System and process for extracting carbon dioxide from mixed hydrocarbons

Abstract

This invention discloses a carbon dioxide extraction system for mixed hydrocarbons, comprising an extraction decarbonization tower connected to a gas source, a decarbonization condenser and a decarbonization reflux tank connected sequentially to the extraction decarbonization tower, and a decarbonization reboiler connected to the bottom of the extraction decarbonization tower; the decarbonization reflux tank is connected to a CO2 purification tower via a pipeline, the top of the CO2 purification tower is connected to a CO2 recovery condenser and a CO2 recovery reflux tank connected sequentially via a pipeline, the bottom of the CO2 purification tower is connected to a CO2 recovery reboiler and a CO2 subcooler, and the CO2 subcooler is connected to a CO2 storage tank area via a pipeline. The extraction process of this invention first decarbonizes the mixed hydrocarbons and stable light hydrocarbons that have undergone the extraction reaction, and then sends the decarbonized CO2 liquid to the CO2 purification tower for purification to obtain CO2 product. The carbon dioxide extraction system and process for mixed hydrocarbons of this invention solve the problems of complex and difficult-to-control operation of existing decarbonization processes, and improves the CO2 recovery rate and purification rate.

Description

Technical Field

[0001] This invention belongs to the field of natural gas deep processing technology, specifically relating to a carbon dioxide extraction system from mixed hydrocarbons, and also to a carbon dioxide extraction process from mixed hydrocarbons. Background Technology

[0002] Methods for removing CO2 from natural gas are mainly divided into wet and dry methods. The wet method uses a regenerable solvent to absorb and remove CO2 from the gas mixture. The CO2-containing natural gas and solvent are contacted countercurrently in an absorption tower to remove CO2. The solvent that has absorbed CO2 is then regenerated to remove CO2 and reused, thus completing the entire cycle. All solvent absorption CO2 removal processes use basically similar process flows and equipment, mainly including the amine method, the formulated solvent method, and the NHD method. The amine method is currently the most widely used natural gas decarbonization technology. While technically mature, the amine method requires large-scale equipment and consumes a lot of energy, extracts less than 90% CO2, and requires further purification and condensation of the extracted CO2, making the process operation complex. Summary of the Invention

[0003] The purpose of this invention is to provide a carbon dioxide extraction system for mixed hydrocarbons, which solves the problems of complex and difficult-to-control operation processes and excessively large overall equipment scale leading to resource waste in existing decarbonization processes.

[0004] Another objective of this invention is to provide a carbon dioxide extraction process from mixed hydrocarbons, which improves the recovery and purification rate of CO2 in mixed hydrocarbons.

[0005] The first technical solution adopted in this invention is a carbon dioxide extraction system for mixed hydrocarbons, including an extraction and decarbonization tower that is connected to a CO2 mixed liquid hydrocarbon and a stable light hydrocarbon liquefied gas tower via pipelines. The top of the extraction and decarbonization tower is connected to a decarbonization condenser and a decarbonization reflux tank via pipelines. The decarbonization reflux tank is connected to the extraction and decarbonization tower via pipelines. The bottom of the extraction and decarbonization tower is also connected to a decarbonization reboiler via pipelines. The decarbonization reboiler is connected to the extraction and decarbonization tower via a secondary steam pipe a and a liquid phase output pipe a, respectively.

[0006] The decarbonization reflux tank is also connected to a CO2 purification tower via a pipeline. The top of the CO2 purification tower is connected in sequence to a CO2 recovery condenser and a CO2 recovery reflux tank via pipelines. The CO2 recovery reflux tank is connected to the CO2 purification tower via a pipeline. The bottom of the CO2 purification tower is connected to a CO2 recovery reboiler and a CO2 subcooler via pipelines. The CO2 recovery reboiler is connected to the CO2 purification tower via a secondary steam pipe b and a liquid phase output pipe b, respectively. The CO2 subcooler is connected to the CO2 storage tank area via a pipeline.

[0007] The first technical solution of the present invention is further characterized in that,

[0008] A flow control valve is installed on the pipeline connecting the stable light hydrocarbon liquefied gas tower and the extraction decarbonization tower. A vent line a is connected to the pipeline connecting the extraction decarbonization tower and the decarbonization condenser. A shut-off valve is installed on the pipeline connecting the vent line a.

[0009] The decarbonization reflux tank is connected to a vent line b via a pipeline. A shut-off valve and a decarbonization reflux tank pressure control valve are installed sequentially on the pipeline connected to the vent line b.

[0010] The pipeline connecting the decarbonization reflux tank and the extraction decarbonization tower is equipped with an extraction decarbonization tower reflux pump and a reflux flow control valve in sequence.

[0011] The decarbonized reboiler is connected to a lean gas source and a product gas output unit via pipelines. A flow and temperature control valve for the decarbonized reboiler is installed on the pipeline connecting the lean gas source and the decarbonized reboiler, and a shut-off valve is installed on the pipeline connecting the decarbonized reboiler and the product gas output unit.

[0012] The bottom of the extraction decarbonization tower is connected to the deethane removal tower via a pipeline. A shut-off valve and an extraction decarbonization tower level control valve are installed sequentially on the pipeline connecting the extraction decarbonization tower and the deethane removal tower.

