Process and device for the liquefaction of co2

Abstract

To provide an apparatus in which a storage facility is combined with a CO2 production unit in order to produce supercooled liquid CO2 at a marginal cost and by a flexible method.SOLUTION: The device for the liquefaction of CO2 comprises a chamber (S), means for placing in direct contact a first liquid stream rich in CO2 (L1) and a first gas stream rich in CO2 (V2) and for condensing at least a portion of the first gas stream to form a condensed gas rich in CO2, means for connecting transport means (B) comprising a liquid CO2 storage facility to the contact means in order to receive the condensed gas rich in CO2 originating from the contact means, means for sending the first liquid stream to the contact means, and means (1A, 2) for regulating the temperature of the first liquid stream upstream of the contact means as a function of the pressure of the contact means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a process and apparatus for the liquefaction of CO2.

[0002] When liquid CO2 from a CO2 separation and / or liquefaction unit is sent to a storage facility, heat intrusion can cause partial evaporation of CO2. Additionally, within the storage facility and within the receiving equipment (truck, train, or ship), heat intrusion will also generate vapor due to evaporation of the liquid (boil-off gas, or BOG). CO2 vapors can also be contained within vehicles equipped with or consisting of liquid CO2 storage facilities, such as trucks, trains, or ships, and these vapors can be stored within the storage facility during the filling of the vehicle's storage facility. It is also desirable to capture gaseous CO2 remaining in the storage facility of a vehicle that is not completely empty and will be filled with a CO2 liquefier or CO2 capture device. Therefore, it is important to minimize this vapor generation and / or attempt to liquefy any CO2 vapor present within the vehicle in order to limit CO2 loss and release to the atmosphere.

[0003] This issue is discussed in an October 2020 report by the Amager Resource Center titled "Pre-feasibility study for CO2 pipeline and storage."

[0004] In the case of CO2 capture and sequestration, the distance between the CO2 separation and / or liquefaction unit and the storage facility can be very large (sometimes on the order of several kilometers), and the storage facility is located close to the transportation means (e.g., a port). [Background technology]

[0005] In the cryogenics industry, the liquid produced by the liquefier is typically subcooled to prevent it from vaporizing during transportation.

[0006] It is also typical to install a unit for liquefying the evaporating gas in a liquid storage facility near the storage facility. In the case of CO2, ammonia or propane or propylene refrigeration units are conventionally used for this purpose.

[0007] In the natural gas liquefaction industry, the use of liquid / gas contactors upstream of storage facilities is known to those skilled in the art. The subcooled liquids produced are brought into contact with vapors generated in the storage facility, liquefying them by direct contact. It is also known to liquefy vapors directly in the storage facility by contact between the liquids produced and their vapor headspace.

[0008] A CO2-rich gas or liquid stream contains at least 60 mol% CO2, at least 70 mol% CO2, at least 80 mol% CO2, indeed even at least 90 mol% CO2, or even at least 95 mol% CO2. [Problem to be solved by the invention]

[0009] Heat intrusions depend heavily on the operating conditions of the storage facility and the associated loading units. This is because, during operation without loading / unloading of the storage facility, heat intrusions only affect the pipes around the storage facility and the storage facility itself. These heat intrusions therefore generate small amounts of vaporized gases that are very stable and consistent over time. On the other hand, during loading (e.g., of a ship), pumps are suddenly activated and other pipes are used to connect the ship to the storage facility, releasing the carbon dioxide vapor contained in the storage facility at temperatures generally above 0°C. These items of equipment generate additional heat intrusions that can represent values ​​of heat intrusion that are more than double those during normal operation without loading / unloading. For this reason, the vaporized gases that must be liquefied can suddenly triple compared to normal operation, and the liquefaction unit (refrigeration unit or liquid / gas contactor) must be calculated accordingly to be able to handle this additional gas. This means particularly flexible installations and considerable additional costs, especially in the case of refrigeration units, where the heat that needs to be dissipated is directly tripled. Summary of the Invention

[0010] The present invention consists in leveraging the capacity of a CO2 production unit to produce supercooled liquid CO2 at marginal cost and in a flexible way by combining a storage facility with the CO2 production unit, the outlet temperature of which will vary depending on the operation mode of the storage facility.

