Carbon dioxide mixed gas recovery processing system and recovery processing method

Abstract

The present application relates to the technical field of carbon dioxide recovery, and discloses a recovery and treatment system and a recovery and treatment method for carbon dioxide mixed gas, the recovery and treatment method comprising the following steps: multi-stage compression of the carbon dioxide mixed gas, gas-liquid separation of the carbon dioxide mixed gas compressed in multiple stages to obtain dense-phase carbon dioxide and gas-phase impurity gas, contacting the dense-phase carbon dioxide with the gas-phase impurity gas to make the gas-phase impurity gas form a mixed medium together with the dense-phase carbon dioxide, and storing the mixed medium. The treatment method does not directly discharge the gas-phase impurity gas generated by separation into the atmosphere, but makes the gas-phase impurity gas enter a subsequent storage path together with the dense-phase carbon dioxide, thereby avoiding direct discharge of non-condensable gas.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide recovery technology, and in particular to a carbon dioxide mixture recovery and treatment system and method. Background Technology

[0002] In the treatment of industrial exhaust gases, produced gases, or other mixed gases containing carbon dioxide, it is usually necessary to compress and separate the mixed gases to bring the carbon dioxide to a state suitable for subsequent transportation or utilization. For mixed gases with high carbon dioxide content, existing technologies typically use pressurization and cooling to form the carbon dioxide into a dense phase or liquid phase before subsequent transportation.

[0003] However, in the above-mentioned process, in addition to obtaining dense-phase carbon dioxide, a portion of non-condensable gas that does not enter the dense or liquid phase is usually generated. This portion of non-condensable gas generally includes light component gases and other non-condensable components in the mixed gas. In the prior art, this portion of non-condensable gas is usually treated by direct venting, that is, directly discharging it into the atmosphere. The above-mentioned treatment method has obvious shortcomings. On the one hand, the direct discharge of non-condensable gas into the atmosphere will create a separate exhaust branch in the treatment process, which is not conducive to the continuity of the overall transportation process. On the other hand, the direct venting of non-condensable gas will also bring environmental emission problems, especially under high-flow continuous operation conditions, which is even more detrimental to environmental protection control in industrial sites. Summary of the Invention

[0004] The objective of this invention is to at least solve the problem of non-condensable gases being directly released into the atmosphere during the processing of carbon dioxide mixtures. This objective is achieved through the following technical solution: This invention proposes a carbon dioxide mixture recovery and treatment system, characterized by comprising a multi-stage compression assembly, a gas-liquid separator, an absorption tower, and a storage tank. The multi-stage compression assembly includes multiple compression units connected sequentially along the gas flow direction. The gas-liquid separator is located downstream of the multi-stage compression assembly, and its inlet is connected to the outlet of the final compression unit in the multi-stage compression assembly. The gas-liquid separator has a dense phase outlet and a gas phase outlet. The absorption tower is located downstream of the gas-liquid separator and has a first inlet, a second inlet, and a discharge port. The first inlet is connected to the dense phase outlet, and the second inlet is connected to the gas phase outlet. The storage tank is located downstream of the absorption tower, and its inlet is connected to the discharge port.

[0005] This invention also proposes a method for recovering and treating a carbon dioxide mixture, comprising the following steps: Multi-stage compression of carbon dioxide mixture; The carbon dioxide mixture after multi-stage compression is subjected to gas-liquid separation to obtain dense phase carbon dioxide and gaseous impurity gas; The dense-phase carbon dioxide is brought into contact with the gaseous impurity gas so that the gaseous impurity gas forms a mixed medium together with the dense-phase carbon dioxide; The mixed medium is stored.

[0006] According to the carbon dioxide mixture recovery and treatment method of the present invention, the carbon dioxide mixture undergoes multi-stage compression followed by gas-liquid separation to obtain dense-phase carbon dioxide and gaseous impurity gas. Furthermore, the present invention does not directly discharge the gaseous impurity gas into the atmosphere, but instead brings the dense-phase carbon dioxide into contact with the gaseous impurity gas, so that the gaseous impurity gas forms a mixed medium together with the dense-phase carbon dioxide, and the mixed medium is then stored. Thus, the non-condensable gas generated during separation is no longer directly discharged into the atmosphere, but enters a subsequent storage path, thereby at least solving the technical problem of directly discharging the non-condensable gas generated during the treatment of carbon dioxide mixtures into the atmosphere.

[0007] In addition, the carbon dioxide mixture recovery and treatment method according to the present invention may also have the following additional technical features: In some embodiments of the present invention, in the step of contacting the dense phase carbon dioxide with the gaseous phase impurity gas, the dense phase carbon dioxide flows from top to bottom and the gaseous phase impurity gas flows from bottom to top, so that the dense phase carbon dioxide and the gaseous phase impurity gas come into contact in opposite directions.

[0008] In some embodiments of the present invention, prior to the step of contacting the dense-phase carbon dioxide with the gaseous impurity gas in reverse, the gaseous impurity gas is further dispersed into microbubbles.

[0009] In some embodiments of the present invention, the step of counter-contacting the dense-phase carbon dioxide with the gaseous impurity gas includes: The dense-phase carbon dioxide is introduced into the upper liquid distribution section; The gaseous impurity gas is introduced into the lower microbubble generation section; The dense-phase carbon dioxide and the gaseous impurity gas are brought into contact within a multi-stage contact section located in the middle. The resulting mixed medium is introduced into the bottom steady flow collection section.

[0010] In some embodiments of the present invention, the step of contacting the dense-phase carbon dioxide and the gaseous impurity gas in a multi-stage contact section located in the middle includes: The gaseous impurity gas is passed sequentially through at least two contact zones spaced apart along the height direction, so that at least a portion of the gaseous impurity gas not entrained by the lower contact zone continues to be entrained by the upper contact zone.

[0011] In some embodiments of the present invention, the step of passing the gaseous impurity gas through the contact region includes: The dense phase carbon dioxide forms a swirling liquid film along the guide surface, and the rising gaseous impurity gas passes through the swirling liquid film.

[0012] In some embodiments of the present invention, the step of forming a swirling liquid film includes: The dense phase carbon dioxide is introduced into the liquid distribution chamber tangentially and then sprayed into the contact area.

[0013] In some embodiments of the present invention, the step of storing the hybrid medium includes: The mixed medium is introduced into the storage tank along the tangential direction of the circumferential sidewall.

[0014] In some embodiments of the present invention, the step of storing the hybrid medium includes: The mixed medium first enters the annular buffer channel, and then enters the storage chamber through the annular buffer channel.

[0015] In some embodiments of the present invention, the step of introducing the mixed medium into the reservoir includes: The mixed medium is diffused and then enters the annular buffer channel, and enters the liquid storage chamber through a plurality of uniformly spaced flow equalization holes along the circumference. Within the liquid storage chamber, multiple surge protection baffles spaced apart along the axial direction reduce the surge of the mixed medium. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a method for recovering and treating a carbon dioxide mixture according to an embodiment of the present invention is shown schematically. Figure 2 A schematic diagram of the structure of a carbon dioxide mixture recovery and treatment system according to an embodiment of the present invention is shown. Figure 3 A schematic diagram of the structure of an absorption tower according to an embodiment of the present invention is shown. Figure 4 A schematic diagram of the storage tank according to an embodiment of the present invention is shown from a first perspective. Figure 5A schematic diagram of the liquid storage tank according to an embodiment of the present invention is shown from a second perspective.

[0017] The attached figures are labeled as follows: 100. A system for recovering and treating carbon dioxide mixtures; 10. Raw material gas inlet pipe; 20. Multi-stage compression assembly; 21. First compression unit; 211. Compressor; 212. Heat exchanger; 22. Second compression unit; 23. Third compression unit; 24. Fourth compression unit; 25. Fifth compression unit; 26. Sixth compression unit; 27. Seventh compression unit; 28. Eighth compression unit; 30. Cooler; 40. Gas-liquid separator; 41. Gas phase outlet; 42. Dense phase outlet; 44. Centrifugal pump; 50. Absorber; 501. Liquid distribution section; 502. Multi-stage contact section; 503. Microbubble generation section; 504. Flow stabilization and collection section; 51. Return gas port; 52. First inlet; 53. Second inlet; 54. Conveying outlet; 55. Micro-interface generator; 56. Frustum-shaped guide plate; 57. Bubble breaking and redispersing component; 58. Spray component; 60. Liquid storage tank; 601. Annular buffer channel; 602. Liquid storage chamber; 61. Connecting pipe; 611. Diffusion section; 62. Flow stabilizing cylinder; 621. Flow equalization hole; 63. Surge protection baffle. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0020] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0021] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations.

