Single pass co2 absorber with integrated ammonia slip mitigation and intercooling

Abstract

A method of removing CO2, the method comprising: contacting a CO2-containing gas stream with a solution mixture in a first absorber stage to produce a partially cleaned gas stream; contacting the partially cleaned gas stream with a CO2-lean solution in a second absorber stage to produce a further cleaned gas stream containing ammonia and a CO2-part-enriched solution; dividing the CO2-part-enriched solution into a first portion and a second portion; removing the first portion of the CO2-part-enriched solution from the second absorber stage; freezing the removed CO2-part-enriched solution; contacting the frozen CO2-part-enriched solution with the further cleaned gas stream containing ammonia in a third absorber stage to produce a treated gas stream and a CO2-part-enriched solution containing recovered ammonia; and combining the solution containing recovered ammonia removed from the third absorber stage with the second portion of the CO2-part-enriched solution to thereby form the solution mixture used in the first absorber stage.

Description

Background Technology

[0001] Carbon dioxide is a major driver of global climate change; therefore, reducing its emissions is crucial. The Mixed Salt Process (MSP) uses an aqueous mixture of potassium carbonate and ammonium salts as a solvent and captures CO2 from the gas stream by dissolving it in the solvent to form bicarbonate and / or carbonate ions. 2。 Therefore, CO2 capture efficiency can be affected by the liquid-phase reaction rate. Unfortunately, many available methods have slow liquid-phase reaction rates. To improve CO2 capture efficiency, some known CO2 capture systems may require larger fill volumes and / or multiple pipes, pumps, and cooling devices for solvent recycling. This can lead to higher power consumption and increased operating costs. Therefore, there is a continued need for energy-efficient methods and systems for CO2 capture. Summary of the Invention

[0002] A method for removing CO2 from a CO2-containing gas stream includes: in a first absorber stage, contacting the CO2-containing gas stream with a solution mixture to generate a partially clean gas stream; in a second absorber stage, contacting the partially clean gas stream with a CO2-lean solution to generate a further clean gas stream containing ammonia and a CO2-partially enriched solution; dividing the CO2-partially enriched solution into a first portion and a second portion; removing the first portion of the CO2-partially enriched solution from the second absorber stage; freezing the removed CO2-partially enriched solution; in a third absorber stage, contacting the frozen CO2-partially enriched solution with a further clean gas stream containing ammonia to generate a treated gas stream and a CO2-partially enriched solution containing recovered ammonia; and combining the solution containing recovered ammonia removed from the third absorber stage with the second portion of the CO2-partially enriched solution to form a solution mixture used in the first absorber stage.

[0003] A CO2 capture system includes: an absorber container comprising a first absorber stage, a second absorber stage, and a third absorber stage; the second absorber stage includes a second gas-liquid contact device and a second liquid collector for collecting a CO2-enriched solution, the CO2-enriched solution being a lean solution that has passed through the second gas-liquid contact device; a gas inlet for introducing a CO2-containing gas stream into the absorber container; a gas outlet for removing the treated gas stream from the absorber container; a liquid inlet for introducing a lean CO2 solution into the second absorber stage; a liquid outlet for removing a CO2-enriched solution from the first absorber stage; and a first liquid transport path for introducing ammonia buffer... The solution is conveyed to the third absorber stage. This ammonia-reducing solution is a first portion of a CO2-enriched solution collected on a second liquid collector above a first liquid distributor in the first absorber stage. A refrigeration unit is used to lower the temperature of the ammonia-reducing solution before conveying it to the third absorber stage. A second liquid conveying path is used to convey the solution containing recovered ammonia drawn from the third absorber stage to the second liquid collector in the second absorber stage or to the first absorber stage at a height above a first gas-liquid contact device in the first absorber stage, such that a second portion of the solution containing recovered ammonia and the CO2-enriched solution are mixed above or in the first gas-liquid contact device. Attached Figure Description

[0004] The following description should not be considered as limiting in any way. Referring to the accompanying drawings, similar element numbers are similar:

[0005] Figure 1 This is a simplified embodiment of a system and method for removing CO2 from a CO2-containing gas stream; and

[0006] Figure 2 This is a simplified representation of the liquid mass flow rate (M) during a method for removing CO2 from a CO2-containing gas stream. Detailed Implementation

[0007] The inventors have discovered an efficient method and system for removing CO2 from CO2-containing gases. The system and method described herein can improve CO2 removal efficiency and / or reduce the required packing volume and / or reduce the required steam consumption, while reducing ammonia emissions.

