Carbon dioxide recovery and conditioning systems and methods for ammonia-based carbon dioxide capture processes

Abstract

A carbon dioxide recovery and conditioning system for an ammonia-based carbon dioxide capture process wherein the system comprises a regeneration column and a regenerator cooling system adapted to cool a gas stream comprising carbon dioxide, ammonia and moisture, the gas stream collected at the top of the regeneration column. The carbon dioxide refrigeration and drying device is fluidly coupled to the regenerator cooling system and the carbon dioxide recovery line. The system effectively removes moisture and ammonia upstream of the dryer. Also disclosed herein is a method for carbon dioxide recovery and conditioning.

Description

[0001] manual Technical Field

[0002] The present disclosure relates to carbon dioxide capture systems. Specifically, embodiments disclosed herein relate to improvements to carbon dioxide recovery and conditioning systems and methods suitable for removing carbon dioxide from ammoniacal solutions loaded with carbon dioxide. Background Art

[0003] Carbon dioxide (CO2) is a greenhouse gas that is considered one of the main factors in global warming and climate change. Carbon dioxide is produced by several industrial processes in which heat energy is generated by burning fossil fuels such as natural gas and oil.

[0004] Carbon capture and storage (CCS) is an effective technology to significantly reduce greenhouse gas emissions. Post-combustion capture (PCC) is a process that uses an aqueous absorption solution containing compounds such as ammonia to capture carbon dioxide from flue gases produced by the combustion of fossil fuels.

[0005] The ammonia-containing solution contacts the CO2-rich flue gas in the absorber and keeps the CO2 trapped in the solution. The CO2-laden absorption solution (CO2-rich absorption solution) is then transferred to the regenerator where the CO2 is removed and sent to the CO2 recovery line for further processing, while the CO2-lean solution obtained by removing the CO2 is recycled to the absorber.

[0006] Regenerating the aqueous ammonia solution and conditioning the recovered carbon dioxide, in particular removing the ammonia escaping from the regenerator, is a complex and expensive process.

[0007] It would be welcome in the art to improve carbon dioxide recovery and conditioning processes to make the processes more efficient and effective, thereby reducing system costs and the energy required to operate the systems.

[0008] It is therefore an object of the subject matter disclosed herein to improve carbon dioxide recovery and conditioning processes downstream of the regenerator for post-combustion capture using aqueous ammonia-based solutions. Summary of the Invention

[0009] According to one aspect, a carbon dioxide recovery and conditioning system for an ammonia-based carbon dioxide capture process is disclosed. The system includes a regeneration tower and a regenerator cooling system adapted to cool a gas stream containing carbon dioxide, ammonia, and moisture, which is collected at the top of the regeneration tower. Furthermore, a carbon dioxide refrigeration and drying unit is fluidly coupled to the regenerator cooling system and the carbon dioxide recovery line.

[0010] In an embodiment disclosed herein, the carbon dioxide refrigeration and drying device includes a first carbon dioxide chiller adapted to be fluidly coupled to the outlet of a regenerator cooling system. The carbon dioxide refrigeration and drying device further includes a first carbon dioxide dryer fluidly coupled to the outlet of the first carbon dioxide chiller. A second carbon dioxide chiller is adapted to be fluidly coupled to the outlet of the regenerator cooling system. The second carbon dioxide dryer is fluidly coupled to the outlet of the second carbon dioxide chiller. The first carbon dioxide dryer and the second carbon dioxide dryer are fluidly coupled to a carbon dioxide recovery line. The dryer and chiller regeneration device is adapted to selectively regenerate one of the first and second carbon dioxide dryers and one of the first and second carbon dioxide chillers while the other of the first and second carbon dioxide dryers and the other of the first and second carbon dioxide chillers are in operation.

[0011] The dryer and refrigerator regeneration arrangement includes fluid couplings between the first CO2 refrigerator and the regenerator cooling system and between the second CO2 refrigerator and the regenerator cooling system, the fluid couplings being adapted to return a flow of regenerated CO2 from the regenerating CO2 refrigerator to the regenerator cooling system.

[0012] Further features and embodiments of the carbon dioxide recovery and conditioning system according to the present disclosure are described in detail below with reference to the accompanying drawings and are set forth in the appended claims.

[0013] According to another aspect, disclosed herein is a method for recovering and regulating carbon dioxide from an ammonia-containing solvent. The method comprises:

[0014] treating the CO2-rich absorption solution in a regeneration tower and collecting a gas stream containing carbon dioxide, ammonia, and moisture from the CO2-rich absorption solution;

[0015] reducing the temperature of the gas stream and removing moisture and ammonia from the gas stream in a regenerator cooling system;

[0016] further refrigerating the gas stream in a carbon dioxide refrigerator and removing additional water and ammonia from the gas stream in the carbon dioxide refrigerator;

[0017] drying the gas stream in a carbon dioxide dryer; and

[0018] The dried carbon dioxide is collected downstream of the carbon dioxide dryer.

