Multistage separation and absorption carbon capture system

Abstract

The utility model relates to the technical field of carbon capture, in particular to a multi-stage separation and absorption carbon capture system. The carbon capture system comprises a first-stage separation and absorption module, a second-stage separation and absorption module and an analysis and regeneration module, the first-stage separation and absorption module is used for carrying out hydrogen separation on raw flue gas and absorbing carbon dioxide by utilizing barren liquor to generate tail gas and first-stage rich liquor, and the second-stage separation and absorption module is used for carrying out nitrogen separation on the tail gas and desorbing the tail gas; the first-stage separation and absorption module is used for carrying out carbon dioxide desorption on the first-stage rich solution and the second-stage rich solution to produce a first-stage rich solution, the semi-barren solution is used for absorbing carbon dioxide to produce a second-stage rich solution, the desorption and regeneration module is used for carrying out carbon dioxide desorption on the first-stage rich solution and the second-stage rich solution to produce the semi-barren solution, part of the desorbed semi-barren solution is circulated to the second-stage separation and absorption module, and the rest semi-barren solution is reproduced into barren solution According to the utility model, multi-stage separation and absorption are utilized, and through the recycling of the semi-barren liquor and the regeneration recycling of the semi-barren liquor, the demanded quantity of absorbents such as barren liquor and the like is greatly reduced, and the energy consumption and the cost are greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon capture, in particular to a multi-stage separation and absorption carbon capture system. Background Art

[0002] In recent years, carbon dioxide capture technology, as a key means of achieving carbon neutrality, has developed rapidly. Conventional carbon dioxide capture processes primarily involve introducing CO2-containing flue gas into a carbon dioxide absorption tower for carbon capture. The resulting CO2-rich liquid is then flashed to remove most of the CO2, transforming it into a semi-lean liquid. This semi-lean liquid is then regenerated and recycled through a regeneration tower.

[0003] Currently, single-stage or two-stage absorption is mostly used for carbon dioxide absorption. Single-stage absorption is to set only one level of lean liquid at the top of the absorption tower for carbon dioxide absorption. However, the demand for lean liquid is usually large, which will lead to a large amount of regeneration and circulation of semi-lean liquid, correspondingly high power consumption of the pump, low carbon dioxide capture rate, and large equipment investment. Two-stage absorption is to set semi-lean liquid in the middle of the absorption tower for primary absorption, and set lean liquid at the top of the absorption tower for secondary absorption. Although two-stage absorption can reduce the demand for semi-lean liquid regeneration and circulation, it also requires additional equipment such as semi-lean liquid pumps and heat exchangers, which will lead to a longer process flow, and the purity of the captured carbon dioxide is not high, and the equipment investment is large. Utility Model Content

[0004] The purpose of the utility model is to provide a multi-stage separation and absorption carbon capture system to solve the problems of large absorbent demand, high equipment energy consumption and high cost in the existing carbon capture process.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model discloses a multi-stage separation and absorption carbon capture system, comprising:

[0007] The first-stage separation and absorption module is used to separate hydrogen from the original flue gas and use the lean liquid to absorb carbon dioxide to produce tail gas and first-stage rich liquid;

[0008] A secondary separation and absorption module, connected to the primary separation and absorption module, for separating nitrogen from the tail gas and using the semi-lean liquid to absorb carbon dioxide to produce a secondary rich liquid;

[0009] The decomposition and regeneration module is connected to the primary separation and absorption module and the secondary separation and absorption module respectively, and is used to perform carbon dioxide decomposition on the primary rich liquid and the secondary rich liquid to produce semi-lean liquid, and circulate part of the semi-lean liquid after decomposition to the secondary separation and absorption module, and the remaining part of the semi-lean liquid is regenerated to produce lean liquid and then circulated to the primary separation and absorption module.

[0010] Optionally, the primary separation and absorption module includes a hydrogen membrane separator and a first absorption tower, the hydrogen membrane separator is provided with a first residual gas transmission pipeline connected to the bottom of the first absorption tower, the first absorption tower is provided with a first mass transfer and heat transfer unit, and the top of the first absorption tower is provided with a tail gas transmission pipeline connected to the secondary separation and absorption module, and the bottom of the first absorption tower is provided with a first rich liquid transmission pipeline connected to the analysis and regeneration module.