[0008] In the systems and methods described herein, the lean CO2 solution introduced into the absorber is not diluted with another solution, thereby maximizing the driving force for CO2 capture. Furthermore, the lean CO2 solution can be allowed to have a relatively high feed temperature, which allows for higher operating temperatures in the absorber, with the aim of improving CO2 dissolution mass transfer through improved liquid-phase reaction kinetics.

[0009] Furthermore, a CO2-partially enriched solution is used to mitigate ammonia loss. Unlike solutions with a high CO2 load, using a CO2-partially enriched solution for ammonia leakage reduction allows the solution to be cooled / frozen without the problem of ammonium bicarbonate precipitation. Therefore, this method and system can achieve a significant reduction in ammonia leakage.

[0010] Furthermore, returning the CO2-partially enriched solution with recovered ammonia to a height within the absorber close to its extraction elevation minimizes disruption to the compositional driving force and the associated potential for CO2 capture. A portion of the relatively cool CO2-partially enriched solution with recovered ammonia can also effectively cool the relatively warm CO2-partially enriched solution during reintroduction and mixing within the absorber, saving on equipment previously required for separate intercooling through functional integration. In other words, this method and system reduce ammonia emissions by adding a single-pass extraction of the CO2-partially enriched solution and the return of the solution after ammonia recovery, while simultaneously serving as an efficient method for solvent intercooling. This method and system also minimize associated absorber fill and avoid solution recirculation, resulting in further cost savings.

[0011] A detailed description of one or more embodiments of the methods and systems disclosed herein is presented by way of example rather than limitation, with reference to the accompanying drawings.

[0012] refer to Figure 1 and Figure 2 An absorber container (800) is provided. The absorber container (800) is configured to receive a CO2-containing gas stream (A) via an inlet (15) located near the bottom of the container (800) and to allow the CO2-containing gas stream (A) to flow upward through the absorber container (800) and exit as a treated gas stream (B) via an outlet (85) located near the top of the container (800).

[0013] The CO2-containing gas stream (A) entering the absorber container (800) may include air, natural gas, industrial effluents, and commercial emissions. In one aspect, the CO2-containing gas stream is a flue gas stream, which may be the gas produced when fossil fuels such as coal, oil, natural gas, or wood are burned for heating or power generation.

[0014] The absorber container (800) is configured to absorb CO2 from a CO2-containing gas stream (A) using an ammonified aqueous solution. As used herein, an ammonified aqueous solution refers to a solution containing ammonium ions and water. Optionally, the ammonified aqueous solution also contains bicarbonate ions, carbonate ions, carbamate ions, potassium ions, dissolved alkanolamines (such as methyldiethanolamine), or a combination containing at least one of the foregoing contents.

[0015] The absorber container (800) includes a first absorber stage (150), a second absorber stage (250), and a third absorber stage (350). When the absorber container is a column, the first absorber stage (150), the second absorber stage (250), and the third absorber stage (350) may be located in the bottom section, the middle section, and the top section of the absorber container 800, respectively.

[0016] Each absorber stage (150, 250, 350) may include at least one gas-liquid contact device (100, 200, and 300), and a liquid distributor (105, 205, and 305) configured to dispense solution into the gas-liquid contact device. The second absorber stage (250) and the third absorber stage (350) may also include liquid collectors (208 and 308) for collecting the solution that has passed through the respective gas-liquid contact device. The first absorber stage (150) may optionally have a liquid collector (108), but is generally not required to have one.

[0017] In each gas-liquid contact device (150, 250, 350), the aqueous ammonia solution contacts the CO2-containing gas stream as the gas flows upward through the absorber container (800) and the ammonia solution travels downward through the absorber container (800). The gas-liquid contact devices (150, 250, and 350) may include, for example, structured or random packing materials.

[0018] Each liquid distributor (105, 205, and 305) may be located on top of the respective absorber stage (150, 250, and 350) and is configured to introduce an ammoniated aqueous solution into the gas-liquid contact device (100, 200, and 300). The liquid distributor may be configured as, for example, a nozzle, a conduit with perforations and / or slots, or a combination thereof.