[0019] Additional features and embodiments of the method are described below and are set out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Reference will now be made briefly to the accompanying drawings, in which:

[0021] Figure 1 is a schematic diagram of a regenerator system including, in one embodiment, a carbon dioxide recovery and conditioning system according to the present disclosure;

[0022] Figure 2 Under different operating conditions Figure 2 The same schematic diagram of ;

[0023] Figure 3 is a schematic diagram of a regenerator system including, in another embodiment, a carbon dioxide recovery and conditioning system according to the present disclosure; and

[0024] Figure 4 is a flow chart outlining a method of carbon dioxide recovery and conditioning according to the present disclosure. DETAILED DESCRIPTION

[0025] The system includes a regeneration tower, which receives the rich CO2 absorbing solution from the absorber. The absorbing solution is processed in the regeneration tower to remove carbon dioxide and obtain lean CO2 absorbing solution, which is returned to the absorber. The gaseous carbon dioxide stream leaving the top of the regeneration tower is processed to remove the ammonia escaping from the regeneration tower and further remove moisture. The low moisture content and very low ammonia content in the carbon dioxide stream are achieved by refrigerating the gas stream in a carbon dioxide refrigerator before making the gas stream pass through a carbon dioxide dryer (such as one comprising a molecular sieve or a desiccant). Therefore, the molecular sieve or the desiccant are exposed to the moisture load reduced and are protected so that they are exempt from contact with ammonia. Compared with the dryer of the prior art, a smaller size dryer can be used. A regeneration device is provided to regenerate the carbon dioxide dryer and the carbon dioxide refrigerator. The additional advantageous features of the system and the carbon dioxide regulating method are described below with reference to the exemplary embodiments shown in the accompanying drawings.

[0026] Turning now to the accompanying drawings, Figure 1 A first schematic diagram of a system according to the present disclosure is shown in FIG.

[0027] according to Figure 1 In the embodiment of the present invention, the carbon dioxide recovery and conditioning system 1 includes a regeneration tower 3 and a carbon dioxide conditioning section 5, which in turn includes a carbon dioxide refrigeration and drying device 6 fluidly coupled to a regenerator cooling system 7 and a carbon dioxide recovery pipeline 9.

[0028] The regeneration tower 3 is adapted to receive a CO2-rich absorption solution from a rich absorption solution inlet line 11, which can be fluidly coupled to an absorber (not shown) in a carbon capture section. The carbon capture section can be based on a chilled ammonia process (CAP), a mixed salt process (MSP), a process using ammonia mixed into an amine mixture, or any other process that uses an ammonia-containing aqueous solution to capture carbon dioxide from flue gas and release it in the regeneration tower 3.

[0029] After removing carbon dioxide from the aqueous solution, the CO2 lean absorption solution is returned to the absorber through the lean solution outlet line 13.

[0030] In embodiments, the rich absorbent solution inlet line 11 is divided into a plurality of liquid feeds (at Figure 1 1 . 3 ) which deliver the CO2-rich absorption solution at three different locations within the regeneration column 3. A first, uppermost liquid feed or inlet line 11.1 may be fluidly coupled to the top of the regeneration column 3 above a regenerator overhead condenser to be described, a second, intermediate liquid feed or inlet line 11.2 may be fluidly coupled to the upper region of the regeneration column 3 upstream of the regenerator overhead condenser, for example, above the regenerator mass transfer internals or packing 3.1, and a third, lower liquid feed or inlet line 11.3 may be fluidly coupled to the regeneration column 3 in a location below the regenerator packing 3.1.

[0031] The regeneration process is an endothermic process and requires heat energy to be transported to the regeneration tower 3. Figure 1 In the embodiment of , heat energy is transferred to the regeneration column 3 via a regenerator reboiler 3.2, which is positioned in the lower part of the regeneration column 3, below the regenerator packing 3.1 and below the lower liquid feed 11.3.

[0032] exist Figure 1 In the embodiment of the present invention, the regeneration tower 3 further includes an upper liquid distribution tray 3.3 arranged above the regenerator packing 3.1 and a lower liquid distribution tray 3.4 arranged below the regenerator packing 3.1. The lean absorption solution is collected at the bottom 3.5 of the regeneration tower 3 and removed through the lean solution outlet line 13.

