Method and apparatus for cooling and separating a CO2 flow containing a first component
The process and device for cooling and separation of a CO2 flow containing a first component optimize the drying and compression of CO2 by using indirect heat exchange with cooling water and liquid CO2, addressing the challenges of energy-intensive drying and compression in existing CO2 capture processes.
Patent Information
- Application Number
- FR2023004897
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-05-17
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2043-05-17
AI Technical Summary
Existing CO2 capture processes produce a CO2 product saturated with water at low pressure, which needs to be purified and compressed to meet product specifications, often requiring energy-intensive drying and compression steps.
A process and device for cooling and separation of a CO2 flow containing a first component, such as water, methanol, or ammonia, involving indirect heat exchange with cooling water and liquid CO2 to achieve partial condensation and separation of the first component, thereby optimizing the drying and compression process.
This solution reduces the energy required for drying and compression by optimizing the cooling and separation process, allowing for the production of purified CO2 at higher pressure with reduced equipment needs and operational costs.
Smart Images
Figure 00000010_0000
Abstract
Description
Title of the invention: Method and apparatus for cooling and separating a CO2 flow containing a first component
[0001] The present invention relates to a method and apparatus for cooling and separating, for example drying, a flow of CO2 containing at least a first component, which may be water, methanol, ammonia, having a condensation temperature higher than that of CO2.
[0002] CO2 may contain at least one other component lighter and / or heavier than CO2.
[0003] The flue gases treated by CO2 capture processes often produce a water-saturated CO2 product, available at low pressure, whereas it is often necessary to produce it purified in water and under pressure (due to the specification of the product or its integration into a CO2 liquefier). It is then necessary to compress and dry it.
[0004] The present invention provides an optimization of an arrangement for partial condensation of water from a wet CO2 fluid by cooling against water and liquid CO2.
[0005] This invention can be applied in the context of different synergies that can be identified during the compression and drying of wet CO2 with various units / technologies (for example, wet CO2 from an amine scrubbing unit on flue gas and cryogenics on residual gas from a PSA H2 of an SMR, or wet CO2 from a pipeline and drying upstream of a liquefier).
[0006] When the water content imposed by the final CO2 specification is restrictive and / or the CO2 is intended for liquefaction at temperatures below 0°C, drying with a TSA is one of the ways to be compliant. It is possible to use a scheme which comprises a first heat exchanger with cooling water at a first temperature followed by a second heat exchanger with cooling water at a second temperature lower than the first temperature (produced by a mechanical refrigeration unit and therefore energy consuming) or with a refrigerant coming from a mechanical refrigeration unit in order to cool the wet CO2 further and reduce the size of the downstream TSA as well as the energy required for its regeneration.
[0007] GB-A-2416389 describes a method of cooling wet CO2 in which the Compressed wet CO2 is cooled first with seawater in a first heat exchanger and then by two flows of gaseous CO2 in a second heat exchanger to condense water contained in the CO2 upstream of a adsorption unit. Water is removed by means of a phase separator downstream of the two exchangers.
[0008] The present invention relates to a method for cooling and separating a CO2 stream containing at least one first component having a dew point temperature between 0 and 70°C at a first pressure and optionally at least one component lighter and / or heavier than CO2 comprising at least the following steps: i. Cooling the CO2 stream at the first pressure from a first temperature to a second temperature by indirect heat exchange with a warming cooling water stream ii. Cooling the CO2 stream at the first pressure to the second temperature by indirect heat exchange with at least one liquid CO2 stream which vaporizes forming a CO2 flow at a third temperature iii. Separation of condensate produced by condensation of the at least one first component present in the CO2 stream during at least one of steps i) or ii) forming a flow enriched in CO2 and purified in the at least one first component iv. steps i) and ii) taking place in a single heat exchanger and the first and / or second temperatures being between 0 and 15°C.
[0009] According to other optional steps:
[0010] -the at least one first component is water, the CO2-enriched flow still contains water and is dried by adsorption of the water.
[0011] -the at least one first component is water, the CO2-enriched flow still contains water and is dried by absorption of the water.
[0012] -the at least one first component is water
[0013] -the at least one first component is methanol
[0014] -the at least one first component is ammonia
[0015] -the flow containing at least a first component is compressed upstream of the step i) and / or the CO2-enriched stream is dried and then compressed.
[0016] -the flow of gaseous CO2 resulting from the vaporization of the at least one stream of liquid CO2 is at least partly mixed with the CO2 containing the first component or a gas produced by drying the flow enriched in CO2.
