Carbon dioxide mixed gas treatment device

Abstract

The application relates to the technical field of pipeline transportation, and discloses a carbon dioxide mixed gas treatment equipment, which comprises a multistage compressor assembly, a gas-liquid separation tank, an absorption tower, a booster pump and a lithium bromide unit which are sequentially connected in communication. The multistage compressor assembly comprises a plurality of compression units which are sequentially connected in communication, at least one compression unit comprises a compressor and a heat exchanger, and the lithium bromide unit comprises first and second heat exchange pipelines which are respectively in heat exchange connection with the heat exchanger and the gas-liquid separation tank. The inlet of the gas-liquid separation tank is in communication with the last compression unit, the dense phase outlet and the gas phase outlet of the gas-liquid separation tank are respectively in communication with the absorption tower, and the delivery outlet of the absorption tower is in communication with an external delivery pipeline through the booster pump. The treatment equipment can treat the carbon dioxide mixed gas into a dense phase state suitable for delivery, and can deliver the gas phase impurity gas together with the dense phase carbon dioxide to an oil field oil displacement end.

Description

Technical Field

[0001] This application relates to the technical field of pipeline transportation, and in particular to a device for processing carbon dioxide mixtures. Background Technology

[0002] In existing technologies, carbon dioxide is typically pressurized to a dense phase for long-distance transport. Carbon dioxide in a dense phase possesses both high density and good flowability, making it more suitable for pipeline transport from the plant side to the oilfield side for oil displacement. Therefore, for carbon dioxide mixtures from sources such as industrial exhaust, processing the carbon dioxide to a dense phase is a crucial prerequisite for subsequent transport and oil displacement.

[0003] However, during the compression, cooling, and liquefaction of carbon dioxide mixtures, even after the carbon dioxide has been liquefied, some non-condensable impurities may still remain. Current technologies for treating such mixtures typically focus on gas-liquid separation or deep purification of the carbon dioxide. However, there is a lack of targeted solutions for handling these non-condensable impurities in oil displacement applications, where excessively high purity is not required, and ensuring they are carried out and transported along with the dense-phase carbon dioxide. Continuing with high-purity purification methods would not only result in complex systems and high energy consumption but also increase processing costs. Furthermore, the lack of effective treatment for non-condensable impurities would be detrimental to environmental emission control. Summary of the Invention

[0004] The objective of this invention is to at least solve the problem of how to process carbon dioxide into a dense phase state suitable for transportation, and how to ensure that non-condensable impurities in the mixed gas are carried out and transported along with the dense-phase carbon dioxide. This objective is achieved through the following technical solution: This invention proposes a carbon dioxide mixture processing device, including a lithium bromide unit and a multi-stage compressor assembly, a gas-liquid separator, an absorption tower and a booster pump connected in sequence. The multi-stage compressor assembly includes a plurality of compression units connected sequentially along the airflow direction, and at least one of the compression units includes a compressor and a heat exchanger located downstream of the compressor. The lithium bromide unit includes a first heat exchange pipe and a second heat exchange pipe. The first heat exchange pipe is connected to the heat exchanger for heat exchange, and the second heat exchange pipe is connected to the gas-liquid separator for heat exchange. The inlet of the gas-liquid separator is connected to the last compression unit in the multi-stage compressor assembly along the airflow direction. The dense phase outlet and gas phase outlet of the gas-liquid separator are respectively connected to the absorption tower, so that the gaseous impurity gas enters the absorption tower and comes into contact with the dense phase carbon dioxide. The absorption tower is provided with a delivery outlet, which is connected to the booster pump for delivering the mixed medium of dense phase carbon dioxide and gaseous impurity gas to the external pipeline.

[0005] According to the carbon dioxide mixture processing equipment of the present invention, by setting up a multi-stage compressor assembly, the carbon dioxide mixture can be pressurized stage by stage, thereby providing pressure conditions for the carbon dioxide to reach a dense phase state. Simultaneously, by setting up a lithium bromide unit, and connecting the first heat exchange pipe of the lithium bromide unit to a heat exchanger and the second heat exchange pipe to a gas-liquid separator, the heat generated after compression can be used for refrigeration, cooling the carbon dioxide mixture entering the gas-liquid separator, thus facilitating the processing of the carbon dioxide to a dense phase state suitable for transportation. Furthermore, by setting up a gas-liquid separator, and connecting the dense phase outlet and the gas phase outlet of the gas-liquid separator to an absorption tower respectively, the dense phase carbon dioxide and the gas phase impurity gas can come into contact within the absorption tower, thereby allowing the non-condensable impurity gas in the mixture to be carried out along with the dense phase carbon dioxide, rather than remaining separately in the system. Then, by connecting a booster pump to an external pipeline, the resulting mixed fluid can be stably transported to the oilfield's oil displacement end. Therefore, this invention can achieve the transformation of carbon dioxide mixture into a dense phase state suitable for transportation while meeting the requirements of oil displacement and transportation, and can transport non-condensable impurity gas together with dense phase carbon dioxide.