[0033] Since the temperature of the lean solution is higher than the temperature of the rich CO2 absorption solution flowing through the rich solution inlet line 11, a recovery heat exchanger may be provided to remove heat from the lean solution and preheat the rich CO2 absorption solution before it is supplied to the regeneration tower 3. Figure 1In some embodiments, a high-temperature heat exchanger 15 and a low-temperature heat exchanger 17 are provided for this purpose. Hot lean solution from the bottom of the regeneration column 3 flows through the hot side of each heat exchanger 15, 17 to heat the CO2-rich absorption solution entering the regeneration column 3. A first side stream of CO2-rich absorption solution is diverted from the rich solution inlet line 11 and fed to an overhead condenser 19 (which will be described in more detail below), specifically at the top of the overhead condenser 19. In some embodiments, the side stream of CO2-rich absorption solution fed to the overhead condenser 19 is diverted via a first upper liquid feed 11.1 located upstream of the two heat exchangers 15, 17 and fed to the top of the regeneration column 3. A second side stream of CO2-rich absorption solution is diverted via a second intermediate liquid feed 11.2 so that the hotter CO2-rich absorption solution is fed to the top of the regenerator packing 3.1. Due to the heat exchange in both the high-temperature heat exchanger 15 and the low-temperature heat exchanger 17 , the remaining CO 2 -rich absorption solution flows at the highest temperature in the regeneration column 3 through the third lower liquid feed 11 . 3 .

[0034] The gaseous carbon dioxide is separated from the solution in the regeneration tower 3 and flows upward to the top 3.6 of the regeneration tower 3, whereby a gas stream consisting mainly of carbon dioxide, moisture and ammonia (hereinafter also referred to as CO2-containing gas stream or CO2-containing gas stream) leaves the top of the regeneration tower 3.

[0035] exist Figure 1 In the embodiment of the present invention, the regenerator cooling system 7 includes a tower top condenser 19, which can be located inside the regeneration tower 3, in the upper part of the regeneration tower, such as Figure 1 In other embodiments, the top condenser 19 can be arranged outside the regeneration tower 3.

[0036] The heat recovery cooling medium flows in the cold side of the overhead condenser 19, exchanging heat with the CO2-containing gas stream flowing from bottom to top within the regeneration column 3 and passing through the hot side of the overhead condenser 19. Water and ammonia condense on the surface of the overhead condenser 19 and are collected on the upper liquid distribution tray 3.3 and supplied to the regenerator packing 3.1 together with the liquid feed 11.2.

[0037] The heat recovery cooling medium flowing through the cold side of the overhead condenser 19 recovers heat from the CO2-containing gas stream. The heat can be recovered at a usefully high temperature, for example, about 70°C to 90°C. In some embodiments, the CO2-containing gas stream entering the overhead condenser 19 may be at a temperature of about 120°C, and the CO2-containing gas stream exiting the overhead condenser at the top of the overhead condenser 19 may be at a temperature of about 80°C.

[0038] The cooling of the CO2-containing gas stream results in the condensation of the moisture and ammonia contained therein. The liquid collected in the liquid distribution tray 3.3 at the bottom of the overhead condenser 19 has a high affinity for ammonia and reduces the moisture and ammonia content of the CO2-containing gas stream.

[0039] According to some embodiments, the regeneration column 3 comprises a recycle line adapted to recycle a portion of the liquid collected at the bottom of the regenerator overhead condenser 19 to the top of the regenerator overhead condenser 19. Figure 1 In the embodiment shown, the recirculation line is indicated at 21 and includes a recirculation pump 23. In this embodiment, the recirculation line 21 merges into the first liquid feed 11.1. The CO2-rich absorption solution from the first liquid feed 11.1, which also contains the recirculation liquid pumped through the recirculation line 21, is sprayed into the top of the overhead condenser 19 via a nozzle device 3.7.

[0040] In other embodiments, the recycle line 21 may be omitted and only the CO2-rich absorption solution from the liquid feed 11.1 may be sprayed through the nozzle 3.7 at the top of the overhead condenser 19. The use of the recycle line 21 may advantageously reduce the amount of cold CO2-rich absorption solution conveyed via the liquid feed 11.1 and may reduce the reabsorption of carbon dioxide and improve thermal system efficiency.

[0041] In both cases, the liquid sprayed on top of the overhead condenser 19 prevents precipitation of ammonia salts, especially during start-up conditions and transients.

[0042] The top 3.6 of the regeneration column 3 is fluidly connected to a carbon dioxide cooler 25 via a line 27. Thus, the CO2-containing stream, which has been cooled in the overhead condenser 19 and from which a portion of the water and ammonia contained therein has been removed, is conveyed to the carbon dioxide cooler 25 for further cooling and removal of water and ammonia.

