Novel device for solid co 2 reliquefaction

Abstract

Present invention relates to a novel device suitable for reliquefaction of solid CO2 (so called dry ice) into gas and / or liquid CO2.

Description

[0001] Title: Novel device for solid CO2 reliquefaction

[0002] TECHNICAL FIELD

[0003] Present invention relates to a novel container or facility for reliquefaction of solid CO2 (so called dry ice) into gas and / or liquid CO2. Present invention also relates to a method for reliquefaction of solid CO2 into gas and / or liquid CO2.

[0004] BACKGROUND ART

[0005] Currently, large quantities (i.e. some tens of millions of tons per year at present and estimated to increase to up to 10 billion of tons per year by 2050) of CO2 are transported by land route, and short distances offshore. Presently, the most cost-effective solution is transport in supercritical fluid phase in CO2 pipelines. To keep the diameter of the pipeline low, it is generally preferred to develop and operate CO2 pipelines at high pressure necessary for the supercritical phase rather than a lower pressure with CO2 in gas phase.

[0006] Projects to develop CO2 pipelines require extensive approvals from the landowners along the route of the pipeline or through governmental expropriation. In e.g. Denmark it is assumed that only state owned companies will build and operate such pipelines, although the legislation opens for private owners and operators. However, such efforts are in general not within the immediate time line. Trunk CO2 pipelines are common in the US but no such pipelines exist in Europe.

[0007] Where pipeline solutions are not feasible, the alternative solution is today transport in liquid form / phase. This takes place in tanks each capable of carrying 20-25 tons of CO2 under a pressure of some 20 bar at a temperature of some -20°C. Such tanks can be mounted in standard container frames for truck, train or barge transport. The pressurized cryogenic tanks are, however, very expensive and presently only exist in relatively small numbers.

[0008] Large scale transportation in liquid form by ships is possible in large so-called “C type” pressurized cryogenic tanks known from transport of liquefied petroleum gasses in “semi-ref” tankers. Only a few ships with such tanks operate today, and their tank size is small - less than 8.000 m3These ships require the availability of intermediate storage tanks at the loading and discharge terminals. Such vessels are generally expensive and in the order of about USD 100 million per vessel or even above when including the cost of the intermediary storage tanks.

[0009] The business case for a ship owner to order such or larger liquefied CO2 tankers is uncertain, and we do not see any orders being placed at this time. An order must be based on a longterm firm commitment from a cargo owner. Shipyards are currently also very busy and unable to deliver such vessels in the next 3-4 years. Prices demanded by shipyards have furthermore risen considerably in the last year.

[0010] The operation of a liquefied CO2 tanker with the associated cargo systems at the terminal is complicated and requires highly trained operators. Since liquid CO2 can only exist under pressure, the loading and offloading systems at the terminals must be always pressurized. Besides issues around cost and scalability, transport of CO2 by tank truck also suffers from an inherent safety challenge arising from the transport under high pressure. An adiabatic process will take place if liquid CO2 under high pressure experiences a rapid loss of pressure. In this process about 45% of the liquid CO2 enters a solid phase (dry ice at -80°C) and the remaining about 55% becomes cold CO2 gas at ambient pressure and initially about -70°C.

[0011] The very cold dry ice and CO2 gas will cause severe frost damage to humans who come in direct contact. Several materials like normal structural steel will also be severely damaged through embrittlement with loss of load carrying capacity.

[0012] A similar damage scenario will take place if a CO2 pipeline is breached. The probability of this to happen is, however, significantly smaller than for a tank truck being hit in the traffic or ending up in a ditch on a slippery road and the main valve being damaged.

[0013] Transport of CO2 in pipelines is in principle simple and safe. However, it requires a large capital investment (CAPEX) and large volumes of CO2 to be economic. Pipeline construction and operation involves extensive regulatory and environmental approvals. The time until the first such trunk pipelines can be in operation in e.g. Denmark is thus in the order of 8-10 years, and overseas import of CO2 from neighboring countries by pipeline has an even longer time horizon.

[0014] Transport of CO2 in liquid form is also in principle simple when a fleet of trucks or trains with cryogenic pressure tanks exist. Such a fleet will, however, not be able to be built in time for the rapidly growing transport demand, and the cost of each vehicle may be prohibitively high. The same applies for transport by ship in liquified CO2 tankers, where the cargo handling systems and intermediate storage tanks at the terminals complicate the transport value chain. The scalability of transport in liquid form is therefore very questionable, and transport in liquid form has an inherent safety challenge, which cannot be eliminated.

