Solid-state carbon dioxide storage tank

Abstract

Solid state carbon dioxide storage tank The present invention relates to a solid state carbon dioxide storage tank (3), comprising a system (4) for unloading solid state carbon dioxide (3), said unloading system (4) comprising a plurality of transfer devices (5) and at least one conveyor (6), said transfer devices (5) being configured to bring the carbon dioxide (3) to the conveyor (6), at least one of the transfer devices (5) comprising a transfer member (7) rotating about an axis of rotation (X), the conveyor (6) being configured to collect the carbon dioxide (3) from the plurality of transfer devices (5), characterized in that the transfer member (7) of at least one of the transfer devices (5) is carried by at least one bearing (8) integral with the tank (1). (figure 1)

Description

Title of the invention: Solid state carbon dioxide storage tank

[0001] The present invention relates to the field of treatment of a gas in the solid state such as carbon dioxide, and more particularly concerns a tank capable of storing a cargo of said gas in the solid state.

[0002] Currently, a new logistics chain for processing a gas such as carbon dioxide is being developed. This chain involves a first phase of capturing the gas, a second phase of transporting this gas, for example within the tank of an entity such as a floating structure, and a final phase of burying the gas at sites very far from the capture sites.

[0003] Conventionally, carbon dioxide is transported in cooled and pressurized liquid form at pressures of 6 to 20 bars. These transport pressures require the use of pressure vessels, such as cylindrical, spherical, multi-lobed or internally reinforced tanks, the mass and cost of which make the construction of large vessels very complex and prohibitive in terms of costs.

[0004] The transport of carbon dioxide is optimal when it is transported in the solid state, a phase in which it can remain at atmospheric pressure while having a maximum density; particularly when it comes to maritime transport. Indeed, carbon dioxide is and can only be in the solid or vapor state at atmospheric pressure.

[0005] A problem arises during the carbon dioxide unloading step. Indeed, there are a plurality of methods for unloading a powdered, granular or blocky bulk cargo from the tank but none of them is suitable for unloading carbon dioxide in solid state which has a strong tendency to aggregation and which, although loaded in particle or blocky state, is likely to form a large aggregated block after a few days of storage or navigation.

[0006] Some unloading methods require opening the tank to ambient air. Such a step is not feasible for extracting carbon dioxide. On the one hand, carbon dioxide sublimes at room temperature and is toxic. The sublimed carbon dioxide would therefore create a lethal atmosphere in the tank environment. On the other hand, since processes using carbon dioxide are sensitive to the presence of water, exposing it to humid air is likely to pollute the material by cryopumping water vapor from the ambient air.

[0007] Other unloading methods operate by flow of the cargo. This is also not possible with carbon dioxide because the latter, as mentioned above, forms aggregates when packaged in bulk in an enclosed, non-refrigerated space. It is therefore impossible to operate a flow of carbon dioxide in order to extract it from the tank.

[0008] The present invention makes it possible to provide a solution for unloading carbon dioxide in the solid state by providing a solid state carbon dioxide storage tank, comprising a system for unloading carbon dioxide in the solid state, said unloading system comprising a plurality of transfer devices and at least one conveyor, said transfer devices being configured to bring the carbon dioxide to the conveyor, at least one of the transfer devices comprising at least one transfer member rotating about an axis of rotation, the conveyor being configured to collect the carbon dioxide from the plurality of transfer devices, characterized in that the transfer member of at least one of the transfer devices is carried by at least one bearing integral with the tank.

[0009] Thanks to the storage tank according to the invention, carbon dioxide can be stored in the solid state, for example for the purpose of transport within a floating structure, and then be discharged from the tank without having to open it to the ambient air. Carbon dioxide emissions into the atmosphere are thus very low and the entry of moisture into the tank is greatly limited. In addition, due to the transfer devices integral with the tank, the discharge system is permanently installed in the tank, which promotes the practicality of said storage tank with regard to its discharge.

[0010] The tank has structural and functional characteristics meeting standards for storing carbon dioxide in the solid state. For example, the tank may be the hold of a floating structure for transporting and / or storing carbon dioxide, such as a bulk carrier. The tank may also be arranged on land, for example in a hangar in which the treatment of carbon dioxide in the solid state is carried out.

[0011] The unloading system installed in the tank can be implemented remotely when an unloading operation of said tank is necessary. The transfer devices are then started to gradually transfer the carbon dioxide cargo to the conveyor. The tank comprises a plurality of transfer devices in order to cover a maximum surface area of the tank and thus to carry out an efficient transfer of the entire carbon dioxide cargo. The unloading system can comprise level sensors between the transfer devices and the conveyor. This makes it possible to adjust the rotation speed of the transfer devices to regulate the flow of carbon dioxide, or to detect a potential anomaly in the unloading system.

[0012] The conveyor collects the carbon dioxide transferred by the transfer devices in order to transport the cargo in turn. In order to optimize the unloading system, the conveyor is arranged across a path of the carbon dioxide transferred by the transfer devices, in order to collect all of the transferred carbon dioxide. The carbon dioxide collected on the conveyor is then moved along it to be discharged from the tank. The conveyor may for example be a conveyor belt.

[0013] The carbon dioxide is transferred in particular using the rotating transfer member. Such rotation generates a translational thrust of the carbon dioxide towards the conveyor.