[0011] Optionally, the secondary separation and absorption module includes a nitrogen membrane separator and a second absorption tower, the nitrogen membrane separator is provided with a second residual gas delivery pipeline connected to the bottom of the second absorption tower, and the first absorption tower is connected to the nitrogen membrane separator through the tail gas delivery pipeline, the second absorption tower is provided with a second mass transfer and heat transfer unit, and the top of the second absorption tower is provided with an exhaust gas outlet pipeline, and the bottom of the second absorption tower is provided with a second rich liquid delivery pipeline connected to the analysis and regeneration module.

[0012] Optionally, the analytical regeneration module includes a flash tank, a regeneration tower and a reboiler.

[0013] The first absorption tower is connected to the top of the flash tank via the first rich liquid delivery pipeline, and the second absorption tower is connected to the top of the flash tank via the second rich liquid delivery pipeline. A semi-lean liquid circulation pipeline connected to the top of the second absorption tower is provided at the bottom of the flash tank, and a lean liquid circulation pipeline connected to the top of the first adsorption tower is provided at the bottom of the regeneration tower.

[0014] The semi-lean liquid circulation line is provided with a semi-lean liquid introduction line connected to the top of the regeneration tower, the bottom of the regeneration tower is provided with a semi-lean liquid outlet line connected to the reboiler, and the reboiler is provided with a lean liquid return line connected to the regeneration tower, and the tops of the flash tank and the regeneration tower are both provided with carbon dioxide outlet lines.

[0015] Optionally, the first-stage separation absorption module further includes a first rich liquid reheater, the first rich liquid reheater includes a first tube side and a first shell side, the first rich liquid delivery pipeline is connected to the first tube side, and the lean liquid circulation pipeline is connected to the first shell side.

[0016] Optionally, the secondary separation absorption module further includes a second rich liquid reheater, the second rich liquid reheater includes a second tube side and a second shell side, the second rich liquid delivery pipeline is connected to the second tube side, and the semi-lean liquid circulation pipeline is connected to the second shell side.

[0017] Optionally, the first-stage separation and absorption module further includes a first-stage rich liquid pump, which is arranged on the first rich liquid delivery pipeline; the second-stage separation and absorption module further includes a second-stage rich liquid pump, which is arranged on the second rich liquid delivery pipeline.

[0018] Optionally, the first-stage separation absorption module also includes a hydrogen induced draft fan, the hydrogen membrane separator includes a first horizontal shell and a first hollow membrane tube arranged in the first horizontal shell, the first hollow membrane tube is provided with hydrogen membrane holes for hydrogen to pass through, and the first horizontal shell is provided with a hydrogen outlet, the hydrogen induced draft fan is connected to the hydrogen outlet, a flue gas inlet corresponding to one end of the first hollow membrane tube is formed on the first horizontal shell, and the other end of the first hollow membrane tube is connected to the first residual gas transmission pipeline.

[0019] Optionally, the secondary separation absorption module also includes a nitrogen induced draft fan, the nitrogen membrane separator includes a second horizontal shell and a second hollow membrane tube arranged in the second horizontal shell, the second hollow membrane tube is provided with nitrogen membrane holes for nitrogen to pass through, and the second horizontal shell is provided with a nitrogen outlet, the nitrogen induced draft fan is connected to the nitrogen outlet, one end of the second hollow membrane tube is connected to the tail gas delivery pipeline, and the other end of the second hollow membrane tube is connected to the second residual gas delivery pipeline.

[0020] Optionally, a plurality of the first hollow membrane tubes are disposed in the first horizontal shell, and the plurality of the first hollow membrane tubes are arranged in an equilateral triangle, and the distance between any two adjacent first hollow membrane tubes is the same;

[0021] A plurality of second hollow membrane tubes are arranged in the second horizontal shell, and the plurality of second hollow membrane tubes are arranged in a regular triangle, and the distance between any two adjacent second hollow membrane tubes is consistent.

[0022] Compared with the prior art, the multi-stage separation and absorption carbon capture system provided by the embodiment of the present invention has the following advantages:

[0023] By first separating the excess gas from the flue gas, purifying the flue gas for carbon dioxide, and then using lean liquid or semi-lean liquid to absorb carbon dioxide from the remaining gas after separation, the absorption rate of carbon dioxide by the lean liquid or semi-lean liquid can be effectively improved. By setting up a primary separation and absorption module and a secondary separation and absorption module to form a multi-stage separation and absorption, on the one hand, compared with the traditional secondary absorption that is carried out in one absorption tower, the absorption tower can be greatly reduced, reducing equipment investment. On the other hand, a small amount of lean liquid is first used to absorb carbon dioxide from the remaining gas after the primary separation, and then a large amount of semi-lean liquid is used to absorb carbon dioxide from the remaining gas after the secondary separation, which can greatly reduce the amount of lean liquid used. At the same time, the analysis and regeneration module is used to circulate part of the semi-lean liquid after carbon dioxide analysis to the secondary separation and absorption module, shortening the process of the capture system for the secondary separation and absorption module, and eliminating the need for semi-lean liquid regeneration, thereby improving the capture purity of carbon dioxide and reducing the energy consumption and investment of the equipment. The analysis and regeneration module is used to regenerate part of the semi-lean liquid after carbon dioxide analysis and circulate it to the first-stage separation and absorption module. Since the first-stage separation and absorption module only requires less lean liquid, the demand for lean liquid regeneration is greatly reduced, thereby effectively reducing the power consumption of the machine pump in the first-stage separation and absorption module to improve the carbon dioxide capture rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0025] Figure 1 This is a schematic diagram of the overall structure of the multi-stage separation and absorption carbon capture system provided in an embodiment of the present invention.

[0026] The symbols in the accompanying drawings represent the following:

[0027] 1. Primary separation and absorption module; 11. Hydrogen membrane separator; 12. First absorption tower; 13. First residual gas transmission pipeline; 14. Tail gas transmission pipeline; 15. First rich liquid transmission pipeline; 16. First rich liquid reheater; 17. Primary rich liquid pump; 18. Hydrogen induced draft fan; 2. Secondary separation and absorption module; 21. Nitrogen membrane separator; 22. Second absorption tower; 23. Second residual gas transmission pipeline; 24. Waste gas outlet pipeline; 25. Second rich liquid transmission pipeline; 26. Second rich liquid reheater; 27. Second rich liquid pump; 28. Nitrogen induced draft fan; 3. Analysis and regeneration module; 31. Flash tank; 32. Regeneration tower; 33. Reboiler; 34. Semi-lean liquid circulation pipeline; 35. Lean liquid circulation pipeline; 36. Semi-lean liquid inlet pipeline; 37. Semi-lean liquid outlet pipeline; 38. Lean liquid return pipeline; 39. Carbon dioxide outlet pipeline. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. Now, in conjunction with the accompanying drawings, a detailed description of the preferred embodiments of the present utility model will be given.

[0029] The utility model discloses a carbon capture system with multi-stage separation and absorption, such as Figure 1 Shown, including:

[0030] The first-stage separation and absorption module 1 is used to separate hydrogen from the original flue gas and use the lean liquid to absorb carbon dioxide to produce tail gas and first-stage rich liquid;

[0031] The secondary separation and absorption module 2 is connected to the primary separation and absorption module and is used to separate nitrogen from the tail gas and absorb carbon dioxide with the semi-lean liquid to produce a secondary rich liquid;

[0032] The analysis and regeneration module 3 is connected to the primary separation and absorption module 1 and the secondary separation and absorption module 2, respectively, and is used to analyze the primary rich liquid and the secondary rich liquid for carbon dioxide to produce a semi-lean liquid, and circulate part of the analyzed semi-lean liquid to the secondary separation and absorption module 2, and the remaining part of the semi-lean liquid to regenerate the lean liquid and circulate it to the primary separation and absorption module 1.

[0033] Through the implementation of the above-described multi-stage separation and absorption carbon capture system, the flue gas is first separated from the excess gases and then purified for carbon dioxide, i.e., hydrogen and nitrogen are filtered out to increase the carbon dioxide content in the flue gas. Lean or semi-lean liquid is then used to absorb carbon dioxide from the remaining gas after separation, effectively improving the absorption rate of the lean or semi-lean liquid for carbon dioxide. On this basis, the combination of the primary separation and absorption module 1 and the secondary separation and absorption module 2 forms a multi-stage separation and absorption system. Compared to traditional two-stage absorption systems, which are performed within a single absorption tower, this significantly reduces the size of the absorption tower and the corresponding equipment costs. Furthermore, a relatively small amount of lean liquid is first used to absorb carbon dioxide from the remaining gas separated from hydrogen, completing primary carbon capture. The remaining tail gas after primary carbon capture is then passed into the secondary separation and absorption module 2, where a relatively large amount of semi-lean liquid is used to deeply absorb carbon dioxide from the remaining gas separated from nitrogen, completing secondary carbon capture. This improves carbon capture efficiency while significantly reducing the amount of lean liquid used. In addition, the analytical regeneration module 3 is used to circulate part of the semi-lean liquid after carbon dioxide analysis to the secondary separation absorption module 2, thereby shortening the process of the capture system for the secondary separation absorption module, and eliminating the need to set up semi-lean liquid regeneration, thereby improving the capture purity of carbon dioxide and significantly reducing energy consumption and costs. The analytical regeneration module 3 is also used to regenerate part of the semi-lean liquid after carbon dioxide analysis and circulate it to the primary separation absorption module 1. Since the primary separation absorption module 1 only requires less lean liquid, and the secondary separation absorption module 2 has more semi-lean liquid, the need for lean liquid regeneration is greatly reduced, and sufficient regenerated lean liquid is ensured to be provided to the primary separation absorption module 1, thereby effectively reducing the power consumption of the pump in the primary separation absorption module 1 and improving the capture rate of carbon dioxide.

