A multi-stage spraying and energy cascade utilization natural gas decarbonization system and process

Abstract

This application relates to a multi-stage spraying and energy cascade utilization natural gas decarbonization system and process, belonging to the field of natural gas decarbonization technology. It includes a spray tower, a stripping tower, and a regeneration tower. The upper-stage spraying is used to spray lean amine solution, the intermediate-stage spraying is used to spray semi-lean amine solution, and the lower-stage spraying is used to spray rich amine solution. The lean amine solution enters the spray tower after passing through the first-stage spraying stage to wash the natural gas. It also includes upper-stage spraying pipelines, intermediate-stage spraying pipelines, and lower-stage spraying pipelines, which are used to transport the corresponding amine solutions into the spray tower. This application facilitates the decarbonization of natural gas.

Description

Technical Field

[0001] This application relates to the field of natural gas decarbonization technology, and in particular to a natural gas decarbonization system and process with multi-stage spraying and energy cascade utilization. Background Technology

[0002] Natural gas, as a clean energy source, is widely used in industry, power generation, and residential applications. However, natural gas typically contains a certain amount of carbon dioxide. The presence of carbon dioxide not only reduces the calorific value of natural gas but also causes pipeline corrosion during transportation and, at low temperatures, forms hydrates with water, clogging equipment. Therefore, natural gas usually needs to undergo decarbonization treatment before entering pipeline networks or liquefying to meet commercial quality standards.

[0003] like Figure 1 As shown, the decarbonization process flow is as follows:

[0004] (1) Absorption stage: After the raw gas 1 is throttled and depressurized and heated by the water jacket furnace, it enters the spray tower 2 from the bottom and comes into countercurrent contact with the lean amine liquid from top to bottom to remove carbon dioxide. The decarbonized raw gas is discharged through the decarbonized gas outlet 35.

[0005] (2) Flash evaporation stage: The rich amine liquid discharged from the bottom of the tower is throttled and depressurized before entering the flash tank 3 to release the co-dissolved light hydrocarbons (flash vapor to fuel gas system 4).

[0006] (3) Regeneration process: After flash evaporation, the rich amine liquid flows through the lean and rich liquid heat exchanger 5 to recover heat, and then enters the regeneration tower 6 for thermal regeneration to desorb carbon dioxide.

[0007] (4) Circulation process: The lean amine liquid collected from the bottom of the regeneration tower 6 is cooled by the lean and rich liquid heat exchanger 5 and pressurized by the lean liquid pump 7 before returning to the spray tower 2 to complete the circulation.

[0008] (5) The carbon dioxide released from the top of the regeneration tower 6 is discharged from the acid gas outlet 10 after passing through the acid gas air cooler 8 and the acid gas separator 9.

[0009] However, existing decarbonization processes have the following drawbacks:

[0010] (1) Large equipment size: Traditional packed towers rely on packing to provide mass transfer area, resulting in large tower diameter and bulky equipment; (2) Complex operation and maintenance: Packing is prone to blockage and damage, resulting in high replacement and maintenance costs and significant losses due to downtime; (3) High energy consumption: Regeneration system energy consumption accounts for 60-70% of the total process energy consumption, and the energy-saving potential has not been fully explored; (4) Poor operational stability: Natural gas hydrates are easily formed at the bottom of the tower, posing a high risk of operation in winter; (5) Insufficient adaptability: Poor adaptability to raw gas composition and load fluctuations, resulting in a narrow operating window. Summary of the Invention

[0011] To facilitate the decarbonization of natural gas, this application provides a natural gas decarbonization system and process with multi-stage spraying and energy cascade utilization.

[0012] Firstly, this application provides a multi-stage spraying and energy cascade utilization natural gas decarbonization system, which adopts the following technical solution:

[0013] A multi-stage spraying and energy cascade utilization natural gas decarbonization system includes a spray tower, a stripping tower, and a regeneration tower. The spray tower has multiple spraying stages, arranged from top to bottom as upper, intermediate, and lower spraying stages. The upper spraying stage is used to spray lean amine solution, the intermediate spraying stage is used to spray semi-lean amine solution, and the lower spraying stage is used to spray rich amine solution. Natural gas enters through the bottom of the spray tower and is washed by the multi-stage spraying to remove carbon dioxide. The carbon dioxide-absorbing rich amine solution is located at the bottom of the spray tower. The lower spraying stage is used to extract the rich amine solution from the bottom of the spray tower. Amine solution enters the spray tower to wash the natural gas. The amine-rich solution at the bottom of the spray tower enters the stripping tower, where it is converted into a semi-lean amine solution. Part of the semi-lean amine solution passes through the intermediate spray and enters the spray tower to wash the natural gas, while the remaining semi-lean amine solution enters the regeneration tower to be regenerated into a lean amine solution. The lean amine solution passes through the primary spray and enters the spray tower to wash the natural gas. The system also includes an upper spray pipeline, an intermediate spray pipeline, and a lower spray pipeline, which are used to transport the corresponding amine solution into the spray tower.

[0014] Optionally, the lower-level spray pipeline includes a first pipeline, an amine-rich liquid pump, and a second pipeline. The first pipeline is connected to the bottom of the spray tower, and the second pipeline is connected to the middle of the spray tower. The amine-rich liquid pump is located between the first pipeline and the second pipeline and is connected to both the first pipeline and the second pipeline.