[0014] Due to the solidarity between the bearing and the tank, the rotational movement of the transfer member is the only movement that the transfer devices can perform. The latter thus remain permanently in the tank while operating the transfer of carbon dioxide to the conveyor.

[0015] According to a characteristic of the invention, at least one of the transfer devices may be a worm screw comprising a shaft and the transfer member, the latter taking the form of a propeller wound around the shaft. The shaft is centered around the axis of rotation of the transfer member, i.e. the propeller. The shaft is driven in rotation for example via a motor and in turn drives the propeller in rotation. Thanks to the rotation of the worm screw, each step of the propeller moves in a translational movement. The steps thus make it possible to capture fragments of carbon dioxide and transfer them to the conveyor, the latter preferably extending in a main direction perpendicular to the shaft of the transfer device.

[0016] According to a characteristic of the invention, the transfer devices are arranged in a portion of the tank equal to 5% + / - 1% of a height of the tank and disposed at the bottom thereof. This is a preferred position of the transfer devices. These are in fact preferably arranged at the bottom of the tank, so that the carbon dioxide stored in the tank and overhanging the transfer devices gradually migrates towards the latter to then be transferred to the conveyor. The architecture of the tank is therefore adapted so that all of the blocks of carbon dioxide can migrate correctly to the transfer devices. Furthermore, such a configuration makes it possible to initially transfer the lower part of the cargo, causing the upper parts of the cargo to gradually fall, which are themselves transferred to the conveyor, and so on until the cargo is completely transferred.

[0017] According to a feature of the invention, the unloading system comprises a cutting device configured to cut or disaggregate the carbon dioxide, the cutting device comprising a plurality of cutting elements. The cutting device makes it possible to fractionate and / or disaggregate the carbon dioxide in the solid state. The cutting device therefore makes it possible to prevent the aggregates of carbon dioxide caused by the storage of the latter in an enclosed space from preventing its transfer to the conveyor.

[0018] The cutting elements may for example be blades or any protrusions, making it possible to at least partially cut the carbon dioxide in the solid state. The cutting elements must be brought into contact with the carbon dioxide with sufficient speed and / or weight for the carbon dioxide to be cut correctly.

[0019] According to a characteristic of the invention, the cutting elements comprise at least one cutting edge configured to come into contact with carbon dioxide in the solid state. The cutting edge corresponds to the part of the cutting element coming into contact with the carbon dioxide and compacting it.

[0020] According to a feature of the invention, the cutting device at least partially overhangs at least one of the transfer devices. Such a configuration allows the cutting device to cut the carbon dioxide above at least one of the transfer devices. Thus, the cut carbon dioxide falls by gravity to said transfer device and can thus be transferred to the conveyor subsequently.

[0021] According to a characteristic of the invention, the cutting device is integrated into the worm screw, the cutting elements being in the form of teeth projecting from the helix of the worm screw. This is an embodiment where the transfer devices are in the form of a worm screw, the latter alone ensuring the cutting and transfer of the carbon dioxide in the solid state. When the helix of the worm screw is rotated, the teeth are also rotated and ensure the cutting of the carbon dioxide. The worm screw subsequently ensures the transfer of the cut carbon dioxide to the conveyor.

[0022] According to a characteristic of the invention, the cutting device and at least one of the transfer devices are unitary and in the form of a cylinder delimiting an internal volume. In such a configuration, the cylinder and its internal volume can allow both cutting or disaggregating and transferring the carbon dioxide. The cylinder is rotated in order to cut or disaggregate the carbon dioxide, but also possibly to transfer said carbon dioxide to the conveyor.

[0023] According to a characteristic of the invention, the cutting elements of the cutting device, otherwise called disintegration device, are arranged on a surface external of the cylinder. The cutting elements are thus oriented towards the tank cargo and can split the carbon dioxide thanks to the rotation of the cylinder.

[0024] According to a characteristic of the invention, the cylinder is capable of performing a rotational movement around an axis of rotation in a clockwise direction or in a counterclockwise direction, the direction of rotation of the cylinder being configured so that the cutting edge comes into contact with the carbon dioxide in the solid state. In other words, the direction of rotation of the cylinder is dependent on the orientation of the cutting edge of the cutting elements arranged on this same cylinder. In order to implement efficient cutting, it is the cutting edge which must come into contact first with the carbon dioxide. If this cutting edge is only on one side of the cutting element, then the cylinder must rotate in the appropriate direction of rotation.

[0025] Each cylinder can be rotated by an intermediate shaft, which then acts as a drive shaft extending outside the internal volume of said cylinder. In such a configuration, the cylinder comprises a plurality of toothed wheels extending circumferentially around the cylinder, while the intermediate shaft also comprises a plurality of toothed wheels, each of which drives a toothed wheel of the cylinder. The cylinder can therefore be rotated without having to arrange a shaft within the internal volume of the cylinder. Furthermore, the toothed wheels arranged around the cylinder make it possible to prevent the carbon dioxide from resting on the cylinder without being cut and / or transferred. According to another example, the intermediate shaft can simply serve as a mechanical support for the cylinders. It is then the toothed wheels of the intermediate shaft which are driven by the toothed wheels of the cylinder.