[0017] -the heat exchanger is of tube and shell technology, comprising at least two tube bundles, the CO2 containing the first component being injected on the shell side and the cooling water being injected into a first tube bundle and the at least one stream of vaporizing liquid CO2 being injected into a second tube bundle.
[0018] -the heat exchanger comprises at least three tube bundles, a stream of liquid CO2 being injected into the second tube bundle and a stream of gaseous CO2 or a stream of liquid CO2 being injected into a third tube bundle.
[0019] -the at least one stream of liquid CO2 comes from a distillation and / or partial condensation process in which a flow containing CO2 and at least one component lighter than CO2 and / or at least one component heavier than CO2 is separated, this flow preferably consisting of the CO2-enriched flow treated by steps i) and ii) to reduce its content of the at least one first component.
[0020] -the first component is water, a gas flow containing CO2 from the distillation and / or partial condensation process is used for the regeneration of the adsorption unit in which the flow enriched in CO2 and purified in the at least one first component is dried.
[0021] - the gas used for regeneration is mixed with the wet CO2 flow upstream of step i).
[0022] -the at least one flow of liquid CO2 which vaporizes in the heat exchanger is at a pressure between 30 and 45 bars abs.
[0023] -the CO2 stream containing at least one first component comes from an amine washing process
[0024] According to another object of the invention, there is provided an apparatus for cooling and separating a CO2 flow containing at least one first component having a dew point temperature between 0 and 70°C at a first pressure and optionally at least one component lighter and / or heavier than CO2 comprising heat exchange means, means for sending a stream of cooling water to the heat exchange means, means for sending at least one stream of liquid CO2 to the heat exchange means,means for sending the CO 2 flow at the first pressure to cool in the heat exchange means from a first temperature to a second temperature by indirect heat exchange with the cooling water stream which heats up and then to cool in the heat exchange means at the first pressure from the second temperature by indirect heat exchange with at least one liquid CO2 stream which vaporizes forming a CO2 flow at a third temperature, means for leaving the exchange means the condensate produced by condensation of the at least one first component present in the CO2 flow, means for leaving the heat exchange means a flow enriched in CO2 and purified in the at least one first component and the heat exchange means being constituted by,
[0025] a single heat exchanger.
[0026] According to other optional aspects of the invention:
[0027] -the heat exchanger consists of a shell and at least two tube bundles arranged in the shell, the means for sending a flow of CO2 to the first pressure to cool, the means for removing the condensate and the means for removing the CO2-enriched flow being fluidly connected to the calender.
[0028] -one of the tube bundles is fluidically connected to the means for sending the cooling water stream and another of the tube bundles is connected to the means for sending the liquid CO2 stream.
[0029] According to another object of the invention, there is provided an apparatus for cooling and separating a CO2 stream containing at least one first component having a dew point temperature between 0 and 70°C at a first pressure and at least one component lighter and / or heavier than CO2 comprising an apparatus as described above, a purification apparatus for reducing the content of the first component of the CO2-enriched stream, a partial condensation and / or distillation apparatus for reducing the content of the at least one component lighter and / or heavier than CO2 of the CO2-enriched stream purified in the purification apparatus and means for removing the liquid CO2 stream from the partial condensation and / or distillation apparatus.
[0030] The present invention proposes an optimization of the scheme by introducing a cooling step upstream of the adsorption unit, for example TSA (if present) with liquid CO2 from a cryogenic unit. This step takes place in a single heat exchanger, also cooled by cooling water.
[0031] The configuration proposed in this invention presents the possibility of using less equipment, mainly a first exchanger with cooling water and a second exchanger with liquid CO2 upstream of the TSA by bringing them together in a single exchanger.
[0032] In the case of a shell and tube exchanger, the condensation of water can take place in the shell of this exchanger, hence saving both the cooler and the separator pot downstream of the cooler, the liquid CO2 will be vaporized in the second tube bundle of the exchanger.
[0033] The vaporized liquid CO2 can be pooled with the dried CO2. To do this, it will be injected into an intermediate section of the common compressor or at its outlet.
[0034] The exchanger with the double tube bundle has a single pass on the shell side, which minimizes the pressure losses on the shell side and allows the installation of a droplet separator on the outlet face of the second bundle.