[0019] Liquid collectors (108, 208, and 308) may be arranged at the bottom of the respective absorber stages (150, 250, 350) to collect the solution that has passed through the respective gas-liquid contact devices (100, 200, and 300). The liquid collectors (108, 208, and 308) may also be configured to allow a rising flow of CO2-containing gas through the absorber container (800) to pass through the liquid collector or alongside it. The liquid collector may, for example, comprise a chimney-type tray. Other suitable known liquid collector designs may also be used. The liquid collector may also have a liquid outlet for removing the collected liquid. In some embodiments, the solution that has passed through the gas-liquid contact device (100) of the first absorber stage (150) may be collected directly in the bottom portion (such as a tank (50)) of the absorber container (800). In such embodiments, the first absorber stage (150) may not require a liquid collector.

[0020] Each absorber stage (150, 250, and 350) performs a specific phase of CO2 absorption. In the methods and systems described herein, the second absorber stage (250) is configured to capture CO2 in a CO2-containing gas stream at a lower CO2 concentration, thereby allowing a high level of overall CO2 capture efficiency. For example, the second absorber stage (250) provides sufficient mass transfer drive to efficiently capture CO2 passing through the first absorber stage (150), thereby allowing a high overall capture efficiency, typically greater than 90% of the CO2 in the CO2-containing gas stream (A).

[0021] In the second absorber stage (250), a lean CO2 solution (D) is introduced into the second liquid distributor (205). The lean CO2 solution (D) may be generated by a CO2 regenerator and includes water and ammonium ions, and optionally potassium ions, carbonate ions, bicarbonate ions, carbamate ions, potassium ions, dissolved alkanolamines (such as methyldiethanolamine), or combinations thereof. The lean CO2 solution (D) from the regenerator is hot and needs to be cooled before being introduced into the CO2 absorber (800). Due to the composition of the lean CO2 solution, CO2 tends to enter and dissolve in the solution after moderate cooling. If the lean CO2 solution is cooled too much (or frozen to significantly below ambient temperature), the slow liquid-phase reaction that would otherwise facilitate the dissolution of CO2 may hinder the uptake of said CO2. Moderate temperatures can improve the kinetics of CO2 consumption in the liquid phase and increase the overall rate of CO2 uptake or the rate at which CO2 in vapor is converted into dissolved CO2 in ionic form (such as carbamate ions, bicarbonate ions, and carbonate ions). The temperature of the lean CO2 solution (D) entering the second absorber stage (250) is preferably high enough to avoid refrigeration, typically between 20°C and 40°C, more preferably between 25°C and 35°C or about 30°C, depending on the environmental conditions and the solution composition.

[0022] Advantageously, in the methods and systems described herein, the lean CO2 solution (D) is not mixed with any solution from the third absorber stage or the first absorber stage. Instead, the lean CO2 solution (D) passes through the gas-liquid contact device (200) once from top to bottom without mixing with other solutions to maximize the CO2 absorption driving force. This configuration increases the likelihood of CO2 removal and / or reduces the absorber system fill volume. Therefore, the methods and systems disclosed herein use a single-pass liquid-side arrangement with a lean CO2 liquid feed at moderate temperatures to increase the solvent reaction kinetics for CO2 absorption.

[0023] The second liquid distributor (205) can distribute or spray a lean CO2 solution (D) into a second gas-liquid contact device (200), wherein the lean CO2 solution (D) contacts a CO2 gas stream that rises through the contact device (200) after entering from the first absorber stage (150), which is also referred to as a partially cleaned gas stream. During contact, CO2 in the partially cleaned gas stream further dissolves into the lean CO2 solution (D), thereby forming a CO2-enriched solution. The dissolution of CO2 forms carbamate ions, carbonate ions, and / or bicarbonate ions. The dissolution reaction is exothermic, and the heat generated by the reaction increases the solution temperature and can drive a portion of the ammonia dissolved in the lean CO2 solution (D) into the gas phase. Therefore, the gas stream leaving the second absorber stage (250) after contacting the lean CO2 solution contains a reduced CO2 concentration and an increased ammonia concentration (referred to as a further cleaned gas stream containing ammonia). A further clean gas stream containing ammonia flows upward from the second absorber stage (250) to the third absorber stage (350). After capturing CO2 using the maximum possible concentration driving force, the CO2-enriched solution is collected for redistribution. The collected CO2-enriched solution has a higher temperature than the lean CO2 solution (D) due to the increased solution temperature via the contact device (200). The temperature of the CO2-enriched solution can be from about 25°C to about 45°C, preferably from about 30°C to about 40°C or about 35°C, depending on environmental conditions and solution composition.