[0043] The CO2-containing gas stream is further cooled, for example from about 80°C to about ambient temperature, by rejecting heat in the CO2 cooler 25. If convenient, the heat removed from the CO2-containing gas stream in the CO2 cooler 25 can be rejected to the environment or recovered.

[0044] In some embodiments, a wash water line 29 may be provided to add water to the top of the carbon dioxide cooler 25, i.e., near its steam inlet. Adding water to the carbon dioxide cooler 25 may result in a further reduction in ammonia in the gas stream because ammonia is absorbed by the wash water delivered through the wash water line 29. The wash water supplied to the carbon dioxide cooler 25 may remove ammonia salts that may form on the metal surfaces of the carbon dioxide cooler 25 to prevent or limit scaling thereof. The ammonia-laden wash water may be removed from the carbon dioxide cooler 25 via a laden wash water discharge line 31.

[0045] The CO2 cooler 25 removes condensed liquid and any suspended ammonia salts from the CO2-containing gas stream, which is further processed in the CO2 refrigeration and drying unit 6, to which the CO2-containing gas stream is fed from the CO2 cooler 25. The purpose of the CO2 refrigeration and drying unit 6 is to further remove moisture and ammonia from the CO2-containing gas stream. The resulting stream leaving the CO2 refrigeration and drying unit consists almost entirely of carbon dioxide, with a small amount of moisture and very small amounts of ammonia, typically less than 10 mole ppm moisture and less than 1 mole ppb NH3, which is collected in the carbon dioxide recovery line 9.

[0046] Generally speaking, the CO2 refrigeration and drying unit 6 has a dual configuration, comprising a first CO2 refrigerator fluidly coupled in series with a first CO2 dryer, and a second CO2 refrigerator fluidly coupled in series with a second CO2 dryer. During operation, one of the first and second CO2 refrigerators cools a CO2-containing gas stream while the other CO2 refrigerator is in a regeneration phase. Similarly, while one of the first and second CO2 dryers is in operation, the other CO2 dryer is in a regeneration phase to remove any moisture trapped therein.

[0047] Now go to Figure 1 The carbon dioxide refrigeration and drying device 6 includes a first carbon dioxide refrigerator 33A and a second carbon dioxide refrigerator 33B. In use, the carbon dioxide refrigerator 33A or 33B can be adapted to reduce the temperature of the CO2-containing gas stream to between 0°C and 10°C, for example, typically about 5°C, at a pressure of, for example, 15-21 barA. It should be understood that the above values are exemplary and should not be construed as limiting the scope of the present disclosure.

[0048] Under these operating conditions, the water contained in the CO 2 -containing gas stream condenses together with the ammonia or can precipitate or desublime to form ammonia salts, in particular ammonium bicarbonate.

[0049] Each CO2 refrigerator 33A, 33B may include a demister that removes liquid or solid particles from the CO2-containing gas stream that flows from the corresponding CO2 refrigerator 33A, 33B to the CO2 dryer, as described below. Each CO2 refrigerator 33A, 33B may be fluidly coupled to a wash water discharge line 31 (via line 31A). In addition, wash water may be supplied to each CO2 refrigerator 33A, 33B via a wash water line 29. Wash water may be supplied to each CO2 refrigerator near the corresponding steam inlet of each CO2 refrigerator 33A, 33B.

[0050] Each CO2 refrigerator 33A, 33B may include a cold side in which a refrigerant circulates.

[0051] In the embodiment described so far, the carbon dioxide exiting at a temperature of approximately 80° C. is cooled, for example, in a two-step refrigeration process to a temperature of approximately 5° C., which is performed partially in the carbon dioxide cooler 25 and partially in one or the other of the first and second carbon dioxide refrigerators 33A and 33B. By way of example, different cooling / refrigeration fluids are used, for example, water in the carbon dioxide cooler 25 and refrigerant in the first and second carbon dioxide refrigerators 33A and 33B.

[0052] In other embodiments, the carbon dioxide cooler 25 may be omitted, or may be incorporated into each of the first carbon dioxide refrigerator 33A and the second carbon dioxide refrigerator 33B.

[0053] The first CO2 refrigerator 33A is fluidly coupled to the first CO2 dryer 35 A. Likewise, the second CO2 refrigerator 33B is fluidly coupled to the second CO2 dryer 35B.

[0054] In some embodiments, each carbon dioxide dryer 35A, 35B may include a molecular sieve or, alternatively, a desiccant bed through which the CO 2 -containing gas stream flows to remove residual moisture content from the gas stream.