[0006] In addition, the carbon dioxide mixture processing device according to the present invention may also have the following additional technical features: In some embodiments of the present invention, the plurality of compression units include a first compression unit, a second compression unit, a third compression unit, a fourth compression unit, a fifth compression unit, a sixth compression unit, a seventh compression unit, and an eighth compression unit connected sequentially along the airflow direction. The outlet of the first compression unit is connected to the inlet of the second compression unit, the outlet of the second compression unit is connected to the inlet of the third compression unit, the outlet of the third compression unit is connected to the inlet of the fourth compression unit, the outlet of the fourth compression unit is connected to the inlet of the fifth compression unit, the outlet of the fifth compression unit is connected to the inlet of the sixth compression unit, the outlet of the sixth compression unit is connected to the inlet of the seventh compression unit, the outlet of the seventh compression unit is connected to the inlet of the eighth compression unit, and the outlet of the eighth compression unit is connected to the inlet of the gas-liquid separator.

[0007] In some embodiments of the present invention, the heat exchanger is provided between two adjacent compression units.

[0008] In some embodiments of the present invention, the carbon dioxide mixture processing device further includes a cooler, and the outlet of the eighth compression unit is connected to the inlet of the gas-liquid separator through the cooler.

[0009] In some embodiments of the present invention, the absorption tower is further provided with a reflux gas port, which is connected to the inlet of the sixth compression unit.

[0010] In some embodiments of the present invention, the gas-liquid separator includes a tank body and a partition cylinder disposed within the tank body. An annular heat exchange region is formed between the partition cylinder and the inner wall of the tank body. The second heat exchange pipe is at least partially disposed within the annular heat exchange region and is arranged around the circumference of the gas-liquid separator to exchange heat with the gas-liquid interface region within the gas-liquid separator.

[0011] In some embodiments of the present invention, the dense phase outlet of the gas-liquid separator is connected to the top of the absorption tower, and the gas phase outlet of the gas-liquid separator is connected to the bottom of the absorption tower.

[0012] In some embodiments of the present invention, a micro-interface generator is provided at the bottom of the absorption tower, and the micro-interface generator is connected to the gas phase outlet.

[0013] In some embodiments of the present invention, the absorption tower includes a tower body, a liquid distribution section located at the upper part of the tower body, a multi-stage contact section located in the middle part of the tower body, a microbubble generating section located at the lower part of the tower body, and a steady flow collecting section located at the bottom of the tower body. The liquid distribution section is connected to the dense phase outlet, the micro-interface generator is disposed in the microbubble generating section, and the steady flow collecting section is connected to the booster pump.

[0014] In some embodiments of the present invention, the multi-stage contact section includes at least two layers of contact units spaced apart along the height direction of the tower body. Each layer of the contact unit includes a frustum-shaped guide plate and a defoaming and redispersing element disposed below the frustum-shaped guide plate. The outer peripheral edge of the frustum-shaped guide plate is connected to the inner wall of the tower body. The frustum-shaped guide plate is used to guide the dense phase carbon dioxide to form a swirling liquid film. The defoaming and redispersing element is used to defoam and redisperse the rising bubbles. The liquid distribution section includes a liquid distribution chamber tangentially connected to the dense phase outlet. The micro-interface generator includes an outlet surface with micropores. Along the height direction, the projection of the outlet surface coincides with the projection of the guide plate. Attached Figure Description

[0015] 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 1A schematic diagram of a carbon dioxide mixture processing device according to an embodiment of the present invention is shown. Figure 2 A schematic diagram of the structure of an absorption tower according to an embodiment of the present invention is shown.

[0016] The attached figures are labeled as follows: 100. Equipment for processing carbon dioxide mixture; 101. Raw material gas inlet; 102. External transmission pipeline; 10. Lithium bromide unit; 11. First heat exchange pipe; 12. Second heat exchange pipe; 20. Multistage compressor 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. Third inlet; 42. Dense phase outlet; 43. Gas phase outlet; 44. Centrifugal pump; 50. Absorption tower; 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. Conveyor outlet; 55. Micro-interface generator; 56. Frustum-shaped guide plate; 57. Bubble breaking and redispersing component; 58. Spray component; 60. Booster pump. Detailed Implementation

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] like Figure 1 and Figure 2 As shown, according to an embodiment of the present invention, a carbon dioxide mixture processing device 100 is provided, comprising a lithium bromide unit 10 and a multi-stage compressor assembly 20, a gas-liquid separator 40, an absorption tower 50, and a booster pump 60 connected in sequence. The multi-stage compressor assembly 20 is used to compress the carbon dioxide mixture in stages. Specifically, the multi-stage compressor assembly 20 includes multiple compression units connected in sequence along the gas flow direction, at least one compression unit including a compressor 211 and a heat exchanger 212 located downstream of the compressor 211. After the carbon dioxide mixture enters the multi-stage compressor assembly 20, it is pressurized sequentially in the multiple compression units, so that the pressure of the carbon dioxide mixture gradually increases, thereby providing pressure conditions for subsequent processing of the carbon dioxide to a dense phase state.

[0022] In this embodiment, the lithium bromide unit 10 includes a first heat exchange pipe 11 and a second heat exchange pipe 12. The first heat exchange pipe 11 is connected to the heat exchanger 212, and the second heat exchange pipe 12 is connected to the gas-liquid separator 40. That is, the compressed carbon dioxide mixture releases heat at the heat exchanger 212, and this heat is transferred to the lithium bromide unit 10 through the first heat exchange pipe 11. The lithium bromide unit 10 uses this heat for cooling and also cools the gas-liquid separator 40 through the second heat exchange pipe 12. Therefore, the heat generated by the multi-stage compressor assembly 20 during compression can be fully utilized, reducing the need for additional cold sources and improving the overall energy efficiency of the system.