[0015] Optionally, the intermediate spray pipeline includes a third pipeline, a lean-rich liquid heat exchanger, a stripping tower, a semi-lean liquid pump, and a fourth pipeline. The third pipeline is connected to the first pipeline. The third pipeline is used to transport the rich amine liquid to the lean-rich liquid heat exchanger and then into the stripping tower. The semi-lean amine liquid is transported by the semi-lean liquid pump through the fourth pipeline into the spray tower.

[0016] Optionally, the upper-level spray pipeline includes a fifth pipeline, a sixth pipeline, and a seventh pipeline. One end of the fifth pipeline is connected to the stripping tower, and the other end is connected to the regeneration tower. One end of the sixth pipeline is connected to the bottom of the regeneration tower, and the other end is connected to the lean and rich liquid heat exchanger. One end of the seventh pipeline is connected to the lean and rich liquid heat exchanger, and the other end is connected to the upper part of the spray tower.

[0017] Optionally, the upper-level spray pipeline, the intermediate-level spray pipeline, and the lower-level spray pipeline all include liquid outlet pipes. Each liquid outlet pipe includes a central pipe, a side pipe, an annular pipe, and an atomizing nozzle. Multiple side pipes are provided and evenly arranged around the circumference of the central pipe. The annular pipe is located outside the side pipes and is fixedly installed at its end. The central pipe, side pipes, and annular pipes are interconnected. Multiple liquid outlet holes are provided on the side pipes and annular pipes. The atomizing nozzles are fixedly installed on the side pipes and annular pipes through the liquid outlet holes. The amine liquid transported into the spray tower through the upper-level spray pipeline, the intermediate-level spray pipeline, and the lower-level spray pipeline is sprayed out through the central pipe, the side pipes, and the atomizing nozzles to perform decarbonization of the natural gas.

[0018] Optionally, the spray tower is fixedly provided with a mounting frame, the central tube is rotatably mounted on the mounting frame, the rotation axis of the central tube is parallel to the axial direction of the spray tower, and it also includes a driving component for driving the central tube to rotate.

[0019] Optionally, a transfer box is fixedly installed on the inner wall of the spray tower. The transfer box is annular and has an annular notch at the top. The amine solution, which is transported into the spray tower through the upper, middle and lower spray pipes, enters the transfer box through the side wall of the transfer box. A connecting pipe is installed on the side wall of the central pipe. The connecting pipe is connected to the central pipe and its other end enters the transfer box through the annular notch. A delivery pump is installed on the connecting pipe. The delivery pump is used to draw the amine solution in the transfer box into the central pipe.

[0020] Optionally, the driving component includes a drive motor mounted on the mounting bracket, a first gear sleeved on the central tube, and a second gear mounted on the output shaft of the drive motor. The first gear and the second gear mesh with each other. A synchronizing rod is provided between the central tubes of adjacent liquid outlet pipes. The synchronizing rod is used to connect the central tubes so that the liquid outlet pipes rotate synchronously. The lateral pipes of the liquid outlet pipes of adjacent layers are staggered.

[0021] Optionally, a liquid cloth is provided inside the spray tower. The liquid cloth is circular and fixed to the inner wall of the spray tower on its side. The liquid cloth is located below the amine liquid, and the sprayed amine liquid wets the liquid cloth. Decarbonization is carried out during the natural gas's ascent and as it breaks through the liquid cloth.

[0022] Secondly, this application provides a natural gas decarbonization process involving multi-stage spraying and energy cascade utilization, employing the following technical solution:

[0023] A natural gas decarbonization process involving multi-stage spraying and energy cascade utilization, using a natural gas decarbonization system, also includes;

[0024] S1: The upper spray uses deeply regenerated lean liquor. The temperature of the lean liquor is precisely controlled at 40±5℃ through a lean-rich liquor heat exchanger. By utilizing the high affinity of amine liquid for carbon dioxide under low temperature conditions, the natural gas is deeply processed to ensure that the carbon dioxide content of the product gas meets the requirements. Through efficient atomization spraying, 50-150μm micro-droplets are formed, providing a huge gas-liquid contact area.

[0025] S2: The intermediate spray uses semi-lean liquor from the stripping tower to handle 60-70% of the carbon dioxide removal task; although the absorption capacity of semi-lean liquor is lower than that of lean liquor, its temperature is higher, which forms a better temperature match with the feed gas and optimizes the mass transfer rate.

[0026] S3: The lower stage spray uses a portion of the rich liquid for circulating spraying, and the temperature is maintained at 60±5℃. On the one hand, the remaining absorption capacity of the rich liquid is used to pre-absorb the raw gas, reducing the load in the upper area; on the other hand, the high-temperature rich liquid circulation maintains the bottom temperature of the tower within a safe range of 60-70℃, effectively preventing the formation of natural gas hydrate under high pressure.