[0015] Neither pipelines for CO2 transport nor cryogenic, pressure tanks for liquid transport can have attractive reuse. The depreciation time in economic calculations may therefore be relatively short for many projects.

[0016] Furthermore, there is always the aspect of risk in handling CO2. When the concentration of CO2 gas in the atmosphere exceeds around 5% it can be lethal for humans.

[0017] Present invention provides for a solution to the above problems and short comings.

[0018] SUMMARY OF THE INVENTION

[0019] Present invention relates to device or apparatus or facility or system (all terms used interchangeably throughout the description) for reliquefaction of solid CO2 (so called dry ice) into gas and / or liquid CO2. Such device will enable transport of CO2 in the solid phase thereby obviating the need for transportation of gaseous or fluid CO2, such as e.g. supercritical CO2, wherein such container will have to be under a relatively high pressure. Moreover, present invention also relates to a method or process for reliquefaction of solid CO2 (so called dry ice) into gas and / or liquid CO2.

[0020] Consequently, present invention provides for one or more of the following advantages;

[0021] • An energy effective process and cost efficient process / handling,

[0022] • Less space demanding,

[0023] • A faster process and handling,

[0024] • A safer and more secure process and handling,

[0025] • Higher degree of flexibility for off-loading and tailor made demand on quantity of liquid CO2.

[0026] Present invention relates to a device which may be a containment. Thus, the invention relates to a facility which receives dry ice and through heat transfer from the natural environment transfers the state of the CO2 from dry ice into CO2 gas and / or liquid CO2.

[0027] The facility will be a critical component in a large-scale CCS (Carbon Capture and Storage) value chain with transport of CO2 in solid form (dry ice).

[0028] The device or facility may comprise one or more containments, which may be in the form of pipes with end closures acting as pressure vessels. In one aspect, the device is illustrated in Fig. 1. As indicated in Fig. 1 , the device may comprise at least one inlet allowing for loading of solid CO2 (dry ice). The device may further comprise at least one outlet for dispensing of fluid / liquid and / or gaseous CO2.

[0029] In one aspect, the device according to the invention may comprise an auxiliary containment connected to the main containment by a pipe and with a pump to allow CCh-gas to be pumped from the main containment to the auxiliary containment and thereby lowering the pressure in the main containment to about 1 bar. This secures an almost zero loss of CO2 during the batch reloading process. When the batch of CO2 has been loaded and the inlet closed, the CO2 gas from the auxiliary containment flows back into the main containment. This aspect is illustrated in Fig. 9.

[0030] The device may comprise additional construction details and material which will become apparent in the subsequent description of the invention.

[0031] BRIEF DESCRIPTION OF FIGURES

[0032] Fig. 1 illustrates the basic set-up of the invention / device with at least one inlet and at least one outlet in connection with a containment or vessel. The figure also illustrates a further outlet for e.g. dispensing of CO2 gas.

[0033] Fig. 2 illustrates the containment with longitudinal fins, placed in the atmosphere. Fig. 3 illustrates the containment with perpendicular fins, placed in the atmosphere.

[0034] Fig. 4 illustrates a plurality of containments placed in seawater and in side view.

[0035] Fig. 5 illustrates a plurality of containments placed in seawater and in top view.

[0036] Fig. 6 illustrates the aspect of piston loading dry ice into the containment.

[0037] Fig. 7 illustrates the aspect of propeller mixing crushed dry ice and liquid CO2.

[0038] Fig. 8 illustrates the temperature / pressure phase transfer diagram for CO2.

[0039] Fig. 9 illustrates the auxiliary containment which may be equipped with a pump and wherein the auxiliary containment is in fluid and / or gaseous connection with the main containment. The figure illustrates the device seen from top view.

[0040] DETAILED DESCRIPTION

[0041] Present invention relates to a novel device or container. The container is suitable for processing of essentially solid CO2 into essentially liquid CO2 and / or gaseous CO2.

[0042] In one aspect, the device according to the invention may comprise i) one or more containments or vessels, ii) one or more openings or inlets into the containment or vessel serving as an inlet for loading solid CO2, iii) one or more outlets from the containment or vessel serving as an outlet for dispensing or collecting essentially liquid CO2.