[0024] The collected CO2-enriched solution is divided into a first portion (F) and a second portion (Z). The first portion (F) of the CO2-enriched solution is drawn from the second absorber stage (250) using a pump (231), cooled / frozen by a cooling / freezing device (232), and then introduced into the third absorber stage (350) via a first liquid transport path (230) to recover ammonia. Lowering the temperature of the CO2-enriched solution (F) increases the solution's ability to absorb ammonia. In this way, ammonia lost from the second absorber stage (250) can be recovered, and ammonia leakage can be mitigated. Ammonia is absorbed more quickly than CO2 in aqueous solution at low temperatures. Since the goal of the third absorber stage (350) is to absorb ammonia, the liquid temperature can be significantly lowered without hindering ammonia mitigation. However, care must be taken to avoid lowering the temperature in the cooling / freezing device (232) to a point where bicarbonate may precipitate in the stream 230. The cooled / frozen CO2-enriched solution (F) entering the third absorber stage 350 may have a temperature of about 5°C to about 20°C, preferably about 5°C to about 15°C or about 10°C, depending on the solution composition.

[0025] Compared to the extract solution from the first absorber stage (150) for ammonia mitigation, which has the highest CO2 loading of all absorber stages, the extract solution from the second absorber stage (250) for ammonia leakage mitigation allows the solution to be cooled without the problem of ammonium bicarbonate precipitation. Therefore, the methods and systems described herein reduce absorber ammonia leakage and associated water washing requirements and stripper steam consumption in downstream treatment facilities.

[0026] Preferably, the cooled CO2-enriched solution (F) is injected into or introduced into the third gas-liquid contact device (300) via a third liquid distributor (308), wherein the solution contacts a further cleaned gas stream containing ammonia generated from the second absorber stage (250), thereby producing treated gas (B) and a solution (E) containing recovered ammonia. The treated gas (B) can exit the absorber container (800) via an outlet (85).

[0027] The solution (E) with recovered ammonia can be collected at the third liquid collector (308). Preferably, the third absorber stage (350) is configured such that solution E does not flow into the second gas-liquid contact device (200). In other words, solution E is not mixed with the lean CO2 solution (D). One advantage is that the lean CO2 solution is not diluted with a partially CO2-loaded solution to avoid reducing the CO2 capture driving force. Another advantage is that the temperature of the lean solution is not lowered by mixing with the solution used to recover ammonia. Thus, in the method and system described herein, the lean CO2 solution (D) fed to the absorber (800) can maintain concentration driving force and maximize CO2 capture potential at the optimal feed temperature of the second absorber stage (250).

[0028] The collected solution (E) is drawn from the third absorber stage (350) and flows downward along the second fluid transport path (320) to be delivered to the gas-liquid contact device (100) in the first absorber stage (150). The solution (E) leaving the third absorber stage 350 may have a temperature of about 10°C to about 20°C. Importantly, the relatively cool solution (E) is mixed with a second portion (Z) of the relatively warm CO2-enriched solution before entering the first gas-liquid contact device (100) in the first absorber stage.

[0029] The second absorber stage (250) typically has a height greater than 8 meters, allowing for significant driving force to move the solution (E) containing the recovered ammonia from the bottom of the third absorber stage (350) (e.g., the third liquid collector (308)) to the top of the first absorber stage (150), for example, to the first liquid distribution device (105), using gravity flow. The second absorber stage (250) may also have multiple gas-liquid contact sections.