[0026] According to a feature of the invention, at least one of the cylinders comprises openings in the vicinity of the cutting elements, said openings being configured to allow the entry of chips of the cut or disintegrated carbon dioxide into the internal volume of the cylinder. When one of the cutting elements attacks the carbon dioxide in the solid state, the carbon dioxide chip subsequently falls into the internal volume of the cylinder via the opening located in the vicinity of the cutting element.

[0027] According to a characteristic of the invention, the cylinder has an inclination relative to a horizontal normal, a lower end of the cylinder being opposite the conveyor. Such an inclination is sufficient to effect the transfer of the carbon dioxide present in the internal volume after having been cut and having passed through one of the openings. The rotation of the cylinder associated with the force of gravity resulting from the inclination of said cylinder allows the transfer to the conveyor and thus acts as a transfer device.

[0028] According to a characteristic of the invention, at least one of the transfer devices is housed in the internal volume of the cylinder. As an alternative to what is described above, it is possible not to tilt the cylinder but to integrate the transfer device into the internal volume of the cylinder. The transfer device may for example be a worm screw as described above. The cylinder and the transfer device arranged in the internal volume of said cylinder rotate in phase with each other in order to facilitate the implementation of the transfer of carbon dioxide. Thus, with a worm screw type transfer device in the internal volume of the cylinder, it is not necessary to tilt said cylinder to use the gravitational force for the transfer of carbon dioxide.

[0029] According to a characteristic of the invention, the tank comprises two adjacent cutting devices, each in the form of a cylinder, the two adjacent cylinders being capable of performing a rotational movement in an opposite direction of rotation relative to each other. Such a configuration makes it possible to optimize the cutting of carbon dioxide. The two cylinders are arranged so that the cutting elements of each cylinder, during the rotation of the latter, are staggered or nested with the cutting elements of the adjacent cylinder. The opposite direction of rotation also makes it possible to further improve the cutting of carbon dioxide.

[0030] In order to avoid any malfunction linked to a desynchronization of two adjacent cutting devices which could harm the cutting efficiency, the latter are controlled by pairs of cylinders. This makes it possible to synchronize the rotation speed of the two adjacent cylinders. According to a preferred example, only one of the cylinders is motorized, or driven in rotation by an intermediate shaft acting as a drive shaft, and then drives the adjacent cylinder in rotation, for example by means of the toothed wheels mentioned above, in order to keep their respective cutting elements staggered or nested with respect to each other.

[0031] According to another example, each of the adjacent cylinders are motorized in a direct or indirect manner and can thus be synchronized with each other, either by measurement-regulation or by constructive arrangement.

[0032] Alternatively, two adjacent cylinders may rotate in an identical direction of rotation relative to each other if the configuration permits.

[0033] According to a characteristic of the invention, the tank comprises at least one gutter arranged at the bottom of the tank, the conveyor being arranged within the gutter. In other words, a bottom of the gutter is at a height lower than the bottom of the tank. This difference in height makes it possible to install the conveyor such that it is at a height lower than the transfer devices. Thus, once the end from the transfer device reached, the carbon dioxide falls directly onto the conveyor to be subsequently transported out of the tank.

[0034] According to a characteristic of the invention, the tank comprises a corridor extending under a volume of the tank and along the gutter, the corridor being delimited by walls, the landing of at least one of the transfer devices being fixed to at least one of the walls of the corridor. The corridor is an area accessible to personnel managing the cargo. The corridor can thus be used for maintenance operations in complete safety for the personnel and without risk of compromising the condition of the carbon dioxide cargo. The motorization of the transfer devices, that is to say any element ensuring their rotation, can also be arranged within the corridor and advantageously fixed to at least one of the walls of the corridor.

[0035] The corridor extends mainly in a direction parallel to the main direction of the conveyor, and therefore perpendicular to the transfer devices. It is therefore possible that the bearing of the transfer devices allows the transfer devices to be secured to the walls of the corridor. It is obvious that the securing zone must be sealed, in order to avoid any air intake between the corridor and the tank.

[0036] According to a characteristic of the invention, the corridor is centered laterally relative to the volume of the tank, the unloading system comprising at least two transfer devices and at least two conveyors, the two transfer devices extending on either side of the corridor, each of the two conveyors extending on either side of the corridor and along the latter. Such a configuration is advantageous in the sense that a central corridor makes it possible to improve the management of the tank by human means.

[0037] In order for the carbon dioxide to be fully discharged from the entire tank, it is therefore necessary for the transfer devices to be arranged on either side of the central corridor. In order to facilitate the mechanical arrangement of the unloading system, the latter comprises two conveyors intended to collect the transferred carbon dioxide, after having been potentially cut or disintegrated, from each end of the tank.

[0038] According to a characteristic of the invention, the corridor comprises a protective roof connecting the walls of the corridor, the protective roof extending within the volume of the tank and overhanging the gutter. The protective roof makes it possible to close the corridor between the walls in order to make the corridor airtight.

[0039] The protective roof extends at least into the tank to completely overhang the conveyor. If the unloading system comprises two conveyors, the protective roof extends on either side to overhang both conveyors. The protective roof thus protects the conveyor from potential carbon dioxide falling directly onto it and potentially damaging it.

[0040] Furthermore, the protective roof may have a slope relative to a normal. This slope allows, when a block of solid carbon dioxide forms on the protective roof, to tip the block towards the transfer devices.