[0043] As will be apparent from the description of the invention, the device or container will comprise one or more outlets. Thus, in one aspect present invention relates to a device which may comprise i) one or more containments or vessels, ii) one or more openings or inlets into the containment or vessel serving as an inlet for loading solid CO2, iii) one or more outlets from the containment or vessel serving as an outlet for dispensing or collecting essentially liquid CO2, wherein e.g. one outlet is for dispensing liquid CO2 and a further outlet is for dispensing gaseous CO2.

[0044] In another aspect, present invention relates to use of a device as described herein for processing of solid CO2 into essentially liquid CO2 and / or gaseous CO2.

[0045] The above discussed containments or vessels may be regarded as main containments or vessels. In a further aspect, present invention relates to a method or process for transforming solid CO2 into liquid or gaseous CO2.

[0046] According to the invention, the method or process for transforming solid CO2 into liquid CO2 may comprise; i) providing solid CO2 into the vessel of the invention, via the one or more inlets to the vessel or containment, ii) allowing the solid CO2 to heat up by passive heating from the surrounding environment, whereby solid CO2 is phase transferred into liquid or gaseous CO2, iii) collecting or dispensing the obtained liquid or gaseous CO2 from the vessel.

[0047] In one aspect, the heating may be by the aid of waste heat from any type of source. One example may be e.g. heated water or heated air from any other processes such as e.g. cooling water from nuclear plants or heated air from storage rooms of e.g. data centres.

[0048] One benefit of the invention is that during the passive heating process of the containment or vessel, the containment or vessel takes up heat and cools down and may effectively function as a heat exchanger, whereby the device may be used for the purpose of cooling.

[0049] In one aspect, the device or apparatus according to the invention may be equipped with an auxiliary containment which may be connected to the main containment. The connection may suitably be made with suitable types of conduits or pipes allowing for fluid connection of CO2 and / or gaseous connection of CO2.

[0050] In a further aspect, the auxiliary containment may be connected with a pump.

[0051] The purpose with the auxiliary containment is to allow CO2 to be pumped from the main containment to the auxiliary containment and thereby lowering the pressure in the main containment to about 1 bar. Apart from increasing safety in operation of the device as a whole, this also secures an almost zero loss of CO2 during the batch reloading process. When the batch of CO2 has been loaded and the inlet closed, the CO2 gas from the auxiliary containment may flow back into the main containment. Thus, this aspects increases the cost efficiency of the device as a whole and increases safety.

[0052] One auxiliary containment may be connected to one or more sections of the main containment.

[0053] This above mentioned aspects are illustrated in Fig. 9.

[0054] In more detail, Fig. 9 illustrates the main containment or main vessel (9.1) which may be a plurality or containment or vessels which. The main containments or vessels may be equipped with support racks (9.3). The auxiliary containment or vessel (9.4) may be equipped with a pump.

[0055] In one aspect and with reference to Fig. 9, the auxiliary vessel may be in fluid or gaseous connection with one or more of the main containments or vessels. The connection may be by any suitable conduit or pipe.

[0056] As mentioned herein, the facility may have one or more containments, which may be in form of pipes with end closures acting as pressure vessels. The containment or vessel should preferably be made of metal to achieve good thermal conductivity. The metal must be corrosion resistant and be able to endure temperatures down to about -80°C. In a non-limiting example, Austenitic stainless-steel alloys or aluminium are two possible metals that may be employed for this purpose.

[0057] • The thermal conductivity of steel is 50 W / mK

[0058] • The thermal conductivity of aluminium is 205 W / mK

[0059] Consequently, aluminium has a thermal conductivity of about 4 times as that of steel. Aluminium is available in a stainless version which is used for e.g. aircrafts. Stainless steel, however, has higher strength that aluminium.

[0060] However, other metals and alloys may be used that fulfil the requirements of high corrosion resistance as well as high thermal stability, especially at low temperature conditions of about -80°C or below.

[0061] The vessel or containment may have any suitable shape such as e.g. a circular cylindrical formation. The dimension of the containment or vessel should preferably be such that the overall size allows for large scale processing, such as e.g. at least 0.5 metric tons or above.

