is in contact with the second gas circulating within the circulation pipe 28.The outer and inner peripheral surfaces cooperate to form the heat exchange surface 29 of the liquefaction device 20. In this way, the first gas transfers its heat to the outer peripheral surface, and the heat is then transferred to the inner peripheral surface, where it is transferred to the second gas. As a result of this heat transfer, the first gas liquefies, while the second gas absorbs heat, thus increasing its temperature. The circulation pipe 28 can adopt different shapes, such as a spiral shape, to increase its outer peripheral surface area and the inner peripheral surface area within the internal space 18 of the protrusion 16. This shape increases the heat exchange surface 29 of the liquefaction device 20 between the first and second gases, thereby enabling more efficient liquefaction of the first gas.The circulation line 28 may also include internal and / or external fins to increase the heat exchange surface area between the first and second gases. Preferably, the external peripheral surface area of ​​the circulation line 28 is between 20 and 100 m². It should be noted that these figures are given as a non-limiting example. In this example, to liquefy 90 kg / h of hydrogen BOG at saturation at 1.1 bar, 11.2 kW of cooling is required. Using helium as the second gas in a Brayton cycle with 2 bar at low pressure (-259°C at the tank inlet) and a minimum pinch-off of 2°C with the first gas to be liquefied (hydrogen), and with the second gas flowing through 20 mm external diameter stainless steel circulation lines, 40 m² of heat exchange surface area is required.Alternatively, the liquefaction device 20 may include a heat exchange surface located at the level of the protrusion's partition 17. In this case, the heat exchange surface is integrated into the protrusion's partition. The liquefaction device 20 includes a cooling means 31 for the second gas, which is part of a second gas refrigeration cycle. In this embodiment, the second gas cooling means 31 is positioned outside the protrusion 16 and also outside the vacuum bell 25. This cooling means 31 is connected to the second gas circulation line 28. The cooling means 31 is shown schematically and, in the case of a reverse Brayton cycle, may include, but is not limited to, an expansion valve, a compressor, and piping.The circulation pipe 28 thus passes through the vacuum bell 25 and the partition 17 of the protrusion 16, to be partially present in the internal space 18 of the protrusion 16 and able to cooperate with the cooling means outside the vacuum bell. More specifically, the circulation pipe 28 passes through two openings in the vacuum bell 25 and two openings in the partition 17 of the protrusion 16 in order to connect to the cooling means 31. In this embodiment, the circulation pipe 28 passes through the partition 17 of the protrusion 16 on its upper panel 21, that is to say, on the same portion of the partition 17 where the drain pipe 27 passes through said partition 17. Furthermore, the circulation pipe 28 passes through the vacuum bell 25 on its upper enclosure wall 261.The protrusion 16 according to the invention allows for three operating modes, including a "BOG subtraction" mode, a liquefaction mode, and a hybrid mode. In the "BOG subtraction" mode, all of the first gas passing through the protrusion 16 is discharged through the discharge pipe 27. In this mode, the liquefaction device 20 is not in operation. The first gas, in vapor form, then passes through the opening 19, then through the internal space 18, and is discharged through the discharge pipe 27 without being significantly cooled. The liquefaction device 20 is activated if the hybrid mode or the liquefaction mode is used. In the hybrid mode, part of the first gas is liquefied by the liquefaction device 20 and another part is discharged through the discharge pipe 27. In the liquefaction mode, all of the first gas is liquefied.It should be noted that the opening 19 in the upper part 9 of the wall 2 is aligned with the first gas discharge pipe 27. This arrangement then forms, when the protrusion 16 is in BOG subtraction mode, a flow path 35 for the first gas through the internal space 18 of the protrusion 16, which is direct, from the opening 19 to the discharge pipe 27. This flow path 35 therefore represents the way in which the first gas moves predominantly within the internal space 18 of the protrusion 16 when the protrusion 16 is in BOG subtraction mode. In this embodiment, the protrusion 16 extends laterally with respect to this flow path 35 for the first gas. It is understood from this that the protrusion 16 extends predominantly in at least one direction perpendicular to the flow path 35 for the first gas.The liquefaction device 20, and more specifically the portion of the circulation pipe 28 housed in the internal space 18, is thus positioned away from this circulation path 35. It is understood that in the case where the protrusion 16 is cylindrical, the opening 19 and the discharge pipe 27 can be centered on the axis of revolution of the protrusion, and the portion of the circulation pipe 28 present in the internal space is positioned against the annular wall, so that this annular arrangement places the portion of the circulation pipe 28 present in the internal space away from this circulation path 35. Positioning the liquefaction device 20 away from the circulation path 35 implies diverting the first gas that one wishes to liquefy when said device is in operation.In liquefaction or hybrid mode, the liquefaction device 20 is activated, which attracts the first gas in gaseous form by cryopumping and diverts it from the flow path 35. In hybrid mode, the flow rate of the second gas associated with the liquefaction device 20 is adjusted so that only a fraction of the first gas is attracted by cryopumping and liquefied upon contact with the portion of the flow path 28 present in the internal volume 18. Thus, a fraction of the first gas is liquefied and a fraction of the first gas is discharged through the discharge pipe 27. The flow rate of the second gas is set between a first threshold value, below which the first gas is not diverted from the flow path 35, and a second