[0011] In particular, when the storage facility is operating without loading / unloading, the CO2 will only be subcooled to offset the heat ingress from the transfer pipes and storage facility (which depends on the length of the pipes and the size of the storage facility). For a storage facility operated at 16 bara, for example, the temperature of the CO2 leaving the CO2 production unit may be, for example, -27°C to -40°C.

[0012] When CO2 vapors from a vehicle, such as a ship, are sent to a storage facility, they increase the pressure in the storage facility, making it necessary to reduce the temperature of the liquid CO2 supplied to the storage facility to offset the pressure increase. Preferably, the liquid CO2 is sent to the upper level of the storage facility and into the gas headspace above the liquid level to create a scrubbing effect that condenses a portion of the gaseous CO2 present. When a vessel for the transport of liquid CO2 is loading, for example, the CO2 will be subcooled to a lower temperature to offset the additional heat ingress. In the same example as above, the temperature of the CO2 leaving the CO2 production unit would therefore be between -40°C and -55°C.

[0013] The storage facility may be, for example, a liquid storage facility having a gas headspace where the gas is liquefied and a liquid resulting from the liquefaction is injected, and / or a separation device, where the liquid is at the temperature required to liquefy the gas.

[0014] If not, the storage facility may be a column and / or a separator for contacting the gas to be liquefied with the liquid resulting from the liquefaction, the liquid being at the temperature required to liquefy the gas.

[0015] The liquid from the column may pass through another storage facility during transit and may be returned to the vehicle from which the gas to be liquefied originates or to another vehicle.

[0016] According to the subject matter of the present invention, there is provided an apparatus for liquefying CO2, comprising: Chambers, contacting means disposed in a chamber in direct contact with the CO2-rich first liquid stream and the CO2-rich first gas stream for condensing at least a portion of the first gas stream to form a CO2-rich condensed gas; means for connecting a transport means comprising or consisting of a liquid CO2 storage facility to the contacting means for receiving the CO2-rich condensed gas resulting from the contacting means; means for delivering the first liquid stream to the contacting means; a liquid CO2 storage facility of the vehicle or means for delivering a first gas stream from the liquid CO2 storage facility to the contacting means; In an apparatus comprising: i) means for detecting the flow rate of the first gas stream that has been or will be fed into the means for feeding the first gas stream; and / or ii) means for detecting the temperature of the first gas stream that has been or will be fed into the means for feeding the first gas stream; and / or iii) means for detecting the pressure in the chamber; and iv) means for adjusting the temperature of the first liquid stream upstream of the contacting means in response to the flow rate and / or temperature of the first gas stream and / or the pressure of the contacting means; An apparatus is provided, comprising:

[0017] Other optional features include: the chamber is designed to store a liquid and does not house a reliable means for facilitating mass exchange, the contacting means comprises a gas headspace formed above the liquid level when the apparatus is operating, and the means for delivering a first liquid stream is connected to deliver the first liquid stream beyond the point of arrival of the first gas stream; the chamber is a scrubber having a bottom, the contacting means being located in the scrubber, the contacting means comprising means for facilitating heat and mass transfer above the bottom, the bottom being connected to receive the first liquid stream at a level of the scrubber above a point of arrival of the first gaseous stream, the bottom of the scrubber being connected to a CO2 storage facility for delivering the liquid to the CO2 storage facility; The first liquid stream, which is rich in CO2, is the liquid other than the bottom liquid of the chamber.