[0062] With respect to the containment or vessel, and in the aspect of the containment or vessel being of cylindrical from, the heat conduction from the outside to the pipe is inversely proportional to the diameter of the cylinder. When the diameter is reduced by a factor of e.g. 2, the volume of the pipe is reduced by a factor of 4, while the surface and the heat transfer is reduced by a factor of 2. The heat transfer per volume is thus increased by a factor of 2 when the diameter is reduced by a factor of 2. On the other hand, the facility will consist of 4 times as many containments to handle the same amount of dry ice.

[0063] Merely as a non-limiting example, it may be possible to transport dry ice in 20 tons batches in standard 20 ft containers. The dry ice is usually in pellet form and the effective density is around 1.05 t / m3. Consequently, a 20-meter-long pipe (cylindrical shape of the vessel or containment) with e.g. an internal diameter of 1.1 meter may hold such a 20 tons batch.

[0064] Consequently, in one aspect, the vessel or containment (main and / or auxiliary) may be in the form of a pipe or a tube which may have an internal diameter of at least about 1 meter, such as e.g. about 1.5 meters etc.

[0065] In another aspect, the containment (main and / or auxiliary) may have an axial length of about 5 meters or more, such as e.g. about 10 meters or more, such as e.g. about 20 meters or more.

[0066] The containment may preferably have such dimensions in terms of wall thickness of the containment or vessel such that it will be able to withstand stresses and avoid buckling from internal gas pressure, internal and external fluid pressure, and temperature variations. The thickness of the wall in this respect in a steel solution may be in a diameter / thickness ratio of about 60 to about 80.

[0067] In one aspect, the containment or vessel may be equipped with fin like structure. This aspect is illustrated by non-limiting Figure 2 and Figure 3. In one aspect, the fin like structure is applied only to the outside structure of the vessel or containment in radial direction. In another aspect, the fin like structure extends from the inside of the vessel or containment to the outside thereof in a radial direction. The fins may be typically placed in axial or longitudinal direction along the axial direction of the vessel or containment and may have at least partly the length of the vessel or containment. The fin like structure may be either welded onto the containment or vessel or may be an integral part of the containment or vessel and may thus be produced by e.g. extruding to add fins to an aluminium containment or vessel.

[0068] In another aspect, the fin like structure may be in form of circular discs extending from the surface of the containment or vessel in radial direction perpendicular to the axial direction of the containment or vessel. This particular aspect is illustrated in Fig. 3.

[0069] With respect to the material to be processed by the aid of the device, dry ice which is another name for solid CO2, may be poured into the vessel or containment as either

[0070] • Pellets of compressed dry ice powder produced in dry ice machine - effective density about 1.05 t / m3, or

[0071] • Crushed dry ice mixture - density about 1.25 t / m3

[0072] Pure dry ice has a density of 1 .6 t / m3. Dry ice has a temperature of a little higher than -80°C at 1 bar pressure. Consequently, the device in its components must be able to tolerate or withstand such temperature and pressure conditions without losing integrity or undergo any structural transformations that may hamper the overall processing.

[0073] As indicated herein, in the processing of dry ice, and in order to improve the cost efficiency of the process, the heat necessary to transform solid CO2 into its liquid or gaseous phase is provided by the surrounding environment by heat transfer. The surrounding environment may be the atmosphere or ocean water. The heat transfer may be composed by one or more of;

[0074] 1 . Heat transfer from the surrounding to the pipe via convection,

[0075] 2. Heat transfer through the metal in the pipe

[0076] 3. Heat transfer from the pipe to the inside dry ice + liquid CO2 + CO2 gas mixture

[0077] 4. Heat transfer within the dry ice + liquid CO2 + CO2 gas mixture,

[0078] 5. Heat transfer to dry ice from ice formation on the outside of the pipe.

[0079] Theoretical calculations show that the limiting element is normally the heat transfer from the surrounding to the vessel or containment through natural convection. This depends on the flow rate around the vessel or containment. The heat transfer from the surrounding to the vessel or containment is proportional to the area, so adding fins increases the transfer.

[0080] In one aspect, the vessel may comprise CO2 in a mixture of phases: gas, liquid and solid. Gravity forces layer the component with dry ice at the bottom, liquid CO2 at the middle and CO2 gas at the top.

[0081] Heat transfer rate from the vessel or containment wall to CO2 gas phase is quite small as CO2 gas is a particularly good insulator. The top part of the pipe containing CO2 gas therefore takes little part in the heat transfer process.