threshold value beyond which it must not go if only partial diversion of the first gas is desired.Indeed, the flow rate of the second gas determines the power of the system and therefore the flow rate of the first liquefied gas. It should be noted that for a given system power, the temperature at which the second gas operates defines the heat exchange surface area required to liquefy a certain flow rate of the first gas. As a non-limiting example, when the first gas is dihydrogen, its temperature will be below -251°C and advantageously between -252.8°C (the liquefaction temperature of dihydrogen at a pressure of 1 atm) and -259.2°C (the triple point of dihydrogen). It is worth noting that maintaining a low temperature for the second gas, i.e., relatively close to -259.2°C, avoids the need to significantly increase the flow rate of the second gas.In liquefaction mode, all of the first gas is diverted from the flow path 35 to the liquefaction device 20 for liquefaction. For this purpose, the liquefaction device 20 operates at a flow rate exceeding the second threshold value. To aid the liquefaction of all of the first gas, the discharge line 27 may include a blocking means preventing the first gas from escaping from the protrusion 16 through this line 27. This blocking means may be an on / off valve, i.e., in the open or closed position depending on the operating mode. In liquefaction mode, the blocking means is in the closed position. In BOG subtraction mode, the blocking means is in the open position, and there is no flow of the second gas into the liquefaction device.In hybrid mode, the blocking means is in the open position, and a Boil-Off Gas (BOG) compressor of the liquefaction unit 20 controls the flow rate drawn from the tank. In other words, in hybrid mode, the flow rate of the first liquefied gas is controlled by the flow rate of the second gas in the liquefaction unit 20. It is therefore understood that the operating mode implemented by the protrusion 16, associated with the operation of the BOG compressor, is dictated by the flow rate of the second gas in the liquefaction unit 20, as well as by the blocking means when the discharge line 27 includes one. The lower panel 37 includes a first face 39 in contact with the external surface 12 of the upper part 9 of the wall 2 and a second face 40 partially delimiting the internal space 18 of the protrusion 16. The first face 39 is horizontal when the tank 1 is positioned on a flat and horizontal floor.The second face 40 is inclined relative to the first face 39 and is therefore also inclined relative to the external surface 12 of the upper part 9 of the wall 2 when the tank 1 is placed on a flat, horizontal surface. It should be understood that the inclination of the second face 40 relative to the first face 39 is due to a variation in the thickness of the lower panel 37, the thickness of the lower panel 37 being greater at the junction of this lower panel 37 with the side panel 22 than at the orifice 38. The lower panel 37 allows, when the first gas is liquefied in hybrid mode or in liquefaction mode and the first gas in liquid form falls by gravity onto the lower panel 37, this first gas in liquid form to be directed by the inclination of the second face 40 of the lower panel 37 towards the common passage formed by the orifice 38 and the opening 19.This first gas, having returned to liquid form under the effect of the liquefaction device and flowing under the effect of gravity towards the orifice 38, is thus evacuated from the internal space 18 of the protrusion 16 by passing through the common passage before falling into the lower volume 4 of the housing 3 of the tank 1. The orifice 38 can be delimited by a collar 41 which extends substantially perpendicularly from the lower panel 37 projecting from the first face 39, the collar 41 being intended to come into contact with a wall of the tank delimiting the opening 19. In this way, the first gas which flows by gravity into the common passage cannot pass between the lower panel 37 and the external surface 12 of the upper part 9 of the wall 2, thus avoiding sealing problems and potential losses of the first gas. Regarding the gas dome 13, its passage 15 defines an evacuation route 36 for the first gas.In this embodiment, the opening 19 in the upper part 9 of the wall 2 and the passage 15 of the gas dome 13 are two distinct passages in the wall 2. Since the passage 15 delimits the exhaust path 36 of the first gas and the opening 19 delimits the flow path 35 of the first gas, it is understood that these are two distinct paths through which the first gas flows. Figure 3 is a cross-sectional view of a second embodiment of the protrusion 16. In this embodiment, the protrusion 16 also includes a liquefaction device 20 positioned partly within its internal space 18. Furthermore, the liquefaction device 20 also includes a flow channel 28 which, by virtue of its external peripheral surface, forms part of the heat exchange surface 29 between the first gas and the second gas.In this embodiment, the liquefaction device 20 includes an additional heat exchanger 34, shown schematically in this figure. This additional heat exchanger 34, through which the second gas also circulates, is located in the internal space 18 of the protrusion 16 and is connected to the cooling means 31. Thanks to this feature, the heat exchange surface 29 of the liquefaction device 20 is no longer solely formed by the circulation line 28, as in the case of the second embodiment, but is composed of the circulation line 28 and the additional heat exchanger 34. Indeed, the additional heat exchanger contributes to liquefying the first gas in the internal space 18, since it is in contact with this first gas. The remaining features of this second embodiment are similar to those of the first embodiment.Figure 4 is a cross-sectional view of a third embodiment of the protrusion 16. In this embodiment, a guide tube 42 is arranged within the opening 19. The guide tube 42 is a cylinder whose diameter is less than the diameter of the opening 19. This guide tube 42 extends within the opening 19 over the entire thickness of the upper part 9 of the wall 2, and protrudes into the internal space 18 of the protrusion 16. It should