[0022] like Figure 1 As shown, in some embodiments, the present invention provides a method for recovering and processing a carbon dioxide mixture, comprising the following steps: first, performing multi-stage compression on the carbon dioxide mixture; second, performing gas-liquid separation on the multi-stage compressed carbon dioxide mixture to obtain dense phase carbon dioxide and gaseous phase impurity gas; then, contacting the dense phase carbon dioxide with the gaseous phase impurity gas so that the gaseous phase impurity gas forms a mixed medium together with the dense phase carbon dioxide; and finally, storing the mixed medium.

[0023] In this embodiment, the feed gas can be a carbon dioxide mixture after pretreatment. The carbon dioxide mixture can originate from industrial waste gas, produced gas, or other carbon dioxide-rich mixed gas streams. In addition to carbon dioxide, it also contains a certain proportion of non-condensable impurity gases, such as one or more of nitrogen, oxygen, hydrogen, methane, carbon monoxide, or argon. Using the method of this embodiment, the non-condensable impurity gases in the mixture are no longer discharged separately into the atmosphere, but instead form a mixed medium along with the dense-phase carbon dioxide and enter the subsequent storage path.

[0024] In some implementations, the carbon dioxide mixture is first subjected to multi-stage compression. Specifically, the carbon dioxide mixture passes through multiple compression stages sequentially along the gas flow direction, gradually increasing its pressure. Multi-stage compression provides the pressure conditions necessary for the subsequent compaction of the carbon dioxide. Compared to single-stage high-pressure-ratio compression, multi-stage compression also reduces the single-stage compression load and improves the stability of the compression process.

[0025] Furthermore, the feed gas inlet pressure entering the multi-stage compression is 5 kPa to 10 kPa. The feed gas first enters the first stage of compression for compression, after which the pressure of the feed gas increases to 0.218 MPa. Then, the feed gas after the first stage of compression enters the second stage of compression, where it continues to be compressed, and the pressure of the feed gas increases to 0.4 MPa.

[0026] Further, the feed gas after the second stage of compression enters the third stage of compression, where it continues to be compressed, increasing its pressure to 0.76 MPa. Subsequently, the feed gas after the third stage of compression enters the fourth stage of compression, where it continues to be compressed, increasing its pressure to 1.31 MPa.

[0027] Furthermore, the feed gas after the fourth stage of compression enters the fifth stage of compression, where it continues to be compressed, increasing its pressure to 2.24 MPa. Then, the feed gas after the fifth stage of compression enters the sixth stage of compression, where it continues to be compressed, increasing its pressure to 3.42 MPa.

[0028] Further, the feed gas compressed in the sixth stage enters the seventh stage, where it continues to be compressed, increasing its pressure to 5.23 MPa. Subsequently, the feed gas compressed in the seventh stage enters the eighth stage, where it continues to be compressed, increasing its pressure to 7.4 MPa. The feed gas compressed in the eighth stage requires subsequent cooling and gas-liquid separation.

[0029] Further, the carbon dioxide mixture after multi-stage compression enters the gas-liquid separation step. In this step, the compressed carbon dioxide mixture is separated into dense-phase carbon dioxide and gaseous impurity gases. Here, dense-phase carbon dioxide refers to a high-density carbon dioxide fluid suitable for transport and subsequent contact processing under the current pressure and temperature conditions, while gaseous impurity gases refer to gaseous components in the mixture that have not entered the dense-phase state. Through this separation step, the two streams that need to be processed together can be distinguished, creating conditions for their subsequent contact.

[0030] In some embodiments, dense-phase carbon dioxide is brought into contact with gaseous impurity gas so that the gaseous impurity gas forms a mixed medium together with the dense-phase carbon dioxide. That is, in this embodiment, the separated gaseous impurity gas is not directly discharged, but is brought into contact with dense-phase carbon dioxide again, so that the gaseous impurity gas is entrained by the dense-phase carbon dioxide and together they form a mixed medium suitable for subsequent storage.

[0031] In some embodiments, during the step of contacting the dense-phase carbon dioxide with the gaseous impurity gas, the dense-phase carbon dioxide flows from top to bottom, while the gaseous impurity gas flows from bottom to top, thus ensuring counter-current contact between the two phases. This counter-current contact method extends the contact path between the two phases, increasing the chances of contact and thereby enhancing the entrainment capacity of the dense-phase carbon dioxide for the gaseous impurity gas. Compared to co-current contact, counter-current contact is more advantageous in ensuring that the rising gaseous impurity gas continues to contact the descending dense-phase carbon dioxide over a longer path.

[0032] In some embodiments, before the dense-phase carbon dioxide and the gaseous impurity gas are brought into countercurrent contact, the gaseous impurity gas is further dispersed into microbubbles. Specifically, the gaseous impurity gas can be dispersed into small-sized microbubbles using a micro-interface generator 55, a microporous gas distributor, an ejector, or other microbubble generating structures. This increases the specific surface area of ​​the gaseous impurity gas, thereby increasing the contact area with the dense-phase carbon dioxide and enhancing the entrainment and mixing capacity of the gaseous impurity gas by the dense-phase carbon dioxide.

[0033] In some embodiments, the step of making dense phase carbon dioxide and gaseous impurity gas come into countercurrent contact includes introducing dense phase carbon dioxide into an upper liquid distribution section 501, introducing gaseous impurity gas into a lower microbubble generation section 503, making the two come into contact in a multi-stage contact section 502 located in the middle, and introducing the resulting mixed medium into a bottom flow stabilization and collection section 504.

[0034] Specifically, after the dense-phase carbon dioxide enters the upper liquid distribution section 501, it can be distributed relatively evenly downwards. The gaseous impurity gas, after entering the lower microbubble generation section 503, undergoes microbubble formation to create numerous tiny bubbles that move upwards. The dense-phase carbon dioxide and the tiny bubbles contact counter-currently in the middle multi-stage contact section 502, thus forming a mixed medium. Subsequently, the mixed medium enters the bottom stabilizing and collecting section 504, where the flow state is further stabilized, providing favorable conditions for subsequent entry into the storage tank.

[0035] In some embodiments, the step of bringing the two into contact within a multi-stage contact section located in the middle includes passing the gaseous impurity gas sequentially through at least two contact zones spaced apart along the height direction, so that at least a portion of the gaseous impurity gas not entrained by the lower contact zone continues to be entrained by the upper contact zone.

[0036] Specifically, the lower contact zone can initially entrain most of the rising gaseous impurities. Any remaining gaseous impurities that are not fully carried away can enter the upper contact zone during their continued ascent and be further entrained. Thus, by arranging at least two contact zones spaced apart along the height, the gaseous impurities can undergo a phased, multiple entrainment process, thereby maximizing the overall carrying capacity of dense-phase carbon dioxide for non-condensable impurities.

[0037] In some embodiments, the step of passing the gaseous impurity gas through the contact zone includes forming a swirling liquid film of dense-phase carbon dioxide along the guide surface and passing the rising gaseous impurity gas through the swirling liquid film.

[0038] In other words, dense-phase carbon dioxide does not fall directly as a single liquid stream, but rather forms a swirling liquid film under the influence of the guiding surface. This swirling liquid film increases the liquid phase spreading area and forms a more stable liquid film contact interface. As rising gaseous impurities pass through this swirling liquid film, they can have more thorough contact with the dense-phase carbon dioxide, thus being more effectively entrained.

[0039] In some embodiments, the step of forming a swirling liquid film includes spraying dense-phase carbon dioxide into the contact area after it enters the liquid distribution chamber tangentially.

[0040] Specifically, dense-phase carbon dioxide first enters the distribution chamber tangentially, forming a swirling flow tendency within it, and then is sprayed into the contact zone by the spray nozzle. This configuration allows the dense-phase carbon dioxide to form a more uniform distribution upon entering the contact zone, and, under the influence of the guide surface, more easily forms a swirling liquid film. This further improves the adequacy of contact between the rising gaseous impurities and the dense-phase carbon dioxide.

[0041] It is understood that the feed gas entering the multi-stage compression is a carbon dioxide mixture that has undergone desulfurization and drying. That is to say, before entering the processing steps of the present invention, the sulfides in the feed gas have been removed, and the moisture has been removed to a degree that meets the requirements of subsequent compression and heat exchange, thereby avoiding adverse effects of sulfides and moisture on subsequent compression, heat exchange, gas-liquid separation, and absorption processes.