[0041] The invention also covers a floating structure for transporting and / or storing carbon dioxide, comprising a tank as described above. Such a floating structure is therefore capable of transporting and / or storing carbon dioxide, but also of unloading it easily, without human risks and without danger to the cargo.

[0042] According to a feature of the invention, the floating structure comprises an elevator configured to transport the carbon dioxide following the conveyor, the elevator extending in height at least up to a deck of the floating structure. The elevator may be another conveyor or several other conveyors arranged in continuity with the conveyor of the unloading system. The elevator may be a bucket elevator, a double belt elevator or a double screw elevator. The carbon dioxide can thus circulate from the conveyor to the elevator.

[0043] Unlike the conveyor, the elevator provides primarily vertical transport, so that the carbon dioxide can be moved to the deck of the floating structure or to a point at a height greater than that of the deck.

[0044] The elevator can be connected for example to an arm, itself connected to an unloading hopper. The floating structure can thus be mechanically connected to a maritime or land platform, or to another floating structure, so that the carbon dioxide is unloaded from the tank. According to another example, the floating structure can integrate a unit for treating the carbon dioxide in the solid state once it has been unloaded from the tank. The carbon dioxide in the solid state is then directly treated without leaving the floating structure.

[0045] The invention also covers a method of unloading solid-state carbon dioxide from a tank as described above, comprising: - a step of transferring the carbon dioxide contained in the tank to the conveyor by the transfer devices, - a step of transporting carbon dioxide out of the tank by the conveyor following the transfer step.

[0046] The operation of the transfer devices and the conveyor can be simultaneous, or offset from one another, the essential thing being to avoid too large a build-up of carbon dioxide at the level of the transfer devices or the conveyor.

[0047] According to a characteristic of the method, the latter comprises a step of cutting the carbon dioxide by the cutting device, the cutting step being simultaneous with or prior to the transfer step. This step is only implemented if the system The unloading device in question is equipped with the cutting device mentioned above. The cutting of the carbon dioxide is carried out prior to or simultaneously with its transfer. However, the transfer devices are put into operation prior to the operation of the cutting device in order to avoid too large a build-up of carbon dioxide at the level of the transfer devices.

[0048] Depending on various parameters, for example the distribution of carbon dioxide within the tank, the cutting device can be divided into sectors which can be operated at variable rotation speeds.

[0049] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0050] [Fig. 1] is a representation of a first embodiment of a tank according to the invention, comprising an unloading system,

[0051] [Fig.2] is a diagram seen from above of the unloading system shown in the [Fig.l],

[0052] [Fig.3] is a representation of a second embodiment of the tank,

[0053] [Fig.4] is a side view of a third embodiment of the tank,

[0054] [Fig.5] is a representation of a fourth embodiment of the tank,

[0055] [Fig.6] is a representation of a fifth embodiment of the tank,

[0056] [Fig.7] is a representation of a floating structure comprising any one of the methods of making the tank.

[0057] [Fig.l] represents a first embodiment of a tank 1 for storing carbon dioxide in the solid state. The tank 1 can be integrated within an entity capable of transporting and / or storing carbon dioxide 3 in the solid state, for example a floating structure 2. In such a configuration and as represented in [Fig.l], the tank 1 corresponds to a hold of the floating structure 2. The tank 1 has sealing and thermal insulation properties ensuring the storage of carbon dioxide 3 in the solid state in an optimal manner. The carbon dioxide 3 can thus, for example, be transported in the form of a cargo, from a departure point to an arrival point for the purpose of delivering said cargo of carbon dioxide 3 in the solid state. In all the figures, it will be considered that the tank 1 is arranged within a floating structure 2.However, alternatively, the tank 1 can also be arranged on land, for example by being stored within a hangar.

[0058] The difficulty, however, does not lie in the transport, but in the unloading of the carbon dioxide 3, for example once the floating structure 2 has arrived at its destination. Indeed, the carbon dioxide 3, by sublimating into the ambient air, creates a toxic, even lethal, atmosphere. In addition, the cargo of carbon dioxide risks being polluted by the humidity of the ambient air. Thus, to preserve the cargo in a solid state, exposing the cargo to the ambient air is not possible. Furthermore, human intervention in tank 1 is also not an option because it presents health risks due to the toxicity of carbon dioxide.

[0059] In order to overcome these problems, the tank 1 is equipped with an unloading system 4 ensuring the unloading of the carbon dioxide 3 from the tank 1, without the need to open the tank 1 to the ambient air, and which can be implemented remotely. The unloading system 4 comprises a plurality of transfer devices 5, as well as at least one conveyor 6. Thanks to the unloading system 4, the carbon dioxide 3 contained in the tank 1 can be transferred in fractions to the conveyor 6 via the transfer devices 5. Subsequently, the conveyor 6 collects the carbon dioxide 3 and transports it out of the tank 1.

[0060] Each transfer device 5 comprises a transfer member 7 capable of being rotated about an axis of rotation X. When the transfer member 7 is rotated, the carbon dioxide 3 is transferred to the conveyor 6 in particular thanks to the structure of the transfer member 7, as will be detailed later. Advantageously, the transfer devices 5 are arranged at the bottom of the tank 1, for example at a height corresponding to 5% of a lowest portion of the tank 1. Thus, the transfer devices 5 can also transfer the carbon dioxide 3 resting at the bottom of the tank 1, the carbon dioxide 3 stored in an upper part of the tank 1 gradually migrating towards the transfer devices 5 as the carbon dioxide is transferred, so that the entire cargo can be unloaded.