be understood from the fact that the guide tube 42 protrudes into the internal space 18 that it extends between a first end, turned towards the tank and which can be flush with the internal surface 11 of the upper part 9 of the wall 2, and a second end, turned towards the protrusion and which extends beyond the second face 40 of the lower panel 37 of the protrusion.In this way, the first gas, in its gaseous form, which rises into the protrusion, passes mainly inside the guide tube 42, while the first gas, having returned to its liquid form following liquefaction within the protrusion, flows along the walls delimiting the opening 19. It is therefore understood that the first liquefied gas flows by gravity into the opening 19 around the guide tube 42, which prevents the return of the first gas in its liquid form by gravity from disrupting the path of the first gas as it passes from the upper volume 5 to the internal space 18 of the protrusion 16. The remaining characteristics of this third embodiment are similar to those of the first embodiment. Figure 5 is a cross-sectional view of a fourth embodiment of the protrusion 16.In this embodiment, the protrusion 16, in addition to being positioned to cover the opening 19, is also positioned to cover a hole 43 that passes through the upper part 9 of the wall 2, separate from the opening 19. The through hole 43 allows fluid communication between the internal space 18 of the protrusion 16 and the upper volume 5 of the housing 3. For this purpose, the lower panel 37 of the protrusion 16 includes, in addition to the orifice 38 that forms a common passage with the opening 19, a supplementary hole 44 which, together with the through hole 43, forms another common passage from the internal space 18 to the upper volume 5. The supplementary hole 44 and the through hole 43 are positioned substantially below the liquefaction device 20, so that when the first gas is liquefied, it falls back down by gravity towards the common passage formed by the supplementary hole. 44 and the hole going through 43.It is therefore understood that these two holes 44 and 43 are used primarily to drain the first liquefied gas from the internal space 18 to the housing 3, while the orifice 38 and the opening 19 are used to supply the protrusion 16 with the first gas in gaseous form from the housing 3. The common passage formed by the complementary hole 44 and the through hole 43 has a diameter that is significantly smaller than the diameter of the common passage formed by the opening 19 and the orifice 38. In this way, the upward flow of gas through the through hole 43 of the first gas in gaseous form is limited, thus preventing disturbance of the first liquefied gas flowing through it. Furthermore, the large diameter of the common passage formed by the opening 19 and the orifice 38 helps to limit the pressure drop of the first gas in gaseous form as it passes from the housing 3 to the internal space 18.Alternatively, the supplementary hole 44 and / or the through hole 43 can be fitted with a liquid seal with a siphon to prevent the first gas in gaseous form from passing from the housing 3 to the internal space 18 through these holes 44, 43. The presence of this additional passage, formed by the complementarity of the through hole 43 and the supplementary hole 44, can be particularly useful when, alternatively, the supply of the first gas in gaseous form from the housing 3 to the protrusion 16 is provided by a supply system located on one of the side panels 22 and replacing the function of the opening 19 and the orifice 38. In this context, the gravity discharge of the first gas, which has returned to a liquid state through liquefaction, is made possible by the presence of the additional passage.Unlike the lower panel 37 of the first embodiment, which guides the first liquefied gas towards the orifice 38, the lower panel 37 of this embodiment has a funnel shape which allows the first liquefied gas falling by gravity from the liquefaction device 20 to be guided to the common passage formed by the complementary hole 44 and the through hole 43. The rest of the features of this fourth embodiment are similar to the features of the first embodiment. Figure 6 is a cross-sectional view of a fifth embodiment of the protrusion 16. In this embodiment, the protrusion 16 is positioned partly above the gas dome 13. The passage 15 of the gas dome 13 is then coincided with the opening 19 of the upper part 9 of the wall 2. The evacuation path of the first gas 36 is thus coincided with the gas circulation path 35 within the internal space 18 of the protrusion 16.Therefore, the first gas 36 exhaust path extends from the opening 19 in the upper part 9 of the wall 2 to the exhaust pipe 27 of the protrusion 16. It should be noted that in this case, the protrusion 16 extends laterally with respect to the first gas 36 exhaust path. It is thus understood that the protrusion 16 extends in a direction perpendicular to the exhaust path 36 on at least one side. The liquefaction device 20 is positioned away from the exhaust path 36. This means that the liquefaction device 20 is positioned so as not to be across the gas exhaust path 36, in accordance with what was described for the first embodiment with respect to the gas flow path 35. The remaining features of this fifth embodiment are similar to those of the first embodiment.As described above, through several examples of implementation, the present invention effectively achieves its stated objectives, namely, optimizing the presence of gas in liquid form within a tank by proposing a tank designed to contain a first gas and equipped with a protrusion incorporating a device for liquefying this first gas. The use of this protrusion optimizes the liquefaction process of the first gas, which is in a gaseous state in the upper part of the tank. The major advantage of this invention is that it allows the gas to be liquefied while consuming significantly less energy than traditional systems described in the prior art. However, the present invention is not limited to the means and configurations described and illustrated herein, and also extends to any equivalent means and configuration, as well as any technically feasible combination of such means.