[0027] S4: The main rich liquid stream (80-90%) exiting the bottom of the spray tower is first depressurized, with the pressure dropping from 6.0 MPa to 0.4-0.6 MPa. The depressurized rich liquid then enters the lean-rich liquid heat exchanger, where it exchanges heat with the high-temperature lean liquid from the regeneration tower, raising the temperature from approximately 60°C to 85-90°C, providing the necessary thermal energy for the stripping process. The stripping tower operates under relatively mild conditions, with the pressure controlled at 0.4-0.6 MPa and the temperature maintained in the range of 90-100°C. This is low enough to promote carbon dioxide desorption while being high enough to reduce the foaming tendency of the solution and the risk of amine degradation. Inside the stripping tower, the carbon dioxide in the rich liquid is released through the combined action of thermal flash evaporation and a small amount of stripping gas, achieving preliminary regeneration.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] The multi-stage spray absorption system employs an innovative six-stage spray structure in the absorption phase, decomposing the traditional single absorption process into three functionally distinct and synergistic zones. Raw natural gas enters from the bottom of the spray tower, operating at a pressure of 5-8 MPa and maintaining a temperature within the optimized range of 40-70℃. The upper-stage spray uses deeply regenerated lean liquor. The lean liquor temperature is precisely controlled at 40±5℃ via a lean-rich liquor heat exchanger, utilizing the high affinity of amine liquid for carbon dioxide under low-temperature conditions to achieve deep treatment of the purified gas, ensuring that the product gas meets carbon dioxide content standards. This zone plays a "refining" role, forming 50-150μm microdroplets through efficient atomization spraying, providing a large gas-liquid contact area. The intermediate-stage spray uses semi-lean liquor from the stripping tower; this zone bears the main decarbonization load of the system, handling 60-70% of the carbon dioxide removal. Although the absorption capacity of the semi-lean liquor is lower than that of the lean liquor, its higher temperature creates a better temperature match with the raw gas, optimizing the mass transfer rate. By rationally designing the spray density and liquid-to-gas ratio, most of the carbon dioxide removal is ensured in this area. The lower-stage spray uses a portion of the rich liquid for circulating spraying, maintaining the temperature at 60±5℃. This innovative design has a dual function: firstly, it utilizes the remaining absorption capacity of the rich liquid to pre-absorb the feed gas, reducing the load on the upper region; secondly, through the circulation of the higher-temperature rich liquid, it maintains the bottom temperature within a safe range of 60-70℃, effectively preventing the formation of natural gas hydrates under high-pressure conditions.

[0030] Micron-sized droplets are generated through atomization spraying technology, increasing the specific surface area by 50-80% compared to traditional packed towers. Innovative functional zoning design effectively optimizes the mass transfer driving force, ensuring an effective mass transfer area utilization rate exceeding 90%. Simultaneously, the empty tower gas velocity is increased to 2.5 m / s, significantly improving the unit volume processing capacity by 60%, greatly enhancing equipment compactness and processing efficiency.

[0031] In terms of energy consumption, regenerative energy consumption is reduced by 40-50% compared with traditional processes, effectively reducing energy waste, improving system efficiency, and realizing the efficient utilization of energy in a tiered manner.

[0032] The equipment achieves optimized lifecycle costs, and its modular design effectively reduces manufacturing and installation costs by 20%. Due to its fillerless structure, annual maintenance costs are reduced by 40%, and downtime losses caused by filler replacement are avoided, significantly improving economic efficiency from a long-term operational perspective.

[0033] The system's reliability has been comprehensively improved. Its fillerless structure provides excellent anti-clogging performance, enabling it to handle natural gas containing complex components such as dust and gum. Within a wide load range of 50-130%, the system maintains stable decarbonization efficiency, demonstrating exceptional operational flexibility. The online cleaning function allows for convenient maintenance without disrupting normal production, ensuring long-term stable system operation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the existing technology structure;

[0035] Figure 2 This is a schematic diagram of a natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to an embodiment of this application;

[0036] Figure 3 This is a schematic diagram of the structure of a spray tower in a natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to an embodiment of this application;

[0037] Figure 4 This is a schematic diagram of the liquid outlet pipeline in a natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of the side pipe structure in a natural gas decarbonization system with multi-stage spraying and energy cascade utilization, according to an embodiment of this application.

[0039] Explanation of reference numerals in the attached diagram: 1. Raw material gas; 2. Spray tower; 3. Flash tank; 4. Flash vapor to fuel gas system; 5. Lean and rich liquid heat exchanger; 6. Regeneration tower; 7. Lean liquid pump; 8. Acid gas air cooler; 9. Acid gas separator; 10. Acid gas outlet; 11. Stripping tower; 12. Upper spray; 13. Intermediate spray; 14. Lower spray;

[0040] 15. Upper-level sprinkler pipeline; 151. Fifth pipeline; 152. Sixth pipeline; 153. Seventh pipeline;

[0041] 16. Intermediate sprinkler piping; 161. Third piping; 162. Fourth piping;

[0042] 17. Sub-spray pipeline; 171. First pipeline; 172. Ammonia-rich liquid pump; 173. Second pipeline;

[0043] 18. Stripper gas cooler; 19. Stripper gas separator; 20. Fuel gas system; 21. Heat transfer oil inlet; 22. Reboiler; 23. Heat transfer oil outlet;

[0044] 24. Liquid outlet pipe; 241. Central pipe; 242. Side pipe; 243. Ring pipe; 244. Atomizing nozzle;

[0045] 25. Liquid outlet; 26. Mounting bracket; 27. Drive motor; 28. First gear; 29. ​​Second gear; 30. Synchronizing rod; 31. Transfer box; 32. Annular notch; 33. Connecting pipe; 34. Liquid cloth; 35. Decarbonization gas outlet; 36. Lean liquid cooler. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 2-5 This application will be described in further detail.