[0055] By providing a CO2 refrigerator upstream of each CO2 dryer, the ammonia content in the CO2-containing gas stream is reduced to a few ppb (parts per billion), thereby protecting the desiccant beds or molecular sieves in the CO2 dryers 35A, 35B from damage that might be caused by higher ammonia content in the gas stream flowing through the dryers.

[0056] The dramatic reduction in moisture and ammonia content in the CO₂-containing gas stream flowing through the dryers 35A, 35B allows for a reduction in the size of the dryers and, therefore, in the amount of desiccant material contained therein. Since the residual ammonia content in the gas stream delivered from the CO₂ refrigerators 33A, 33B is typically less than 1 ppb, a protective guard bed suitable for further removal of ammonia from the gas stream, as is typically provided in prior art dryers, can be omitted.

[0057] The gas stream exiting the carbon dioxide dryers 35A, 35B ultimately consists almost entirely of carbon dioxide, possibly free of ammonia (e.g., less than 1 ppb) and is essentially dry, with moisture content ranging between, for example, 1 ppm and 10 ppm, depending on the desired CO2 moisture specification.

[0058] A filter 37 may be provided in the carbon dioxide recovery line 9 downstream of the carbon dioxide dryers 35A, 35B to remove dust that may be entrained in the carbon dioxide flow.

[0059] As described above, the first CO2 refrigerator 33A and the first CO2 dryer 35A and the second CO2 refrigerator 33B and the second CO2 dryer 35B on one side are operated alternately, that is, used alternately, while the others are in the regeneration stage. Figure 1 Under the operating conditions of , the solid lines show active fluid connections, while the dashed lines show inactive (closed) fluid connections. Figure 1 Under the operating conditions shown, the fluid connection between the first CO2 refrigerator 33A and the first CO2 dryer 35A is open (shown in solid lines), and the fluid connection between the CO2 cooler 25 and the first CO2 refrigerator 33A is also open. Thus, the CO2-containing gas stream can flow from the CO2 cooler 25 through the first CO2 refrigerator 35A, and from there through the first CO2 dryer 35A, thereby reaching the CO2 recovery line 9.

[0060] Conversely, any CO2-containing gas stream cannot flow from the CO2 cooler 25 to the second CO2 refrigerator 33B and the second CO2 dryer 35B because the corresponding fluid connections (illustrated by dashed lines) are closed. For this purpose, corresponding opening and closing valves are foreseen.

[0061] In use, residual moisture in the CO2-containing gas stream reaching the respective CO2 dryers 35A, 35B accumulates in the molecular sieves contained in the CO2 dryers. This requires periodic regeneration of the CO2 dryers to remove the accumulated moisture.

[0062] to this end, Figure 1The system includes a dryer and refrigerator regeneration device 40, which uses a portion of the dry carbon dioxide from the carbon dioxide recovery line 9 to regenerate the carbon dioxide dryers 35A and 35B that are not in use temporarily. Figure 1 Under the operating conditions of , when the first CO2 dryer 35A is in use, the second CO2 dryer 35B is in the regeneration phase. This is diagrammatically represented by the solid line connecting the second CO2 dryer 35B to the CO2 compressor 43 forming part of the dryer and refrigerator regeneration device 40.

[0063] The dryer and refrigerator regeneration device 40 further comprises a heater 45, for example an electric heater, which is positioned downstream of the carbon dioxide compressor 43 in a regeneration line 47 which fluidly connects the carbon dioxide compressor 43 to the carbon dioxide dryer which is temporarily in the regeneration phase. Figure 1 Under the operating conditions of , the regeneration line 47 is fluidly connected to the second carbon dioxide dryer 35B so that the compressed and heated dry carbon dioxide flows through the second carbon dioxide dryer 35B to remove moisture therefrom. The dryer and refrigerator regeneration device 40 further includes a temporarily regenerated carbon dioxide dryer and a corresponding carbon dioxide refrigerator (in Figure 1 Under the operating conditions of the second carbon dioxide refrigerator 33B), the fluid connection 49 is connected between the second carbon dioxide refrigerator 33B.

[0064] Therefore, the regenerated carbon dioxide delivered by the carbon dioxide compressor 43 through the second carbon dioxide dryer 35B flows from the second carbon dioxide dryer 35B through the second carbon dioxide refrigerator 33B. The carbon dioxide refrigerator temporarily in the regeneration stage, that is, Figure 1 The second carbon dioxide refrigerator 33B under the operating condition of is fluidly connected to the regeneration tower 3 through the return line 51. Figure 1 In the embodiment of FIG. 3 , a return line 51 connects the regenerated carbon dioxide refrigerator to the upper part of the regeneration column 3, above the regenerator packing 3.1 and upstream of the overhead condenser 19. The regenerated carbon dioxide flowing through the carbon dioxide refrigerator 35B is freed from condensate, moisture, and possible ammonia salt deposits by evaporation and sublimation, and moisture and ammonia are recycled to the regeneration column 3.