Claims

CLAIMS:

1. A tank (1) for the transport and / or storage of a first gas, comprising a wall (2) delimiting a compartment (3) having a lower volume (4) intended to contain the first gas in liquid form and an upper volume (5) intended to contain the first gas in gaseous form, the wall (2) having an upper portion (9) contributing to the delimitation of the upper volume (5) of the compartment (3), characterized in that said tank (1) comprises a protrusion (16) positioned outside the compartment (3) and provided with a partition (17) delimiting an internal space (18), the upper portion (9) of the wall (2) comprising an opening (19) leading on the one hand into the upper volume (5) of the compartment (3) and on the other hand into the internal space (18) of the protrusion (16), the internal space (18) of the protrusion (16) containing at least in part a liquefaction device (20) of the first gas containing a second gas different from the first gas. 2.

1. Tank (1) according to claim 1, wherein the liquefaction device (20) comprises a heat exchange surface (29) disposed within the internal space (18) of the protrusion (16).

2. Tank (1) according to claim 2, wherein the liquefaction device (20) comprises a circulation conduit (28) for the second gas, the heat exchange surface (29) being at least partially defined by an external peripheral surface of the circulation conduit (28).

3. Tank (1) according to claim 3, wherein the external peripheral surface of the circulation conduit (28) is between 20 and 100 m².

4. Tank (1) according to any one of claims 1 to 4, wherein the opening (19) forms a single means of communication between the internal space (18) of the protrusion (16) and the housing (3) of the tank (1). 5.Tank (1) according to any one of claims 1 to 5, in which the protrusion (16) includes an evacuation conduit (27) for the first gas passing through the partition (17) of the protrusion (16).

7. Tank (1) according to any one of claims 1 to 6, comprising a vacuum bell (25) covering the protrusion (16) and hermetically connected to the upper part (9) of the wall (2).

8. Tank (1) according to claim 7, in which the vacuum bell (25) is welded to the upper part (9) of the wall (2).

9. Tank (1) according to claim 6 in combination with any one of claims 7 or 8, in which the discharge pipe (27) passes through the vacuum bell (25).

10. Tank (1) according to any one of claims 1 to 9, in which the liquefaction device (20) comprises a means for cooling (31) the second gas, the cooling means (31) being positioned outside the protrusion (16). 11.A tank (1) according to any one of claims 1 to 10, wherein the upper part (9) of the wall (2) comprises a gas dome (13) having a passage (15) defining an outlet (36) for the first gas in vapor form, the internal space (18) of the protrusion (16) being configured so that the heat exchange surface (29) of the liquefaction device (20) is positioned away from the outlet (36) for the first gas.

12. A tank (1) according to any one of claims 1 to 11, wherein the protrusion (16) is welded to the upper part (9) of the wall (2).

13. A tank (1) according to claim 12, wherein the protrusion (16) comprises a welding flange (23).

14. Tank (1) according to any one of claims 1 to 13, in which the first gas discharge pipe (27) and the second gas circulation pipe (28) pass through the partition (17) of the protrusion (16) on the same portion of the partition (17).

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