[0035] The liquid CO2 used for the second cooling step can come from a process operating at low temperature, for example by distillation and / or partial condensation producing CO2. This process replaces the mechanical refrigeration unit used to produce cooling water often used for this purpose. Description of the invention
[0036] The invention will be described in more detail with reference to the figure:
[0037] [Fig.l] schematically represents a method according to the invention.
[0038] The invention makes it possible to recover and dry wet CO2 1 which can come, for example, from an amine M washing unit or from a gaseous CO2 pipeline at the inlet of a liquefier.
[0039] The wet CO2 is compressed in a first compressor C1, cooled by means of water in a cooler RI to condense part of the water it contains. The water 6 is removed in a separator SI and the CO2 3 still containing water is compressed in a compressor C2 up to the adsorption pressure of the TSA Al, A2 between 5 and 30 bara, preferably 10 bara and recovered at the outlet of compressor C2 at a temperature between 80°C and 150°C.
[0040] The flow 7 at a first pressure between 5 and 30 bara is sent to a shell and tube heat exchanger R3, having two bundles of tubes F1, F2, the flow 7 being sent to the shell. The water contained in the flow 7 has a dew point temperature between 0 and 70°C at this first pressure. Cooling water is sent to the first bundle F1 to cool the wet CO2 by circulating in the tubes of the first bundle. This water is preferably at room temperature. A flow of liquid CO2 19 is sent to the second bundle F2 where it vaporizes forming dry gaseous CO2 by circulating in the tubes of the second bundle F2, preferably at a pressure between 25 bar abs or even 30 bar abs and 45 bar abs.
[0041] Condensed water 8 produced by cooling the wet CO2 7 is removed from the calender.
[0042] At least two streams of liquid CO2 can be sent to the exchanger R3 by adding tube bundles.
[0043] Otherwise at least one flow of liquid CO2 and at least one flow of gaseous CO2 can be sent to the exchanger R3 by adding tube bundles.
[0044] An intermediate drying step of the gas 9 dried in the exchanger R3 will be carried out for example in a TSA adsorption unit Al to ensure that the final CO2 product complies with the water specification. The drying unit can also be a triethylene glycol TEG dryer.
[0045] Temperature swing adsorption (TSA) is a gas mixture separation process in which a gas is alternately adsorbed by a solid or liquid at a given temperature, followed by its desorption at a higher temperature.
[0046] Temperature-modulated adsorption uses the temperature dependence of adsorption. The adsorbent is loaded with the compound to be separated and is largely freed of this compound in a subsequent step by means of the introduction of thermal energy. For the continuous operation of a temperature-modulated adsorption system, at least two adsorbent beds are required; one being loaded and the other being desorbed. While the gas is adsorbed in bed Al, it is desorbed in bed A2 and vice versa.
[0047] The dry CO2 11 leaving the adsorbent bed Al (or A2 depending on the cycle) can then be further compressed to the final pressure by a compressor C3 in common with the vaporized CO2 stream(s) 19.
[0048] If the vaporized CO2 19 is at a sufficiently high pressure, it can be mixed with the dry CO2 downstream of the compressor C3.
[0049] Otherwise the vaporized CO2 can be sent as flow 19A upstream of compressor C2, if its pressure is not high enough to be sent upstream of compressor C3.
[0050] The flow of dry CO2 can be mixed with the flow of vaporized liquid CO2 19 in the bundle F2 upstream or downstream of the compressor C3. The compressed flow 21 can be cooled by a cooler R4 to form a flow 23 of dry CO2. The gas 23 can feed a CO2 liquefier.
[0051] This solution is favourably economical in terms of investment costs because the number of equipment required is reduced. Only a single R3 dual cold fluid exchanger will be required instead of several exchangers and potentially gas / liquid separation pots. In addition, this solution potentially does without a dedicated refrigeration unit.
[0052] The at least one stream 19 can be produced by a distillation and / or partial condensation apparatus 20 producing a gas flow enriched in CO2 25 and / or a gas flow 27 enriched in at least one component lighter or heavier than CO2.
[0053] The flow rate 7 at the first pressure may contain another first component than water, having a dew point temperature between 0 and 70°C at this first pressure, for example methanol or ammonia.
[0054] The flow rate 7 at the first pressure may contain another first component instead of water or in addition to water, having a dew point temperature between 0 and 70°C at this first pressure, for example methanol or ammonia.