[0042] In addition to carbon dioxide, the feed gas also contains a certain proportion of non-condensable gases. In most production tail gas applications, the total volume fraction of non-condensable gases in the feed gas is approximately 10%, with the remainder being carbon dioxide. Non-condensable gases may include one or more of nitrogen, oxygen, hydrogen, methane, carbon monoxide, and argon. Furthermore, in the case of transporting high-concentration carbon dioxide industrial tail gas from a coal chemical plant after desulfurization and drying, the feed gas may include approximately 90 vol% carbon dioxide and approximately 10 vol% non-condensable gases, wherein the non-condensable gases may, for example, include approximately 4 vol% nitrogen, approximately 2 vol% oxygen, approximately 2 vol% methane, approximately 1 vol% hydrogen, and approximately 1 vol% argon. Of course, the specific types and proportions of non-condensable gases may vary depending on the source of the industrial tail gas or produced gas, and this invention does not limit this.

[0043] In this embodiment, the gas-liquid separation step of the carbon dioxide mixture after multi-stage compression does not serve to separately discharge the non-condensable gases, but rather to ensure sufficient contact between the dense-phase carbon dioxide and the non-condensable gases, thereby entraining and mixing the non-condensable gases with the dense-phase carbon dioxide. To facilitate quantification of the treatment effect under different structures, this embodiment uses the concentration of non-condensable gases at the return port 51 as an evaluation index. That is, by detecting whether there is still non-condensable gas flowing back to the multi-stage compression assembly 20 at the return port 51, the entrainment and mixing effect of the absorption tower 50 on the non-condensable gases can be determined. The lower the concentration of non-condensable gases at the return port 51, the higher the proportion of non-condensable gases entrained by the dense-phase carbon dioxide and carried out with the conveying fluid. When almost no non-condensable gases can be detected at the return port 51, it indicates that under this operating condition, almost all the non-condensable gases have been entrained and mixed.

[0044] In a comparative embodiment, the absorber 50 adopts a conventional tower structure, without the micro-interface generator 55, multi-stage contact units, or frustum-shaped guide vanes 56, etc., for enhanced structures. Mixing is achieved solely through the natural counter-current contact between dense-phase carbon dioxide (top-down) and non-condensable gases (bottom-up). Under this condition, online concentration detection via the reflux port 51 shows a residual reflux concentration of approximately 4.0 vol%. In other words, with a total non-condensable gas fraction of 10 vol% in the feed gas, approximately 6.0 vol% of the non-condensable gases are entrained and carried out by the dense-phase carbon dioxide, while approximately 4.0 vol% of the non-condensable gases are still refluxed back to the multi-stage compression assembly 20 via the reflux port 51.

[0045] In another embodiment, a micro-interface generator 55 is added to the lower part of the ordinary absorption tower 50, so that the gaseous non-condensable gas is first dispersed into microbubbles when it enters the absorption tower 50. Since the microbubbles have a larger specific surface area, they are more conducive to sufficient contact with the dense phase carbon dioxide. Under this condition, the residual reflux concentration of non-condensable gas can be reduced to about 2.0 vol% by online concentration detection at the reflux port 51. That is, of the approximately 10 vol% of non-condensable gas in the raw gas, approximately 8.0 vol% of the non-condensable gas can be entrained and carried out by the dense phase carbon dioxide, and only about 2.0 vol% of the non-condensable gas is still refluxed through the reflux port 51.

[0046] In another embodiment, based on the micro-interface generator 55, at least two layers of contact units are arranged at intervals along the height direction in the middle of the absorption tower 50. Each contact unit includes a frustum-shaped guide plate 56 and a bubble-breaking and redispersing element 57 located below the frustum-shaped guide plate 56, so that the remaining non-condensable gas that is not fully entrained after the microbubbles rise from the bottom pass through the lower contact unit continues to rise and comes into contact again with the swirling liquid film region formed by the upper contact unit. Tests have shown that under this operating condition, the residual concentration of non-condensable gas at the return port 51 can be further reduced to approximately 0.5 vol%. In other words, approximately 9.5 vol% of the non-condensable gas can be entrained and carried out by dense-phase carbon dioxide, with only approximately 0.5 vol% of the non-condensable gas continuing to flow back.

[0047] In a preferred embodiment, based on the aforementioned micro-interface generator 55 and multi-stage contact unit, the frustum-shaped guide plate 56 has multiple through holes with small diameters to allow dense-phase carbon dioxide to form a local liquid film in the through-hole area. Thus, the rising non-condensable gas can not only contact the swirling liquid film formed on the outer surface of the frustum-shaped guide plate 56, but also re-contact the local liquid film in the through-hole area, further increasing the probability of non-condensable gas being entrained by dense-phase carbon dioxide. Under this condition, the concentration of non-condensable gas at the reflux port 51 can be reduced to below the detection limit by online concentration detection. For example, under online chromatographic analysis conditions with a detection accuracy of 0.05 vol%, no obvious non-condensable gas signal was detected at the reflux port 51. Therefore, it can be considered that in this preferred embodiment, approximately 10 vol% of the non-condensable gas in the feed gas has been essentially completely entrained by dense-phase carbon dioxide and mixed and transported into the external pipeline.

[0048] Therefore, it can be seen that as the enhanced structure inside the absorber 50 gradually increases, the residual reflux concentration of non-condensable gases gradually decreases. Specifically, under normal operating conditions of the absorber 50, the residual concentration of non-condensable gases at the reflux port 51 is approximately 4.0 vol%. After adding the micro-interface generator 55, the residual concentration is approximately 2.0 vol%. After further adding multi-stage contact units, the residual concentration is approximately 0.5 vol%. After further setting through holes on the frustoconical guide plate 56, non-condensable gases are basically undetectable at the reflux port 51. In other words, the micro-interface generator 55 is mainly used to increase the initial gas-liquid contact area, the multi-stage contact units are mainly used to achieve staged and multiple entrainment, and the through holes on the frustoconical guide plate 56 further capture the remaining non-condensable gases by forming a local liquid film, thereby ensuring that as much of the non-condensable gases as possible are carried out by the dense phase carbon dioxide.

[0049] In some embodiments, the mixed medium is stored after it is formed. The storage is not intended to separate the dense-phase carbon dioxide from the gaseous impurity gases again, but rather to store the mixed medium formed by the two together in a storage tank.

[0050] In some embodiments, the step of storing the mixed medium includes allowing the mixed medium to enter the storage tank tangentially along the circumferential sidewall of the storage tank.

[0051] By using a tangential entry method, the mixed medium can flow circumferentially along the inner wall of the storage tank upon entering, without directly impacting the main storage area inside the tank. This helps reduce local impact and pressure drop at the inlet, and decreases the possibility of local phase separation between dense-phase carbon dioxide and gaseous impurities caused by severe inlet disturbances.

[0052] In some embodiments, the step of storing the mixed medium includes allowing the mixed medium to first enter an annular buffer channel and then enter the storage chamber through the annular buffer channel.

[0053] In other words, after the mixed medium enters the storage tank tangentially, it does not directly enter the main storage area. Instead, it is first buffered, decelerated, and pressure-equalized in the annular buffer channel before entering the storage chamber. This makes the mixed medium entering the storage chamber more stable, avoiding large-scale turbulence or local gas evolution caused by high-speed fluid directly rushing into the storage chamber, thus helping to maintain a stable coexistence of the mixed medium in the storage chamber.

[0054] In some embodiments, the step of introducing the mixed medium into the reservoir includes diffuser-driven introduction of the mixed medium into an annular buffer channel, and then through a plurality of circumferentially spaced equalization orifices into the reservoir. Within the reservoir, surge protection baffles spaced axially reduce surges in the mixed medium.

[0055] Specifically, the diffusion step can further reduce the flow velocity and reduce the local throttling effect before the mixed medium enters the annular buffer channel. Multiple flow equalization holes enable the mixed medium to enter the storage cavity from the annular buffer channel in a multi-point, uniform and slow manner, avoiding the direct entry of local high-speed jets into the storage cavity. The anti-surge baffle can weaken the large-scale surges and turbulence in the storage cavity during transportation, loading and unloading or liquid level fluctuations, thereby further suppressing significant gas-liquid redistribution or phase separation inside the mixed medium.