[0013] A decarbonization reflux tank level control valve is installed on the pipeline connecting the decarbonization reflux tank and the CO2 purification tower. A vent line c is connected to the pipeline connecting the CO2 purification tower and the CO2 recovery condenser. A shut-off valve is installed on the pipeline connecting the vent line c.

[0014] The CO2 recovery reflux tank is also connected to a CO2 non-condensable gas compressor via a pipeline. A shut-off valve and a CO2 recovery reflux tank pressure control valve are installed sequentially on the pipeline connecting the CO2 recovery reflux tank and the CO2 non-condensable gas compressor. The CO2 non-condensable gas compressor is connected to a demethanizer via a pipeline.

[0015] The pipeline connecting the CO2 recovery reflux tank and the CO2 purification tower is equipped with a CO2 purification tower reflux pump, a flow sensor, and a CO2 recovery reflux tank level control valve.

[0016] The CO2 recovery reboiler is also connected to an ethane stripper and a downstream ethane gas unit via pipelines. A CO2 purification tower bottom flow and temperature control valve is installed on the pipeline connecting the ethane stripper and the CO2 recovery reboiler, and a shut-off valve is installed on the pipeline connecting the CO2 recovery reboiler and the downstream ethane gas unit.

[0017] A shut-off valve and a bottom liquid level control valve for the CO2 purification tower are installed sequentially on the pipeline connecting the CO2 purification tower and the CO2 subcooler.

[0018] The decarbonization condenser, CO2 recovery condenser, and CO2 subcooler are each connected to a propane delivery unit via pipelines. The pipelines connecting the propane delivery unit to the decarbonization condenser, the propane delivery unit to the CO2 recovery condenser, and the propane delivery unit to the CO2 subcooler are respectively equipped with a temperature control valve for the decarbonization condenser, a level control valve for the CO2 recovery condenser, and a level control valve for the CO2 subcooler.

[0019] The decarbonization condenser, CO2 recovery condenser, and CO2 subcooler are also connected to the low-pressure gaseous propane discharge unit via pipelines.

[0020] The second technical solution of the present invention is a carbon dioxide extraction process in mixed hydrocarbons. The flow control valve is opened, and the CO2 mixed liquid hydrocarbons and stable light hydrocarbons enter the extraction decarbonization tower for extraction reaction. The extracted CO2 gas enters the decarbonization condenser and is cooled to -15℃ to -25℃ by propane before entering the decarbonization reflux tank. After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank, it is pressurized to 2.63MPa to 2.7MPa by the extraction decarbonization tower reflux pump and then returned to the extraction decarbonization tower.

[0021] The condensate generated from the extraction reaction of CO2 mixture with hydrocarbons and stable light hydrocarbons flows into the bottom of the extraction decarbonization tower and becomes tray liquid. It then enters the decarbonization reboiler. The flow and temperature control valve of the decarbonization reboiler is opened, and lean gas enters the decarbonization reboiler. The tray liquid is heated to 26℃~30℃ to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower and exchanges heat with the liquid CO2 that returned from the decarbonization reflux tank to the extraction decarbonization tower, causing the liquid CO2 to vaporize. After the liquid phase enters the extraction decarbonization tower, the liquid level control valve of the extraction decarbonization tower is opened, and the liquid enters the deethanerization tower.

[0022] Liquid CO2 in the decarbonization reflux tank enters the CO2 purification tower under the action of the liquid level control valve of the decarbonization reflux tank. The liquid CO2 flows to the bottom of the CO2 purification tower and enters the CO2 recovery reboiler. Under the action of ethane, it is heated to -8℃ to -15℃ to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower to exchange heat with the liquid CO2. The liquid level control valve at the bottom of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower to the CO2 subcooler. After being cooled to -21℃ to -23℃ by the CO2 subcooler, it is transported to the CO2 storage tank area.

[0023] The evaporated CO2 gas enters the CO2 recovery condenser and is cooled to -20℃ to -25℃ before entering the CO2 recovery reflux tank. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank, it is pressurized to 2.4MPa to 2.6MPa by the CO2 purification tower reflux pump and returned to the CO2 purification tower. The pressure control valve of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank enters the CO2 non-condensable gas compressor and is then sent to the demethanizer.

[0024] The beneficial effects of this invention are:

[0025] (1) The carbon dioxide extraction system in the mixed hydrocarbons of the present invention has a moderate overall scale, which improves the utilization efficiency of existing resources and has a simple structure that is easy to operate.

[0026] (2) The carbon dioxide extraction process in the mixed hydrocarbons of this invention achieves the extraction of CO2 and C2. + The effective separation of liquid hydrocarbons enables a CO2 recovery rate of over 95%, without the need for further concentration and condensation. The resulting food-grade CO2 liquid byproduct can be used to improve the economic efficiency of the project, achieving economical and effective recovery of CO2 from hydrocarbon-containing condensate. Furthermore, the extraction process is simple, requiring no complex operation, thus reducing equipment damage caused by operational errors. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the carbon dioxide extraction system in mixed hydrocarbons according to the present invention.