[0047] This application discloses a natural gas decarbonization system with multi-stage spraying and energy cascade utilization. (Refer to...) Figure 2 The multi-stage spraying and energy cascade utilization natural gas decarbonization system includes spray tower 2, stripping tower 11 and regeneration tower 6;

[0048] Reference Figure 2 The spray tower 2 is equipped with multiple spray stages, which are divided into upper spray 12, middle spray 13 and lower spray 14 from top to bottom. Upper spray 12 is used to spray lean amine solution, middle spray 13 is used to spray semi-lean amine solution, and lower spray 14 is used to spray rich amine solution.

[0049] Natural gas enters through the bottom of spray tower 2 and is washed by multiple spray stages to remove carbon dioxide. The carbon dioxide-rich amine solution is located at the bottom of spray tower 2. The lower spray 14 is used to extract the rich amine solution from the bottom of spray tower 2 and enter spray tower 2 to wash the natural gas. The rich amine solution at the bottom of spray tower 2 enters stripping tower 11. After passing through stripping tower 11, the rich amine solution is converted into semi-lean amine solution. Part of the semi-lean amine solution enters spray tower 2 through intermediate spray 13 to wash the natural gas. The remaining semi-lean amine solution enters regeneration tower 6 to be regenerated into lean amine solution. The lean amine solution enters spray tower 2 through primary spray stage to wash the natural gas.

[0050] Reference Figure 2 It also includes an upper spray pipe 15, an intermediate spray pipe 16 and a lower spray pipe 17, which are used to transport the corresponding amine liquid into the spray tower 2.

[0051] The raw material natural gas enters from the bottom of spray tower 2, operating at a pressure of 5-8 MPa and maintained at an optimized temperature range of 40-70℃. Upper spray 12 uses deeply regenerated lean liquor, with the lean liquor temperature precisely controlled at 40±5℃ via a lean-rich liquor heat exchanger 5. Utilizing the high affinity of amine liquid for carbon dioxide under low-temperature conditions, deep treatment of the purified gas is achieved, ensuring the product gas meets carbon dioxide content standards. This area plays a crucial role in refining, forming 50-150μm micro-droplets through efficient atomization spraying, providing a large gas-liquid contact area. Intermediate spray 13 uses semi-lean liquor from stripping tower 11. This area bears the main decarbonization load of the system, handling approximately 60-70% of the carbon dioxide removal. Although the absorption capacity of the semi-lean liquor is lower than that of the lean liquor, its higher temperature creates a better temperature match with the raw material gas 1, optimizing the mass transfer rate. Through a rationally designed spray density and liquid-to-gas ratio, most of the carbon dioxide removal is ensured in this area. The lower-level spray 14 uses a portion of the rich liquid for circulating spraying, maintaining the temperature at 60±5℃. This innovative design has a dual function: on the one hand, it utilizes the remaining absorption capacity of the rich liquid to pre-absorb the feed gas 1, reducing the load on the upper region; on the other hand, it maintains the bottom temperature of the tower within a safe range of 60-70℃ through the circulation of the rich liquid at a higher temperature, effectively preventing the formation of natural gas hydrates under high pressure conditions.

[0052] Reference Figure 2 In this embodiment, the lower-level spray pipeline 17 includes a first pipeline 171, a rich amine liquid pump 172, and a second pipeline 173. The first pipeline 171 is connected to the bottom of the spray tower 2, and the second pipeline 173 is connected to the middle of the spray tower 2. The rich amine liquid pump 172 is located between the first pipeline 171 and the second pipeline 173 and is connected to both the first pipeline 171 and the second pipeline 173. After the lean amine liquid absorbs carbon dioxide from the natural gas, it is converted into rich amine liquid and located at the bottom of the spray tower 2. At this time, the rich amine liquid pump 172 is started, and the rich amine liquid pump 172 draws the rich amine liquid through the first pipeline 171 and the second pipeline 173 back into the spray tower 2 to flush and wash the natural gas that subsequently enters the spray tower 2.

[0053] Reference Figure 2 In this embodiment, the intermediate spray pipeline 16 includes a third pipeline 161, a lean-rich liquid heat exchanger 5, a stripping tower 11, a semi-lean liquid pump 7, and a fourth pipeline 162. The third pipeline 161 is connected to the first pipeline 171. The third pipeline 161 is used to transport the rich amine liquid to the lean-rich liquid heat exchanger 5 and then into the stripping tower 11. The semi-lean amine liquid is transported by the semi-lean liquid pump 7 through the fourth pipeline 162 into the spray tower 2. The semi-lean liquid pump 7 is started, and the semi-lean liquid pump 7 draws the rich amine liquid in the third pipeline 161 and returns it to the spray tower 2 through the lean-rich liquid heat exchanger 5, the stripping tower 11, and the fourth pipeline 162 to flush and wash the natural gas that enters the spray tower 2 afterward.

[0054] Reference Figure 2 In this embodiment, the upper-level spray pipeline 15 includes a fifth pipeline 151, a sixth pipeline 152, and a seventh pipeline 153. One end of the fifth pipeline 151 is connected to the stripping tower 11, and the other end is connected to the regeneration tower 6. One end of the sixth pipeline 152 is connected to the bottom of the regeneration tower 6, and the other end is connected to the lean-rich liquid heat exchanger 5. One end of the seventh pipeline 153 is connected to the lean-rich liquid heat exchanger 5, and the other end is connected to the upper part of the spray tower 2. The semi-lean liquid exiting the stripping tower 11 enters the regeneration tower 6 through the fifth pipeline 151. After being processed by the regeneration tower 6, the semi-lean amine liquid is converted into a rich amine liquid. Then, it returns to the spray tower 2 through the lean-rich liquid heat exchanger 5, the seventh pipeline 153, and the lean liquid cooler 36, thereby flushing and washing the natural gas entering the spray tower 2.