[0023] It is understood that the lithium bromide unit 10 is a closed-loop vacuum absorption refrigeration device driven by thermal energy. Its internal main structure includes four core heat exchange components: a generator, a condenser, an evaporator, and an absorber. These components are connected by sealed piping, forming an internal circulation loop between the refrigerant (water) and the absorbent (lithium bromide aqueous solution). In addition, it includes a solution heat exchanger for heat recovery within the solution and a shielded pump to drive the fluid circulation.

[0024] In this embodiment, the lithium bromide unit 10 is connected to the heat exchanger 212 via a first heat exchange pipe 11. Since the heat exchanger 212 dissipates a large amount of heat during the process, in this embodiment, the first heat exchange pipe 11 specifically connects the hot fluid outlet of the heat exchanger 212 to the heating tube bundle of the generator in the lithium bromide unit 10. Its function is to introduce the process waste heat dissipated by the heat exchanger 212 into the generator, serving as the power heat source to drive the entire lithium bromide unit 10. The lithium bromide unit 10 is connected to the gas-liquid separator 40 via a second heat exchange pipe 12. Since the gas-liquid separator 40 needs to be cooled, in this embodiment, the second heat exchange pipe 12 specifically connects the chilled water tube bundle of the evaporator in the lithium bromide unit 10 to the internal cooling structure of the gas-liquid separator 40. Its function is to transport the chilled water produced by the lithium bromide unit 10 to the gas-liquid separator 40, providing it with the required cooling load.

[0025] The fluid carrying waste heat from heat exchanger 212 enters the generator via the first heat exchange pipe 11. Inside the generator, this waste heat heats the dilute lithium bromide solution from the absorber, causing it to boil. Water in the solution evaporates to form high-temperature steam, while the dilute solution, having lost water, is reconcentrated into a concentrated lithium bromide solution. The heat source fluid, after heat exchange, cools and is discharged from the generator. This process effectively recovers and utilizes the heat dissipated by heat exchanger 212. The high-temperature steam generated in the generator enters the condenser, where it is cooled by cooling water flowing through the condenser tube bundle and condenses into liquid refrigerant water. The liquid refrigerant water, after being throttled and depressurized, enters the evaporator under a high vacuum and is evenly sprayed onto the outer surface of the heat exchange tube bundle. Under this high vacuum environment, the refrigerant water vaporizes rapidly at extremely low temperatures (e.g., 4°C to 7°C). The vaporization process absorbs a large amount of heat from the fluid within the tube bundle, thereby cooling the circulating water flowing through the tube bundle to produce chilled water. The chilled water is continuously supplied to the gas-liquid separator 40 via the second heat exchange pipe 12, completing the cooling task of the gas-liquid separator 40. Water vapor generated by vaporization in the evaporator continuously enters the adjacent absorber. Simultaneously, the high-concentration lithium bromide solution concentrated in the generator is cooled by the solution heat exchanger and then sprayed into the absorber. The high-concentration lithium bromide solution is extremely thirsty and rapidly absorbs water vapor, thereby maintaining the high vacuum state within the evaporator and ensuring the continuous operation of the evaporative cooling process. After absorbing water vapor, the concentrated solution returns to a dilute solution, releasing absorbed heat. Subsequently, this dilute solution is returned to the generator by a shielded pump to begin the next cycle.

[0026] Furthermore, the third inlet 41 (i.e., the inlet of the gas-liquid separator 40) is connected to the last compression unit in the multi-stage compressor assembly 20 along the airflow direction. That is, the carbon dioxide mixture compressed by the last compression unit enters the gas-liquid separator 40. Since the gas-liquid separator 40 is heat-exchange connected to the second heat exchange pipe 12 of the lithium bromide unit 10, the carbon dioxide mixture entering the gas-liquid separator 40 can be further cooled. Under the combined effect of the aforementioned pressurization and cooling, the carbon dioxide in the carbon dioxide mixture reaches a dense phase state suitable for transport.

[0027] In this embodiment, the gas-liquid separator 40 is used to separate the cooled fluid into dense-phase carbon dioxide and gaseous impurity gases. These gaseous impurity gases can be light components that have not entered the dense-phase state in the mixture, other non-condensable impurity gases, etc. Since oil displacement applications do not require carbon dioxide to be purified to a particularly high purity, this embodiment does not aim to completely remove the gaseous impurity gases, but rather to allow them to be carried out and transported along with the dense-phase carbon dioxide.

[0028] Furthermore, the dense phase outlet 42 and gas phase outlet 43 of the gas-liquid separator 40 are respectively connected to the absorption tower 50, so that the gaseous impurity gas enters the absorption tower 50 and contacts the dense phase carbon dioxide. Specifically, the dense phase carbon dioxide and the gaseous impurity gas enter the absorption tower 50 from different paths, forming a contact mixing process within the absorption tower 50. Through the arrangement of the absorption tower 50, the dense phase carbon dioxide can entrain and carry the gaseous impurity gas, thereby causing the gaseous impurity gas to flow along with the dense phase carbon dioxide. In other words, in this embodiment, the absorption tower 50 mainly plays the role of enhancing the contact between the two phases and promoting the formation of the mixed fluid, rather than simply being used for deep separation and purification in the traditional sense.