[0028] In the diagram, 1. Extraction decarbonization tower, 2. Decarbonization condenser, 3. Decarbonization condenser temperature control valve, 4. Decarbonization reflux tank, 5. Decarbonization reflux tank pressure control valve, 6. Decarbonization reflux tank level control valve, 7. Extraction decarbonization tower reflux pump, 8. Reflux flow control valve, 9. Decarbonization reboiler, 10. Decarbonization reboiler flow and temperature control valve, 11. Extraction decarbonization tower level control valve, 12. CO2 purification tower, 13. CO2 recovery condenser, 14. CO2 recovery condenser level control valve, 15. CO2 recovery reflux tank, 16. CO2 recovery reflux tank pressure control valve, 17. CO2 purification tower reflux pump, 18. CO2 recovery reflux tank level control valve, 19. CO2 recovery reboiler, 20. CO 2. Bottom flow and temperature control valve of purification tower; 21. Bottom liquid level control valve of CO2 purification tower; 22. CO2 subcooler; 23. CO2 subcooler liquid level control valve; 24. CO2 non-condensable gas compressor; 25. Demethanizer tower; 26. CO2 mixed liquid hydrocarbon; 27. Vent line a; 28. Lean gas source; 29. ​​Product gas output unit; 30. Vent line b; 31. CO2 storage tank area; 32. Stabilized light hydrocarbon liquefied gas tower; 33. Deethaner tower; 34. Ethane downstream unit; 35. Condenser propane conveying unit; 36. Low-pressure gaseous propane discharge unit; 37. Vent line c; 38. Secondary steam pipe a; 39. Liquid phase output pipe a; 40. Secondary steam pipe b; 41. Liquid phase output pipe b. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] The structure of the carbon dioxide extraction system from mixed hydrocarbons of the present invention is as follows: Figure 1As shown, the extraction and decarbonization tower 1 includes an extraction and decarbonization tower 1 connected by a pipeline to a CO2 mixture 26 and a stabilized light hydrocarbon liquefied gas tower 32. The stabilized light hydrocarbon liquefied gas tower 32 is mainly used as an extractant in the extraction and decarbonization tower 1. A flow control valve is installed on the pipeline connecting the stabilized light hydrocarbon liquefied gas tower 32 and the extraction and decarbonization tower 1. The flow control valve can monitor the flow rate in the pipeline in real time. The bottom of the extraction and decarbonization tower 1 is connected to an ethane removal tower 33 by a pipeline. A shut-off valve and an extraction and decarbonization tower liquid level control valve 11 are installed sequentially on the pipeline connecting the extraction and decarbonization tower 1 and the extraction and decarbonization tower 33. With the cooperation of the shut-off valve and the extraction and decarbonization tower liquid level control valve 11, the ethane condensate at the bottom of the extraction and decarbonization tower 1 is output to the ethane removal tower 33.

[0031] The top of the extraction decarbonization tower 1 is connected to the decarbonization condenser 2 and the decarbonization reflux tank 4 in sequence through pipes to form a closed loop. The pipe connecting the extraction decarbonization tower 1 and the decarbonization condenser 2 is connected to a vent line a27. A shut-off valve is installed on the vent line a27. When a problem occurs in the closed loop, the gas can be discharged to the vent line a27 to avoid danger. The pipe connecting the decarbonization reflux tank 4 and the extraction decarbonization tower 1 is connected to the extraction decarbonization tower 1 and is equipped with an extraction decarbonization tower reflux pump 7 and a reflux flow control valve 8 in sequence. The flow sensor of the reflux flow control valve 8 monitors the flow rate in the pipe connecting the decarbonization reflux tank 4 and the extraction decarbonization tower 1.

[0032] The decarbonization reflux tank 4 is connected to a vent line b30 via a pipeline. A shut-off valve and a decarbonization reflux tank pressure control valve 5 are installed sequentially on the vent line b30. The pressure sensor of the decarbonization reflux tank pressure control valve 5 is connected to the decarbonization reflux tank 4 via a line to monitor the pressure inside the decarbonization reflux tank 4 and prevent dangerous accidents caused by excessive pressure inside the decarbonization reflux tank 4.

[0033] The bottom of the extraction decarbonization tower 1 is also connected to a decarbonization reboiler 9 via a pipeline. The decarbonization reboiler 9 is connected to the extraction decarbonization tower 1 via a secondary steam pipe a38 and a liquid phase output pipe a39, respectively. The secondary steam pipe a38 is connected to the bottom of the tray inside the extraction decarbonization tower 1, and the liquid phase output pipe a39 is connected to the bottom of the extraction decarbonization tower 1. The decarbonization reboiler 9 is also connected to a lean gas source 28 and a product gas output unit 29 via a pipeline. The lean gas source 28 serves as the heat source for the decarbonization reboiler 9. A decarbonization reboiler flow and temperature control valve 10 is installed on the pipeline connecting the lean gas source 28 and the decarbonization reboiler 9. The flow sensor in the decarbonization reboiler flow and temperature control valve 10 is used to monitor the flow rate in the pipeline connecting the decarbonization reboiler 9 and the product gas output unit 29. The temperature sensor is connected to the extraction decarbonization tower 1 via a line. A shut-off valve is installed on the pipeline connecting the decarbonization reboiler 9 and the product gas output unit 29.