[0065] exist Figure 1 In the embodiment of the present invention, the heat recovery exchanger 55 recovers heat from the carbon dioxide stream discharged from the second carbon dioxide dryer 35B to preheat the regenerated carbon dioxide delivered by the carbon dioxide compressor 43. As a result, the power (usually electricity) supplied to the heater 45 can be reduced.

[0066] In short, Figure 1Under the operating conditions of , the CO 2 -containing gas stream flowing from bottom to top in the regeneration tower 3 is cooled in the top condenser 19 and further cooled and refrigerated in the carbon dioxide cooler 25 and the first carbon dioxide refrigerator 33A to remove moisture and ammonia therefrom. The CO 2 -containing gas stream, which contains almost no ammonia, is further dried in the first dryer 35A and collected in the carbon dioxide recovery line 9. When the above-mentioned branch of the carbon dioxide adjustment section 5 is in use, the second carbon dioxide dryer 35B and the second carbon dioxide refrigerator 33B are regenerated by a small amount (about 2% to 5% of the total carbon dioxide stream in the carbon dioxide recovery line 9) of carbon dioxide stream flowing countercurrently in the second carbon dioxide dryer 35B and the second carbon dioxide refrigerator 33B in sequence.

[0067] When the regeneration of the second carbon dioxide dryer 35B and the second carbon dioxide refrigerator 33B is completed and the first carbon dioxide dryer 35B needs to be regenerated, Figure 2 The system is switched under the operating conditions of . The closed fluid pipeline is shown in dotted lines, and the open (active) pipeline is shown in solid lines. Under this operating condition, the second carbon dioxide refrigerator 33B and the second carbon dioxide dryer 35B are in use, while the first carbon dioxide dryer 35A and the first carbon dioxide refrigerator 33A are in the regeneration stage. Dry and ammonia-free carbon dioxide is compressed by the carbon dioxide compressor 43, heated by the heater 45, and flows in countercurrent through the first carbon dioxide dryer 35A and the first carbon dioxide refrigerator 33A, and is finally transported to the regeneration tower 3 through the pipeline 51.

[0068] Typically, a switchover from one CO2 refrigerator and corresponding CO2 dryer to another CO2 refrigerator and corresponding CO2 dryer occurs after the time required to saturate the molecular sieve or desiccant of the currently used CO2 dryer with water has elapsed. By design, the CO2 dryer currently in regeneration is fully regenerated within the same time interval.

[0069] Figure 3 Another embodiment of the system according to the present disclosure is shown. The same reference numerals are used to indicate the system already incorporated. Figure 1 and Figure 2 Elements corresponding to the elements described above will not be described again.

[0070] Figure 3 The structure and operation of System 1 is similar to Figure 1 and Figure 2 The structure and operation of the system. Figure 3 Implementation plan and Figure 1 and Figure 2 The main difference between the implementations is that Figure 1 and Figure 2The top condenser 19 and the carbon dioxide cooler 25 are Figure 3 The single condenser / cooler 19 / 25 shown in FIG is replaced by the regeneration tower 3 outside and belongs to the regenerator cooling system 7 upstream of the carbon dioxide refrigeration and drying device 6. Similar to Figure 1 and Figure 2 system, in Figure 3 In the regenerator cooling system 7, a first cooling step of the CO2-containing gas stream is performed. Thus, a first portion of the water in the CO2-containing gas stream is condensed in the condenser / cooler 19 / 25. The condensate contains ammonia and can be recycled via the recycle line 21 toward the top of the condenser / cooler 19 / 25 to flow therethrough.

[0071] The resulting cooled CO2-containing gas stream is further processed in one of the first carbon dioxide refrigerator 33A and the second carbon dioxide refrigerator 33B and then dried in the corresponding first carbon dioxide dryer 35A or second carbon dioxide dryer 35B, in conjunction with the above Figure 1 and Figure 2 The other CO2 refrigerator and CO2 dryer not in use are in a regeneration phase by passing a side stream of compressed and heated dehydrated CO2 recycled from the collection line 9 through the CO2 compressor 43 .