Claims
Claims
1. A method for cooling and separating a CO2 stream (1, 3, 7) containing at least one first component having a dew point temperature between 0 and 70°C at a first pressure which is water and optionally at least one component lighter and / or heavier than CO2 comprising at least the following steps: i) Cooling the CO2 stream at the first pressure from a first temperature to a second temperature by indirect heat exchange with a heating cooling water stream ii) Cooling the CO2 stream at the first pressure to the second temperature by indirect heat exchange with at least one liquid CO2 stream (19) which vaporizes forming a CO2 flow at a third temperature iii) Separating condensate (8) produced by condensation of the at least one first component present in the CO2 stream during at least one of steps i) or ii) forming a flow (9) enriched in CO2 and purified of the at least onefirst component iv) steps i) and ii) taking place in a single heat exchanger (R3) and the first and / or second temperatures being between 0 and 15°C, v) the CO2-enriched flow (9) still containing water is dried by adsorption (A1, A2) or absorption of the water vi) the gaseous CO2 flow resulting from the vaporization of the at least one liquid CO2 stream (19) being at least partly mixed with a gas produced (11, 21) by drying the CO2-enriched flow of water.
2. Method according to one of the preceding claims in which the stream (1, 3, 7) containing at least a first component is compressed (C1, C2) upstream of step i) and / or the CO2-enriched stream (9) is compressed after having been dried (C3).
3. Method according to one of the preceding claims in which the heat exchanger (R3) is of tube and shell technology, comprising at least two tube bundles (F1, F2), the CO2 containing the first component being injected on the shell side and the cooling water being injected into a first tube bundle (F1) and the at least one stream of vaporizing liquid CO2 (19) being injected into a second tube bundle (F2).
4. A method according to claim 3 wherein the heat exchanger comprises at least three tube bundles (F1, F2), a liquid CO2 stream (19) being injected into the second tube bundle (F2) and a gaseous CO2 stream or a liquid CO2 stream being injected into a third tube bundle.
5. Method according to one of the preceding claims in which the at least one liquid CO2 stream (19) comes from a distillation and / or partial condensation process (20) in which a flow containing CO2 and at least one component lighter than CO2 and / or at least one component heavier than CO2 is separated, this flow preferably consisting of the CO2-enriched flow treated by steps i) and ii) (9, 21, 23) to reduce its content of the at least one first component.
6. Method according to claim 5 in which a gas flow (21, 29) containing CO2 from the distillation and / or partial condensation process (20) is used for the regeneration of the adsorption unit (A1, A2) in which the flow (9) enriched in CO2 and purified of the at least one first component is dried.
7. Method according to claim 6 in which the gas used for regeneration (31, 35, 37, 39) is mixed with the stream of wet CO2 (1, 3, 7) upstream of step i).
8. Method according to one of the preceding claims in which the at least one flow of liquid CO2 (19) which vaporizes in the heat exchanger (R3) is at a pressure between 25 and 45 bars abs, or even between 30 and 45 bars abs.
9. Apparatus for cooling and separating a CO2 stream (1,3,7) containing at least one first component having a dew point temperature between 0 and 70°C at a first pressure which is water and optionally at least one component lighter and / or heavier than CO2 comprising heat exchange means (R3), means for sending a cooling water stream to the heat exchange means, means for sending at least one liquid CO2 stream (19) to the heat exchange means,means for sending the CO2 stream at the first pressure to cool in the heat exchange means from a first temperature to a second temperature by indirect heat exchange with the cooling water stream which heats up and then to cool in the heat exchange means at the first pressure from the second temperature by indirect heat exchange with at least one liquid CO2 stream (19) which vaporizes forming a CO2 flow at, a third temperature, means for removing from the exchange means the condensate (8) produced by condensation of the at least one first component present in the CO2 flow, means for removing from the heat exchange means a flow (9) enriched in CO2 and purified in the at least one first component and the heat exchange means being constituted by a single heat exchanger, means (A1, A2) for drying the flow enriched in CO2 and means for mixing the flow of CO2 at the third temperature with the flow dried by the means for drying the flow enriched in CO2.
10. Apparatus according to claim 9 wherein the heat exchanger (R3) is constituted by a shell and at least two tube bundles (F1, F2) arranged in the shell, the means for sending a flow of CO2 (7) at the first pressure to cool, the means for removing the condensate (8) and the means for removing the flow enriched in CO2 (9) being fluidly connected to the shell.
11. Apparatus according to claim 10 in which one of the tube bundles (F1) is fluidically connected to the means for sending the cooling water stream and another of the tube bundles (F2) is connected to the means for sending the liquid CO2 stream (19).