[0030] The solution (E) containing recovered ammonia has a lower temperature than the second portion (Z) of the CO2 semi-enriched solution. When the cold solution (E) containing recovered ammonia is mixed with the warm CO2 semi-enriched solution (Z), the warm CO2 semi-enriched solution (Z) is cooled to form a mixed solution (G) with a temperature lower than that of the CO2 semi-enriched solution (Z), thereby achieving intercooling before the mixed solution (G) is introduced into the first gas-liquid contact device (100) of the absorber stage (150). Therefore, the CO2 capture system may include a second liquid delivery path (320) for conveying the solution containing recovered ammonia drawn from the third absorber stage to a second liquid collector in the second absorber stage or to the first absorber stage at a height above the first gas-liquid contact device in the first absorber stage, such that the cold solution containing recovered ammonia and the second portion of the warm CO2 semi-enriched solution are mixed above or in the first gas-liquid contact device (100).

[0031] How they are mixed is not important. The solutions (E) and (Z) may be mixed in the liquid collector (208) or liquid distributor (105) before being jointly dispensed onto the first gas-liquid contact device (100), or the solutions (E) and (Z) may be dispensed in parallel and allowed to mix above the first gas-liquid contact device (100) and in the first gas-liquid contact device.

[0032] This method minimizes the disruption to the potential for CO2 capture because the removed material (solution F) is similar to the material brought back (solution E). Simultaneously, the method reduces the fill volume, thereby allowing for a faster bulk liquid reaction rate without compromising increased ammonia leakage.

[0033] A liquid distributor (105) allows a mixed solution (G) (if mixing takes place in the second absorber stage) or a second portion of a CO2-enriched solution (if mixing takes place in the first absorber stage) to enter the first absorber stage (150), such as by using a gravity flow into the first absorber stage (150). The function of the first absorber stage (150) is to achieve maximum solution loading. In the first gas-liquid contact device (100) of the first absorber stage (150), the mixed solution (G) contacts a CO2-containing gas stream (A), thereby producing a partially cleaned gas stream and a CO2-enriched solution (C). The partially cleaned gas stream flows upward into the second absorber stage (250). The CO2-enriched solution (C) is collected at a tank (50) and then transferred out of the CO2 absorber (800) via an outlet (55) using a pump (56).

[0034] Depending on the concentration of CO2 in the CO2-containing gas (A), the first absorber stage (150) may have several gas-liquid contact sections. Optionally, for high CO2 concentrations, the solution from the first absorber stage (150) may be removed, cooled, and recycled back to the first absorber stage (150) to maximize the load on the solution prior to regeneration.

[0035] Preferably, the disclosed method and system avoid solution recirculation from the first absorber stage (150) to the second absorber stage (250) and / or avoid solution recirculation from the first absorber stage (150) to the third absorber stage (350), while still achieving improved CO2 capture efficiency and / or reduced ammonia leakage. Therefore, the disclosed method and system reduce the number of pumps required and the associated power while improving CO2 capture and / or improving ammonia leakage mitigation performance.

[0036] The methods and systems disclosed herein utilize a single-pass liquid-side arrangement to increase operating temperature and improve solution reaction kinetics for CO2 absorption, thereby increasing the likelihood of CO2 removal and / or reducing the absorber system packing volume. Furthermore, the methods and systems combine ammonia leakage reduction with solvent intercooling, thereby improving solvothermal integration and reducing regeneration steam consumption. For a given CO2 removal target, the disclosed methods and systems significantly reduce ammonia leakage in addition to significantly reducing system costs.

[0037] The following section elaborates on some of the aforementioned public disclosures:

[0038] Aspect 1. A method for removing CO2 from a CO2-containing gas stream, the method comprising: in a first absorber stage, contacting the CO2-containing gas stream with a solution mixture to generate a partially clean gas stream; in a second absorber stage, contacting the partially clean gas stream with a CO2-lean solution to generate a further clean gas stream containing ammonia and a CO2-partially enriched solution; dividing the CO2-partially enriched solution into a first portion and a second portion; removing the first portion of the CO2-partially enriched solution from the second absorber stage; freezing the removed CO2-partially enriched solution; in a third absorber stage, contacting the frozen CO2-partially enriched solution with the further clean gas stream containing ammonia to generate a treated gas stream and a CO2-partially enriched solution containing recovered ammonia; and combining the solution containing the recovered ammonia removed from the third absorber stage with the second portion of the CO2-partially enriched solution to form the solution mixture used in the first absorber stage.