[0072] Figure 4 A schematic overview of a method for carbon dioxide recovery and conditioning according to the present disclosure is shown in FIG. The method includes the following steps: feeding a CO2-rich absorption solution into a regeneration tower 3 (step 101); flowing a CO2-containing gas stream collected at the top of the regeneration tower 3 in a regenerator cooling system 7, and condensing moisture from the gas stream (step 102); recycling the condensate from the regenerator cooling system 7, and feeding the recycled condensate mixed with the CO2-rich absorption solution stream to the regenerator cooling system 7 (step 103); removing ammonia and moisture from the CO2-containing gas stream in a first carbon dioxide refrigerator 33A and a first carbon dioxide dryer 35A (step 104); and collecting dried carbon dioxide in a carbon dioxide recovery line 9 (step 105).

[0073] In parallel with the above steps, the method includes the additional steps of: regenerating the second carbon dioxide dryer 35B and the second carbon dioxide refrigerator 33B with a flow of heated and compressed regenerated carbon dioxide material stream from the carbon dioxide recovery pipeline 9 (step 106); and supplying the regenerated carbon dioxide material stream from the second carbon dioxide refrigerator 33B to the regeneration tower 3 (step 107).

[0074] The second carbon dioxide dryer 35B and the second carbon dioxide refrigerator 33B are regenerated with the flow of heated and compressed regenerated carbon dioxide stream from the carbon dioxide recovery line 9 .

[0075] The regenerated carbon dioxide stream is supplied from the second carbon dioxide refrigerator 33B to the regeneration tower 3 .

[0076] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. Those skilled in the art will appreciate that various changes, omissions and additions may be made to the specific disclosure herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A carbon dioxide recovery and conditioning system for an ammonia-based carbon dioxide capture process, wherein the system comprises: a regeneration tower adapted to receive a CO2-rich absorption solution from a rich absorption solution inlet line, the absorption solution comprising ammonia; a regenerator cooling system adapted to cool a gas stream comprising carbon dioxide, ammonia, and moisture, the gas stream being collected at the top of the regenerator column; wherein the regenerator cooling system comprises a regenerator overhead condenser having a hot side and a cold side; wherein the hot side is adapted to receive a gas stream comprising carbon dioxide, moisture, and ammonia from the regenerator column, and the cold side is adapted to circulate a heat recovery cooling medium therethrough; and wherein the regenerator overhead condenser is adapted to condense and remove moisture and ammonia from the gas stream; A carbon dioxide refrigeration and drying device is fluidly coupled to the regenerator cooling system and the carbon dioxide recovery line.

2. The system according to claim 1, wherein the carbon dioxide refrigeration and drying device comprises: a first carbon dioxide refrigerator adapted to be fluidly coupled to an outlet of the regenerator cooling system; a first carbon dioxide dryer fluidly coupled to an outlet of the first carbon dioxide refrigerator; a second carbon dioxide refrigerator adapted to be fluidly coupled to the outlet of the regenerator cooling system; a second carbon dioxide dryer fluidly coupled to an outlet of the second carbon dioxide refrigerator; wherein the first carbon dioxide dryer and the second carbon dioxide dryer are fluidly coupled to a carbon dioxide recovery line; and a dryer and refrigerator regeneration device adapted to selectively regenerate one of the first and second carbon dioxide dryers and one of the first and second carbon dioxide refrigerators while the other of the first and second carbon dioxide dryers and the other of the first and second carbon dioxide refrigerators are in operation; wherein the dryer and refrigerator regeneration device includes fluid connections between the first and second carbon dioxide refrigerators and the regenerator cooling system and between the second carbon dioxide refrigerator and the regenerator cooling system, the fluid connections being adapted to return a flow of regenerated carbon dioxide from the carbon dioxide refrigerator being regenerated to the regenerator cooling system.

3. The system of claim 2 , wherein the dryer and refrigerator regeneration apparatus comprises a carbon dioxide compressor and a heater adapted to feed a stream of compressed, dry carbon dioxide from the carbon dioxide recovery line through the one of the first and second carbon dioxide dryers and through the one of the first and second carbon dioxide refrigerators, the one of the first and second carbon dioxide dryers and the one of the first and second carbon dioxide refrigerators being selectively regenerated.

4. The system of claim 3 , wherein the dryer and refrigerator regeneration device includes a recovery heat exchanger adapted to heat carbon dioxide from the carbon dioxide compressor for heat exchange with a regenerated carbon dioxide flow flowing from the carbon dioxide dryer to the carbon dioxide refrigerator, the carbon dioxide dryer and the carbon dioxide refrigerator being selectively regenerated.

5. The system of any one of the preceding claims, further comprising a CO2-rich absorption solution feed fluidly coupled to the regenerator overhead condenser.

6. The system of any one of the preceding claims, wherein the regenerator overhead condenser is arranged in the regeneration column.