[0082] Heat transfer rate from the vessel or containment wall to liquid CO2 is much higher, and the transfer can be increased if a flow is created in the liquid CO2. A certain flow is created by liquid CO2 formed by the melting process flowing from the dry ice upwards in the vessel or containment. The heat transfer may also be increased by adding internal fins.

[0083] Heat transfer rate from the vessel or containment wall to dry ice is high and not a limiting factor.

[0084] The heat transfer and sublimation / melting start at the interface between the inner vessel or containment wall and the dry ice. The vessel or containment may therefore be inclined to avoid that a boundary layer with poor transfer properties is formed. The inclination ensures that there is always direct contact between the pipe wall and the dry ice fraction.

[0085] In one aspect, the device is in an upright longitudinal direction without any inclination.

[0086] In a further aspect, the device may have an inclination of from about 0° to about 45°. In a further aspect, the device may have an inclination of from about 0° to about 5°.

[0087] If crushed dry ice is used, then the mixture of dry ice and liquid CO2 will have a slush ice behaviour and a flow can be created by an inside operated propeller in the longitudinal direction. This can be relevant in situations where the heat transfer inside the pipe is the limiting factor. Consequently, in one aspect, present invention relates to a device wherein the vessel or containment may be equipped with a propeller-like structure or the likes with the purpose of ensuring proper mixing of the various phases of CO2. This aspect is illustrated in Fig. 7.

[0088] As mentioned herein, present invention also relates to a process.

[0089] In one aspect, at the beginning of the process the dry ice is at about 1 bar and about -80° C. The dry ice fills the whole length on the vessel or containment except for perhaps some meters added at the top end for the dry ice loading system allowing for expansion of the liquid CO2 at higher temperatures.

[0090] Heat transfers through the vessel or containment wall and sublimation starts at the interface leading to pressure build up as the density of CO2 gas is about 1 / 1000th the density of dry ice. Some heat also goes to heating the solid dry ice.

[0091] The first phase ends with the pressure and temperature at the triple point of 5.1 bar and - 56.6°C (triple point conditions).

[0092] The second phase is a melting phase where the dry ice melts to liquid CO2 at triple point conditions. The sublimated CO2 gas stays at the top of the vessel or containment. This phase is the most energy consuming. Theoretical calculations show that about 80% of the time is spent at this stage.

[0093] The third phase is a heating of the liquid CO2 and CO2 gas mixture. It takes place at the pressure / temperature boundary defined by the CO2 phase diagram (Fig. 8). The CO2 liquid or gas will be tapped from the vessel or containment at the end of this process. The maximum temperature that can be achieved is the temperature of the surrounding. With heat from sea water the maximum pressure is about 40-50 bar at emptying.

[0094] Pressure and temperature gauges can be placed to follow the process. Theoretical calculations show a total time of some 2 hours for 20 tons of CO2 in a 1.1 -meter diameter vessel or containment in sea water with a sea water flow velocity of 1 m / s. For a 1 .5 m / s sea water flow velocity the calculations give a total time of 1.5 hours.

[0095] As a consequence of the process and its nature, depending on the flow rate of sea water around the vessel or containment a thin ice layer will form and later disappear during the process. For example, at 1 m / s flow rate the theoretical calculations shows that a 5 mm ice layer will form.

[0096] If the vessel or containment is in atmospheric air, the conduction from the air to the vessel or containment is much smaller than in water and the process takes much longer. A thicker ice layer from air humidity will also form often in the order of centimetres. The energy used to form this ice is accelerating the melting of the dry ice, and it is the main energy for the process inside the vessel or containment. Any formation of an ice layer may be removed at regular intervals to avoid it acting as an insulator.

[0097] Present invention also provides for a further advantage. When the dry ice is loaded in pellet or crushed form into the vessel or containment, some dry atmospheric air follows along - in the order of maximum a few kilos of dry air. Atmospheric air consists of N2 (78%), O2 (21%) and Argon (1 %). Argon is an inert gas and harmless in the further CCS value chain. N2 and O2 should, however, be removed.

[0098] Before the melting starts, the CO2 gas and the small amount of atmospheric air stays at the top of the vessel or containment. Since the density of the atmospheric air is 60% of the density of CO2 gas and there is no air flow inside the pipe, the gas is layered with atmospheric air at the top of the vessel or containment. In one aspect, the vessel or containment may be equipped with one or more valves. In a further aspect one valve may be placed at the top of the vessel or containment. The valve at the top may then be opened shortly to flush out the atmospheric air.