[0034] The decarbonization reflux tank 4 is also connected to the CO2 purification tower 12 via a pipeline. A decarbonization reflux tank liquefaction control valve 6 is installed on the pipeline connecting the decarbonization reflux tank 4 and the CO2 purification tower 12. The liquefaction sensor in the decarbonization reflux tank liquefaction control valve 6 is connected to the decarbonization reflux tank 4 via a line.

[0035] The top of the CO2 purification tower 12 is connected in sequence to the CO2 recovery condenser 13 and the CO2 recovery reflux tank 15 via pipelines, forming a closed loop. The pipeline connecting the CO2 purification tower 12 and the CO2 recovery condenser 13 is connected to a vent line c37, and a shut-off valve is installed on the vent line c37. The pipeline connecting the CO2 recovery reflux tank 15 and the CO2 purification tower 12 is sequentially equipped with a CO2 purification tower reflux pump 17, a flow sensor, and a CO2 recovery reflux tank level control valve 18. The level sensor of the CO2 recovery reflux tank level control valve 18 is connected to the CO2 recovery reflux tank 15 via a line.

[0036] The CO2 recovery reflux tank 15 is also connected to the CO2 non-condensable gas compressor 24 via a pipeline. A shut-off valve and a CO2 recovery reflux tank pressure control valve 16 are sequentially installed on the pipeline connecting the CO2 recovery reflux tank 15 and the CO2 non-condensable gas compressor 24. The pressure sensor of the CO2 recovery reflux tank pressure control valve 16 is used to monitor the internal pressure of the CO2 recovery reflux tank 15. The CO2 non-condensable gas compressor 24 is connected to the demethanizer 25 via a pipeline.

[0037] The bottom of the CO2 purification tower 12 is connected to a CO2 recovery reboiler 19 via a pipeline. The CO2 recovery reboiler 19 is connected to the CO2 purification tower 12 via a secondary steam pipe b40 and a liquid phase output pipe b41. The secondary steam pipe b40 is connected to the bottom of the tray inside the CO2 purification tower 12, and the liquid phase output pipe b41 is connected to the bottom of the CO2 purification tower 12. Ethane gas is used as the heat source for the CO2 recovery reboiler 19. The recovery reboiler 19 is also connected to the ethane removal tower 33 and the downstream ethane gas unit 34 via a pipeline. The fuel used by the recovery reboiler 19 is the liquid transported from the extraction decarbonization tower 1 to the ethane removal tower 33, realizing reuse and saving existing resources.

[0038] A CO2 purification tower bottom flow and temperature control valve 20 is installed on the pipeline connecting the ethane removal tower 33 and the CO2 recovery reboiler 19. The flow sensor of the CO2 purification tower bottom flow and temperature control valve 20 is used to monitor the flow rate in the pipeline connecting the CO2 recovery reboiler 19 and the downstream ethane gas unit 34. The temperature sensor is connected to the CO2 purification tower 12 through a line. A shut-off valve is installed on the pipeline connecting the CO2 recovery reboiler 19 and the downstream ethane gas unit 34.

[0039] The bottom of the CO2 purification tower 12 is also connected to a CO2 subcooler 22 via a pipeline. A shut-off valve and a bottom liquid level control valve 21 of the CO2 purification tower are installed sequentially on the pipeline connecting the CO2 purification tower 12 and the CO2 subcooler 22. The liquid level sensor of the bottom liquid level control valve 21 of the CO2 purification tower is used to monitor the liquid level at the bottom of the CO2 purification tower 12. The CO2 subcooler 22 is connected to the CO2 storage tank area 31 via a pipeline and is used to store the extracted CO2 liquid.

[0040] The decarbonization condenser 2, CO2 recovery condenser 13, and CO2 subcooler 22 are each connected to a propane delivery unit 35 via pipelines. Propane is used as the condensate for these three components. Temperature control valves 3 and 3 are installed on the pipelines connecting the propane delivery unit 35 to the decarbonization condenser 2, the CO2 recovery condenser 13, and the CO2 subcooler 22, respectively. Level control valve 14 and CO2 subcooler level control valve 23; the temperature sensor of decarbonization condenser temperature control valve 3 is connected to decarbonization condenser 2 via a line; the level sensors of CO2 recovery condenser level control valve 14 and CO2 subcooler level control valve 23 are connected to CO2 recovery condenser 13 and CO2 subcooler 22 via lines respectively, to monitor their internal temperature and refrigerant content, so as to replenish them in time; decarbonization condenser 2, CO2 recovery condenser 13 and CO2 subcooler 22 are also connected to low-pressure gaseous propane discharge unit 36 ​​via pipelines.

[0041] The carbon dioxide extraction system for mixed hydrocarbons of this invention has a moderate overall size, improves the utilization efficiency of existing resources, and has a simple structure that is easy to operate.