[0018] According to another subject of the present invention, there is provided a process for liquefying CO2, in which a first liquid stream rich in CO2 and a first gaseous stream rich in CO2 are mixed, the first liquid stream being passed to contact means in a chamber and the first gaseous stream being passed to the contact means so as to condense at least a portion of the first gaseous stream, the liquid being passed from the contact means to transport means comprising or consisting of a liquid CO2 storage facility connected to the contact means for receiving the condensed CO2-rich gas emerging from the contact means, the liquid CO2 storage facility or the first gaseous stream emerging from the liquid CO2 storage facility being formed by partial evaporation above the liquid level in the liquid CO2 storage facility as a result of heat intrusion, i) the temperature of the CO2-rich first liquid stream increases when the flow rate and / or temperature of the gaseous CO2 first gas stream decreases and / or the pressure in the chamber decreases, and the temperature of the CO2-rich first liquid stream decreases when the flow rate and / or temperature of the first gaseous stream increases and / or the pressure in the chamber increases; and / or ii) the temperature of the CO2-rich first liquid stream is increased to account for a reduction in the flow rate and / or temperature of the gaseous CO2 first gas stream and / or the pressure in the chamber, and the temperature of the CO2-rich first liquid stream is decreased to account for an increase in the flow rate and / or temperature of the first gas stream and / or the pressure in the chamber. A process is provided, characterized in that

[0019] According to another aspect of the present invention, the temperature of the CO2-rich first liquid stream is adjusted in response to its flow rate so that the temperature of the contacting means is sufficient to liquefy at least a portion of the first gaseous stream; the temperature of the first liquid stream is modified by dividing it into two variable fractions, one of the variable fractions being cooled and the other variable fraction not being cooled, the cooled variable fraction being mixed with the not-cooled variable fraction, the proportions of the variable fractions being varied so as to change the temperature of the mixture comprising the first liquid stream passed to the contacting means; The first CO2-rich liquid stream and the second CO2-rich liquid are sent to different levels of the chamber; A first liquid stream rich in CO2 is withdrawn from an apparatus for separation or liquefaction of CO2 by distillation and / or partial condensation in order to send it to the contacting means.

[0020] There is provided a process for operation of an apparatus as described above or a process as described above, wherein the CO2-rich first liquid stream is passed to the contacting means before the CO2-rich first gaseous stream is passed to the contacting means and before passing the liquid from the contacting means to a CO2 storage facility on the vehicle.

[0021] According to other optional aspects: the sending of the CO2-rich first liquid stream is triggered by a signal indicating an expected connection and / or arrival of a vehicle within a period of time; the first liquid stream is not delivered to the chamber if the first gas stream flow is not expected to be delivered to the chamber or if the first gas stream flow is not delivered to the chamber within a given time period; The gas flow is not drawn out of the chamber, The CO2-rich first liquid stream is a liquid other than the bottom liquid of the chamber; the CO2-rich first liquid stream is passed directly from the CO2 separator to the contacting means; The first liquid stream is subcooled in a heat exchanger of the CO2 separator.

[0022] According to the present invention, it is not necessarily required to operate the storage facility at constant pressure. In the event that the arrival of a vehicle, such as a ship, that will be loaded with liquid CO2 is anticipated, the process according to the present invention may be 1. So that the gas is ready to be cold enough in the contact means to re-liquefy the gas when it arrives (thus already overcoming the thermal inertia of pipes, storage facilities, and the like); 2. so that the pressure drops in the contact means before the gas arrives; It is known that the means provided for contacting the gas coming from the transport means can be subcooled in anticipation of the gas arriving from the transport means being present in the contact means, i.e. before it is present, the arrival of the gas inevitably increases the pressure when the gas is introduced into the contact means. This makes it possible, even if the gas is not instantly reliquefied, to at least slow down the gas in the contact means, and indeed even store it therein, without reaching the maximum pressure of the chamber containing the contact means, thus avoiding the loss of the gas during the time required for its reliquefaction (for example by escaping through a vent safety pipe).

[0023] It should be noted that the contacting means may consist of means that promote contact, such as trays, or random or stacked packing, etc. However, the contacting means may simply consist of empty space, such as the gas headspace above a liquid in a storage facility, where liquid and gas may mix simply by virtue of the fact that they are both in the same space.

[0024] For example, the change in temperature of the liquid leaving the CO2 production unit and being sent to the contacting means can be anticipated to take into account the thermal inertia of the system, for example, to be ready to liquefy additional vapors coming from the storage facility of the vehicle upon connection to the vehicle. This can therefore be planned in advance while the arrival of the vehicle, e.g., a ship, is imminent. Similarly, to optimize the energy consumption of the CO2 production unit, subcooling can be limited at the end of the preloading phase to take advantage of the thermal inertia of the still-cold system.