[0099] Any gas unintentionally following the liquid CO2 in the further process will thus be pure CO2 gas. Consequently, present invention provides for a further opportunity in enabling a purification of the obtained liquid CO2.

[0100] In one aspect, the liquid CO2 can be unloaded from the vessel or containment through one or more outlets. The one or more outlets are suitable placed at the bottom end of the vessel or containment. The outlets may be equipped with a valve. The unloading of the liquid CO2 may take place any time after the completion of the melting process. The longer the time after melting is completed the higher the temperature and associated pressure inside the vessel or containment.

[0101] The liquid CO2 flows to the a further storage facility for permanent storage of CO2 or utilization in the CCS value chain. In a storage facility the pressure and temperature are suitably increased to bring the CO2 in supercritical fluid form before it is pumped into the wells to the geological storage formations.

[0102] During emptying the CO2 initially flows under its own pressure and gravity and later the flow may be supported by a cryogenic pump. The emptying suitably takes place at a fast rate such that little liquid CO2 goes into gas form as the volume for CO2 gas increases. When the unloading of liquid CO2 is completed and the lower valve closed, the vessel or containment is filled with CO2 gas at a low pressure. The upper inlet of the vessel or containment may then be safely opened, and a new batch of dry ice may be inserted. The loss of CO2 in this process is calculated to be less than 0.5%, or less than e.g. about 1 % in case of 5 bar, of the original batch weight which is yet a further advantage.

[0103] In one aspect, CO2 in gas form may be unloaded after the melting has been completed. After melting the liquid CO2 is boiling and boil off CO2 gas can be exported. The rate of unloading must be such that the boiling process is controlled until the containment is emptied.

[0104] Merely as a non-limiting example, theoretical analysis shows that this is possible within a reasonable time of a few hours for 20 tons dry ice with pressure of the exported CO2 gas at e.g. about 10 bar or about 20 bar.

[0105] Alternatively, a small CO2 gas storage tank is connected to the reliquefication unit. By means of a pump the gaseous CO2 remaining in the pipe is pumped to the storage tank, which keeps the gas under pressure while the new batch of dry ice is loaded. When the loading is finished the CO2 has from the tank is transferred back to the pipe.

[0106] Alternatively, the next batch of dry ice may be inserted in a lock mechanism at the top or the vessel or containment, which allow for filling dry ice into the pipe under some excess internal pressure. Technologies from piston engines can be utilized. This aspect is illustrated in Fig 6. In one aspect, a set-up as illustrated may comprise a loading opening (6.1) with the mechanism having a piston (6.2) with piston rings (6.3), a cylinder (6.4) and an opening [6.5) for dispensing solid CO2 into the containment (6.6).

[0107] As previously pointed out, one of the many advantages with present invention is the safety aspect. As is well known in the art, CO2 is an inert gas, consequently no fire hazards are present.

[0108] In case the receiving facility breaks down, the vessel or containment can act as an intermediate storage unit. If the temperature of the surrounding water or air exceeds 31°C, the liquid CO2 goes into supercritical form at a pressure of 74 bar. The maximum pressure that can occur in the pipe is therefore limited by this pressure.

[0109] The valve at the top inlet may at any time act as a safety valve to reduce the pressure in the vessel or containment.

[0110] The valve at the bottom may also act as a safety valve and discharge liquid CO2 into the sea water. Here it will quickly evaporate into CO2 gas and enter the atmosphere. Some sea water ice will also form during the process. As indicated, this safety valve may be in combination with the outlet.

[0111] When the containment has been emptied to a high degree, some CO2 gas will remain in the containment. Depending on the discharge method the pressure of the residual CO2 gas can be around 5 bar or around 10-20 bar. CO2 gas is exposed to an environment of 1 bar pressure when the containment is opened to reload dry ice. A loss of CO2 gas will happen, which should be minimized. The loss is minimized by introducing an auxiliary containment which is connected to the main containment by a pump. CO2 gas is pumped from the main containment to the auxiliary containment thereby reducing the pressure in the main containment to around 1 bar. The loss of CO2 gas is then small when the main containment is opened for reloading of dry ice. When the reloading is complete, the containment is closed after which it is connected to the auxiliary containment and the pressure is balanced such that the pump recirculates the gaseous CO2 back to the main containers or vessels. The inventors of present invention have surprisingly found that by the aid of a device illustrated in Fig. 9, a minimum of CO2 is lost during re-loading of the containers or vessels.