[0029] In some embodiments, the dense phase outlet 42 can be connected to the upper part of the absorption tower 50, and the gas phase outlet 43 can be connected to the lower part of the absorption tower 50, so that the dense phase carbon dioxide flows from top to bottom and the gas phase impurity gas flows from bottom to top, and the two form counter-current contact in the absorption tower 50 to improve the entrainment capacity of the dense phase carbon dioxide for the gas phase impurity gas.

[0030] The absorption tower 50 is equipped with a delivery outlet 54, which is connected to the external transmission pipeline 102 via a booster pump 60. That is, after the mixed fluid formed inside the absorption tower 50 is discharged through the delivery outlet 54, it is further pressurized by the booster pump 60 and then transported to the oilfield's oil displacement end via the external transmission pipeline 102. In this embodiment, the booster pump 60 can pressurize the mixed fluid according to the external transmission pressure requirements to ensure that the formed mixed fluid meets the requirements for long-distance transportation and oil displacement applications.

[0031] The carbon dioxide mixture processing equipment 100 provided in this embodiment, by setting up a multi-stage compressor assembly 20 and a lithium bromide unit 10, can process the carbon dioxide in the carbon dioxide mixture into a dense phase state suitable for transportation. By setting up a gas-liquid separator 40 and an absorption tower 50, the gaseous impurities in the mixture can be fully contacted with the dense carbon dioxide, so that the gaseous impurities can be carried out along with the dense carbon dioxide. Then, through a booster pump 60 and an external pipeline 102, the formed mixed fluid can be stably transported to the oilfield's oil displacement end, thereby meeting the actual needs for transporting carbon dioxide mixtures in oil displacement scenarios.

[0032] It should be understood that the preferred engineering application scenario for the carbon dioxide mixed gas treatment equipment 100 in this embodiment is carbon dioxide enhanced oil recovery (CEOR) projects in oil fields. The core purpose of this system is to capture carbon dioxide waste gas containing non-condensable impurities from industrial sources (such as chemical plants, power plants, etc.), purify it efficiently, remove impurities, and regulate its phase state through this system, and then safely and efficiently transport it to the target oil field for underground injection via a long-distance ground pipeline network.

[0033] In this application context, the process and structural design of this invention are constrained by the characteristics of long-distance pipeline transportation. Specifically, the long-distance transportation pipeline network connecting the plant side and the oilfield side typically spans tens to hundreds of kilometers in length. During the transportation of fluids over such long distances, significant pressure drops caused by frictional resistance and severe environmental temperature fluctuations across regions and time zones are inevitable. If conventional gas-phase transportation is used, the extremely low density results in a very small transport capacity per pipeline, leading to extremely poor economic efficiency. If low-pressure liquid-phase transportation is used, under the temperature or pressure fluctuations of long-distance pipelines, the fluid is highly susceptible to flash evaporation across the phase envelope, forming a dangerous gas-liquid two-phase flow within the pipeline. This can trigger cavitation, water hammer, and severe pipeline vibration, seriously threatening the safety of the pipeline network.

[0034] Therefore, based on the aforementioned limitations of long-distance transportation over distances of tens to hundreds of kilometers, the fluid ultimately output from the processing equipment in this embodiment is limited and controlled for transmission in a dense-phase carbon dioxide state. Dense-phase carbon dioxide (i.e., a high-pressure compressed fluid with pressure above its critical pressure) possesses both extremely high density close to that of a liquid (significantly increasing the transmission throughput of long-distance pipelines and reducing pumping power consumption) and low kinematic viscosity, and does not undergo any gas-liquid phase change when the ambient temperature fluctuates.

[0035] In thermodynamics, carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.1 °C. When the pressure is greater than 7.38 MPa and the temperature is above 31.1 °C, carbon dioxide exists in a supercritical phase; when the pressure is less than 7.38 MPa and the temperature is below 31.1 °C, it exists in a dense phase. Furthermore, during long-distance transport, the ambient temperature of underground pipelines is typically maintained between 10 °C and 20 °C. This means that regardless of how the fluid is heated at the plant, the temperature of carbon dioxide will inevitably decrease gradually with the cooling of the ground temperature during its long journey, eventually inevitably crossing the critical temperature line of 31.1 °C, falling from the supercritical phase with strong carrying capacity to the dense phase, which is sensitive to impurities. This cooling process is inevitable in long-distance transport engineering. Without special treatment, the mixed fluid entering the dense phase region will quickly reach the phase envelope boundary, precipitating a large number of free impurity bubbles, causing pipeline cavitation, water hammer effects, and serious safety accidents.

[0036] Based on this engineering necessity, this implementation method abandons the technical approach of simply relying on supercritical phase to mask impurities. This implementation method utilizes an absorption tower 50 to force impurity gas into the dense-phase fluid. This ensures that the discharged high-pressure dense-phase fluid, with its absolutely pure single-phase liquid structure, can safely and stably adapt to long-distance underground pipelines spanning hundreds of kilometers at low temperatures, eliminating the risk of flash evaporation during transportation.

[0037] In some embodiments, the multi-stage compressor 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 third inlet 41. 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.

[0038] 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 10.

[0039] Understandably, the compression units in the second to eighth compression units 28 also adopt a similar structural form to the first compression unit 21, namely, including a compressor 211 and a heat exchanger 212 located downstream of the compressor 211. In this way, the carbon dioxide mixture can undergo corresponding heat exchange after each stage of compression, thereby matching the pressure increase and heat removal in the multi-stage compression process, and thus providing conditions for the subsequent processing of the carbon dioxide mixture to a dense phase state suitable for transportation.