7. The system of any one of claims 1 to 5, wherein the regenerator overhead condenser is combined with a carbon dioxide cooler to form a combined condenser / cooler therewith.

8. The system of any one of the preceding claims, wherein the regenerator cooling system further comprises a carbon dioxide cooler having a hot side inlet and a hot side outlet, the hot side inlet being fluidly coupled to the outlet of the hot side of the regenerator overhead condenser, the hot side outlet being fluidly coupled to the carbon dioxide refrigeration and drying device and being adapted to circulate a gas stream containing carbon dioxide for heat exchange with a stream of cooling medium flowing in the cold side of the carbon dioxide cooler; wherein the carbon dioxide cooler is further coupled to a wash water line adapted to supply wash water to the cooler to remove ammonia salts that may form on the carbon dioxide cooler.

9. The system of claim 8, further comprising a wash water supply line fluidly coupled to the CO2 cooler and adapted to distribute wash water within the CO2 cooler.

10. The system of any one of the preceding claims, further comprising a recycle line adapted to recycle liquid condensed in the regenerator overhead condenser to an upper section of the regenerator overhead condenser in countercurrent to the gas stream flowing through the regenerator overhead condenser.

11. The system of any one of the preceding claims, further comprising a wash water supply line fluidly coupled to the first and second CO2 refrigerators. 12 . The system of claim 11 , wherein the wash water supply line is adapted to distribute wash water among the first and second CO 2 refrigerators during operation of the first and second CO 2 refrigerators.

13. A method for recovering and regulating carbon dioxide from an ammonia-containing solvent, the method comprising the steps of: treating the CO2-rich absorption solution in a regeneration tower and collecting a gas stream containing carbon dioxide, ammonia, and moisture from the CO2-rich absorption solution; reducing the temperature of the gas stream and removing moisture and ammonia from the gas stream in a regenerator cooling system by flowing the gas stream through an overhead condenser of the regenerator column to exchange heat with a cooling medium flowing in a cold side of the overhead condenser to cause condensation of moisture and ammonia; further refrigerating the gas stream in a carbon dioxide refrigerator and removing additional water and ammonia from the gas stream in the carbon dioxide refrigerator; drying the gas stream in a carbon dioxide dryer; and Dried carbon dioxide is collected downstream of the carbon dioxide dryer.

14. The method according to claim 13, further comprising the step of regenerating the carbon dioxide dryer and the carbon dioxide refrigerator with a stream of regenerated dry carbon dioxide.

15. The method of claim 14, further comprising the steps of compressing and heating the regenerated dry carbon dioxide upstream of the carbon dioxide dryer.

16. The method according to claim 14 or 15, further comprising the steps of flowing the regenerated carbon dioxide through the carbon dioxide dryer and the carbon dioxide refrigerator connected in series and further recycling the regenerated carbon dioxide from the carbon dioxide refrigerator toward the regeneration tower.

17. A method according to claim 14, 15 or 16, wherein the carbon dioxide refrigerator comprises a first carbon dioxide refrigerator and a second carbon dioxide refrigerator; wherein the carbon dioxide dryer comprises a first carbon dioxide dryer and a second carbon dioxide dryer; and wherein the step of regenerating the carbon dioxide dryer and the carbon dioxide refrigerator with the feed stream of regenerated dry carbon dioxide comprises the step of regenerating one of the first carbon dioxide dryer and the second carbon dioxide dryer and one of the first carbon dioxide refrigerator and the second carbon dioxide refrigerator while the other of the first carbon dioxide dryer and the second carbon dioxide dryer are in use.

18. The method according to any one of claims 13 to 17, further comprising the step of recovering heat from the cooling medium flowing through the overhead condenser.

19. The method of any one of claims 13 to 18, further comprising the step of collecting condensate from the regenerator cooling system and recirculating a portion of the condensate through the regenerator cooling system.

20. The method of claim 19, further comprising the step of collecting condensate from the bottom of the overhead condenser and recycling the condensate to the top of the overhead condenser.

21. A method according to claim 19 or 20, comprising the step of mixing the recycled condensate with a CO2-rich absorption solution fed to the regeneration column.

22. The process according to any one of claims 13 to 21, further comprising the step of feeding a side stream of the CO2-rich absorption solution which is sent to the overhead condenser to prevent precipitation of ammonium salts.

23. The method according to any one of claims 13 to 22, further comprising the step of flowing the gas stream from the overhead condenser through a carbon dioxide cooler, the carbon dioxide cooler being positioned upstream of the carbon dioxide refrigerator and receiving an aqueous scrubbing solution to avoid precipitation.

24. The method according to claim 23, further comprising the step of supplying wash water to the carbon dioxide cooler.

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