[0056] In summary, the processing method in this embodiment first performs multi-stage compression on the carbon dioxide mixture, then performs gas-liquid separation to obtain dense-phase carbon dioxide and gaseous impurity gases. These two are then subjected to counter-current, multi-stage, microbubbling, and swirling liquid film enhanced contact conditions to form a mixed medium. Finally, the mixed medium is stored using tangential feeding, annular buffering, uniform flow entry, and surge-proof storage. This allows non-condensable gases that might otherwise be directly released into the atmosphere to no longer be vented separately, but instead form a mixed medium along with the dense-phase carbon dioxide and enter the subsequent storage path, thereby achieving further utilization of the non-condensable gases and stable storage of the mixed medium.

[0057] like Figures 2 to 5 As shown, a carbon dioxide mixture recovery and treatment system 100 is proposed. The carbon dioxide mixture recovery and treatment method of this embodiment is applied to this recovery and treatment system, which includes a multi-stage compression assembly 20, a gas-liquid separator 40, an absorption tower 50, and a storage tank 60. The multi-stage compression assembly 20 is used to compress the carbon dioxide mixture in stages. Specifically, the raw material gas inlet pipe 10 is connected to the multi-stage compression assembly 20, which includes multiple compression units connected sequentially along the gas flow direction. After entering the multi-stage compression assembly 20, the carbon dioxide mixture passes through multiple compression units sequentially, thereby gradually increasing the pressure of the carbon dioxide mixture. Using multiple compression units connected sequentially facilitates the gradual pressurization of the raw material gas under relatively stable conditions, thus providing a pressure basis for subsequent treatment.

[0058] In this embodiment, the gas-liquid separator 40 is located downstream of the multi-stage compression assembly 20. Specifically, the inlet of the gas-liquid separator 40 is connected to the outlet of the final compression unit in the multi-stage compression assembly 20. That is, the carbon dioxide mixture, after being compressed stage by stage by stage in the multi-stage compression assembly 20, flows out of the final compression unit and enters the gas-liquid separator 40. The gas-liquid separator 40 is used to separate the carbon dioxide mixture entering it. Further, the gas-liquid separator 40 has a dense phase outlet 42 and a gas phase outlet 41. Thus, the dense phase carbon dioxide formed after separation by the gas-liquid separator 40 can be discharged through the dense phase outlet 42, and the gas phase impurities that have not entered the dense phase state can be discharged through the gas phase outlet 41.

[0059] Furthermore, the absorption tower 50 is located downstream of the gas-liquid separator 40. The absorption tower 50 has a first inlet 52, a second inlet 53, and a discharge outlet. The first inlet 52 is connected to the dense phase outlet 42 of the gas-liquid separator 40, and the second inlet 53 is connected to the gas phase outlet 41 of the gas-liquid separator 40. Thus, dense phase carbon dioxide and gaseous impurity gas from the gas-liquid separator 40 can enter the absorption tower 50 through different inlets. With this arrangement, the dense phase carbon dioxide and gaseous impurity gas can contact within the absorption tower 50, thereby forming the mixed medium that needs to be stored subsequently.

[0060] In this embodiment, the storage tank 60 is located downstream of the absorption tower 50, and the inlet of the storage tank 60 is connected to the outlet of the absorption tower 50. That is, the fluid treated by the absorption tower 50 flows out of the outlet and into the storage tank 60. Since the medium entering the storage tank 60 is the mixed medium discharged from the absorption tower 50, the storage tank 60 is used to store the mixed medium formed by dense-phase carbon dioxide and gaseous impurity gas. In this embodiment, the purpose of the storage tank 60 is not to further separate the dense-phase carbon dioxide and the gaseous impurity gas, but rather to store the mixed medium together.

[0061] Therefore, the carbon dioxide mixture recovery and processing system 100 in this embodiment forms the following processing path: the carbon dioxide mixture first enters the multi-stage compression assembly 20 for progressive compression, then enters the gas-liquid separator 40 to form dense-phase carbon dioxide and gaseous impurity gas, which then separately enter the absorption tower 50 for contact. Finally, the mixed medium discharged from the absorption tower 50 is stored in the storage tank 60. Through the above structural arrangement, progressive compression, gas-liquid separation, contact mixing, and subsequent co-storage of the carbon dioxide mixture can be achieved.

[0062] In some embodiments, the multi-stage compression assembly 20 includes a first compression unit 21, a second compression unit 22, a third compression unit 23, a fourth compression unit 24, a fifth compression unit 25, a sixth compression unit 26, a seventh compression unit 27, and an eighth compression unit 28 connected sequentially along the airflow direction. Specifically, the outlet of the first compression unit 21 is connected to the inlet of the second compression unit 22, the outlet of the second compression unit 22 is connected to the inlet of the third compression unit 23, the outlet of the third compression unit 23 is connected to the inlet of the fourth compression unit 24, the outlet of the fourth compression unit 24 is connected to the inlet of the fifth compression unit 25, the outlet of the fifth compression unit 25 is connected to the inlet of the sixth compression unit 26, the outlet of the sixth compression unit 26 is connected to the inlet of the seventh compression unit 27, the outlet of the seventh compression unit 27 is connected to the inlet of the eighth compression unit 28, and the outlet of the eighth compression unit 28 is connected to the inlet of the gas-liquid separator 40. Thus, the carbon dioxide mixture can flow and be pressurized step by step along the first compression unit 21 to the eighth compression unit 28, and finally enter the gas-liquid separator 40 for further processing.

[0063] In this embodiment, the first compression unit 21 is used as an example. The first compression unit 21 includes a compressor 211 and a heat exchanger 212 located downstream of the compressor 211. Specifically, the carbon dioxide mixture first enters the compressor 211 of the first compression unit 21 and is compressed within the compressor 211 to increase the pressure of the carbon dioxide mixture. Since the gas temperature usually increases during compression, the carbon dioxide mixture output from the compressor 211 continues to flow into the heat exchanger 212, where it exchanges heat with an external heat exchange medium, thereby reducing the temperature of the compressed carbon dioxide mixture. By setting the heat exchanger 212 downstream of the compressor 211, the gas temperature at the inlet of the subsequent compression unit can be reduced, alleviating the compression load on the next stage. Furthermore, it facilitates the removal of heat generated during compression for use by the lithium bromide unit.

[0064] It is understandable that the compression units in the second to eighth compression units 28 may also adopt the same or similar structural form as the first compression unit 21, that is, including a compressor 211 and a heat exchanger 212 disposed downstream of the compressor 211. In this way, the carbon dioxide mixture can undergo corresponding heat exchange after each stage of compression, so that the pressure increase and heat removal in the multi-stage compression process are coordinated, thereby providing conditions for the subsequent processing of the carbon dioxide mixture to a dense phase state suitable for transportation.

[0065] Furthermore, in this embodiment, after the carbon dioxide mixture is compressed by the eighth compression unit 28, it directly enters the gas-liquid separator 40 from the outlet of the eighth compression unit 28. Since the gas-liquid separator 40 is also connected to an external refrigeration device, the carbon dioxide mixture after multi-stage compression can be further cooled after entering the gas-liquid separator 40, causing the carbon dioxide in it to reach a dense phase state and be separated from the gaseous impurities. In this way, the structure of eight compression units arranged in series and finally connected to the gas-liquid separator 40 allows the carbon dioxide mixture to gradually reach a higher pressure before entering the gas-liquid separator 40, creating favorable conditions for subsequent dense phase formation and transportation.

[0066] In some embodiments, adjacent compression units are connected via heat exchangers 212. That is, along the flow direction of the carbon dioxide mixture, the outlet of the previous compression unit is not directly connected to the inlet of the next compression unit; instead, it first passes through heat exchanger 212 before connecting to the inlet of the next compression unit. For example, the outlet of the first compression unit 21 is connected to the inlet of the second compression unit 22 via heat exchanger 212, the outlet of the second compression unit 22 is connected to the inlet of the third compression unit 23 via heat exchanger 212, and so on. Thus, the carbon dioxide mixture compressed by each compression unit can be cooled in the heat exchanger 212 before entering the next compression unit for further compression.

[0067] Furthermore, in some embodiments, the carbon dioxide mixture recovery and processing system 100 also includes a cooler 30, and the outlet of the eighth compression unit 28 is connected to the inlet of the gas-liquid separator 40 through the cooler 30. That is, the carbon dioxide mixture compressed by the eighth compression unit 28 does not directly enter the gas-liquid separator 40, but first enters the cooler 30, where it is further cooled before entering the gas-liquid separator 40.