[0061] The unloading system 4 may comprise level sensors, not shown, between the transfer devices 5 and the conveyor 6. This makes it possible to adjust the rotation speed of the transfer devices 5 to regulate the flow rate of carbon dioxide 3, or even to detect a potential anomaly of the unloading system 4.

[0062] The transfer devices 5 extend in a main direction parallel to a direction of movement of the carbon dioxide fractions 3 when they are transferred by the transfer devices 5. The latter comprise a bearing 8, for example at their ends, allowing them to be secured to the tank 1. Thus, the transfer devices 5 are permanently installed in the tank 1 which improves the practicality thereof, the elements of the unloading system 4 being ready and functional at any time. The bearings 8 can for example be fixed to the walls of the tank 1, in a sealed manner to prevent any entry of ambient air into the tank 1 or any pollution of the enclosed spaces of the floating structure 2 by carbon dioxide.

[0063] The tank 1 also comprises at least one gutter 9, as well as a corridor 10 arranged under the bottom of the tank 1. The corridor 10 allows the personnel responsible for managing the tank 1 to circulate and carry out various maintenance operations without exposing their health or risking damaging the cargo. The corridor 10 is delimited by walls 11 and by a protective roof 12 which guarantee the seal between a volume of the tank 1 and the corridor 10. As shown in [Fig.l], the bearings 8 of the transfer devices 5 can also be secured to the walls 11 of the corridor 10 in a sealed manner. The corridor 10 can further contain one or more motors, not shown, ensuring the motorization of the transfer devices 5. These motors can therefore be controlled manually from the corridor 10 in order to cause the transfer devices 5 to rotate.

[0064] Advantageously, the corridor 10 extends mainly centrally with respect to the tank 1, along one dimension thereof. Such positioning allows better management of the tank 1 by the maintenance personnel. In such a configuration, and as illustrated in [Fig.l], the unloading system 4 comprises a plurality of transfer devices 5 arranged on either side of the corridor 10 so that the carbon dioxide 3 can be transferred from the entire tank 1. In addition, in order to simplify the arrangement of the tank 1, the unloading system 4 also comprises two conveyors 6 extending on either side of the corridor 10 and parallel to the latter.

[0065] Still according to [Fig.l], the tank 1 comprises two gutters 9 extending on either side of the corridor 10. It is within the gutters 9 that the conveyors 6 are housed. The gutters 9 make it possible to arrange the conveyors 6 at a lower height than the transfer devices 5, despite the fact that the latter are arranged at the bottom of the tank 1. Thus, at the end of a transfer step of a process for unloading the carbon dioxide 3, the latter falls by gravity onto the conveyor 6. The tank 1 may optionally comprise a ramp 13 to improve the guidance of the carbon dioxide 3 onto the conveyor 6. This being done, the unloading process continues with a step of moving the carbon dioxide 3 via the conveyors 6.The latter may be in the form of a conveyor belt ensuring a movement of the carbon dioxide 3 perpendicular or substantially perpendicular to the direction of transfer by the transfer devices 5 until it leaves the tank 1. The fate of the carbon dioxide 3 at the outlet of the tank 1 will be detailed later.

[0066] The protective roof 12 makes it possible to protect the corridor 10, but also extends within the tank 1 in order to overhang the conveyors 6. Such a configuration makes it possible to avoid a fall of the carbon dioxide 3 directly onto the conveyors 6 which could damage them. The protective roof 12 may have a slope ensuring the tilting of the blocks forming at the top of said protective roof 12 to the transfer devices 5.

[0067] [Fig.2] is a top view of the transfer devices 5, the conveyor 6 and the landing 8. As previously described, the landing 8 is fixed to a wall, for example one of the walls 11 of the corridor 10.

[0068] In [Fig.2], the transfer devices 5 are in the form of endless screws 14. Several endless screws 14 are aligned side by side in order to cover a maximum surface area of the tank and to completely discharge the carbon dioxide.

[0069] The endless screws 14 each comprise a shaft 15 around which the transfer member 7 is arranged, which in [Fig.2] is in the form of a propeller 16. When the transfer of the carbon dioxide is to be carried out, the shafts 15 are set in rotation and drive the propellers 16. The carbon dioxide is carried by the steps 17 of the propeller 16 to the conveyor 6, while the bearing 8 remains stationary because it is integral with the tank.

[0070] The shaft 15 passes through the wall 11 of the corridor 10 in a sealed manner as previously described. The shaft 15 is thus connectable to the motor 32 arranged at the corridor 10 so that it can be controlled safely, for example, by a member of the crew of the floating structure. In [Fig. 2], the motor 32 controls two transfer devices 5, but the motor 32 can control any number of transfer devices 5.

[0071] [Fig.3] represents a second embodiment of the tank 1 according to the invention. This second embodiment is similar to the first embodiment, except that the unloading system 4, in addition to the transfer devices 5 and the conveyors 6, comprises a cutting device 18. In [Fig. 3], at least two cutting devices 18 are arranged on either side of the corridor 10.