[0034] Furthermore, the primary separation and absorption module 1 includes a hydrogen membrane separator 11 and a first absorption tower 12. A first residual gas delivery pipeline 13 is provided on the hydrogen membrane separator 11 and connected to the bottom of the first absorption tower 12. A first mass and heat transfer unit is provided within the first absorption tower 12, and a tail gas delivery pipeline 14 is provided at the top of the first absorption tower 12 and connected to the secondary separation and absorption module 2. A first rich liquid delivery pipeline 15 is provided at the bottom of the first absorption tower 12 and connected to the analytical regeneration module 3.

[0035] Through the implementation of the above-mentioned multi-stage separation and absorption carbon capture system, the hydrogen in the original flue gas is separated by using the hydrogen membrane separator 11, and the first-level residual gas from which the hydrogen is separated is introduced into the first absorption tower 12 from the bottom of the first absorption tower 12, so that the first-level residual gas and a relatively small amount of lean liquid absorb carbon dioxide in the first absorption tower 12, and the use of the first mass transfer and heat transfer unit helps to improve the efficiency of the absorption process. The tail gas after absorption is collected at the top of the first absorption tower 12 and transported to the secondary separation absorption module 2 through the tail gas delivery pipeline 14, and the first-level rich liquid after absorption is collected at the bottom of the first absorption tower 12 and transported to the analysis and regeneration module 3 through the first rich liquid delivery pipeline 15. The above-mentioned structural arrangement helps to improve the stability and reliability of the long-term operation of the entire system.

[0036] Furthermore, the secondary separation and absorption module 2 includes a nitrogen membrane separator 21 and a second absorption tower 22. A second residual gas delivery pipeline 23 connected to the bottom of the second absorption tower 22 is provided on the nitrogen membrane separator 21, and the first absorption tower 12 is connected to the nitrogen membrane separator 21 via a tail gas delivery pipeline 14. A second mass and heat transfer unit is provided in the second absorption tower 22, and an exhaust gas outlet pipeline 24 is provided at the top of the second absorption tower 22. A second rich liquid delivery pipeline 25 connected to the analytical regeneration module 3 is provided at the bottom of the second absorption tower 22.

[0037] Through the implementation of the above-mentioned multi-stage separation and absorption carbon capture system, the hydrogen in the tail gas is separated by using a nitrogen membrane separator 21, and the secondary residual gas from which the nitrogen is separated is introduced into the second absorption tower 22 from the bottom of the second absorption tower 22, so that the secondary residual gas and a relatively large amount of semi-lean liquid absorb carbon dioxide in the second absorption tower 22, and the secondary separation and secondary absorption treatment of the tail gas after the first-stage absorption are completed, thereby improving the carbon capture efficiency and the purity of the captured carbon dioxide. The use of the second mass transfer and heat transfer unit helps to improve the efficiency of the absorption process. The waste gas after absorption is collected at the top of the second absorption tower 22 and discharged through the waste gas outlet pipeline 24, and the secondary rich liquid after absorption is collected at the bottom of the second absorption tower 22 and transported to the analysis and regeneration module 3 through the second rich liquid delivery pipeline 25. The above-mentioned structural arrangement helps to improve the stability and reliability of the long-term operation of the entire system.

[0038] Furthermore, the analytical regeneration module 3 includes a flash tank 31, a regeneration tower 32 and a reboiler 33.

[0039] The first absorption tower 12 is connected to the top of the flash tank 31 via a first rich liquid delivery line 15, and the second absorption tower 22 is connected to the top of the flash tank 31 via a second rich liquid delivery line 25. A semi-lean liquid circulation line 34 connected to the top of the second absorption tower 22 is provided at the bottom of the flash tank 31, and a lean liquid circulation line 35 connected to the top of the first adsorption tower is provided at the bottom of the regeneration tower 32.