[0040] In some embodiments, the carbon dioxide mixture, after being compressed by the eighth compression unit 28, 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 the lithium bromide unit 10 for heat exchange, the carbon dioxide mixture, after undergoing multi-stage compression, can be further cooled upon entering the gas-liquid separator 40, causing the carbon dioxide to reach a dense phase state and separating it from gaseous impurities. Thus, the structure of eight compression units connected in series and ultimately linked 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 transport.

[0041] In a specific embodiment, the feed gas inlet pressure of the feed gas entering the multi-stage compressor assembly 20 through the feed gas inlet 101 is 5 kPa to 10 kPa. The feed gas first enters the first compression unit 21 for compression, and after compression in the first compression unit 21, the pressure of the feed gas increases to 0.218 MPa. Then, the feed gas compressed by the first compression unit 21 enters the second compression unit 22, where it continues to be compressed, increasing its pressure to 0.4 MPa. The feed gas compressed by the second compression unit 22 then enters the third compression unit 23, where it continues to be compressed, increasing its pressure to 0.76 MPa. Subsequently, the feed gas compressed by the third compression unit 23 enters the fourth compression unit 24, where it continues to be compressed, increasing its pressure to 1.31 MPa. Finally, the feed gas compressed by the fourth compression unit 24 enters the fifth compression unit 25, where it continues to be compressed, increasing its pressure to 2.24 MPa. Subsequently, the raw material gas compressed by the fifth compression unit 25 enters the sixth compression unit 26, where it continues to be compressed, increasing its pressure to 3.42 MPa. The compressed raw material gas then enters the seventh compression unit 27, where it continues to be compressed, increasing its pressure to 5.23 MPa. Following this, the compressed raw material gas enters the eighth compression unit 28, where it continues to be compressed, increasing its pressure to 7.4 MPa. Finally, the compressed raw material gas from the eighth compression unit 28 enters the gas-liquid separator 40 for further cooling and gas-liquid separation.

[0042] In this embodiment, the feed gas is compressed in stages from 5 kPa to 10 kPa, reaching a pressure of 7.4 MPa. This ensures the carbon dioxide mixture reaches a higher pressure before entering the gas-liquid separator 40, providing the necessary conditions for the subsequent cooling effect of the lithium bromide unit 10 within the separator 40, allowing the carbon dioxide to reach a dense phase. Simultaneously, the multi-stage gradual pressurization method, compared to single-stage high-pressure-ratio compression, is more advantageous in reducing the single-stage compression load, improving the stability of the compression process, and facilitating the removal of compression heat after each compression stage via heat exchanger 212 for utilization by the lithium bromide unit 10.

[0043] 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.

[0044] With the above structure, on the one hand, the heat generated by the carbon dioxide medium after each stage of compression can be promptly discharged through the heat exchanger 212, thereby reducing the gas temperature entering the next stage of compression unit, alleviating the compression load of the next stage of compression unit, and improving the stability of the multi-stage compression process. On the other hand, the heat discharged by the heat exchanger 212 can also be utilized through the first heat exchange pipe 11 of the lithium bromide unit 10 for cooling, thereby improving the overall energy utilization efficiency of the system.

[0045] Furthermore, in some embodiments, the carbon dioxide mixture processing device 100 also includes a cooler 30, and the outlet of the eighth compression unit 28 is connected to the third inlet 41 through the cooler 30. That is, the carbon dioxide medium 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.

[0046] In this embodiment, since the carbon dioxide medium has reached a relatively high pressure after being compressed by the eighth compression unit 28, but the fluid temperature is still relatively high, it may be supercritical carbon dioxide. If it directly enters the subsequent units, it will not be conducive to the carbon dioxide further forming a dense phase state suitable for transportation. By setting a cooler 30 between the eighth compression unit 28 and the gas-liquid separator 40, the high-pressure carbon dioxide medium after final compression can be further cooled, thereby making the carbon dioxide medium entering the gas-liquid separator 40 closer to or reaching the dense phase condition.

[0047] In other words, the cooler 30 does not only serve to cool the water; 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 its final delivery to the oilfield's oil displacement end via the booster pump 60.

[0048] Understandably, in conventional thermodynamics, to allow carbon dioxide to absorb and carry away as many non-condensable impurity gases as possible, it is generally preferred to maintain the fluid in a supercritical state (temperature > 31.1℃). This is because carbon dioxide molecules in the supercritical state have extremely high kinetic energy and a very strong ability to carry impurity gases, easily achieving miscibility with a large number of impurity gases within 50℃ of the absorption tower.

[0049] However, the ultimate goal of this system is to transport the treated fluid through ultra-long pipelines spanning tens to hundreds of kilometers in oil fields. If supercritical absorption is used within the absorption tower 50, once the supercritical fluid carrying excessive impurities enters the ultra-long underground pipeline network, the supercritical state will be difficult to maintain due to the continuous cooling effect of the ground temperature around the surface or deeply buried pipelines, and the fluid temperature will inevitably drop below 31.1℃. At this point, the fluid will inevitably undergo a phase transition, falling from the supercritical phase to the dense phase. Once it transforms into a dense phase, the carbon dioxide fluid's ability to dissolve and carry light impurity gases will decrease. The excessive impurity gases that were forcibly miscible in the supercritical state will instantly exceed the solubility limit of the dense phase liquid and precipitate out in large quantities from the fluid, thus forming an extremely dangerous gas-liquid two-phase flow inside the long-distance pipeline, which should have been a single-phase flow. This will directly cause gas resistance, water hammer effect, and severe vibrations along the pipeline, posing a significant safety hazard. Therefore, in order to completely eliminate the risk of impurity precipitation during ultra-long pipeline transportation from the source, this implementation adopts a control strategy of pre-cooling and dimension reduction absorption.