[0055] Reference Figure 2 The main amine-rich liquid stream (80-90%) exiting from the bottom of spray tower 2 is first depressurized, with the pressure dropping from 6.0 MPa to 0.4-0.6 MPa. The depressurized rich liquid then enters the lean-rich liquid heat exchanger 5, where it exchanges heat with the high-temperature lean liquid from regeneration tower 6, raising the temperature from approximately 60°C to 85-90°C, providing the necessary thermal energy for the stripping process. Stripping tower 11 operates under relatively mild conditions, with the pressure controlled at 0.4-0.6 MPa and the temperature maintained in the range of 90-100°C. This temperature is low enough to promote carbon dioxide desorption while being high enough to reduce the foaming tendency of the solution and the risk of amine degradation. Inside stripping tower 11, carbon dioxide in the rich liquid is released through thermal flash evaporation and the combined action of a small amount of stripping gas, achieving preliminary regeneration.

[0056] Reference Figure 2 The stripping tower 11 employs structured packing or tray internals to ensure good gas-liquid distribution and mass transfer efficiency. The gas phase generated in the stripping tower 11 is condensed and cooled by the stripping gas cooler 18 and stripping gas separator 19 before entering the fuel gas system. The lean liquid obtained at the bottom of the stripping tower 11 is split at a ratio of 40-60%: one part is pressurized to 5.0-7.0 MPa by the semi-lean liquid pump 7 and directly returned to the middle of the spray tower 2 for spraying; the other part enters the regeneration tower 6 for deep regeneration. This split design is one of the key innovations of this invention, allowing some amine liquid to avoid the energy-intensive deep regeneration process, significantly reducing the total regeneration energy consumption of the system. Simultaneously, the semi-lean liquid directly returned to the middle of the spray tower 2 forms a reasonable temperature gradient with the temperature in the middle of the spray tower 2 (~60°C), allowing the ideal absorption temperature to be achieved through appropriate cooling control. Furthermore, the flue gas generated in the stripping tower is discharged through the fuel gas system 20 after passing through the stripping gas cooler 18 and stripping gas separator 19.

[0057] Reference Figure 2Furthermore, the semi-lean liquor entering regeneration tower 6 undergoes deep regeneration within the tower. Regeneration tower 6 typically uses a reboiler 22 to provide heat energy, which can be low-pressure steam, thermal oil, or other process waste heat. In this application, the heat source is thermal oil, which is heated through the thermal oil inlet 21, reboiler 22, and thermal oil outlet 23. Under relatively high temperature and low pressure, the chemical bond between the amine liquor and carbon dioxide is broken, and the carbon dioxide is desorbed, achieving the requirements for deep regeneration. The design of regeneration tower 6 fully considers the thermal stability and degradation characteristics of the amine liquor. The regeneration gas generated at the top of regeneration tower 6 is also condensed by an acid gas air cooler 8 and an acid gas separator 9. After moisture recovery, the high-purity carbon dioxide can be collected and utilized or emitted. Energy integration and optimization: The high-temperature lean liquid at the bottom of regeneration tower 6 first enters the lean-rich liquid heat exchanger 5, where it exchanges heat with the rich liquid entering stripping tower 11, recovering a large amount of heat energy. After being cooled to about 40°C, the lean liquid is pressurized to 5.0-7.0 MPa by lean liquid pump 7 and transported to the upper part of the absorption tower for spraying, completing the entire solvent cycle.

[0058] Reference Figure 3 , Figure 4 and Figure 5 In this embodiment, the upper-level spray pipe 15, the intermediate-level spray pipe 16, and the lower-level spray pipe 17 all include a liquid outlet pipe 24. The liquid outlet pipe 24 includes a central pipe 241, side pipes 242, an annular pipe 243, and atomizing nozzles 244. Multiple side pipes 242 are evenly arranged circumferentially along the central pipe 241. The annular pipe 243 is located outside the side pipes 242 and fixedly installed at its end. The central pipe 241, side pipes 242, and annular pipe 243 are... Pipe 242 and annular pipe 243 are interconnected. Multiple liquid outlet holes 25 are provided on the side pipe 242 and annular pipe 243. Atomizing nozzles 244 are fixedly installed on the side pipe 242 and annular pipe 243 through the liquid outlet holes 25. The amine liquid, which is transported into the spray tower 2 through the upper spray pipeline 15, the middle spray pipeline 16 and the lower spray pipeline 17, is sprayed out through the central pipe 241, the side pipe 242 and the atomizing nozzles 244 to perform decarbonization of natural gas.

[0059] The amine solution entering the spray tower 2 is transformed from liquid to atomized amine solution through the central pipe 241, side pipe 242, annular pipe 243, and atomizing nozzle 244. This increases the contact area with natural gas, thereby improving the treatment effect on natural gas. Furthermore, the side pipe 242 and annular pipe 243 increase the distribution range of the atomized amine solution, further enhancing the contact effect between the amine solution and natural gas, thus improving the decarbonization effect and efficiency of natural gas. Moreover, the atomizing nozzle 244 atomizes and sprays the solution into 50-150μm microdroplets, providing a large gas-liquid contact area.