[0072] The cutting device 18 makes it possible to facilitate the fractionation of the carbon dioxide 3 by cutting it. Advantageously, the cutting device 18 is arranged so as to overhang at least one of the transfer devices 5. Thus, when the carbon dioxide 3 in the solid state in the tank 1 must be discharged, it is first cut by the cutting device 18, then falls to the level of the transfer devices 5 and is transferred to the conveyor 6 by the latter. The presence of the cutting device 18 in the second embodiment of the tank 1 thus reduces the size of the blocks of carbon dioxide in the solid state. The smaller blocks are then more easily transferable by the transfer devices 5, thus limiting the torque to be applied to the transfer devices 5 during the step of transferring the carbon dioxide.

[0073] Thus, during the unloading process mentioned above, the transfer step can be preceded by or carried out simultaneously with a step of cutting the carbon dioxide 3 into the solid state.

[0074] The rest of the structural and functional characteristics of the tank 1 being identical to the first embodiment, reference will be made to the description of [Fig.l] concerning the characteristics common to the two embodiments.

[0075] [Fig.4] is a schematic representation seen from the front of a third embodiment of the tank according to the invention, more particularly of the unloading system 4 of the latter.

[0076] In this third embodiment, the cutting device 18 and the transfer device 5 are combined into a cylinder 19. Each cylinder 19 is equipped with a cutting device 18 arranged on an external surface 20 of said cylinder 19, while the transfer device 5 is arranged within an internal volume 21 of said cylinder 19. In [Fig. 4], two adjacent cylinders 19 are shown. The transfer devices 5 may for example be endless screws as described in [Fig. 2].

[0077] [Fig. 4] also makes it possible to detail an example of a cutting device 18 for cutting or fractionating the carbon dioxide in the solid state stored in the tank. In [Fig. 4], the cutting device 18 comprises a plurality of cutting elements 22 projecting from the external surface 20 of the cylinder 19. It is these cutting elements 22 which come into contact with the carbon dioxide in the solid state to cut the latter. The cutting elements 22 may for example be in the form of blades or protrusions coming into contact with the carbon dioxide.

[0078] Each cutting element 22 may comprise a cutting edge 23 which corresponds to the portion of the cutting element 22 which initially comes into contact with the carbon dioxide to cut it. In addition, the cylinders 19 comprise openings 24 arranged near the cutting elements 22, allowing the carbon dioxide chips to penetrate into the internal volume 21 of the cylinder 19 and thus to interact with the transfer device 5 to be transferred to the conveyor 6.

[0079] Just like the transfer devices 5 described previously, the cylinders 19 are capable of being rotated. It is therefore the cutting devices 18 and the transfer devices 5 which are rotated. Preferably, a direction of rotation R of a cylinder 19 is defined as a function of an orientation of the cutting edges 23 of said cylinder 19. In other words, the direction of rotation R is chosen such that the cutting elements 22 considered attack the carbon dioxide by their cutting edge 23, in order to improve the efficiency of the cutting of the carbon dioxide.

[0080] The rotation can be carried out by means of an intermediate shaft 35, acting here as a drive shaft, arranged outside the internal volume 21 of the cylinder 19. In order for the rotation of the intermediate shaft 35 to be transmitted to the cylinder 19, the unloading system 4 comprises a set of toothed wheels 33, 34 ensuring the transmission of the torque from the intermediate shaft 35 to the cylinder 19. The cylinder 19 comprises a plurality of first toothed wheels 33 arranged regularly along the cylinder 19 and circumferentially around it, while the intermediate shaft 35 comprises a plurality of second toothed wheels 34 arranged regularly along the intermediate shaft 35 and circumferentially around it. Each of the first toothed wheels 33 interacts with one of the second toothed wheels 34 by being nested with respect to one another.The intermediate shaft 35 is thus driven in rotation, for example by the motor described above. The rotation is thus transmitted from the intermediate shaft 35 to the second toothed wheels 34, then to the first toothed wheels 33 and finally to the cylinder 19. Such a configuration makes it possible to do without a shaft in the internal volume 21 of the cylinder 19.

[0081] Depending on the configuration of the toothed wheels 33, 34, the intermediate shaft 35 can act as a drive shaft as illustrated in [Fig.4], or act as a simple mechanical support to support the cylinder 19.

[0082] The first toothed wheels 33 also have another function which is to prevent the carbon dioxide from resting on the cylinder 19 without being cut and / or transferred.

[0083] Furthermore, advantageously, the unloading system 4 is configured so that two adjacent cylinders 19 are rotated in a direction of rotation R opposite to each other. This allows, when the cutting elements 22 of one of the cylinders 19 are opposite the adjacent cylinder 19, that the cutting elements 22 of each cylinder 19 can have a phase where they are staggered or nested with respect to each other, further improving the cutting efficiency of the cutting devices 18. In order to maintain the staggered or nested positioning of the cutting elements 22 of the adjacent cylinders 19, the latter are preferably synchronized with respect to each other, for example by means of the first toothed wheels 33 of each of the cylinders 19.Thus, in a manner not illustrated, one of the cylinders 19 can be motorized, directly or indirectly, and drive the adjacent cylinder 19 in rotation in order to maintain synchronization of the latter, in particular at the level of rotation speed, and thus optimize the cutting efficiency of the cutting elements 22.

[0084] Alternatively, each of the adjacent cylinders 19 are motorized in a direct or indirect manner and can thus be synchronized with each other, either by measurement-regulation or by constructive arrangement. Two cylinders 19 adjacent ones can rotate in an identical direction of rotation R relative to each other if the configuration allows it.