[0039] Aspect 2. The method according to any of the preceding aspects, wherein the CO2-enriched solution containing the recovered ammonia is not mixed with the CO2-poor solution.

[0040] Aspect 3. The method according to any of the preceding aspects, wherein the lean CO2 solution introduced into the second absorber stage is not mixed with any solution obtained from the first absorber stage or the third absorber stage.

[0041] Aspect 4. The method according to any of the preceding aspects, wherein the lean CO2 solution introduced into the second absorber stage has a temperature of about 20°C to about 35°C.

[0042] Aspect 5. The method according to any of the preceding aspects, wherein the lean CO2 solution introduced into the second absorber stage comprises ammonium ions, water, and optionally potassium ions, carbonate ions, bicarbonate ions, carbamate ions, potassium ions, dissolved alkanolamines, or combinations thereof.

[0043] Aspect 6. The method according to any of the preceding aspects, wherein the CO2-enriched solution containing the recovered ammonia is combined and mixed with a second portion of the CO2-enriched solution exiting the second absorber stage to form the solution mixture having a lower temperature compared to the temperature of the second portion of the CO2-enriched solution before the solution mixture is introduced into the first absorber stage.

[0044] Aspect 7. The method according to any of the preceding aspects, wherein the combination and mixing are completed to produce the solution mixture, and the solution mixture is subsequently introduced into the first absorber stage by gravity.

[0045] Aspect 8. The method according to any of the preceding aspects, wherein the solution in which the frozen CO2 is partially enriched has a temperature of about 5°C to about 15°C.

[0046] Aspect 9. The method according to any of the preceding aspects, wherein the CO2-enriched solution containing the recovered ammonia exiting the third absorber stage has a temperature of about 10°C to about 20°C.

[0047] Aspect 10. The method according to any of the preceding aspects, the method further comprising: cooling the second portion of the CO2-enriched solution by mixing it with the CO2-enriched solution containing the recovered ammonia.

[0048] Aspect 11. The method according to any of the preceding aspects, wherein the method does not include recycling the solution from the first absorber stage to the second absorber stage.

[0049] Aspect 12. The method according to any of the preceding aspects, wherein the method does not include recycling the solution from the first absorber stage to the third absorber stage.

[0050] Aspect 13. A CO2 capture system, the CO2 capture system comprising: an absorber container, the absorber container including a first absorber stage, a second absorber stage and a third absorber stage, the second absorber stage including a second gas-liquid contact device and a second liquid collector for collecting a CO2-partially enriched solution, the CO2-partially enriched solution being a lean solution that has passed through the second gas-liquid contact device; a gas inlet for introducing a CO2-containing gas stream into the absorber container; a gas outlet for removing the treated gas stream from the absorber container; a liquid inlet for introducing a lean CO2 solution into the second absorber stage; a liquid outlet for removing a CO2-rich solution from the first absorber stage; and a first liquid transport path for conveying ammonia buffer... The solution is conveyed to the third absorber stage, the ammonia relief solution being a first portion of the CO2-enriched solution collected on a second liquid collector above a first liquid distributor in the first absorber stage; a refrigeration unit for reducing the temperature of the ammonia relief solution before conveying it to the third absorber stage; and a second liquid conveying path for conveying the solution containing recovered ammonia drawn from the third absorber stage to the second liquid collector in the second absorber stage or to the first absorber stage at a height above a first gas-liquid contact device in the first absorber stage, such that the solution containing the recovered ammonia and a second portion of the CO2-enriched solution are mixed above or in the first gas-liquid contact device.

[0051] Aspect 14. The CO2 capture system according to any of the preceding aspects, wherein the third absorber stage includes a third liquid distributor, a third gas-liquid contact device and a third liquid collector, and the first liquid delivery path is configured to deliver the frozen ammonia relief solution to the third liquid distributor.

[0052] Aspect 15. The CO2 capture system according to any of the preceding aspects, wherein the third liquid collector is configured such that the solution having the recovered ammonia collected on the third liquid collector does not flow into the second absorber stage to mix with the lean CO2 solution.