[0060] Reference Figure 3 , Figure 4 and Figure 5 To further improve the treatment effect of atomized amine liquid on natural gas, a mounting frame 26 is fixedly installed inside the spray tower 2. The central pipe 241 is rotatably mounted on the mounting frame 26, and the rotation axis of the central pipe 241 is parallel to the axis of the spray tower 2. A driving component for driving the central pipe 241 to rotate is also included. The driving component includes a drive motor 27 mounted on the mounting frame 26, a first gear 28 sleeved on the central pipe 241, and a second gear 29 mounted on the output shaft of the drive motor 27. The first gear 28 and the second gear 29 mesh with each other. The central pipe 241 of the adjacent liquid outlet pipe 24... A synchronizing rod 30 is installed between the layers. The synchronizing rod 30 is used to connect the central pipe 241 so that the liquid outlet pipe 24 rotates synchronously. The side pipes 242 of the liquid outlet pipe 24 of adjacent layers are staggered. After the amine liquid enters the spray tower 2, the drive motor 27 is started. The drive motor 27 drives the second gear 29 to rotate. The rotation of the second gear 29 drives the first gear 28 to rotate. The rotation of the first gear 28 drives the central pipe 241 to rotate. The rotation of the central pipe 241 drives the side pipes 242 and the annular pipe 243 to rotate, thereby increasing the distribution range of the atomized amine liquid and further improving the combination effect of the amine liquid and natural gas.

[0061] Reference Figure 3 , Figure 4 and Figure 5 In this embodiment, a transfer box 31 is fixedly installed on the inner wall of the spray tower 2. The transfer box 31 is annular, and an annular notch 32 is opened at the top of the transfer box 31. The amine liquid that is transported into the spray tower 2 through the upper spray pipe 15, the intermediate spray pipe 16 and the lower spray pipe 17 enters the transfer box 31 through the side wall of the transfer box 31. A connecting pipe 33 is provided on the side wall of the central pipe 241. The connecting pipe 33 is connected to the central pipe 241 and its other end enters the transfer box 31 through the annular notch 32. A delivery pump is provided on the connecting pipe 33. The delivery pump is used to draw the amine liquid in the transfer box 31 into the central pipe 241. The amine liquid transported from the outside to the spray pipe enters the transfer box 31. Then the delivery pump is started. The delivery pump draws the amine liquid in the transfer box 31 and transports it from the central pipe 241 to the side pipe 242 and the annular pipe 243, so that the liquid outlet pipe 24 is rotating and the amine liquid is atomized and sprayed.

[0062] Reference Figure 3 and Figure 4In this embodiment, a liquid cloth 34 is installed inside the spray tower 2. The liquid cloth 34 is made of hemp fabric, synthetic fiber fabric, etc. The liquid cloth 34 is circular and fixed to the inner wall of the spray tower 2. The liquid cloth 34 is located below the amine liquid, and the sprayed amine liquid wets the liquid cloth 34. Decarbonization is carried out during the natural gas's ascent and as it breaks through the liquid cloth 34. The atomized amine liquid is dispersed in the spray tower 2, and some of the amine liquid wets the liquid cloth 34 and adheres to it. When the natural gas breaks through the liquid cloth 34, the amine liquid combines with the natural gas for treatment, thereby improving the decarbonization efficiency and effect of the natural gas. Furthermore, under the action of adjacent layers of liquid cloth 34, the liquid outlet pipe 24 is located between the liquid cloth 34, so that the atomized amine liquid fills between the liquid cloth 34, thereby limiting the range of the atomized amine liquid and facilitating the combination of natural gas and amine liquid.

[0063] The implementation principle of a natural gas decarbonization system with multi-stage spraying and energy cascade utilization in this application embodiment is as follows:

[0064] The multi-stage spray absorption system employs an innovative six-stage spray structure in the absorption stage, decomposing the traditional single absorption process into three functionally distinct and synergistic zones. Raw natural gas enters from the bottom of spray tower 2, operating at a pressure of 5-8 MPa and maintaining a temperature within the optimized range of 40-70℃. The upper-stage spray 12 uses deeply regenerated lean liquor. The lean liquor temperature is precisely controlled at 40±5℃ via the lean-rich liquor heat exchanger 5, utilizing the high affinity of amine liquid for carbon dioxide under low-temperature conditions to achieve deep treatment of the purified gas, ensuring that the carbon dioxide content of the product gas meets the requirements. This zone plays a "refining" role, forming 50-150μm micro-droplets through efficient atomization spraying, providing a large gas-liquid contact area. The intermediate-stage spray 13 uses semi-lean liquor from stripping tower 11. This zone bears the main decarbonization load of the system, handling 60-70% of the carbon dioxide removal. Although the absorption capacity of the semi-lean liquor is lower than that of the lean liquor, its higher temperature creates a better temperature match with the raw gas 1, optimizing the mass transfer rate. By rationally designing the spray density and liquid-to-gas ratio, most of the carbon dioxide removal is ensured in this area. The lower-stage spray 14 uses a portion of the rich liquid for circulating spraying, maintaining the temperature at 60±5℃. This innovative design has a dual function: firstly, it utilizes the remaining absorption capacity of the rich liquid to pre-absorb the feed gas 1, reducing the load on the upper region; secondly, through the circulation of the higher-temperature rich liquid, it maintains the bottom temperature within a safe range of 60-70℃, effectively preventing the formation of natural gas hydrates under high-pressure conditions.