[0040] A semi-lean liquid inlet line 36 is provided on the semi-lean liquid circulation line 34, connected to the top of the regeneration tower 32. A semi-lean liquid outlet line 37 is provided at the bottom of the regeneration tower 32, connected to the reboiler 33. The reboiler 33 is provided with a lean liquid return line 38, connected to the regeneration tower 32. A carbon dioxide outlet line 39 is provided at the top of both the flash tank 31 and the regeneration tower 32.

[0041] Through the implementation of the above-mentioned multi-stage separation and absorption carbon capture system, the flash tank 31 is preferably equipped with heating and heat preservation, and has a hollow structure inside. After the flash tank 31 is used to collect the first-stage rich liquid and the second-stage rich liquid, carbon dioxide is then analyzed to separate carbon dioxide from the mixed rich liquid, and the separated carbon dioxide is drawn out through the carbon dioxide outlet line 39 at the top of the flash tank 31. At this time, the mixed liquid inside the flash tank 31 becomes a semi-lean liquid due to the decomposition of most of the carbon dioxide. Part of the semi-lean liquid in the flash tank 31 is directly circulated to the second adsorption tower through the semi-lean liquid circulation line 34 to recycle the semi-lean liquid and ensure that there is enough semi-lean liquid for carbon dioxide absorption in the second adsorption tower. At the same time, the remaining semi-lean liquid in the flash tank 31 is introduced into the regeneration tower 32 through the semi-lean liquid introduction line 36, and regenerated through the reboiler 33 to obtain lean liquid, which is then introduced back into the regeneration tower 32 to achieve the regeneration of part of the semi-lean liquid, without consuming a large amount of steam to provide a heat source for lean liquid regeneration. The regenerated lean liquid is then circulated to the first adsorption tower via lean liquid circulation line 35 for regeneration and recycling of the semi-lean liquid. This significantly reduces the need for lean liquid regeneration and ensures sufficient regenerated lean liquid is available for carbon dioxide absorption in the first adsorption tower, effectively reducing the power consumption of the pump in the primary separation and absorption module 1 and improving the carbon dioxide capture rate. Furthermore, the carbon dioxide produced after regeneration of the semi-lean liquid in regeneration tower 32 is removed via a carbon dioxide extraction line 39 at the top of regeneration tower 32. This combined process of flash evaporation, regeneration, and circulation effectively separates carbon dioxide from the regenerated absorbent, improving the performance and stability of the entire system.

[0042] Furthermore, the primary separation absorption module 1 further includes a first rich liquid reheater 16. The first rich liquid reheater 16 includes a first tube side and a first shell side, the first rich liquid delivery pipeline 15 is connected to the first tube side, and the lean liquid circulation pipeline 35 is connected to the first shell side.

[0043] Furthermore, the secondary separation absorption module 2 further includes a second rich liquid reheater 26. The second rich liquid reheater 26 includes a second tube side and a second shell side, a second rich liquid delivery pipeline 25 is connected to the second tube side, and a semi-lean liquid circulation pipeline 34 is connected to the second shell side.

[0044] Through the implementation of the above-described multi-stage separation and absorption carbon capture system, the first rich liquid reheater 16 allows the primary rich liquid in the first rich liquid transfer line 15 to exchange heat with the heat exchange medium in the first tube side, raising the temperature of the primary rich liquid and making it easier to process. Simultaneously, the regenerated lean liquid in the lean liquid circulation line 35 exchanges heat with the heat exchange medium in the first shell side, cooling the regenerated lean liquid and improving the capture efficiency of the lean liquid during reuse. Furthermore, the second rich liquid reheater 26 allows the secondary rich liquid in the second rich liquid transfer line 25 to exchange heat with the heat exchange medium in the second tube side, raising the temperature of the secondary rich liquid and making it easier to process. Furthermore, the semi-lean liquid in the semi-lean liquid circulation line 34 exchanges heat with the heat exchange medium in the second shell side, cooling the semi-lean liquid and improving the capture efficiency of the semi-lean liquid during reuse. This configuration eliminates the need for additional equipment such as heat exchangers, thereby shortening the process flow and significantly reducing equipment investment.

[0045] Furthermore, the primary separation absorption module 1 further includes a primary rich liquid pump 17 disposed on the first rich liquid delivery pipeline 15 . The secondary separation absorption module 2 further includes a secondary rich liquid pump 27 disposed on the second rich liquid delivery pipeline 25 .