[0068] In this embodiment, the cooler 30 plays a crucial role. Since the carbon dioxide mixture reaches a high pressure after compression in the eighth compression unit 28, but the fluid temperature remains high, directly entering subsequent units would hinder the carbon dioxide from forming a dense phase suitable for transport. By installing the cooler 30 between the eighth compression unit 28 and the gas-liquid separator 40, the high-pressure carbon dioxide mixture after final compression can be further cooled, allowing the carbon dioxide mixture entering the gas-liquid separator 40 to approach or reach a dense phase condition. Thus, when it subsequently enters the absorption tower 50, the carbon dioxide can remain in a dense phase state or be more conducive to forming a dense phase state, thereby facilitating sufficient contact with gaseous impurities within the absorption tower 50 and carrying them out and transported along with the impurities.

[0069] In other words, the cooler 30 does not only serve a general cooling function; its more important function is to work with the high pressure provided by the eighth compression unit 28 to maintain the carbon dioxide entering the gas-liquid separator 40 and even the absorber 50 in a dense phase state suitable for transportation. This creates conditions for the subsequent formation of a stable mixture of dense phase carbon dioxide and gaseous impurities in the absorber 50, and facilitates the final input into the storage tank 60.

[0070] Furthermore, the dense phase outlet 42 of the gas-liquid separator 40 is connected to the first inlet 52 of the absorption tower 50 via a centrifugal pump 44.

[0071] Furthermore, the gas-liquid separator 40 is also provided with a reflux port 51, which is connected to the inlet of the sixth compression unit 26. That is to say, after the gas-liquid separator 40 completes the gas-liquid separation, in addition to introducing the fluid into the absorption tower 50 through the dense phase outlet 42 and the gas phase outlet 41, it can also guide some of the gas that has not reached the expected treatment state back to the inlet of the sixth compression unit 26 through the reflux port 51 to participate in the subsequent compression process.

[0072] In this embodiment, the reflux port 51 is mainly used to treat the non-condensable gases that still exist in the system. When the fluid separated in the gas-liquid separator 40 still contains a large amount of non-condensable gases, these non-condensable gases can be returned to the inlet of the sixth compression unit 26 through the reflux port 51. The reason for connecting the reflux port 51 to the inlet of the sixth compression unit 26 is that the pressure at the inlet of the sixth compression unit 26 is close to the gas pressure discharged from the reflux port 51 at the top of the absorber tower 50. This setting not only reduces pressure fluctuations during the reflux process and lowers reflux resistance, but also facilitates the smooth reintegration of the returned non-condensable gases into the subsequent compression process without having to return them to the earlier low-pressure compression unit.

[0073] It should be noted that, under normal operating conditions, the gaseous impurity gas should be carried away by the dense phase carbon dioxide after adopting the absorption tower 50 of this embodiment. However, under extreme operating conditions, the carbon capture of the raw material gas may fail, resulting in a low concentration of carbon dioxide in the raw material gas and a high concentration of non-condensable gas. Therefore, as a safety loop, the absorption tower 50 should still be equipped with a return gas port 51.

[0074] Furthermore, by returning the non-condensable gas to the inlet of the sixth compression unit 26, this portion of the non-condensable gas can continue to be compressed again by the sixth compression unit 26, the seventh compression unit 27, and the eighth compression unit 28, and then continue to be processed by the cooler 30 and the gas-liquid separator 40. Thus, even when non-condensable gas still exists in the system, a reprocessing path can be formed through the return gas port 51, so that the non-condensable gas is not directly retained in the system or directly discharged, but participates again in the subsequent compression and cooling processes, thereby improving the overall processing capacity of the system for the mixed gas and helping to maintain the stability of the fluid state entering the absorption tower 50.

[0075] In some embodiments, a control valve may be installed at the reflux port 51 to regulate the flow rate of the refluxed non-condensable gas, or a one-way valve may be installed at the reflux port 51 to reduce the risk of gas backflow during the reflux process. The above structure can further improve the stability and reliability of the reflux process.

[0076] In summary, by setting up heat exchangers 212 between adjacent compression units, the gas compressed in each stage of the multi-stage compression process can be cooled down in time. By setting up a cooler 30 between the eighth compression unit 28 and the gas-liquid separator 40, it can be further ensured that the carbon dioxide entering the gas-liquid separator 40 and finally entering the absorption tower 50 is in a dense phase state. By setting up a return gas port 51 on the gas-liquid separator 40 that is connected to the inlet of the sixth compression unit 26, when there is still non-condensable gas in the system, this part of the non-condensable gas can be guided back to the inlet of the sixth compression unit 26 with a similar pressure for reprocessing, thereby improving the overall treatment effect and enhancing the system's operational stability.

[0077] In some embodiments, the dense phase outlet 42 of the gas-liquid separator 40 is connected to the top of the absorption tower 50, and the gas phase outlet 41 of the gas-liquid separator 40 is connected to the bottom of the absorption tower 50. That is, the dense phase carbon dioxide separated by the gas-liquid separator 40 enters the absorption tower 50 from top to bottom, while the gaseous phase impurity gas separated by the gas-liquid separator 40 enters the absorption tower 50 from bottom to top. This arrangement allows the dense phase carbon dioxide and the gaseous phase impurity gas to form a counter-current contact within the absorption tower 50, thereby extending their contact path and improving the entrainment and carrying capacity of the dense phase carbon dioxide for the gaseous phase impurity gas. Consequently, the gaseous phase impurity gas can be more stably carried out and transported along with the dense phase carbon dioxide.

[0078] Furthermore, in some embodiments, the micro-interface generator 55 is connected to the gas phase outlet 41 to disperse the gaseous impurity gas discharged from the gas-liquid separator 40 into fine bubbles before or during its entry into the absorber 50. By providing the micro-interface generator 55, the gaseous impurity gas can be prevented from directly entering the absorber 50 in the form of large gas masses, thereby reducing the possibility of gas short-circuiting or local flow deviation, and facilitating an increase in the contact area between the gaseous impurity gas and the dense phase carbon dioxide. It is understood that the micro-interface generator 55 can be located at the lower part of the absorber 50 and connected to the gas phase outlet 41 of the gas-liquid separator 40, so that the gaseous impurity gas is dispersed at the bottom of the absorber 50 and then moves upward.

[0079] In some embodiments, the absorption tower 50 includes a tower body, a liquid distribution section 501 located at the upper part of the tower body, a multi-stage contact section 502 located in the middle part of the tower body, a microbubble generating section 503 located at the lower part of the tower body, and a steady flow collecting section 504 located at the bottom of the tower body. The liquid distribution section 501 is connected to the dense phase outlet 42, the micro-interface generator 55 is disposed in the microbubble generating section 503, and the steady flow collecting section 504 is connected to the liquid storage tank 60.

[0080] The function of the liquid distribution section 501 is to introduce the dense phase carbon dioxide from the dense phase outlet 42 of the gas-liquid separator 40 into the upper part of the absorption tower 50, and to form a more uniform liquid flow distribution of the dense phase carbon dioxide before entering the multi-stage contact section 502. In this way, the dense phase carbon dioxide will not directly impact downwards in a single stream, but can be fully spread in the upper part of the tower, creating conditions for subsequent contact with the rising gaseous impurity gas.

[0081] The microbubble generating section 503 is located at the bottom of the tower and is mainly used to receive gaseous impurity gas from the gas phase outlet 41 of the gas-liquid separator 40. Since the micro-interface generator 55 is located within the microbubble generating section 503, the gaseous impurity gas entering the bottom of the absorption tower 50 can form a large number of tiny bubbles under the action of the micro-interface generator 55, and then enter the multi-stage contact section 502 from bottom to top. Therefore, the gaseous impurity gas and the dense phase carbon dioxide flowing downwards can form a more thorough countercurrent contact within the tower.

[0082] The flow stabilization and collection section 504 is located at the bottom of the tower and is connected to the liquid storage tank 60. After sufficient contact in the distribution section 501, the multi-stage contact section 502, and the microbubble generation section 503, the mixed fluid formed in the tower enters the flow stabilization and collection section 504. The flow stabilization and collection section 504 can rectify and stabilize the fluid collected at the bottom of the tower, thereby reducing local turbulence fluctuations and facilitating the delivery of the mixed medium to the liquid storage tank 60.

[0083] Furthermore, in some embodiments, the multi-stage contact section 502 includes at least two layers of contact units spaced apart along the height of the tower. Each contact unit includes a frustum-shaped guide plate 56 and a defoaming and redispersing element 57 disposed below the frustum-shaped guide plate 56, the outer peripheral edge of the frustum-shaped guide plate 56 being connected to the inner wall of the tower.