[0042] The carbon dioxide extraction process in mixed hydrocarbons employs a CO2 extraction system. With the flow control valve open, the CO2 mixture (hydrocarbon 26) and stable light hydrocarbons enter the extraction decarbonization tower 1 for extraction. The extracted CO2 gas enters the decarbonization condenser 2, is cooled to -15℃ to -25℃ with propane, and then enters the decarbonization reflux tank 4. After flash evaporation to remove non-condensable gases in the decarbonization reflux tank 4, the gas is pressurized to 2.63MPa to 2.7MPa by the extraction decarbonization tower reflux pump 7 before returning to the extraction decarbonization tower 1.

[0043] The condensate generated from the extraction reaction of CO2 mixture hydrocarbon 26 and stable light hydrocarbons flows into the bottom of extraction decarbonization tower 1 and becomes tray liquid, which enters decarbonization reboiler 9. The flow and temperature control valve 10 of decarbonization reboiler is opened, and lean gas enters decarbonization reboiler 9. The tray liquid is heated to 26℃~30℃ to form secondary steam and liquid phase. The secondary steam enters extraction decarbonization tower 1 and exchanges heat with the liquid CO2 that returned from decarbonization reflux tank 4 to extraction decarbonization tower 1, causing the liquid CO2 to vaporize. After the liquid phase enters extraction decarbonization tower 1, the liquid level control valve 11 of extraction decarbonization tower is opened and enters deethanerization tower 33.

[0044] Liquid CO2 in the decarbonization reflux tank 4 enters the CO2 purification tower 12 under the action of the liquid level control valve 6. The liquid CO2 flows to the bottom of the CO2 purification tower 12 and enters the CO2 recovery reboiler 19. Under the action of ethane, it is heated to -8℃ to -15℃ to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower 12 to exchange heat with the liquid CO2. The bottom liquid level control valve 21 of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower 12 to the CO2 subcooler 22. After being cooled to -21℃ to -23℃ by the CO2 subcooler 22, it is transported to the CO2 storage tank area 31.

[0045] The evaporated CO2 gas enters the CO2 recovery condenser 13 and is cooled to -20℃ to -25℃ before entering the CO2 recovery reflux tank 15. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank 15, it is pressurized to 2.4MPa to 2.6MPa by the CO2 purification tower reflux pump 17 and returns to the CO2 purification tower 12. The pressure control valve 16 of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank 15 enters the CO2 non-condensable gas compressor 24 and is then sent to the demethanizer tower 25.

[0046] The carbon dioxide extraction process from mixed hydrocarbons of the present invention achieves the extraction of both CO2 and C2. + The effective separation of liquid hydrocarbons enables CO2 recovery rates of up to 95% or more, and the extraction process is simple, requiring no complex operation, thus reducing equipment damage caused by operational errors.

[0047] Example 1

[0048] A carbon dioxide extraction system for mixed hydrocarbons is used. With the flow control valve open, mixed hydrocarbon 26 with CO2 at 4℃ and 2.7MPa and stable light hydrocarbon at 40℃ and 2.7MPa enter the extraction decarbonization tower 1 for extraction reaction. The extraction temperature is -7℃ and the pressure is 2.64MPa. The CO2 gas enters the decarbonization condenser 2, is cooled to -15℃ by propane, and then enters the decarbonization reflux tank 4. After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank 4, it is pressurized to 2.63MPa by the extraction decarbonization tower reflux pump 7 and then returns to the extraction decarbonization tower 1.

[0049] The bottom of the extraction decarbonization tower 1 becomes tray liquid and enters the decarbonization reboiler 9. The decarbonization reboiler flow and temperature control valve 10 is opened, and lean gas enters the decarbonization reboiler 9. The tray liquid is heated to 26°C to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower 1 and the liquid CO2 that returns from the decarbonization reflux tank 4 to the extraction decarbonization tower 1 for heat exchange, causing the liquid CO2 to vaporize. After the liquid phase enters the extraction decarbonization tower 1, the extraction decarbonization tower liquid level control valve 11 is opened to enter the deethaner 33.

[0050] Part of the liquid CO2 in the decarbonization reflux tank 4 enters the CO2 purification tower 12. The liquid CO2 flows to the bottom of the CO2 purification tower 12 and enters the CO2 recovery reboiler 19. Under the action of ethane, it is heated to -8°C to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower 12 to exchange heat with the liquid CO2. The bottom liquid level control valve 21 of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower 12 to the CO2 subcooler 22. After being cooled to -21°C by the CO2 subcooler 22, it is transported to the CO2 storage tank area 31.

[0051] The evaporated CO2 gas enters the CO2 recovery condenser 13 and is cooled to -20°C before entering the CO2 recovery reflux tank 15. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank 15, it is pressurized to 2.4 MPa by the CO2 purification tower reflux pump 17 and returns to the CO2 purification tower 12. The pressure control valve 16 of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank 15 enters the CO2 non-condensable gas compressor 24 and is then sent to the demethanizer tower 25.

[0052] The concentration of liquid CO2 collected in CO2 storage tank area 31 was detected and found to be 97.5% / mol.