[0050] By installing a cooler 30 before the gas-liquid separator 40, this system mandates that carbon dioxide within the absorption tower 50 be in a dense phase state. This design essentially utilizes the solubility boundary condition under dense phase conditions as a safety threshold. Utilizing the efficient fluid mechanical structure within the absorption tower 50, impurities are stably absorbed and encapsulated under dense phase conditions. As long as the impurity gas can be stably dissolved and carried under dense phase conditions within the absorption tower 50, it will essentially not vaporize and precipitate during subsequent transport in the lower-temperature, more stable underground ultra-long dense phase pipeline.

[0051] In summary, the scheme of setting up a pre-cooler 30 to maintain dense phase absorption in this embodiment, although theoretically sacrificing some carbon dioxide carrying capacity, in engineering practice, achieves single-phase stability and operational safety of the entire long-distance pipeline network with extremely high reliability, thus breaking through the bottleneck of safe transportation of industrial waste gas to oilfields for oil recovery.

[0052] In some embodiments, the absorber 50 is also provided with a reflux port 51, which is connected to the inlet of the sixth compression unit 26. That is to say, under special circumstances, non-condensable gas may still exist in the absorber 50. In this case, the absorber 50 can also guide some of the non-condensable gas that has not reached the expected treatment state back to the inlet of the sixth compression unit 26 through the reflux port 51, so that it can re-participate in the subsequent compression process.

[0053] In this embodiment, the reflux port 51 is mainly used to treat the non-condensable gases that still remain in the system. When the absorber 50 still contains a large amount of non-condensable gases after absorption, this portion of non-condensable gases can be guided back 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 relatively close to the gas pressure discharged from the reflux port 51 at the top of the absorber 50. This setting not only reduces pressure fluctuations during the reflux process and lowers reflux resistance, but also facilitates the smooth reintegration of the refluxed non-condensable gases into the subsequent compression process, without having to return them to the earlier low-pressure compression unit.

[0054] 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.

[0055] 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.

[0056] In some embodiments, the gas-liquid separator 40 includes a tank body and a partition cylinder disposed within the tank body. The partition cylinder is disposed inside the tank body and forms an annular heat exchange region between itself and the inner wall of the tank body. The second heat exchange pipe 12 of the lithium bromide unit 10 is at least partially disposed within this annular heat exchange region and is arranged circumferentially around the gas-liquid separator 40 to exchange heat at the gas-liquid interface region within the gas-liquid separator 40.

[0057] Specifically, the tank can be a hollow container structure to hold carbon dioxide medium that has undergone multi-stage compression and cooling by the cooler 30. With the partition cylinder installed inside the tank, the internal space can be further divided into different functional areas. Since an annular heat exchange region is formed between the partition cylinder and the inner wall of the tank, the second heat exchange pipe 12 can be arranged along this annular heat exchange region. Thus, the second heat exchange pipe 12 no longer simply cools the fluid within the gas-liquid separator 40 in general, but preferentially exchanges heat around the region where the gas-liquid interface is located.

[0058] In this embodiment, the second heat exchange pipe 12 is at least partially arranged around the circumference of the gas-liquid separator 40. In other words, the second heat exchange pipe 12 can be arranged in a ring, spiral, or segmented manner around the outer periphery of the separator or near the inner wall of the tank. With this arrangement, the second heat exchange pipe 12 can form a relatively continuous heat exchange zone around the gas-liquid interface region within the gas-liquid separator 40, thereby preferentially cooling the fluid near the gas-liquid interface. Since the area near the interface is usually the region where state changes are most active when carbon dioxide forms a gas phase region and a dense phase region within the gas-liquid separator 40, directional heat exchange in this region is beneficial for enhancing the stability of the carbon dioxide transition to the dense phase state and for facilitating the smooth progress of the gas-liquid separation process.

[0059] Furthermore, the partition cylinder helps improve the flow state of the fluid inside the gas-liquid separator 40. Through the partition cylinder, the fluid flow path inside the tank can be guided, allowing the fluid entering the gas-liquid separator 40 to form a more stable flow state near the gas-liquid interface region, thereby reducing interface fluctuations caused by excessive local disturbances. Combined with the second heat exchange pipe 12 arranged circumferentially, continuous heat exchange in the gas-liquid interface region can be achieved under relatively stable conditions, avoiding the impact of local overcooling or insufficient local heat exchange on the gas-liquid separation effect.

[0060] In some embodiments, the second heat exchange pipe 12 may be arranged in a spiral shape within the annular heat exchange area, or the second heat exchange pipe 12 may include multiple arc-shaped heat exchange sections spaced apart circumferentially. Through this arrangement, the second heat exchange pipe 12 can form a larger coverage area along the gas-liquid interface region, thereby improving the overall heat exchange uniformity of the gas-liquid interface region.

[0061] In some embodiments, the dense phase outlet 42 of the gas-liquid separator 40 is connected to the first inlet 52 at the top of the absorption tower 50 via a centrifugal pump 44, and the gas phase outlet 43 of the gas-liquid separator 40 is connected to the second inlet 53 at 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.