[0084] In this embodiment, the frustum-shaped guide plate 56 is mainly used to guide dense-phase carbon dioxide to form a swirling liquid film. Specifically, the dense-phase carbon dioxide entering the upper part of the tower from the liquid distribution section 501 is dispersed and flows along the surface of the guide plate 56 under the action of the frustum-shaped guide plate, forming a swirling and falling liquid film structure on the surface of the guide plate and near the inner wall of the tower. Compared with simple free-falling liquid flow, the swirling liquid film can significantly increase the spread range of dense-phase carbon dioxide in the tower and increase its contact area with rising bubbles.

[0085] The bubble-breaking and redispersing component 57, located below the frustum-shaped guide plate 56, is mainly used to break and redisperse the rising bubbles. When the gaseous impurity gas from the microbubble generating section 503 enters the multi-stage contact section 502 in the form of microbubbles, some of the bubbles will gradually coalesce and form larger bubbles during the ascent. By setting the bubble-breaking and redispersing component 57, these larger bubbles can be broken again and redispersed into smaller bubbles, thereby continuously maintaining a large gas-liquid contact interface and improving the contact uniformity between the gaseous impurity gas and the dense phase carbon dioxide.

[0086] In some embodiments, the liquid distribution section 501 includes a liquid distribution chamber tangentially connected to the dense phase outlet 42. That is, the dense phase carbon dioxide does not enter the liquid distribution section 501 radially directly, but rather tangentially. This tangential entry allows the dense phase carbon dioxide to form a swirling flow within the liquid distribution chamber, making it easier to form a swirling liquid film when it enters the multi-stage contact section 502, thereby further improving the liquid's spreading effect and contact efficiency within the tower.

[0087] Specifically, after entering the liquid distribution section 501 from the dense phase outlet 42 of the gas-liquid separator 40, the dense phase carbon dioxide does not directly enter the multi-stage contact section 502 in the form of a stream, but first enters the spray element 58. The spray element 58 can divert and atomize the dense phase carbon dioxide entering the liquid distribution section 501, so that the dense phase carbon dioxide is dispersed into the absorption tower 50 in the form of droplets, liquid jets, or thin liquid streams. This arrangement helps to make the dense phase carbon dioxide more evenly distributed in the upper part of the absorption tower 50, thereby avoiding the dense phase carbon dioxide from only concentrating in a local area and falling, thus improving the contact uniformity between it and the gaseous impurity gas moving from bottom to top.

[0088] In some embodiments, the spray element 58 may be a spray disc, spray pipe, nozzle assembly, or a spray plate with multiple spray holes. Preferably, the spray element 58 includes multiple spray nozzles spaced apart circumferentially along the absorption tower 50, so that the dense phase carbon dioxide is sprayed and distributed more uniformly along the circumference in the upper part of the absorption tower 50. By dispersing the spray through multiple spray nozzles, the dense phase carbon dioxide can form a more uniform liquid phase coverage area, which is beneficial for sufficient countercurrent contact with the gaseous impurity gas generated in the microbubble generation section 503.

[0089] Furthermore, in some embodiments, the spray direction of the spray element 58 is directed toward the multi-stage contact section 502, or at least a portion of the spray nozzles of the spray element 58 are inclined along the tangential direction of the absorption tower 50. With this configuration, the sprayed dense-phase carbon dioxide can not only enter the multi-stage contact section 502 downwards, but also form a certain swirling tendency within the absorption tower 50, thereby cooperating with the swirling liquid film guided by the frustum-shaped guide plate 56 to further enhance the gas-liquid contact effect.

[0090] By providing a spray element 58 in the liquid distribution section 501, the dense-phase carbon dioxide in this embodiment can achieve a more uniform distribution and more thorough initial dispersion before entering the multi-stage contact section 502. On the one hand, this is beneficial for increasing the contact area between the dense-phase carbon dioxide and the gaseous impurity gas. On the other hand, it also helps to make fuller use of each layer of contact units in the subsequent multi-stage contact section 502, thereby further enhancing the effect of carrying out and transporting the gaseous impurity gas along with the dense-phase carbon dioxide.

[0091] Furthermore, in some embodiments, the micro-interface generator 55 includes an outlet surface with micropores. After the gaseous impurity gas enters the micro-interface generator 55 through the gas phase outlet 41, it is uniformly dispersed and discharged through the micropores to form a large number of fine bubbles. Because the micropores are small in size, the resulting bubbles have relatively small particle sizes, which can significantly increase the gas-liquid contact area per unit volume of gas, thereby facilitating the entrainment of gaseous impurity gas by dense-phase carbon dioxide.

[0092] Furthermore, along the height direction, the projection of the outlet surface coincides with the projection of the guide plate. In other words, the rising path of the microbubbles released from the lower micro-interface generator 55 corresponds in the height direction to the liquid film region guided by the upper frustum-shaped guide plate 56. With this configuration, the microbubbles moving from bottom to top can more fully pass through the swirling liquid film region formed by the frustum-shaped guide plate 56, and are less likely to deviate from the main contact area. As a result, the microbubble generating section 503 and the multi-stage contact section 502 can form a more targeted correspondence in spatial position, thereby further improving the contact sufficiency between dense phase carbon dioxide and gaseous phase impurity gas.

[0093] In summary, in this embodiment, by connecting the dense phase outlet 42 of the gas-liquid separator 40 to the top of the absorption tower 50 and the gas phase outlet 41 of the gas-liquid separator 40 to the bottom of the absorption tower 50, a counter-current contact relationship of liquid above and gas below can be formed within the absorption tower 50. By installing a micro-interface generator 55 at the bottom of the absorption tower 50, gaseous impurity gas can be formed into microbubbles. By installing a multi-stage contact section 502 including a frustum-shaped guide plate 56 and a bubble-breaking and redispersing component 57 in the middle of the absorption tower 50, dense phase carbon dioxide can form a swirling liquid film, and rising bubbles can be continuously broken and redispersed. Furthermore, by connecting the bottom stabilizing and collecting section 504 to the liquid storage tank 60, the mixed fluid formed in the tower can be output more stably. Thus, gaseous impurity gas can be carried out and transported along with dense phase carbon dioxide more effectively.

[0094] In the optimal embodiment of the present invention, the target state is that no non-condensable gas flows back to the multi-stage compression assembly 20 at the return port 51. That is, when no non-condensable gas is detected online at the return port 51, it can be considered that the absorption tower 50 has achieved the optimal effect of entraining and mixing non-condensable gas, so that the system no longer needs to perform circulating back pressure treatment on non-condensable gas, which helps to reduce the system's backflow burden and improve the overall transportation stability.

[0095] In some embodiments, the outlet of the absorption tower 50 is connected to the inlet of the storage tank 60 via a connecting pipe 61, which is tangential to the circumferential sidewall of the storage tank 60. That is, the mixed medium from the absorption tower 50 does not enter the storage tank 60 radially, but rather tangentially along the circumferential sidewall. This configuration allows the mixed medium to flow circumferentially along the inner wall of the storage tank 60 upon entry, preventing direct impact on the main storage area inside the tank. This helps reduce local impact and pressure drop at the inlet and minimizes the risk of local phase separation between dense carbon dioxide and gaseous impurities caused by severe inlet disturbance.

[0096] Furthermore, the storage tank 60 includes a tank body and a flow stabilizer 62 disposed within the tank body. A storage cavity 602 is formed inside the flow stabilizer 62, and an annular buffer channel 601 is formed between the flow stabilizer 62 and the inner wall of the tank body. The storage cavity 602 and the annular buffer channel 601 are connected, and the connecting pipe 61 is connected to the annular buffer channel 601. That is, after the mixed medium enters the storage tank 60 through the connecting pipe 61, it does not directly enter the storage cavity 602, but first enters the annular buffer channel 601 outside the flow stabilizer 62. Through the annular buffer channel 601, the mixed medium can first flow circumferentially along the periphery of the flow stabilizer 62 and gradually be buffered and decelerated before entering the storage cavity 602 inside the flow stabilizer 62. Therefore, the annular buffer channel 601 can play a buffering and pressure equalization role, making the mixed medium entering the storage cavity 602 more stable and helping to maintain the compositional homogeneity of the mixed medium within the storage cavity 602.