[0046] Through the implementation of the above-mentioned multi-stage separation and absorption carbon capture system, the first-stage rich liquid pump 17 is used to control the delivery of the first-stage rich liquid in the first rich liquid delivery pipeline 15, and the second-stage rich liquid pump 27 is used to control the delivery of the second-stage rich liquid in the second rich liquid delivery pipeline 25. The pressure and flow rate of the rich liquid during the delivery process can be accurately controlled to improve the delivery efficiency and ensure that the rich liquid can be stably supplied to the next processing module.

[0047] Furthermore, the primary separation absorption module 1 also includes a hydrogen induced draft fan 18. The hydrogen membrane separator 11 includes a first horizontal shell and a first hollow membrane tube disposed within the first horizontal shell. The first hollow membrane tube is provided with hydrogen membrane holes for hydrogen to pass through, and the first horizontal shell is provided with a hydrogen outlet. The hydrogen induced draft fan 18 is connected to the hydrogen outlet. The first horizontal shell is formed with a flue gas inlet corresponding to one end of the first hollow membrane tube, and the other end of the first hollow membrane tube is connected to the first residual gas delivery pipeline 13.

[0048] Through the implementation of the above-described multi-stage separation and absorption carbon capture system, a negative pressure is generated within the first horizontal shell by a hydrogen induced draft fan 18. Furthermore, hydrogen is rapidly separated from the raw flue gas through the hydrogen membrane pores, which only allow hydrogen to pass through, in the first hollow membrane tubes under the action of the negative pressure. The hydrogen is then extracted through the hydrogen outlet by the hydrogen induced draft fan 18. Simultaneously, the first-stage residual gas from which hydrogen has been separated cannot pass through the hydrogen membrane pores and is therefore transported exclusively to the first absorption tower 12 via the first residual gas delivery pipeline 13. This achieves efficient hydrogen separation and increases the carbon dioxide concentration in the first-stage residual gas.

[0049] Furthermore, the secondary separation and absorption module 2 also includes a nitrogen induced draft fan 28. The nitrogen membrane separator 21 includes a second horizontal shell and a second hollow membrane tube disposed within the second horizontal shell. The second hollow membrane tube is provided with nitrogen membrane holes for nitrogen to pass through, and the second horizontal shell is provided with a nitrogen outlet. The nitrogen induced draft fan 28 is connected to the nitrogen outlet. One end of the second hollow membrane tube is connected to the tail gas delivery pipeline 14, and the other end of the second hollow membrane tube is connected to the second residual gas delivery pipeline 23.

[0050] Through the implementation of the multi-stage separation and absorption carbon capture system described above, a nitrogen induced draft fan 28 creates a negative pressure within the second horizontal shell. Nitrogen is rapidly separated from the tail gas through the nitrogen membrane pores in the second hollow membrane tube, which only allow nitrogen to pass through, under the action of the negative pressure. The nitrogen is then extracted by nitrogen induced draft fan 28 through the nitrogen outlet, completing a secondary separation of the tail gas after primary separation and absorption, further separating the nitrogen therein. Simultaneously, the secondary residual gas from which nitrogen has been separated cannot pass through the nitrogen membrane pores and is therefore transported exclusively to the second absorption tower 22 via the second residual gas delivery pipeline 23. This achieves efficient nitrogen separation and increases the concentration of carbon dioxide in the secondary residual gas.

[0051] Furthermore, a plurality of first hollow membrane tubes are provided in the first horizontal shell, and the plurality of first hollow membrane tubes are arranged in an equilateral triangle, and the distance between any two adjacent first hollow membrane tubes is the same;

[0052] A plurality of second hollow membrane tubes are arranged in the second horizontal shell, and the plurality of second hollow membrane tubes are arranged in a regular triangle, and the distance between any two adjacent second hollow membrane tubes is consistent.

[0053] By implementing the aforementioned multi-stage separation and absorption carbon capture system, the arrangement of multiple first and second hollow membrane tubes enables simultaneous multi-channel residual gas transport, improving residual gas transport efficiency. The equilateral triangle arrangement ensures uniform distribution of the multiple first and second hollow membrane tubes within their corresponding housings, allowing residual gas to flow more evenly through each tube, improving separation efficiency. Furthermore, it enhances the structural stability of the entire system, making it resilient to external pressure and vibration. Furthermore, the consistent spacing between any two adjacent hollow membrane tubes helps maintain stable fluid flow, reducing flow resistance and localized pressure drop, thereby ensuring stable operation of the entire module.