[0062] In some embodiments, a micro-interface generator 55 is provided at the bottom of the absorption tower 50. The micro-interface generator 55 is connected to the gas phase outlet 43 and is used to disperse the gaseous impurity gas discharged from the gas-liquid separator 40 into fine bubbles when it enters the absorption tower 50. By setting the micro-interface generator 55, the gaseous impurity gas can be prevented from directly entering the absorption tower 50 in the form of a large gas cloud, thereby reducing the possibility of gas short-circuiting upward or local deflection, 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 set at the bottom of the absorption tower 50 and connected to the gas phase outlet 43 of the gas-liquid separator 40, so that the gaseous impurity gas is dispersed at the bottom of the absorption tower 50 and then moves upward.

[0063] 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 flow stabilizing and 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 flow stabilizing and collecting section 504 is connected to the booster pump 60.

[0064] The function of the liquid distribution section 501 is to introduce 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. 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.

[0065] 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 43 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.

[0066] The flow stabilization and collection section 504 is located at the bottom of the tower and is connected to the booster pump 60. After sufficient contact in the liquid 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 booster pump 60 to continuously extract the mixed fluid and deliver it to the external pipeline 102.

[0067] 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 is connected to the inner wall of the tower, and the frustum-shaped guide plate 56 is disposed facing downward.

[0068] 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.

[0069] Specifically, the frustum-shaped guide plate 56 has multiple through holes, which connect the upper and lower spaces of the frustum-shaped guide plate 56. These through holes can be spaced apart circumferentially and / or radially. By providing multiple through holes on the frustum-shaped guide plate 56, dense-phase carbon dioxide located above the frustum-shaped guide plate 56 can flow through these through holes to the lower part of the frustum-shaped guide plate 56, thereby enabling fluid communication between the upper and lower sides of the frustum-shaped guide plate 56.

[0070] Because of the small size of the through-hole, when dense-phase carbon dioxide flows through the through-hole, it does not pass directly through the frustum-shaped guide plate 56 in a large stream. Instead, it spreads more easily on the wall of the through-hole and forms an adhering flow state. In other words, as the dense-phase carbon dioxide passes through the through-hole, it can form a thin liquid layer around the periphery of the through-hole, thereby forming a liquid film on the lower side of the frustum-shaped guide plate 56. Thus, the frustum-shaped guide plate 56 can not only guide the dense-phase carbon dioxide to form a swirling liquid film through its guiding surface, but also further form a local liquid film structure in the through-hole area by relying on the flow-limiting and spreading effect of the through-hole.

[0071] Furthermore, since multiple through holes are dispersed on the frustoconical guide plate 56, dense-phase carbon dioxide can flow downwards simultaneously through multiple through holes. In this way, multiple dispersed liquid film regions can be formed on the lower side of the frustoconical guide plate 56. These multiple liquid film regions can further merge or spread along the lower surface of the frustoconical guide plate 56, thereby increasing the liquid phase coverage area near the frustoconical guide plate 56.

[0072] Furthermore, the through-holes can be circular, oblong, strip-shaped, or other pore structures capable of forming a liquid film. Preferably, the aperture of the through-holes is set to a size range that allows dense phase carbon dioxide to pass through without easily forming a large, straight flow of liquid, thus facilitating the formation of a liquid film around the periphery of the through-holes. The opening ratio of multiple through-holes can also be adjusted according to the flow rate of dense phase carbon dioxide and the required liquid film coverage area to balance vertical connectivity and liquid film formation.

[0073] By creating multiple small through holes on the frustoconical guide plate 56, the frustoconical guide plate 56 in this embodiment not only enables vertical space communication but also allows dense phase carbon dioxide to form a liquid film in the through hole region. Thus, the frustoconical guide plate 56 serves both as a guide and as a liquid film reinforcement function in the multi-stage contact section 502, thereby improving the contact sufficiency between gaseous impurity gases and dense phase carbon dioxide, and further enhancing the carrying capacity of dense phase carbon dioxide for non-condensable impurity gases.

[0074] In some embodiments, the bubble-breaking and redispersing element 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 gradually coalesce and form larger bubbles during the ascent. By providing the bubble-breaking and redispersing element 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.

[0075] In some embodiments, the liquid distribution section 501 includes a liquid distribution chamber tangentially connected to the dense phase outlet 42, with a spray element 58 disposed below the liquid distribution chamber. That is, the dense phase carbon dioxide does not enter the liquid distribution section 501 radially directly, but rather tangentially. This tangential liquid inlet allows the dense phase carbon dioxide to form a swirling flow state within the liquid distribution chamber, making it easier to form a swirling liquid film upon entering the multi-stage contact section 502, thereby further improving the liquid's spreading effect and contact efficiency within the tower.

[0076] In some embodiments, the micro-interface generator 55 includes an outlet surface with micropores. After entering the micro-interface generator 55 through the gas phase outlet 43, the gaseous impurity gas is uniformly dispersed and discharged through the micropores to form a large number of fine bubbles. Because the micropores are small, the resulting bubbles have relatively small particle sizes, which significantly increases the gas-liquid contact area per unit volume of gas, thereby facilitating the entrainment of gaseous impurity gas by dense-phase carbon dioxide.

[0077] 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.

[0078] 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 43 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 booster pump 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.