[0085] Once the carbon dioxide is cut and in the internal volume 21 of the cylinder 19, the transfer device 5 located there transfers the carbon dioxide to the end of the cylinder so that the carbon dioxide falls onto the conveyor 6.

[0086] [Fig. 5] represents a fourth embodiment of the tank 1. Like the previous embodiments, this fourth embodiment is distinguished by the characteristics of the unloading system 4. The fourth embodiment of the tank 1 comprises cutting devices 18 identical to what is described in [Fig. 4], that is to say in the form of cylinders 19. However, unlike the third embodiment, there are no worm-type transfer devices 5 within the internal volume 21 of the cylinder 19.

[0087] The transfer devices 5 are the cylinders 19 themselves. Indeed, in this fourth embodiment, the cylinders 19 are inclined so that a lower end of the cylinder 19 is opposite the conveyor 6. Thus, when the cut carbon dioxide chips 3 enter the internal volume 21 of the cylinder 19 via the openings described above, it is the rotation of the cylinder 19 associated with the gravitational force resulting from the inclination of the cylinder 19 which makes it possible to carry out the transfer of the carbon dioxide 3 by flow within the internal volume 21 of the cylinder 19 to the conveyor 6. This embodiment thus makes it possible to do without transfer devices 5 of the endless screw type for example, by means of a control between the cutting of the chips and their transfer in order to avoid any risk of clogging of the internal volume 21 of the cylinder 19.

[0088] In order to avoid any loss of carbon dioxide 3 between the cylinder 19 and the bottom of the tank 1, the latter can also be inclined at the same inclination as that of the cylinder 19.

[0089] Just like the third embodiment, the cylinders 19 can be driven in rotation by means of toothed wheels and an intermediate shaft arranged outside the internal volume 21 of said cylinder 19.

[0090] The operation of the cutting device 18 being identical to the third embodiment, reference will be made to the description of [Fig.4] concerning the cutting step of the method of discharging carbon dioxide 3 in the solid state.

[0091] [Fig. 6] is a representation of a fifth embodiment of the tank. Like the embodiments previously described, the fifth embodiment is distinguished mainly from the other embodiments by the structural characteristics of the unloading system 4. The transfer devices 5 are here of the endless screw type 14 as is also represented in [Fig. 2].

[0092] The cutting device 18 is directly integrated at the level of the worm screw 14. The cutting elements 22 are here teeth 31 which project from a periphery of the propeller 16. When the worm screw 14 is rotated, the teeth 31 are also driven in rotation and cut the carbon dioxide close to the transfer devices 5. The worm screw 14 therefore ensures by itself the cutting and the transfer of the carbon dioxide to the conveyor 6.

[0093] [Fig.7] is a partial representation of the floating structure 2 containing the tank according to the invention. [Fig.7] makes it possible to describe the fate of the carbon dioxide in the solid state once it is moved out of the tank via the conveyor 6. The latter is represented in [Fig.7], more particularly one end of the latter opposite the tank.

[0094] [Fig.7] thus illustrates the path of the carbon dioxide when an operation of unloading said tank is carried out, for example for the purpose of delivering the cargo to a reception platform, a port or another floating structure. This is a non-exhaustive list of examples of the unloading of carbon dioxide. According to an alternative example, the carbon dioxide can be unloaded from the tank and be treated by a treatment unit arranged on the same floating structure 2 of the tank.

[0095] To carry out an unloading from the tank, the floating structure 2 comprises an elevator 25 arranged in the continuity of the conveyor 6 and so that the carbon dioxide arriving at the end of the conveyor 6 falls onto the elevator 25. Unlike the conveyor 6, the elevator 25 is capable of circulating the carbon dioxide unloaded from the tank vertically. The elevator 25 can be equipped with platforms preventing the carbon dioxide from falling at a vertical section 26 of the elevator 25. The elevator 25 can be a bucket elevator, a double belt elevator or a double screw elevator.

[0096] The vertical section 26 makes it possible to move the carbon dioxide to a deck 27 of the floating structure 2 or to a point of a height greater than this same deck 27.

[0097] Furthermore, the floating structure 2 may be provided with an arm 28 capable of being deployed towards a carbon dioxide reception area, for example a discharge hopper 29. The arm 28 is positioned so that the discharged carbon dioxide can circulate from the elevator 25 to the arm 28. The latter may comprise a conveyor belt 30 allowing the carbon dioxide to be transported along the arm 28 to the discharge hopper 29. Although not illustrated in [Fig. 7], it is obvious that the elevator 25, the conveyor belt 30 of the arm 28 and a connection of the latter to the discharge hopper 29 are arranged in a closed volume in order to prevent the discharged solid carbon dioxide from being exposed to the open air.

[0098] As mentioned previously, this is not an exhaustive configuration allowing the movement of carbon dioxide from the tank to a treatment unit arranged within the floating structure 2 or outside of it.

[0099] Once the entire cargo has been unloaded, the carbon dioxide is thus stored or treated at its destination point and can subsequently be used for further purposes, or be treated directly within the floating structure 2.

[0100] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0101] The invention, as just described, achieves the aim it set itself, and makes it possible to propose a tank with an unloading system adapted to the constraints of storing carbon dioxide in the solid state. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they comprise a tank in accordance with the invention.