[0053] Aspect 16. The CO2 capture system according to any of the preceding aspects, wherein the second liquid delivery path is configured to deliver the solution containing the recovered ammonia, collected at the third liquid collector in the third absorber stage, to the second liquid collector in the second absorber stage, such that the solution containing the recovered ammonia is mixed with the second portion of the CO2 partially enriched solution to form a mixed solution, and then the mixed solution is distributed to the first gas-liquid contact device in the first absorber stage.

[0054] Aspect 17. The CO2 capture system according to any of the preceding aspects, wherein the second liquid delivery path is configured to deliver the solution containing the recovered ammonia, collected at the third liquid collector in the third absorber stage, to the first liquid distributor in the first absorber stage, such that the solution containing the recovered ammonia is mixed with a second portion of the CO2-enriched solution distributed to the first liquid distributor to form a mixed solution, and then the mixed solution is distributed to the first gas-liquid contact device.

[0055] Aspect 18. The CO2 capture system according to any of the preceding aspects, wherein the second liquid distributor in the second absorber stage is configured to receive the lean CO2 solution and distribute the lean CO2 solution to the second gas-liquid contact device.

[0056] Aspect 19. The CO2 capture system according to any of the preceding aspects, wherein the system does not include a fluid transport path for transporting the solution from the first absorber stage to the second absorber stage.

[0057] Aspect 20. The CO2 capture system according to any of the preceding aspects, wherein the system does not include a fluid transport path for transporting the solution from the first absorber stage to the third absorber stage.

[0058] All scopes disclosed herein include endpoints, and endpoints can be combined independently of each other. As used herein, "combination" includes blends, mixtures, alloys, and reaction products, etc. All references are incorporated herein by reference.

[0059] In the context of describing the invention (particularly in the context of the appended claims), the terms “an” and “the”, and similar designations, should be interpreted to cover both singular and plural forms, unless otherwise specified herein or clearly contradicted by the context. Furthermore, it should be noted that the terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms “about,” “substantially,” and “generally” are intended to include, based on the equipment available at the time of filing, the degree of error associated with a particular number of measurements. For example, “about” and / or “substantially” and / or “generally” may include a range of ±8%, 5%, or 2% of a given value.

[0060] Although the invention has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for elements therein without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, it is contemplated that the invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but rather that the invention will encompass all embodiments falling within the scope of the claims. Additionally, exemplary embodiments of the invention have been disclosed in the drawings and detailed descriptions, and although specific terminology has been used, it is used in a general and descriptive sense only, and not for limiting purposes, unless otherwise specified; therefore, the scope of the invention is not limited thereto.

Claims

1. A method for removing CO2 from a CO2-containing gas stream, characterized in that: In the first absorber stage (150), a CO2-containing gas stream (A) is contacted with a solution mixture (G) to generate a partially clean gas stream; In the second absorber stage (250), the partially cleaned gas stream is contacted with a lean CO2 solution (D) to generate a further cleaned gas stream containing ammonia and a CO2-enriched solution. The CO2-enriched solution is divided into a first part (F) and a second part (Z). Remove the first portion (F) of the CO2-enriched solution from the second absorber stage (250); A solution enriched with CO2 removed by freezing; In the third absorber stage (350), the solution containing partially frozen CO2 is contacted with the further cleaned gas stream containing ammonia to generate a treated gas stream (B) and a solution containing partially CO2-enriched recovered ammonia (E). as well as The solution (E) containing the recovered ammonia removed from the third absorber stage is combined with the second portion (Z) of the CO2 partially enriched solution to form the solution mixture (G) used in the first absorber stage (150).

2. The method according to claim 1, wherein the CO2-enriched solution (E) containing the recovered ammonia is not mixed with the CO2-lean solution (D).

3. The method according to claim 1, wherein the lean CO2 solution (D) introduced into the second absorber stage (250) is not mixed with any solution obtained from the first absorber stage (150) or the third absorber stage (350).

4. The method according to claim 1, wherein the lean CO2 solution (D) introduced into the second absorber stage (250) comprises ammonium ions, water, and optionally potassium ions, carbonate ions, bicarbonate ions, carbamate ions, potassium ions, dissolved alkanolamines, or combinations thereof.