[0097] In this embodiment, the purpose of the flow stabilizer 62 is not to separate the dense phase carbon dioxide and the gaseous impurity gas, but to divide the interior of the storage tank 60 into two functional areas: an annular buffer channel 601 and a storage chamber 602. The former is mainly used to receive the mixed medium discharged from the absorption tower 50 and reduce inlet disturbance, while the latter is mainly used to store the buffered mixed medium. Through the above structure, the mixed medium can be prevented from entering the storage chamber 602 directly at high speed, thereby reducing large-scale turbulence and local gas evolution phenomena within the storage chamber 602.

[0098] Furthermore, in some embodiments, the connecting pipe 61 includes a diffuser section 611, which is connected to the annular buffer channel 601. That is, the mixed medium discharged from the absorber tower 50 passes through the diffuser section 611 before entering the annular buffer channel 601. The function of the diffuser section 611 is to gradually slow down and diffuse the mixed medium before it enters the storage tank 60, thereby reducing the flow rate and decreasing the local pressure gradient. This further avoids local pressure drops caused by sudden expansion or sudden entry into the tank, thus reducing the possibility of impurity gases precipitating from the dense phase carbon dioxide. In other words, the diffuser section 611, in conjunction with the annular buffer channel 601, forms a feed path at the inlet of the storage tank 60 that first diffuses and then buffers, which is beneficial for improving the phase stability of the mixed medium entering the storage tank 60.

[0099] In some embodiments, the flow stabilizing cylinder 62 has multiple flow equalization holes 621 evenly spaced circumferentially on its wall, and the liquid storage chamber 602 and the annular buffer channel 601 are connected through the flow equalization holes 621. Specifically, after the mixed medium in the annular buffer channel 601 flows and is buffered circumferentially, it can gradually enter the liquid storage chamber 602 through the multiple flow equalization holes 621. Since the multiple flow equalization holes 621 are evenly spaced circumferentially, the mixed medium will not enter the liquid storage chamber 602 from a single local area, but can enter the liquid storage chamber 602 dispersedly at multiple circumferential positions. This arrangement reduces the possibility of local high-speed jets directly entering the liquid storage chamber 602, and also makes the distribution of the mixed medium in the liquid storage chamber 602 more uniform, thereby helping to reduce the risk of local component enrichment or local phase separation in the liquid storage chamber 602.

[0100] Furthermore, the axis of the flow equalization orifice 621 is inclined relative to the radial direction of the flow stabilizer 62 towards the direction of rotation of the mixing medium, and is also inclined downward towards the liquid storage chamber 602. In this way, after the mixing medium enters the liquid storage chamber 602 through the flow equalization orifice 621, it can form a gentle tangential downward flow, and is less likely to form a radial straight jet, thereby reducing local impact and local pressure drop, and further suppressing the precipitation of gaseous impurities from the dense phase carbon dioxide.

[0101] Furthermore, the inlet edge of the flow equalization orifice 621 has a rounded corner transition or a flared mouth transition. By smoothing the transition of the orifice of the flow equalization orifice 621, the local throttling effect when the mixed medium flows through the flow equalization orifice 621 can be reduced, thereby reducing the possibility of gaseous impurities being released near the flow equalization orifice 621 due to a sudden drop in local pressure.

[0102] Furthermore, in some embodiments, the flow stabilizing cylinder 62 does not have flow equalization holes 621 in a section of its axial length near the top, thus forming a non-porous buffer section. This prevents the mixed medium in the annular buffer channel 601 from directly entering the top region of the liquid storage chamber 602, thereby reducing disturbance in the top region and suppressing the preferential precipitation of gaseous impurities at the top of the liquid storage tank 60.

[0103] Furthermore, in some embodiments, the aperture of the plurality of flow equalization holes 621 can be set to a size range that allows the mixed medium to maintain a gentle flow state during passage. Preferably, the total open area of ​​the flow equalization holes 621 matches the flow area of ​​the annular buffer channel 601, preferably ranging from 0.5 to 0.8 times the flow area of ​​the annular buffer channel 601, so as to maintain the required buffering and flow equalization effect while ensuring that the mixed medium can smoothly enter the liquid storage chamber 602. By setting multiple flow equalization holes 621, a uniform and gentle transition flow can be formed between the annular buffer channel 601 and the liquid storage chamber 602, which is beneficial to the stable storage of the mixed medium in the liquid storage chamber 602.

[0104] In some embodiments, multiple surge protectors connected to the cylinder wall are provided inside the liquid storage chamber 602 along the axial direction of the flow stabilizer 62. That is, multiple surge protectors are arranged sequentially at intervals along the circumferential direction of the flow stabilizer 62 and connected to the inner wall of the flow stabilizer 62. The function of the surge protectors is to reduce the large-amplitude reciprocating flow of the mixed medium in the liquid storage chamber 602 along the axial direction when the liquid storage tank 60 is affected by transportation vibration, loading and unloading disturbances, or periodic fluctuations of the fluid, thereby reducing liquid surface turbulence and overall surge phenomena. This reduces the redistribution, local gas evolution, or significant stratification of dense-phase carbon dioxide and gaseous impurities caused by violent shaking inside the liquid storage tank 60.

[0105] Furthermore, the surge protector can be further provided with connecting holes to allow the mixed medium in the liquid storage chamber 602 to flow slowly between axially adjacent areas. With this configuration, the surge protector can suppress violent surges without completely dividing the liquid storage chamber 602 into multiple independent spaces that are not interconnected. This helps to maintain the uniformity of the overall composition of the mixed medium in the liquid storage chamber 602 while reducing large-scale shaking.

[0106] In summary, in this embodiment, by tangentially connecting the connecting pipe 61 along the circumferential sidewall of the storage tank 60, installing a flow stabilizer 62 inside the storage tank 60 to form an annular buffer channel 601, installing a diffuser section 611 on the connecting pipe 61, installing multiple flow equalization holes 621 on the wall of the flow stabilizer 62, and installing multiple anti-surge baffles inside the storage chamber 602, the mixed medium discharged from the absorption tower 50 can be buffered and decelerated before entering the storage tank 60, and then uniformly enter the storage chamber 602, where it is stably stored. This effectively reduces inlet disturbance and transport disturbance, suppresses significant phase separation between dense-phase carbon dioxide and gaseous impurities within the storage tank 60, thereby improving the storage stability and compositional uniformity of the mixed medium.

[0107] In some embodiments, to quantitatively evaluate the effect of the above-defined storage tank 60 structure on suppressing the precipitation of gaseous impurities carried by dense-phase carbon dioxide, the following parameters are used as evaluation indicators: Firstly, the free gas phase volume fraction αg at the top of the tank is defined as the ratio of the free gas phase volume at the top of the storage tank 60 to the effective volume of the storage tank 60. The smaller αg is, the less gaseous impurity gas is released from the dense phase carbon dioxide in the storage tank 60, and the less likely significant phase separation will occur in the mixed medium within the storage tank 60.

[0108] Secondly, the gas evolution rate Qg per unit time is defined as the volumetric flow rate of gas emanating from the top detection port of the storage tank 60 per unit time. The smaller Qg is, the less likely the gaseous impurities carried by the dense phase carbon dioxide in the storage tank 60 are to be emanated.

[0109] Third, the temperature-corrected tank pressure fluctuation amplitude ΔPtc is defined as the range of pressure fluctuation within the storage tank 60 within a unit observation period under the same filling rate and temperature conversion conditions. Since the pressure in the storage tank 60 is affected by ambient temperature, filling rate, and transportation disturbances, tank pressure is preferred as an auxiliary judgment parameter. When ΔPtc decreases, it usually indicates that the mixed medium phase in the storage tank 60 is more stable and the tendency for gaseous impurities to precipitate is weaker.

[0110] In a practical operating condition, the mixed medium entering the storage tank 60 is a mixture of dense-phase carbon dioxide discharged from the absorption tower 50 and gaseous impurity gas, with the total integral of the gaseous impurity gas being approximately 7 vol%. The pressure of the mixed medium entering the storage tank 60 is 7.4 MPa, the temperature is 18℃, and the filling rate of the storage tank 60 is 75%. The transportation condition uses simulated vibration conditions, with a horizontal reciprocating vibration acceleration of 0.2g, a vibration frequency of 1.5Hz, and a duration of 30 minutes. Under these conditions, αg, Qg, and ΔPtc corresponding to different structural schemes are measured.