[0025] Subcooling of CO2 on the side of the CO2 production unit can be carried out in the following ways: The liquid CO2 produced is separated into two fractions. The first fraction is subcooled in a heat exchanger to a first temperature, e.g. the minimum temperature required (for loading / unloading), in fact even lower (to the minimum temperature the liquefier can reach). The second fraction bypasses at least a portion of the heat exchanger via the control valve and is therefore not fully subcooled, but is at a second temperature higher than the first temperature, and is mixed with the first subcooled fraction for reheating. The final subcooling temperature is adjusted by opening or closing a control valve to modify the ratio of the flow rates between the first and second fractions. In normal operation without loading / unloading, the valve is open to reheat the second fraction and hence limit the subcooling. In operation with loading / unloading, it is at least partially closed.

[0026] The invention will now be explained in more detail with reference to the figures. [Brief explanation of the drawings]

[0027] [Figure 1] 1 illustrates a schematic representation of a process according to the present invention. [Figure 2] 1 illustrates a schematic representation of a process according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 shows a CO2 storage device having an insulated chamber S containing liquid CO2, in which gaseous CO2 is generated, for example, by heat intrusion. The liquid stored in chamber S originates from a CO2 liquefier or CO2 separator CC, in which a CO2-containing stream is liquefied and / or separated by partial condensation and / or distillation and / or solidification to form liquid CO2 stream 1. This liquid is preferably subcooled by sending it for cooling in heat exchanger E and then delivered by distribution means to the top of chamber S as subcooled liquid L1 into the gas headspace above the liquid level. Liquid can also be delivered to other levels of chamber S; for example, subcooled liquid L2 is delivered to a lower level of chamber S. Liquid descending in chamber S encounters gas formed at the top of chamber S. The gas is thereby at least partially liquefied, and the liquid formed retreats into chamber S.

[0029] Sometimes the liquid L3 is sent from the bottom of the chamber S to another element B, which may be a liquid CO2 storage facility forming part of a means of transport, for example a ship, a train, a tanker, a pipeline or a wagon. Element B may be a pipeline constituting a CO2 transport means allowing CO2 to be temporarily stored.

[0030] Upon arrival of Component B (or upon its connection in the case of a pipeline), Component B may contain gaseous CO resulting from previous transportation. The arrival of liquid CO in Component B at a temperature higher than that of the liquid CO otherwise may also generate gaseous CO.

[0031] The storage facility S comprises a pipe for potentially venting the gas V1 to the air, equipped with a valve J, allowing the gas to be sent to the air in case of excessive pressure in the gas headspace above the liquid level.

[0032] In order not to lose the gas CO2V2 coming from the means of transport B, this gas V2 is sent to the storage facility S at a level below the reach of the liquid L1 so that it is liquefied by direct contact with the liquid L1.

[0033] It is also possible to have gas V2 enter the storage facility through pipe V1, from which the gas is washed with a CO2-rich liquid stream L1.

[0034] The liquids coming from the device CC can be introduced into the storage facility through a single opening, but are preferably sent to different points at the same level of the chamber S in order to spray a larger surface area of ​​the chamber S. From this it can be seen that the liquid L2 is introduced into the storage facility S at a lower level than the liquid L1.

[0035] This process uses means for modifying the temperature of the cleaning liquids L1, L2 sent to chamber S. These can take several forms, the simplest form illustrated here consisting in short-circuiting a portion 1A of the liquid around the exchanger so that a variable fraction of the liquid is cooled in the exchanger and the remaining part that has not been cooled mixes with the variable fraction to form liquid L1. The greater the fraction 1A, the higher the temperature of the liquids L1, L2.

[0036] In a basic alternative, pressure sensing means PIC measures the pressure in the chamber and, if this exceeds a threshold, regulates the temperature of liquid L1, for example by closing valve 2 to prevent liquid 1A from short-circuiting supercooling and thereby reducing the temperature of liquids L1, L2.

[0037] From this it follows that the temperature of the liquids L1 and / or L2 is reduced when an increase in the gas flow rate and / or an increase in the temperature of the gas is provided, so that the cold air sent to the storage facility S is sufficient to liquefy the gas. Following the same principle, during an increase in the gas flow rate and / or its temperature, the pressure in the chamber S increases, and the reduction in the temperature of the liquid L1 makes it possible to limit, and indeed even counteract, this increase in pressure.