[0079] It is understood that the feed gas entering the multi-stage compressor assembly 20 is a carbon dioxide mixture that has undergone desulfurization and drying. In other words, before entering the processing equipment of this invention, the sulfides in the feed gas have been removed, and the moisture has been removed to a level 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.

[0080] 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.

[0081] In this embodiment, the function of the absorption tower 50 is not to separately discharge non-condensable gases, but to ensure sufficient contact between dense-phase carbon dioxide and 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 compressor 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.

[0082] In a comparative embodiment, the absorption tower 50 adopts a conventional tower structure, without the micro-interface generator 55, multi-stage contact units, or through-hole structures such as the frustum-shaped guide plate 56. 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 compressor assembly 20 via the reflux port 51.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] In the optimal embodiment of the present invention, the target state is that no non-condensable gas flows back to the multi-stage compressor 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, thereby eliminating the need for the system to perform cyclic backpressure treatment on the non-condensable gas, which helps to reduce the system's backflow burden and improve the overall transportation stability.

[0088] 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 device for processing a carbon dioxide mixture, characterized in that, It includes a lithium bromide generator set and a multi-stage compressor assembly, a gas-liquid separator, an absorption tower, and a booster pump connected in sequence. The multi-stage compressor assembly includes a plurality of compression units connected sequentially along the airflow direction, and at least one of the compression units includes a compressor and a heat exchanger located downstream of the compressor. The lithium bromide unit includes a first heat exchange pipe and a second heat exchange pipe. The first heat exchange pipe is connected to the heat exchanger for heat exchange, and the second heat exchange pipe is connected to the gas-liquid separator for heat exchange. The inlet of the gas-liquid separator is connected to the last compression unit in the multi-stage compressor assembly along the airflow direction, the dense phase outlet of the gas-liquid separator is connected to the top of the absorption tower, and the gas phase outlet of the gas-liquid separator is connected to the bottom of the absorption tower, so that the gas phase impurity gas enters the absorption tower and comes into contact with the dense phase carbon dioxide. The absorption tower is provided with a delivery outlet, which is connected to the booster pump for delivering the mixed medium of dense phase carbon dioxide and gaseous impurity gas to the external pipeline.

2. The carbon dioxide mixture processing equipment according to claim 1, characterized in that, The plurality of compression units include a first compression unit, a second compression unit, a third compression unit, a fourth compression unit, a fifth compression unit, a sixth compression unit, a seventh compression unit, and an eighth compression unit connected sequentially along the airflow direction. The outlet of the first compression unit is connected to the inlet of the second compression unit, the outlet of the second compression unit is connected to the inlet of the third compression unit, the outlet of the third compression unit is connected to the inlet of the fourth compression unit, the outlet of the fourth compression unit is connected to the inlet of the fifth compression unit, the outlet of the fifth compression unit is connected to the inlet of the sixth compression unit, the outlet of the sixth compression unit is connected to the inlet of the seventh compression unit, the outlet of the seventh compression unit is connected to the inlet of the eighth compression unit, and the outlet of the eighth compression unit is connected to the inlet of the gas-liquid separator.

3. The carbon dioxide mixture processing equipment according to claim 2, characterized in that, The heat exchanger is provided between two adjacent compression units.

4. The carbon dioxide mixture processing equipment according to claim 3, characterized in that, The carbon dioxide mixture processing equipment also includes a cooler, and the outlet of the eighth compression unit is connected to the inlet of the gas-liquid separator through the cooler.

5. The carbon dioxide mixture processing equipment according to claim 3, characterized in that, The absorption tower is also provided with a reflux gas port, which is connected to the inlet of the sixth compression unit.

6. The apparatus for processing carbon dioxide mixtures according to any one of claims 1 to 5, characterized in that, The gas-liquid separator includes a tank body and a partition cylinder disposed within the tank body. An annular heat exchange region is formed between the partition cylinder and the inner wall of the tank body. The second heat exchange pipe is at least partially disposed within the annular heat exchange region and is arranged around the circumference of the gas-liquid separator to exchange heat with the gas-liquid interface region within the gas-liquid separator.

7. The carbon dioxide mixture processing equipment according to claim 1, characterized in that, The bottom of the absorption tower is equipped with a micro-interface generator, which is connected to the gas phase outlet.

8. The carbon dioxide mixture processing equipment according to claim 7, characterized in that, The absorption tower includes a tower body, a liquid distribution section located at the upper part of the tower body, a multi-stage contact section located in the middle part of the tower body, a microbubble generating section located at the lower part of the tower body, and a steady flow collecting section located at the bottom of the tower body. The liquid distribution section is connected to the dense phase outlet, the micro-interface generator is located in the microbubble generating section, and the steady flow collecting section is connected to the booster pump.

9. The carbon dioxide mixture processing equipment according to claim 8, characterized in that, The multi-stage contact section includes at least two layers of contact units spaced apart along the height direction of the tower body. Each layer of the contact unit includes a frustum-shaped guide plate and a defoaming and redispersing element disposed below the frustum-shaped guide plate. The outer peripheral edge of the frustum-shaped guide plate is connected to the inner wall of the tower body. The frustum-shaped guide plate is used to guide the dense phase carbon dioxide to form a swirling liquid film. The defoaming and redispersing element is used to defoam and redisperse the rising bubbles. The liquid distribution section includes a liquid distribution chamber tangentially connected to the dense phase outlet. The micro-interface generator includes an outlet surface with micropores. Along the height direction, the projection of the outlet surface coincides with the projection of the guide plate.

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