[0054] The specific working process of the multi-stage separation and absorption carbon capture system of the utility model is as follows:

[0055] Flue gas containing carbon dioxide enters the hydrogen membrane separator 11 and flows along the first hollow membrane tube, allowing hydrogen contained in the flue gas to permeate the hydrogen membrane pores and be extracted by the hydrogen induced draft fan 18. The primary residual gas from which hydrogen is separated is transported via the first residual gas transmission pipeline 13 to the first absorption tower 12 for the primary absorption reaction of carbon dioxide. The separated hydrogen is then guided to the downstream system by the hydrogen induced draft fan 18.

[0056] The primary residual gas and a relatively small amount of lean liquid undergo mass and heat transfer in the first mass and heat transfer unit within the first absorption tower 12 to carry out the primary absorption reaction of carbon dioxide. The absorbed tail gas is collected at the top of the first absorption tower 12 and transported to the nitrogen membrane separator 21 via the tail gas pipeline 14. The absorbed primary rich liquid is collected at the bottom of the first absorption tower 12 and transported to the flash tank 31 via the first rich liquid pipeline 15 after waste heat recovery in the first rich liquid reheater 16.

[0057] The tail gas containing residual carbon dioxide enters the nitrogen membrane separator 21 and flows along the second hollow membrane tube. The nitrogen contained in the tail gas passes through the nitrogen membrane pores and is extracted by the nitrogen induced draft fan 28. The secondary residual gas from which the nitrogen is separated is transported through the second residual gas transmission pipeline 23 to the second absorption tower 22 for the secondary absorption reaction of carbon dioxide. The separated nitrogen is then guided to the downstream system by the nitrogen induced draft fan 28.

[0058] The secondary residual gas and a relatively large amount of semi-lean liquid undergo mass and heat transfer in the second mass and heat transfer unit within the second absorption tower 22 to carry out the secondary absorption reaction of carbon dioxide. The absorbed waste gas is collected at the top of the second absorption tower 22 and discharged through the waste gas outlet pipeline 24. The absorbed secondary rich liquid is collected at the bottom of the second absorption tower 22 and transported to the flash tank 31 through the second rich liquid transfer pipeline 25 after waste heat recovery in the second rich liquid reheater 26.

[0059] The first-stage rich liquid and the second-stage rich liquid enter the flash tank 5 for decomposition reaction, releasing a large amount of carbon dioxide gas and generating semi-lean liquid. The separated carbon dioxide is led to the downstream system through the carbon dioxide lead-out line 39 at the top of the flash tank 31. The semi-lean liquid generated, one way is to directly circulate part of the semi-lean liquid in the flash tank 31 through the semi-lean liquid circulation line 34 after the waste heat is recovered in the second rich liquid reheater 26 to the second adsorption tower; the other way is to introduce the remaining semi-lean liquid in the flash tank 31 into the regeneration tower 32 through the semi-lean liquid introduction line 36, and regenerate it through the reboiler 33 to obtain lean liquid, which is then led back to the regeneration tower 32. The regenerated lean liquid is then circulated to the first adsorption tower through the lean liquid circulation line 35 after the waste heat is recovered in the first rich liquid reheater 16.

[0060] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art may modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A multi-stage separation and absorption carbon capture system, characterized in that: The carbon capture system comprises: The first-stage separation and absorption module is used to separate hydrogen from the original flue gas and use the lean liquid to absorb carbon dioxide to produce tail gas and first-stage rich liquid; A secondary separation and absorption module, connected to the primary separation and absorption module, is used to separate nitrogen from the tail gas and absorb carbon dioxide using the semi-lean liquid to produce a secondary rich liquid; The decomposition and regeneration module is connected to the primary separation and absorption module and the secondary separation and absorption module respectively, and is used to perform carbon dioxide decomposition on the primary rich liquid and the secondary rich liquid to produce semi-lean liquid, and circulate part of the semi-lean liquid after decomposition to the secondary separation and absorption module, and the remaining part of the semi-lean liquid is regenerated to produce lean liquid and then circulated to the primary separation and absorption module.

2. The multi-stage separation and absorption carbon capture system according to claim 1, characterized in that: The primary separation and absorption module includes a hydrogen membrane separator and a first absorption tower. The hydrogen membrane separator is provided with a first residual gas transmission pipeline connected to the bottom of the first absorption tower. A first mass transfer and heat transfer unit is provided in the first absorption tower. The top of the first absorption tower is provided with a tail gas transmission pipeline connected to the secondary separation and absorption module, and the bottom of the first absorption tower is provided with a first rich liquid transmission pipeline connected to the analysis and regeneration module.