5. The method of claim 1, wherein the CO2-enriched solution (E) containing the recovered ammonia is combined and mixed with the second portion (Z) of the CO2-enriched solution leaving the second absorber stage to form the solution mixture (G), which has a lower temperature compared to the temperature of the second portion (Z) of the CO2-enriched solution before the solution mixture is introduced into the first absorber stage (150).

6. The method of claim 5, wherein the combination and mixing are completed to produce the solution mixture (G), and the solution mixture is subsequently introduced into the first absorber stage (150) by gravity.

7. The method according to claim 1, further comprising: The second portion (Z) of the CO2-enriched solution is cooled by mixing it with the CO2-enriched solution (E) containing the recovered ammonia.

8. The method according to any one of claims 1 to 7, wherein the method does not include recycling the solution from the first absorber stage (150) to the second absorber stage (250).

9. The method according to any one of claims 1 to 7, wherein the method does not include recycling the solution from the first absorber stage (150) to the third absorber stage (350).

10. A CO2 capture system, characterized in that: An absorber container (800) includes a first absorber stage (150), a second absorber stage (250), and a third absorber stage (350). The second absorber stage (250) includes a second gas-liquid contact device (200) and a second liquid collector (208) for collecting a CO2-enriched solution that is a lean solution that has passed through the second gas-liquid contact device (200). Gas inlet (15), the gas inlet being used to introduce a CO2-containing gas stream (A) into the absorber container (800); Gas outlet (85), the gas outlet being used to remove the treated gas stream (B) from the absorber container (800); A liquid inlet for introducing a lean CO2 solution (D) into the second absorber stage (800). Liquid outlet (55), the liquid outlet being used to remove CO2-rich solution (C) from the first absorber stage (800); A first liquid delivery path (230) is used to deliver an ammonia relief solution to the third absorber stage (350), the ammonia relief solution being a first portion (F) of the CO2-enriched solution collected on a second liquid collector (208) above a first liquid distributor (105) in the first absorber stage (150). A refrigeration unit (232) is used to reduce the temperature of the ammonia relief solution before it is delivered to the third absorber stage (350); and A second liquid transport path (320) is used to transport the solution (E) containing recovered ammonia drawn from the third absorber stage (350) to the second liquid collector (208) in the second absorber stage (250) or to the first absorber stage (150) at a height above the first gas-liquid contact device (100) in the first absorber stage (150), so as to allow the solution (E) containing the recovered ammonia and a second portion (Z) of the CO2 partially enriched solution to mix above or in the first gas-liquid contact device (100).

11. The CO2 capture system of claim 10, wherein the third absorber stage (350) comprises a third liquid distributor (305), a third gas-liquid contact device (300) and a third liquid collector (308), and the first liquid delivery path (230) is configured to deliver the frozen ammonia relief solution to the third liquid distributor (305).

12. The CO2 capture system of claim 10, wherein the third liquid collector (308) is configured such that the solution (E) having the recovered ammonia collected on the third liquid collector (308) does not flow into the second absorber stage (250) to mix with the lean CO2 solution (D).

13. The CO2 capture system according to any one of claims 10 to 12, wherein the second liquid delivery path (320) is configured to deliver the solution (E) containing the recovered ammonia collected at the third liquid collector (308) in the third absorber stage (350) to the second liquid collector (205) in the second absorber stage (250), such that the solution (E) containing the recovered ammonia is mixed with the second portion (Z) of the CO2 partially enriched solution to form a mixed solution (G), and then the mixed solution (G) is dispensed into the first gas-liquid contact device (100) in the first absorber stage (105).

14. The CO2 capture system according to any one of claims 10 to 12, wherein the second liquid delivery path (320) is configured to deliver the solution (E) containing the recovered ammonia collected at the third liquid collector (308) in the third absorber stage (350) to the first liquid distributor (105) in the first absorber stage (150), such that the solution (E) containing the recovered ammonia is mixed with the second portion (Z) of the CO2-enriched solution distributed to the first liquid distributor (105) to form a mixed solution (G), and then the mixed solution (G) is distributed to the first gas-liquid contact device (100).

15. The CO2 capture system according to any one of claims 10 to 12, wherein the second liquid distributor (205) in the second absorber stage (250) is configured to receive the lean CO2 solution (D) and distribute the lean CO2 solution (D) into the second gas-liquid contact device (200).

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