[0038] Similarly, the temperature of liquid L1 decreases when a reduction in gas flow rate and / or a reduction in the temperature of gas V1 is expected, for example when the arrival of transport means B is expected but before gas V2 arrives in the storage facility.

[0039] Instead of or in addition to the pressure sensing means PIC, the device may comprise flow detection means FIC and / or temperature detection means TIC for measuring the flow rate and / or temperature, respectively, of the first gas stream sent or to be sent to the storage facility S.

[0040] The same changes are expected if the flow rate and / or temperature of gas V2 from element B is changed. According to the same principle, during a decrease in the flow rate of the gas and / or its temperature, the pressure in chamber S decreases, and the increase in the temperature of liquid L1 makes it possible to limit, and indeed even counteract, this pressure decrease.

[0041] As the whole system has a certain thermal inertia, it is advisable to reduce the temperature of the liquid L1 before the gas flow rate and / or temperature is increased, so that the top of the storage facility S is at an appropriate temperature to ensure liquefaction. Thus, for example, before the arrival of the vessel B, the temperature of the liquid L1 is reduced in anticipation of the arrival of the gas V2.

[0042] 2 shows an alternative form of the process, with contact column K, a column containing trays or random or stacked packings, as contact means. This column K is located between the apparatus CC and the storage facility in order to receive the liquid L1 coming from the apparatus CC and also the gas V2 coming from the transport means B. As with the previous diagram, the gas is liquefied by direct contact with the liquid L1, but in this diagram it enters the bottom of column K, rises in column K and encounters the liquid going down the column. The gas V2 is thus liquefied, and the liquid L2 formed at the bottom is sent to the storage facility S. The bottom liquid L3 from the storage facility S is pressurized by pump P2 and fed to the transport means B.

[0043] Alternatively, the column K can also be used to liquefy a gas V1 formed in the storage facility S, for example by heat ingress. The gases V1 and V2 are mixed to form a gas V', which reaches the base of the column K.

[0044] Alternatively, a portion of the liquid coming out of the device CC can be sent directly to the storage facility S, and only a portion of the liquid can be fed to the top of the column K.

[0045] Gas V1 passes through a valve (not shown) that regulates the pressure in storage facility S, as shown in Figure 1. A pressure detector PIC (not shown) in tower K regulates the opening of valve 2.

Claims

1. CO 2 1. An apparatus for liquefying a liquid containing 1,000 ppm or more of ethanol, the apparatus comprising: Chamber (S, K), ・CO 2 a first liquid stream (L1) rich in CO 2 and placing the first gas stream (V2, V) in the chamber in direct contact with the first gas stream (V1) enriched in CO2 to condense at least a portion of the first gas stream to produce CO2. 2 contacting means for forming a condensed gas enriched in CO generated from the contact means 2 liquid CO to receive the condensed gas enriched in CO 2 Storage facilities or liquid CO 2 a means for connecting a transport means (B) comprising a storage facility to said contact means; - means for delivering said first liquid stream to said contacting means; Liquid CO of the transport means 2 Storage facility or the liquid CO 2 means for delivering said first gas stream from a storage facility to said contacting means; In an apparatus comprising: i) means for detecting the flow rate of the first gas stream that has been or will be fed into the means for feeding the first gas stream; and / or ii) means for detecting the temperature of said first gas stream; and / or iii) means for detecting the pressure in said chamber (PIC); and iv) means (1A, 2) for adjusting the temperature of the first liquid stream upstream of the contact means in response to the flow rate and / or temperature of the first gas stream and / or the pressure of the contact means; An apparatus comprising:

2. The transport means (B) is a liquid CO 2 10. The apparatus of claim 1, wherein the apparatus is a ship, train, tanker, pipeline, or wagon capable of at least temporarily storing

3. 3. The apparatus according to claim 1, wherein the chamber (S) is designed to store a liquid and does not contain a reliable means for facilitating mass exchange, the contact means consists of a gas headspace formed above the liquid level when the apparatus is in operation, and the means for delivering the first liquid stream (L1) is connected to deliver the first liquid stream beyond the point of arrival of the first gas stream (V2).