3. The multi-stage separation and absorption carbon capture system according to claim 2, characterized in that: The secondary separation and absorption module includes a nitrogen membrane separator and a second absorption tower. The nitrogen membrane separator is provided with a second residual gas transmission pipeline connected to the bottom of the second absorption tower, and the first absorption tower is connected to the nitrogen membrane separator through the tail gas transmission pipeline. A second mass and heat transfer unit is provided in the second absorption tower, and an exhaust gas outlet pipeline is provided at the top of the second absorption tower. A second rich liquid transmission pipeline connected to the analytical regeneration module is provided at the bottom of the second absorption tower.

4. The multi-stage separation and absorption carbon capture system according to claim 3, characterized in that: The analytical regeneration module includes a flash tank, a regeneration tower and a reboiler. The first absorption tower is connected to the top of the flash tank via the first rich liquid delivery pipeline, and the second absorption tower is connected to the top of the flash tank via the second rich liquid delivery pipeline. A semi-lean liquid circulation pipeline connected to the top of the second absorption tower is provided at the bottom of the flash tank, and a lean liquid circulation pipeline connected to the top of the first absorption tower is provided at the bottom of the regeneration tower. The semi-lean liquid circulation line is provided with a semi-lean liquid introduction line connected to the top of the regeneration tower, the bottom of the regeneration tower is provided with a semi-lean liquid outlet line connected to the reboiler, and the reboiler is provided with a lean liquid return line connected to the regeneration tower, and the tops of the flash tank and the regeneration tower are both provided with carbon dioxide outlet lines.

5. The multi-stage separation and absorption carbon capture system according to claim 4, characterized in that: The primary separation absorption module further includes a first rich liquid reheater, which includes a first tube side and a first shell side. The first rich liquid delivery pipeline is connected to the first tube side, and the lean liquid circulation pipeline is connected to the first shell side.

6. The multi-stage separation and absorption carbon capture system according to claim 4, characterized in that: The secondary separation absorption module further includes a second rich liquid reheater, which includes a second tube side and a second shell side. The second rich liquid delivery pipeline is connected to the second tube side, and the semi-lean liquid circulation pipeline is connected to the second shell side.

7. The multi-stage separation and absorption carbon capture system according to claim 4, characterized in that: The primary separation and absorption module further includes a primary rich liquid pump, which is disposed on the first rich liquid delivery pipeline. The secondary separation and absorption module further includes a secondary rich liquid pump, which is disposed on the second rich liquid delivery pipeline.

8. The multi-stage separation and absorption carbon capture system according to any one of claims 3 to 7, characterized in that: The first-stage separation absorption module also includes a hydrogen induced draft fan, and the hydrogen membrane separator includes a first horizontal shell and a first hollow membrane tube arranged in the first horizontal shell, the first hollow membrane tube is provided with hydrogen membrane holes for hydrogen to pass through, and the first horizontal shell is provided with a hydrogen outlet, the hydrogen induced draft fan is connected to the hydrogen outlet, a flue gas inlet corresponding to one end of the first hollow membrane tube is formed on the first horizontal shell, and the other end of the first hollow membrane tube is connected to the first residual gas transmission pipeline.

9. The multi-stage separation and absorption carbon capture system according to claim 8, characterized in that: The secondary separation and absorption module also includes a nitrogen induced draft fan, and the nitrogen membrane separator includes a second horizontal shell and a second hollow membrane tube arranged in the second horizontal shell, the second hollow membrane tube is provided with nitrogen membrane holes for nitrogen to pass through, and the second horizontal shell is provided with a nitrogen outlet, the nitrogen induced draft fan is connected to the nitrogen outlet, one end of the second hollow membrane tube is connected to the tail gas delivery pipeline, and the other end of the second hollow membrane tube is connected to the second residual gas delivery pipeline.

10. The multi-stage separation and absorption carbon capture system according to claim 9, characterized in that: A plurality of the first hollow membrane tubes are arranged in the first horizontal shell, and the plurality of the first hollow membrane tubes are arranged in an equilateral triangle, and the distance between any two adjacent first hollow membrane tubes is the same; A plurality of second hollow membrane tubes are arranged in the second horizontal shell, and the plurality of second hollow membrane tubes are arranged in a regular triangle, and the distance between any two adjacent second hollow membrane tubes is consistent.

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