[0065] This application discloses a natural gas decarbonization process using multi-stage spraying and energy cascade utilization, employing a natural gas decarbonization system, and further comprising:

[0066] S1: The upper spray 12 uses deeply regenerated lean liquor. The temperature of the lean liquor is precisely controlled at 40±5℃ by the lean-rich liquor heat exchanger 5. By utilizing the high affinity of amine liquid for CO2 under low temperature conditions, the natural gas is deeply processed to ensure that the CO2 content of the product gas meets the requirements. Through efficient atomization spraying, 50-150μm micro-droplets are formed, providing a huge gas-liquid contact area.

[0067] S2: The intermediate spray 13 uses semi-lean liquor from stripper 11 to handle 60-70% of the CO2 removal task; although the absorption capacity of semi-lean liquor is lower than that of lean liquor, its temperature is higher, which forms a better temperature match with the raw material gas 1, and the mass transfer rate is optimized.

[0068] S3: The lower spray 14 uses a portion of the rich liquid for circulating spraying, and the temperature is maintained at 60±5℃. On the one hand, the remaining absorption capacity of the rich liquid is used to pre-absorb the raw gas 1, reducing the load in the upper area. On the other hand, the high-temperature rich liquid circulation maintains the bottom temperature of the tower within a safe range of 60-70℃, effectively preventing the formation of natural gas hydrate under high pressure.

[0069] S4: The main rich liquid stream (80-90%) exiting from the bottom of spray tower 2 is first depressurized, with the pressure dropping from 6.0 MPa to 0.4-0.6 MPa. The depressurized rich liquid then enters the lean-rich liquid heat exchanger 5, where it exchanges heat with the high-temperature lean liquid from regeneration tower 6, raising the temperature from approximately 60°C to 85-90°C, providing the necessary thermal energy for the stripping process. Stripping tower 11 operates under relatively mild conditions, with the pressure controlled at 0.4-0.6 MPa and the temperature maintained in the range of 90-100°C. This is low enough to promote CO2 desorption while being high enough to reduce the foaming tendency of the solution and the risk of amine degradation. Inside stripping tower 11, CO2 in the rich liquid is released through the combined action of thermal flash evaporation and a small amount of stripping gas, achieving preliminary regeneration.

[0070] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A natural gas decarbonization system with multi-stage spraying and energy cascade utilization, characterized in that: The system includes a spray tower (2), a stripping tower (11), and a regeneration tower (6). The spray tower (2) is equipped with multiple spray stages, which are arranged from top to bottom as an upper spray (12), a middle spray (13), and a lower spray (14). The upper spray (12) is used to spray lean amine solution, the middle spray (13) is used to spray semi-lean amine solution, and the lower spray (14) is used to spray rich amine solution. Natural gas enters through the bottom of the spray tower (2) and is washed by multiple spray stages to remove carbon dioxide. The rich amine solution that absorbs carbon dioxide is located at the bottom of the spray tower (2). The lower spray (14) is used to extract the rich amine solution from the bottom of the spray tower (2) and bring it into the spray tower (2) to clean the natural gas. Washing: The rich amine liquid at the bottom of the spray tower (2) enters the stripping tower (11). After passing through the stripping tower (11), the rich amine liquid is converted into a semi-lean amine liquid. Part of the semi-lean amine liquid passes through the intermediate spray (13) and enters the spray tower (2) to wash the natural gas. The remaining semi-lean amine liquid enters the regeneration tower (6) to be regenerated into a lean amine liquid. The lean amine liquid passes through the primary spray and enters the spray tower (2) to wash the natural gas. It also includes an upper spray pipeline (15), an intermediate spray pipeline (16), and a lower spray pipeline (17). The upper spray pipeline (15), the intermediate spray pipeline (16), and the lower spray pipeline (17) are used to transport the corresponding amine liquid into the spray tower (2). The lower spray pipeline (15) 7) Includes a first pipe (171), a rich amine liquid pump (172), and a second pipe (173). The first pipe (171) is connected to the bottom of the spray tower (2), and the second pipe (173) is connected to the middle of the spray tower (2). The rich amine liquid pump (172) is located between the first pipe (171) and the second pipe (173) and is connected to both the first pipe (171) and the second pipe (173). The intermediate spray pipeline (16) includes a third pipe (161), a lean and rich liquid heat exchanger (5), a stripping tower (11), a semi-lean liquid pump (7), and a fourth pipe (162). The third pipe (161) is connected to the first pipe (171), and the third pipe (162) is connected to the first pipe (172). 1) Used to transport rich amine liquid to the lean-rich liquid heat exchanger (5) and then into the stripping tower (11), and transport the semi-lean amine liquid through the semi-lean liquid pump (7) into the spray tower (2) through the fourth pipe (162); the upper spray pipeline (15) includes the fifth pipe (151), the sixth pipe (152) and the seventh pipe (153). One end of the fifth pipe (151) is connected to the stripping tower (11) and the other end is connected to the regeneration tower (6). One end of the sixth pipe (152) is connected to the bottom of the regeneration tower (6) and the other end is connected to the lean-rich liquid heat exchanger (5). One end of the seventh pipe (153) is connected to the lean-rich liquid heat exchanger (5) and the other end is connected to the upper part of the spray tower (2);The upper-level spray pipe (15), the middle-level spray pipe (16), and the lower-level spray pipe (17) all include a liquid outlet pipe (24). The liquid outlet pipe (24) includes a central pipe (241), side pipes (242), annular pipes (243), and atomizing nozzles (244). Multiple side pipes (242) are arranged evenly around the circumference of the central pipe (241). The annular pipes (243) are located outside the side pipes (242) and fixedly installed at the end of the annular pipes (243). The central pipe (241), side pipes (242), and atomizing nozzles (244) are all part of the central pipe (241). 2) The side pipe (242) and the annular pipe (243) are interconnected. Multiple liquid outlet holes (25) are provided on the side pipe (242) and the annular pipe (243). The atomizing nozzle (244) is fixedly installed on the side pipe (242) and the annular pipe (243) through the liquid outlet holes (25). The amine liquid, transported into the spray tower (2) through the upper spray pipeline (15), the middle spray pipeline (16), and the lower spray pipeline (17), is sprayed out through the central pipe (241), the side pipe (242), and the atomizing nozzle (244) to perform decarbonization of the natural gas.