[0053] Example 2

[0054] A carbon dioxide extraction system for mixed hydrocarbons is used. With the flow control valve open, mixed hydrocarbon 26 with CO2 at 5℃ and 2.68MPa and stable light hydrocarbon at 42℃ and 2.68MPa enter the extraction decarbonization tower 1 for extraction reaction. The extraction temperature is -6℃ and the pressure is 2.64MPa. The CO2 gas enters the decarbonization condenser 2, is cooled to -18℃ by propane, and then enters the decarbonization reflux tank 4. After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank 4, it is pressurized to 2.65MPa by the extraction decarbonization tower reflux pump 7 and then returns to the extraction decarbonization tower 1.

[0055] The bottom of the extraction decarbonization tower 1 becomes tray liquid and enters the decarbonization reboiler 9. The decarbonization reboiler flow and temperature control valve 10 is opened, and lean gas enters the decarbonization reboiler 9. The tray liquid is heated to 28°C to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower 1 and the liquid CO2 that returns from the decarbonization reflux tank 4 to the extraction decarbonization tower 1 for heat exchange, causing the liquid CO2 to vaporize. After the liquid phase enters the extraction decarbonization tower 1, the extraction decarbonization tower liquid level control valve 11 is opened to enter the deethaner 33.

[0056] Part of the liquid CO2 in the decarbonization reflux tank 4 enters the CO2 purification tower 12. The liquid CO2 flows to the bottom of the CO2 purification tower 12 and enters the CO2 recovery reboiler 19. Under the action of ethane, it is heated to -10°C to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower 12 to exchange heat with the liquid CO2. The bottom liquid level control valve 21 of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower 12 to the CO2 subcooler 22. After being cooled to -22°C by the CO2 subcooler 22, it is transported to the CO2 storage tank area 31.

[0057] The evaporated CO2 gas enters the CO2 recovery condenser 13 and is cooled to -22°C before entering the CO2 recovery reflux tank 15. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank 15, it is pressurized to 2.48 MPa by the CO2 purification tower reflux pump 17 and returns to the CO2 purification tower 12. The pressure control valve 16 of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank 15 enters the CO2 non-condensable gas compressor 24 and is then sent to the demethanizer tower 25.

[0058] The concentration of liquid CO2 collected in CO2 storage tank area 31 was detected and found to be 98% / mol.

[0059] Example 3

[0060] A carbon dioxide extraction system for mixed hydrocarbons is used. With the flow control valve open, mixed hydrocarbon 26 with CO2 at 5℃ and 2.68MPa and stable light hydrocarbon at 42℃ and 2.68MPa enter the extraction decarbonization tower 1 for extraction reaction. The extraction temperature is -6℃ and the pressure is 2.64MPa. The CO2 gas enters the decarbonization condenser 2, is cooled to -22℃ by propane, and then enters the decarbonization reflux tank 4. After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank 4, it is pressurized to 2.68MPa by the extraction decarbonization tower reflux pump 7 and then returns to the extraction decarbonization tower 1.

[0061] The bottom of the extraction decarbonization tower 1 becomes tray liquid and enters the decarbonization reboiler 9. The decarbonization reboiler flow and temperature control valve 10 is opened, and lean gas enters the decarbonization reboiler 9. The tray liquid is heated to 29°C to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower 1 and the liquid CO2 that returns from the decarbonization reflux tank 4 to the extraction decarbonization tower 1 for heat exchange, causing the liquid CO2 to vaporize. After the liquid phase enters the extraction decarbonization tower 1, the extraction decarbonization tower liquid level control valve 11 is opened to enter the deethaner 33.

[0062] Part of the liquid CO2 in the decarbonization reflux tank 4 enters the CO2 purification tower 12. The liquid CO2 flows to the bottom of the CO2 purification tower 12 and enters the CO2 recovery reboiler 19. Under the action of ethane, it is heated to -13°C to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower 12 to exchange heat with the liquid CO2. The bottom liquid level control valve 21 of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower 12 to the CO2 subcooler 22. After being cooled to -22°C by the CO2 subcooler 22, it is transported to the CO2 storage tank area 31.

[0063] The evaporated CO2 gas enters the CO2 recovery condenser 13 and is cooled to -24°C before entering the CO2 recovery reflux tank 15. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank 15, it is pressurized to 2.54 MPa by the CO2 purification tower reflux pump 17 and returns to the CO2 purification tower 12. The pressure control valve 16 of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank 15 enters the CO2 non-condensable gas compressor 24 and is then sent to the demethanizer tower 25.

[0064] The concentration of liquid CO2 collected in CO2 storage tank area 31 was detected and found to be 98.2% / mol.

[0065] Example 4

[0066] A carbon dioxide extraction system for mixed hydrocarbons is used. With the flow control valve open, mixed hydrocarbon 26 with CO2 at 5℃ and 2.68MPa and stable light hydrocarbon at 42℃ and 2.68MPa enter the extraction decarbonization tower 1 for extraction reaction. The extraction temperature is -6℃ and the pressure is 2.64MPa. The CO2 gas enters the decarbonization condenser 2, is cooled to -25℃ by propane, and then enters the decarbonization reflux tank 4. After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank 4, it is pressurized to 2.7MPa by the extraction decarbonization tower reflux pump 7 and then returns to the extraction decarbonization tower 1.