4. The chamber (K) is a scrubber having a bottom, the contact means being located in the scrubber, these contact means consisting of means for promoting heat and mass transfer above the bottom, the bottom being connected to receive the first liquid stream (L1) at a level of the scrubber above the arrival point of the first gas stream (V'), the bottom of the scrubber being connected to receive the first liquid stream (L1) at a level of the scrubber above the arrival point of the first gas stream (V'), 2 The CO 2 A device according to any one of claims 1 to 3, connected to a storage facility (S, B).

5. CO 2 5. The device according to claim 1, wherein the first liquid stream (L1) enriched in is a liquid other than the bottom liquid of the chamber.

6. CO 2 a first liquid stream (L1) rich in CO 2 the first liquid stream is passed to a contacting means in a chamber (S, K) and the first gas stream is passed to the contacting means so as to mix with a first gas stream (V2, V') rich in CO and condense at least a portion of the first gas stream; 2 wherein the liquid is CO 2 resulting from said contacting means. 2 liquid CO connected to said contacting means for receiving condensed gas enriched in CO 2 Storage facilities or liquid CO 2 The liquid CO is sent from the contact means to a transport means (B) comprising a storage facility. 2 Storage facility or the liquid CO 2 The first gas stream originating from the storage facility is converted into the liquid CO 2 as a result of heat ingress. 2 In the process, formed by partial evaporation above the liquid level in the storage facility, i) CO 2 The temperature of the first liquid stream rich in gaseous CO 2 increases when the flow rate and / or temperature of the first gas stream is reduced and / or when the pressure in the chamber is reduced, and 2 the temperature of the first liquid stream enriched in is reduced when the flow rate and / or temperature of the first gas stream is increased and / or when the pressure in the chamber is increased; and / or ii) Liquid CO 2 The temperature of the first liquid stream of gaseous CO 2 and increasing the flow rate and / or temperature of the first gas stream and / or the pressure of the chamber to account for the reduction in liquid CO 2 the temperature of the first liquid stream is reduced to allow for an increase in the flow rate and / or temperature of the first gas stream and / or the pressure in the chamber. A process characterized by:

7. CO 2 7. The process of claim 6, wherein the temperature of the first liquid stream (L1) rich in is adjusted depending on its flow rate so that the temperature of the contact means is sufficient to liquefy at least a portion of the first gaseous stream.

8. 8. A process according to claim 6 or 7, wherein the temperature of the first liquid stream (L1) is modified by dividing it into two variable fractions (1, 1A), one of which is cooled and the other variable fraction is not cooled, and the cooled variable fraction is mixed with the non-cooled variable fraction, the proportions of the variable fractions being varied so as to change the temperature of the mixture constituting the first liquid stream fed to the contacting means.

9. CO 2 said first liquid stream (L1) rich in CO 2 A process according to any one of claims 6 to 8, wherein another liquid (L2) rich in is sent to a different level of said chamber (S).

10. CO 2 The first liquid stream (1, L1) rich in CO is subjected to distillation and / or partial condensation to remove CO in order to send it to the contacting means. 2 The process according to any one of claims 6 to 9, wherein the liquefied or non-liquefied hydrocarbons are withdrawn from an apparatus for the separation or liquefaction of the hydrocarbons.

11. CO 2 The process according to any one of claims 6 to 10, wherein the first liquid stream (L1) enriched in is a liquid other than the bottom liquid of the chamber.

12. CO 2 The first liquid stream (L1) rich in CO 2 12. The process of claim 11, wherein the separation unit (CC) is fed directly to the contacting means.

13. The first liquid stream is 2 13. The process according to claim 12, wherein the subcooling is carried out in a heat exchanger of the separation unit (CC).

14. A process for the operation of an apparatus according to any one of claims 1 to 5 or a process according to any one of claims 6 to 13, comprising CO 2 The first liquid stream (1, L1) rich in CO 2 before the first gas stream rich in CO is sent to the contacting means and from the contacting means, 2 The process of claim 1, wherein the liquid is delivered to said contacting means before being delivered to a storage facility.

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