2. The natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to claim 1, characterized in that: The spray tower (2) is fixedly provided with an installation frame (26), and the central tube (241) is rotatably mounted on the installation frame (26). The rotation axis of the central tube (241) is parallel to the axis of the spray tower (2), and the spray tower (2) is also provided with a driving component for driving the central tube (241) to rotate.

3. The natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to claim 2, characterized in that: A transfer box (31) is fixedly installed on the inner wall of the spray tower (2). The transfer box (31) is annular and has an annular notch (32) at the top. The amine liquid transported into the spray tower (2) through the upper spray pipe (15), the middle spray pipe (16) and the lower spray pipe (17) enters the transfer box (31) through the side wall of the transfer box (31). A connecting pipe (33) is provided on the side wall of the central pipe (241). The connecting pipe (33) is connected to the central pipe (241) and its other end enters the transfer box (31) through the annular notch (32). A delivery pump is provided on the connecting pipe (33). The delivery pump is used to draw the amine liquid in the transfer box (31) into the central pipe (241).

4. A natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to claim 2, characterized in that: The driving component includes a drive motor (27) mounted on the mounting bracket (26), a first gear (28) sleeved on the central tube (241), and a second gear (29) mounted on the output shaft of the drive motor (27). The first gear (28) and the second gear (29) mesh with each other. A synchronizing rod (30) is provided between the central tubes (241) of adjacent liquid outlet pipes (24). The synchronizing rod (30) is used to connect the central tubes (241) so that the liquid outlet pipes (24) rotate synchronously. The side pipes (242) of the liquid outlet pipes (24) of adjacent layers are staggered.

5. A natural gas decarbonization system with multi-stage spraying and energy cascade utilization according to claim 1, characterized in that: The spray tower (2) is equipped with a liquid cloth (34), which is circular and fixed on the side of the inner wall of the spray tower (2). The liquid cloth (34) is located below the amine liquid, and the sprayed amine liquid wets the liquid cloth (34). Decarbonization is carried out during the natural gas rising and during the process of breaking through the liquid cloth (34).

6. A multi-stage spraying and energy cascade utilization natural gas decarbonization process, using the natural gas decarbonization system as described in any one of claims 1-5, characterized in that: Also includes; S1: The upper spray (12) uses deep regenerated lean liquid. The temperature of the lean liquid is precisely controlled at 40±5℃ through the lean-rich liquid heat exchanger (5). By utilizing the high affinity of amine liquid for carbon dioxide under low temperature conditions, the natural gas is deeply processed to ensure that the carbon dioxide content of the product gas meets the requirements. Through efficient atomization spraying, 50-150μm micro-droplets are formed, providing a huge gas-liquid contact area. S2: The intermediate spray (13) uses semi-lean liquor from the stripping tower (11) to handle 60-70% of the carbon dioxide removal task; although the absorption capacity of the semi-lean liquor is lower than that of the lean liquor, its temperature is higher, which forms a better temperature match with the raw gas (1) and optimizes the mass transfer rate. S3: The lower spray (14) uses a portion of the rich liquid in the diversion for circulating spraying, and the temperature is maintained at 60±5℃. On the one hand, the remaining absorption capacity of the rich liquid is used to pre-absorb the raw gas (1) to reduce the load in the upper area. On the other hand, the rich liquid at a higher temperature is circulated to maintain the bottom temperature of the tower within a safe range of 60-70℃, effectively preventing the formation of natural gas hydrate under high pressure. S4: The main rich liquid stream (80-90%) coming out of the bottom of the spray tower (2) is first depressurized, and the pressure is reduced from 6.0 MPa to 0.4-0.6 MPa. The depressurized rich liquid enters the lean-rich liquid heat exchanger (5) and exchanges heat with the high-temperature lean liquid from the regeneration tower (6). The temperature rises from 60℃ to 85-90℃, providing the necessary heat energy for the stripping process. The stripping tower (11) operates under relatively mild conditions, with the pressure controlled at 0.4-0.6 MPa and the temperature maintained in the range of 90-100℃. On the one hand, it is low enough to promote the desorption of carbon dioxide, and on the other hand, it is high enough to reduce the foaming tendency of the solution and the degradation risk of the amine liquid. In the stripping tower (11), the carbon dioxide in the rich liquid is released through the combined action of thermal flash evaporation and a small amount of stripping gas, achieving preliminary regeneration.

Images