[0067] The bottom of the extraction decarbonization tower 1 becomes tray liquid and enters the decarbonization reboiler 9. The decarbonization reboiler flow and temperature control valve 10 is opened, and lean gas enters the decarbonization reboiler 9. The tray liquid is heated to 30°C to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower 1 and the liquid CO2 that returns from the decarbonization reflux tank 4 to the extraction decarbonization tower 1 for heat exchange, causing the liquid CO2 to vaporize. After the liquid phase enters the extraction decarbonization tower 1, the extraction decarbonization tower liquid level control valve 11 is opened to enter the deethaner 33.

[0068] Part of the liquid CO2 in the decarbonization reflux tank 4 enters the CO2 purification tower 12. The liquid CO2 flows to the bottom of the CO2 purification tower 12 and enters the CO2 recovery reboiler 19. Under the action of ethane, it is heated to -15°C to form secondary steam and liquid phase. The secondary steam returns to the CO2 purification tower 12 to exchange heat with the liquid CO2. The bottom liquid level control valve 21 of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower 12 to the CO2 subcooler 22. After being cooled to -23°C by the CO2 subcooler 22, it is transported to the CO2 storage tank area 31.

[0069] The evaporated CO2 gas enters the CO2 recovery condenser 13 and is cooled to -25°C before entering the CO2 recovery reflux tank 15. After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank 15, it is pressurized to 2.6 MPa by the CO2 purification tower reflux pump 17 and returns to the CO2 purification tower 12. The pressure control valve 16 of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank 15 enters the CO2 non-condensable gas compressor 24 and is then sent to the demethanizer tower 25.

[0070] The concentration of liquid CO2 collected in CO2 storage tank area 31 was measured and found to be 97.9% / mol.

Claims

1. A carbon dioxide extraction system for mixed hydrocarbons, characterized in that, The extraction decarbonization tower (1) includes a CO2 mixed liquid hydrocarbon (26) and a stable light hydrocarbon liquefied gas tower (32) connected by pipelines. The top of the extraction decarbonization tower (1) is connected in sequence by pipelines to a decarbonization condenser (2) and a decarbonization reflux tank (4). The decarbonization reflux tank (4) is connected to the extraction decarbonization tower (1) by pipelines. The bottom of the extraction decarbonization tower (1) is also connected by pipelines to a decarbonization reboiler (9). The decarbonization reboiler (9) is connected to the extraction decarbonization tower (1) by a secondary steam pipe a (38) and a liquid phase output pipe a (39), respectively. The decarbonization reflux tank (4) is also connected to a CO2 purification tower (12) via a pipeline. The top of the CO2 purification tower (12) is connected to a CO2 recovery condenser (13) and a CO2 recovery reflux tank (15) via pipelines. The CO2 recovery reflux tank (15) is connected to the CO2 purification tower (12) via a pipeline. The bottom of the CO2 purification tower (12) is connected to a CO2 recovery reboiler (19) and a CO2 subcooler (22) via pipelines. The CO2 recovery reboiler (19) is connected to the CO2 purification tower (12) via a secondary steam pipe b (40) and a liquid phase output pipe b (41) respectively. The CO2 subcooler (22) is connected to the CO2 storage tank area (31) via a pipeline.

2. The carbon dioxide extraction system from mixed hydrocarbons according to claim 1, characterized in that, A flow control valve is installed on the pipeline connecting the stable light hydrocarbon liquefied gas tower (32) and the extraction decarbonization tower (1). A vent line a (27) is connected to the pipeline connecting the extraction decarbonization tower (1) and the decarbonization condenser (2). A shut-off valve is installed on the pipeline connecting the vent line a (27). The decarbonization reflux tank (4) is connected to a vent line b (30) via a pipeline. A shut-off valve and a decarbonization reflux tank pressure control valve (5) are sequentially installed on the vent line b (30). The decarbonization reflux tank (4) and the extraction decarbonization tower (1) are connected by a reflux pump (7) and a reflux flow control valve (8) in sequence.

3. The carbon dioxide extraction system from mixed hydrocarbons according to claim 2, characterized in that, The decarbonized reboiler (9) is connected to a lean gas source (28) and a product gas output unit (29) via a pipeline. A decarbonized reboiler flow and temperature control valve (10) is installed on the pipeline connecting the lean gas source (28) and the decarbonized reboiler (9). A shut-off valve is installed on the pipeline connecting the decarbonized reboiler (9) and the product gas output unit (29).

4. The carbon dioxide extraction system from mixed hydrocarbons according to claim 3, characterized in that, The bottom of the extraction decarbonization tower (1) is connected to the deethane removal tower (33) via a pipeline. A shut-off valve and an extraction decarbonization tower level control valve (11) are sequentially installed on the pipeline connecting the extraction decarbonization tower (1) and the deethane removal tower (33).