Claims

Claims

1. Tank (1) for storing carbon dioxide (3) in the solid state, comprising a system (4) for unloading carbon dioxide (3) in the solid state, said unloading system (4) comprising a plurality of transfer devices (5) and at least one conveyor (6), said transfer devices (5) being configured to bring the carbon dioxide (3) to the conveyor (6), at least one of the transfer devices (5) comprising at least one transfer member (7) rotating about an axis of rotation (X), the conveyor (6) being configured to collect the carbon dioxide (3) from the plurality of transfer devices (5), characterized in that the transfer member (7) of at least one of the transfer devices (5) is carried by at least one bearing (8) integral with the tank (1), the tank (1) comprising at least one gutter (9) arranged at the bottom of the tank (1), the conveyor (6) being arranged within the gutter (9),the tank (1) comprising a corridor (10) extending under a volume of the tank (1) and along the gutter (9), the corridor (10) being delimited by walls (11), the bearing (8) of at least one of the transfer devices (5) being fixed to at least one of the walls (11) of the corridor (10).,

2. Tank (1) according to claim 1, in which at least one of the transfer devices (5) is a worm screw (14) comprising a shaft (15) and the transfer member (7), the latter taking the form of a helix (16) wound around the shaft (15).

3. Tank (1) according to claim 1 or 2, wherein the transfer devices (5) are arranged in a portion of the tank (1) equal to 5% + / -1% of a height of the tank (1) and arranged at the bottom thereof.

4. Cl. Tank (1) according to any one of claims 1 to 3, wherein the unloading system (4) comprises a cutting device (18) configured to cut or disaggregate the carbon dioxide (3), the cutting device (18) comprising a plurality of cutting elements (22).

5. Tank (1) according to claim 4, wherein the cutting elements (22) comprise at least one cutting edge (23) configured to come into contact with the carbon dioxide (3) in the solid state.

6. Tank (1) according to claim 4 or 5, wherein the cutting device (18) at least partially overhangs at least one of the transfer devices (5).

7. Tank (1) according to claim 4 or 5, in combination with claim 2, in which the cutting device (18) is integrated into the worm screw (14), the cutting elements (22) being in the form of teeth (31) projecting from the helix (16) of the worm screw (14).

8. Tank (1) according to any one of claims 4 to 6, in which the cutting device (18) and at least one of the transfer devices (5) are unitary and in the form of a cylinder (19) delimiting an internal volume (21).

9. Tank (1) according to the preceding claim, in which the cutting elements (22) of the cutting device (18) are arranged on an external surface (20) of the cylinder (19).

10. Tank (1) according to any one of claims 8 to 9, combined with claim 5, in which the cylinder (19) is capable of performing a rotational movement around an axis of rotation in a clockwise direction or in an anticlockwise direction, the direction of rotation (R) of the cylinder (19) being configured so that the cutting edge (23) comes into contact with the carbon dioxide (3) in the solid state.

11. Tank (1) according to any one of claims 8 to 10, wherein at least one of the cylinders (19) comprises openings (24) in the vicinity of the cutting elements (22), said openings (24) being configured to allow the entry of chips of the carbon dioxide (3) cut within the internal volume (21) of the cylinder (19).

12. Tank (1) according to any one of claims 8 to 11, in which the cylinder (19) has an inclination relative to a horizontal normal, a lower end of the cylinder (19) being opposite the conveyor (6).

13. Tank (1) according to any one of claims 8 to 11, in which at least one of the transfer devices (5) is housed in the internal volume (21) of the cylinder (19).

14. Tank (1) according to any one of claims 8 to 13, comprising two adjacent cutting devices (18), each in the form of a cylinder (19), the two cylinders (19) adjacent being capable of performing a rotational movement in a direction of rotation (R) opposite to each other.

15. Tank (1) according to any one of claims 1 to 14, in which the corridor (10) is centered laterally relative to the volume of the tank (1), the unloading system (4) comprising at least two transfer devices (5) and at least two conveyors (6), the two transfer devices (5) extending on either side of the corridor (10), each of the two conveyors (6) extending on either side of the corridor (10) and along the latter.

16. Tank (1) according to any one of claims 1 to 15, wherein the corridor (10) comprises a protective roof (12) connecting the walls (11) of the corridor (10), the protective roof (12) extending within the volume of the tank (1) and overhanging the gutter (9).

17. Floating structure (2) for transporting and / or storing carbon dioxide (3), comprising a tank (1) according to any one of the preceding claims.

18. Floating structure (2) according to claim 17, comprising an elevator (25) configured to transport the carbon dioxide (3) following the conveyor (6), the elevator (25) extending in height at least up to a deck (27) of the floating structure (2).

19. A method of unloading carbon dioxide (3) in solid state from a tank (1) according to any one of claims 1 to 16, comprising: - a step of transferring the carbon dioxide (3) contained in the tank (1) to the conveyor (6) by the transfer devices (5), - a step of transporting the carbon dioxide (3) out of the tank (1) by the conveyor (6) following the transfer step.

20. Unloading method according to the preceding claim, implementing a tank according to any one of claims 4 to 14, comprising a step of cutting the carbon dioxide (3) by the cutting device (18), the cutting step being simultaneous or prior to the transfer step.

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