[0111] In a comparative example, the mixed medium discharged from the absorber 50 directly enters a standard storage tank 60 via a standard connecting pipe 61. The storage tank 60 lacks a tangential feed structure, an annular buffer channel 601, a diffuser section 611, a flow equalization orifice 621, and a surge protection baffle. Under this condition, the free gas phase volume fraction αg at the tank top is approximately 6.5 vol%, the gas evolution rate Qg per unit time is approximately 1.18 NL / min, and the temperature-corrected tank pressure fluctuation amplitude ΔPtc is approximately 16.2 kPa / 30 min. These results indicate that, under the standard structure, the local impact and local pressure drop when the mixed medium enters the storage tank 60 are significant, leading to easier precipitation of gaseous impurities carried by the dense-phase carbon dioxide.

[0112] In Example 1, the outlet is connected to the inlet of the storage tank 60 via a connecting pipe 61, which is tangentially connected to the circumferential sidewall of the storage tank 60. Test results show that αg is approximately 4.9 vol%, Qg is approximately 0.82 NL / min, and ΔPtc is approximately 11.4 kPa / 30 min. Compared to the comparative example, tangential feeding transforms the radial impact of the mixed medium entering the storage tank 60 into a gentle circumferential flow, reducing local impact and pressure drop, thereby mitigating the precipitation of gaseous impurities.

[0113] In Example 2, based on Example 1, the storage tank 60 includes a tank body and a flow stabilizer 62 disposed within the tank body. A storage cavity 602 is formed inside the flow stabilizer 62, and an annular buffer channel 601 is formed between the flow stabilizer 62 and the inner wall of the tank body. The storage cavity 602 is connected to the annular buffer channel 601, and a connecting pipe 61 is connected to the annular buffer channel 601. Detection results show that αg is approximately 3.1 vol%, Qg is approximately 0.46 NL / min, and ΔPtc is approximately 7.6 kPa / 30 min. Therefore, the annular buffer channel 601 can buffer, equalize, and reduce the velocity of the mixed medium before it enters the storage cavity 602, thereby further suppressing local gas evolution.

[0114] In Example 3, based on Example 2, the connecting pipe 61 includes a diffuser section 611, which is connected to the annular buffer channel 601. Detection results show that αg is approximately 1.9 vol%, Qg is approximately 0.24 NL / min, and ΔPtc is approximately 4.3 kPa / 30 min. This indicates that the diffuser section 611 can further reduce the velocity gradient and local throttling effect before the mixed medium enters the annular buffer channel 601, thereby reducing the possibility of gaseous impurities precipitating in the inlet region.

[0115] In Example 4, based on Example 3, the flow stabilizing cylinder 62 has multiple uniformly spaced flow equalization holes 621 on its wall, and the liquid storage chamber 602 and the annular buffer channel 601 are connected through the flow equalization holes 621. The test results show that αg is approximately 0.8 vol%, Qg is approximately 0.09 NL / min, and ΔPtc is approximately 1.7 kPa / 30 min. This indicates that the flow equalization holes 621 allow the mixed medium to enter the liquid storage chamber 602 from the annular buffer channel 601 in a multi-point, uniform, and slow manner, avoiding the direct entry of local high-speed jets into the liquid storage chamber 602, thereby significantly reducing the precipitation of gaseous impurities carried by dense-phase carbon dioxide.

[0116] In Example 5, based on Example 4, multiple surge protectors connected to the cylinder wall are installed in the liquid storage chamber 602 along the axial direction of the flow stabilizer 62. Test results show that αg is approximately 0.18 vol%, Qg is approximately 0.02 NL / min, and ΔPtc is approximately 0.6 kPa / 30 min. This demonstrates that the surge protectors effectively reduce axial surges and liquid surface turbulence during transport, reducing component redistribution and localized gas evolution caused by transport disturbances, thereby maintaining a more stable mixed state of the mixed medium within the liquid storage tank 60.

[0117] In summary, under the same operating conditions, with the gradual adoption of the internal structure of the storage tank 60, the free gas phase volume fraction αg at the tank top gradually decreased from 6.5 vol% to 0.18 vol%, the gas evolution rate Qg per unit time gradually decreased from 1.18 NL / min to 0.02 NL / min, and the temperature-corrected tank pressure fluctuation amplitude ΔPtc gradually decreased from 16.2 kPa / 30 min to 0.6 kPa / 30 min. This indicates that adopting the aforementioned limiting structure can effectively reduce the local impact, local pressure drop, and surge disturbance during transportation when the mixed medium enters the storage tank 60, thereby suppressing the evolution of gaseous impurities carried by dense-phase carbon dioxide within the storage tank 60 and improving the storage stability of the mixed medium.

[0118] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A carbon dioxide mixture recovery and treatment system, characterized in that, The system includes a multi-stage compression assembly, a gas-liquid separator, an absorption tower, and a storage tank. The multi-stage compression assembly comprises multiple compression units connected sequentially along the gas flow direction. The gas-liquid separator is located downstream of the multi-stage compression assembly, and its inlet is connected to the outlet of the final compression unit in the multi-stage compression assembly. The gas-liquid separator has a dense phase outlet and a gas phase outlet. The absorption tower is located downstream of the gas-liquid separator and has a first inlet, a second inlet, and a discharge port. The first inlet is connected to the dense phase outlet, and the second inlet is connected to the gas phase outlet. The storage tank is located downstream of the absorption tower, and its inlet is connected to the discharge port. The storage tank includes a tank body and a flow stabilizer cylinder disposed within the tank body, with a storage cavity formed inside the flow stabilizer cylinder.

2. A method for recovering and treating a carbon dioxide mixture, characterized in that, The carbon dioxide mixture recovery and treatment system according to claim 1, wherein the recovery and treatment method comprises the following steps: Multi-stage compression of carbon dioxide mixture; The carbon dioxide mixture after multi-stage compression is subjected to gas-liquid separation to obtain dense phase carbon dioxide and gaseous impurity gas; The dense phase carbon dioxide flows from top to bottom, and the gaseous phase impurity gas flows from bottom to top, so that the dense phase carbon dioxide and the gaseous phase impurity gas come into countercurrent contact, so that the gaseous phase impurity gas and the dense phase carbon dioxide together form a mixed medium. The mixed medium is stored.

3. The method for recovering and treating carbon dioxide mixture according to claim 2, characterized in that, Prior to the step of contacting the dense-phase carbon dioxide with the gaseous impurity gas in reverse, the gaseous impurity gas is further dispersed into microbubbles.

4. The method for recovering and treating carbon dioxide mixture according to claim 3, characterized in that, The step of contacting the dense-phase carbon dioxide with the gaseous impurity gas in a counter-current manner includes: The dense-phase carbon dioxide is introduced into the upper liquid distribution section; The gaseous impurity gas is introduced into the lower microbubble generation section; The dense-phase carbon dioxide and the gaseous impurity gas are brought into contact within a multi-stage contact section located in the middle. The resulting mixed medium is introduced into the bottom steady flow collection section.

5. The method for recovering and treating carbon dioxide mixture according to claim 4, characterized in that, The step of contacting the dense-phase carbon dioxide and the gaseous impurity gas in a multi-stage contact section located in the middle includes: The gaseous impurity gas is passed sequentially through at least two contact zones spaced apart along the height direction, so that at least a portion of the gaseous impurity gas not entrained by the lower contact zone continues to be entrained by the upper contact zone.

6. The method for recovering and treating carbon dioxide mixture according to claim 5, characterized in that, The step of allowing the gaseous impurity gas to pass through the contact area includes: The dense phase carbon dioxide forms a swirling liquid film along the guide surface, and the rising gaseous impurity gas passes through the swirling liquid film.

7. The method for recovering and treating carbon dioxide mixture according to claim 6, characterized in that, The step of forming the swirling liquid film includes: The dense phase carbon dioxide is introduced into the liquid distribution chamber tangentially and then sprayed into the contact area.

8. The method for recovering and treating carbon dioxide mixture according to claim 2, characterized in that, The step of storing the hybrid medium includes: The mixed medium is introduced into the storage tank along the tangential direction of the circumferential sidewall.

9. The method for recovering and treating carbon dioxide mixture according to claim 8, characterized in that, The step of storing the hybrid medium includes: The mixed medium first enters the annular buffer channel, and then enters the storage chamber through the annular buffer channel.

10. The method for recovering and treating a carbon dioxide mixture according to claim 9, characterized in that, The step of introducing the mixed medium into the reservoir includes: The mixed medium is diffused and then enters the annular buffer channel, and enters the liquid storage chamber through a plurality of uniformly spaced flow equalization holes along the circumference. Within the liquid storage chamber, multiple surge protection baffles spaced apart along the axial direction reduce the surge of the mixed medium.

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