5. The carbon dioxide extraction system from mixed hydrocarbons according to claim 4, characterized in that, A decarbonization reflux tank level control valve (6) is installed on the pipeline connecting the decarbonization reflux tank (4) and the CO2 purification tower (12). A venting line c (37) is connected to the pipeline connecting the CO2 purification tower (12) and the CO2 recovery condenser (13). A shut-off valve is installed on the pipeline connecting the venting line c (37). The CO2 recovery reflux tank (15) is also connected to a CO2 non-condensable gas compressor (24) via a pipeline. A shut-off valve and a CO2 recovery reflux tank pressure control valve (16) are sequentially installed on the pipeline connecting the CO2 recovery reflux tank (15) and the CO2 non-condensable gas compressor (24). The CO2 non-condensable gas compressor (24) is connected to a demethanizer (25) via a pipeline. The CO2 recovery reflux tank (15) and the CO2 purification tower (12) are connected by a CO2 purification tower reflux pump (17), a flow sensor and a CO2 recovery reflux tank level control valve (18) in sequence.

6. The carbon dioxide extraction system from mixed hydrocarbons according to claim 5, characterized in that, The CO2 recovery reboiler (19) is also connected to an ethane stripper (33) and an ethane downstream unit (34) via a pipeline. A CO2 purification tower bottom flow and temperature control valve (20) is installed on the pipeline connecting the ethane stripper (33) and the CO2 recovery reboiler (19). A shut-off valve is installed on the pipeline connecting the CO2 recovery reboiler (19) and the ethane downstream unit (34).

7. The carbon dioxide extraction system from mixed hydrocarbons according to claim 6, characterized in that, A shut-off valve and a bottom liquid level control valve (21) of the CO2 purification tower (12) are sequentially installed on the pipeline connecting the CO2 purification tower (12) and the CO2 subcooler (22).

8. The carbon dioxide extraction system from mixed hydrocarbons according to claim 7, characterized in that, The decarbonization condenser (2), CO2 recovery condenser (13), and CO2 subcooler (22) are respectively connected to a condenser propane delivery unit (35) via pipelines. The pipelines connecting the condenser propane delivery unit (35) to the decarbonization condenser (2), the pipelines connecting the condenser propane delivery unit (35) to the CO2 recovery condenser (13), and the pipelines connecting the condenser propane delivery unit (35) to the CO2 subcooler (22) are respectively equipped with a decarbonization condenser temperature control valve (3), a CO2 recovery condenser liquid level control valve (14), and a CO2 subcooler liquid level control valve (23).

9. The carbon dioxide extraction system from mixed hydrocarbons according to claim 8, characterized in that, The decarbonization condenser (2), CO2 recovery condenser (13) and CO2 subcooler (22) are also connected to the low-pressure gaseous propane discharge unit (36) via pipelines.

10. A process for extracting carbon dioxide from mixed hydrocarbons, characterized in that, Using the carbon dioxide extraction system for mixed hydrocarbons as described in claim 9, the flow control valve is opened, and the CO2 mixed hydrocarbon (26) and stable light hydrocarbons enter the extraction decarbonization tower (1) for extraction reaction. The extracted CO2 gas enters the decarbonization condenser (2), is cooled to -15℃ to -25℃ by propane, and then enters the decarbonization reflux tank (4). After the non-condensable gas is removed by flash evaporation in the decarbonization reflux tank (4), it is pressurized to 2.63MPa to 2.7MPa by the extraction decarbonization tower reflux pump (7) and then returned to the extraction decarbonization tower (1). The condensate generated from the extraction reaction of CO2 mixed hydrocarbon (26) and stable light hydrocarbon flows into the bottom of the extraction decarbonization tower (1) and becomes the tray liquid, which enters the decarbonization reboiler (9). The flow and temperature control valve (10) of the decarbonization reboiler is opened, and the lean gas enters the decarbonization reboiler (9). The tray liquid is heated to 26℃~30℃ to form secondary steam and liquid phase. The secondary steam enters the extraction decarbonization tower (1) and exchanges heat with the liquid CO2 that returned to the extraction decarbonization tower (1) from the decarbonization reflux tank (4) to vaporize the liquid CO2. After the liquid phase enters the extraction decarbonization tower (1), the liquid level control valve (11) of the extraction decarbonization tower is opened and enters the deethaner tower (33). Liquid CO2 in the decarbonization reflux tank (4) enters the CO2 purification tower (12) under the action of the liquid level control valve (6). Liquid CO2 flows to the bottom of the CO2 purification tower (12) and enters the CO2 recovery reboiler (19). Under the action of ethane, it is heated to -8℃ to -15℃ to form secondary steam and liquid phase. Secondary steam returns to the CO2 purification tower (12) to exchange heat with liquid CO2. The bottom liquid level control valve (21) of the CO2 purification tower is opened to transport the liquid phase entering the CO2 purification tower (12) to the CO2 subcooler (22). After being cooled to -21℃ to -23℃ by the CO2 subcooler (22), it is transported to the CO2 storage tank area (31). The evaporated CO2 gas enters the CO2 recovery condenser (13) and is cooled to -20℃~-25℃ before entering the CO2 recovery reflux tank (15). After the non-condensable gas is removed by flash evaporation in the CO2 recovery reflux tank (15), it is pressurized to 2.4MPa~2.6MPa by the CO2 purification tower reflux pump (17) and returned to the CO2 purification tower (12). The pressure control valve (16) of the CO2 recovery reflux tank is opened, and the non-condensable gas in the CO2 recovery reflux tank (15) enters the CO2 non-condensable gas compressor (24) and is then transported to the demethanizer tower (25).

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