[0112] In one aspect, the device according to the invention may be at least partially submersed in sea water. This enables an effective and cost-efficient exchange of energy in transforming the CO2 into its various phases.

[0113] In a further aspect, present invention also relates to a plurality of vessels or containments as described herein. The above describes a single unit in a reliquefaction facility. Consequently, the invention relates to a plurality of such units comprising of several vessels or containments, which may be mounted in e.g. a rack, which is fastened to the sea floor. This aspect of the invention is illustrated in Fig 4 and 5, illustrating the situation wherein the plurality of containments are placed in seawater. However, this set-up may also be on land. The vessel or containment may be connected to the rack in a way that allows deformations from temperature and pressure loads.

[0114] In a non-limiting example, a facility of 20 vessels or containments each of which may be e.g. 20 meter length, about 1.1 meter diameter and 18 mm thickness in austenitic stainless steel or aluminium may process about 1 mega ton of dry ice per year for permanent storage in a deep geological reservoir.

Claims

CLAIMS1. A device comprising: i) one or more inlets (1.1), ii) one or more vessels or containments (1.2), iii) one or more outlets (1.3; 1.4), wherein the one or more inlets (1.1) are placed at the top end of the one or more vessels or containments, and wherein the one or more outlets (1.3) are placed at the bottom end of the one or more vessels or containments.

2. The device according to claim 1 , wherein the device is tilted at least about 0° to about 45°, or preferably about 0° to about 5° from the axial position perpendicular to the horizontal plane.

3. The device according to any one of the preceding claims, wherein the one or more inlets are equipped with a valve (1.5).

4. The device according to any one of the preceding claims, wherein the one or more outlets (1.3; 1.4) are equipped with a valve.

5. The device according to any one of the preceding claims, wherein the one or more vessels or containments (1.2) have a cylindrical or pipe-like shape.

6. The device according to any one of the preceding claims, wherein the one or more vessels or containments are equipped with fin like structures (2.1) protruding out from the surface plane of the vessels or containments and are at least partly distributed along the axial direction of the one or more vessels or containments or wherein the fin like structures (3.1) are circular discs protruding from the containment or vessel surface in radial direction.

7. The device according to any one of the preceding claims, wherein the one or more vessels or containments are equipped with fin-like structures protruding out from the surface plane of the vessels or containments and extends in radial direction inside the one or more vessels or containments.

8. The device according to any one of the preceding claims, wherein the device is made of a metallic material such as e.g. a metal or metal alloy, which is e.g. austenitic stainless steel or extruded aluminium.

9. The device according to any one of the preceding claims, wherein the one or more vessels or containments are equipped with a propeller-like structure (7.5) or element inside the one or more vessels or containments for mixing.

10. The device according to any one of the preceding claims, wherein the propeller like structure (7.5) or element is placed at the bottom half of the one or more vessels or containments.

11. The device according to any one of the preceding claims, wherein the one or more vessels or containments are equipped with a screw conveyor or auger conveyor at the inlet on the top end of the one or more vessels or containments.

12. The device according to any one of the preceding claims, wherein the one or more vessels or containments are equipped with a piston pumping element (6.2;6.3;6.4)at the inlet on the top end of the one or more vessels or containments (6.6).

13. The device according to any of the preceding claims, wherein the containment (1.2) has a diameter / wall thickness ratio of about 60 to about 80.

14. The device according to any of the preceding claims, wherein the containment (1.2) has have an axial length of about 5 meters or more, such as e.g. about 10 meters or more, such as e.g. about 20 meters or more, and a radius of about 1 meter and a wall thickness of about 10 mm.

15. The device according to any of the preceding claims, wherein the device is equipped with an auxiliary containment (9.4) which is in fluid and / or gaseous connection with the with or more one or more vessels or containments (1.2) or (9.1).

16. The device according to any of the preceding claims, wherein the auxiliary containment or vessel (9.4) is equipped with a pump.

17. The device according to any one of the preceding claims, wherein the device is at least partially submersed in sea water.

18. Use of a device according to any of the preceding claims for reliquefaction of CO2.

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