A mixed amine decarbonation system

Abstract

This invention belongs to the field of carbon dioxide capture technology and relates to a mixed amine decarbonization system, comprising: a decarbonization unit, a decarbonization energy-saving unit, a desorption unit, and a desorption energy-saving unit. An internal circulation pipeline is formed between the decarbonization unit and the decarbonization unit. An external circulation pipeline is also formed between the decarbonization unit, the decarbonization unit, and the desorption unit, with a portion of the liquid returned to the decarbonization unit and another portion transported to the desorption unit. The desorption energy-saving unit is connected to the pipelines of the decarbonization unit, the desorption unit, and the decarbonization unit, and is used to regulate the feed state of the carbon-rich amine solution, recover heat from the desorption unit, and transport the regenerated carbon-lean amine solution back to the decarbonization unit. This invention can adapt to different operating conditions, amine solution types, and processing scales, effectively reducing unit energy consumption while ensuring a high CO2 processing capacity, exhibiting significant economic and environmental benefits, and providing an efficient and feasible solution for industrial decarbonization.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide capture technology, specifically relating to a mixed amine decarbonization system. Background Technology

[0002] Currently, flue gas from industrial sectors (such as thermal power generation, cement, steel, and chemical industries) is the main source of CO2 emissions. For these flue gas sources with low partial pressure (typically 3%–15% by volume) and large flow rates, post-combustion carbon capture technology is the most widely used and has the greatest potential for modification. Among existing post-combustion carbon capture technologies, chemical absorption has become the mainstream in industrial applications due to its advantages such as fast absorption rate, high capture efficiency, and high technological maturity. This process typically utilizes an alkaline absorbent (such as an alkanolamine solution) to chemically react with CO2 in the flue gas within an absorption tower, and then the solution is passed through a rich-liquid desorption tower for heating and decomposition, thereby achieving CO2 separation and recovery.

[0003] However, existing post-combustion trapping systems have excessively high regeneration energy consumption: traditional organic amine absorbents (such as monoethanolamine MEA) require a large amount of steam heat energy (typically as high as 3.5-4.2 GJ·tCO2) during desorption. -1 This results in high operating costs for carbon capture systems, which greatly limits their large-scale commercialization.

[0004] Therefore, a low-cost, high-capture-efficiency carbon dioxide capture system is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention reduces the energy consumption of the decarbonization system by regulating the temperature distribution of key equipment and the liquid circulation volume within the system through decarbonization and desorption energy-saving processes.

[0006] This invention provides the following technical solution: a mixed amine decarbonization system, comprising: a decarbonization unit for reacting CO2-rich flue gas with mixed amine to generate CO2-poor gas and carbon-rich amine liquid; a decarbonization energy-saving unit for interstage cooling or reactor liquid circulation cooling of the amine liquid in the decarbonization unit to regulate the temperature of the decarbonization unit, improve CO2 absorption efficiency, and recover energy; a desorption unit for heating and regenerating the carbon-rich amine liquid to separate CO2 from the carbon-rich amine liquid, obtaining high-purity CO2 gas and carbon-poor amine liquid; and a desorption energy-saving unit for recovering heat from the desorption unit and optimizing heat distribution to reduce the energy consumption of amine liquid regeneration. An internal circulation pipeline is formed between the decarbonization energy-saving unit and the decarbonization unit to draw out and cool part of the amine liquid in the decarbonization unit and send it back to the decarbonization unit. The decarbonization energy-saving unit also forms an external circulation pipeline with the decarbonization unit and the desorption unit to cool the carbon-rich amine liquid discharged from the decarbonization unit, send part of it back to the decarbonization unit, and send the other part to the desorption unit. The desorption energy-saving unit is connected to the pipelines of the decarbonization energy-saving unit, the desorption unit, and the decarbonization unit respectively, and is used to regulate the feeding state of the carbon-rich amine liquid, recover the heat of the desorption unit, and send the regenerated carbon-lean amine liquid back to the decarbonization unit.

[0007] Preferably, the decarbonization energy-saving unit employs both interstage cooling and reactor liquid circulation cooling: interstage cooling draws out a portion of the amine liquid from the decarbonization unit, cools it, and then returns it to the decarbonization unit; reactor liquid circulation cooling cools the carbon-rich amine liquid discharged from the decarbonization unit, with a portion flowing back to the decarbonization unit and a portion being transported to the desorption unit. The desorption energy-saving unit regulates the temperature of the carbon-rich amine liquid from the decarbonization energy-saving unit before sending it to different parts of the desorption unit; the desorption energy-saving unit receives the carbon-lean amine liquid from the desorption unit, recovers heat to generate a high-temperature gas phase, and sends it back to the desorption unit, while also transporting the cooled carbon-lean amine liquid to the decarbonization unit. The desorption energy-saving unit achieves heat recovery and distribution using one or more of the following methods: rich liquid diversion, side-stream reheat, negative pressure flash evaporation, or heat pump compression.

[0008] Preferably, the decarbonization unit includes: an amine liquid storage tank and an amine liquid decarbonization tower. The inlet of the amine liquid storage tank is connected to an amine solution source, and the outlet of the amine liquid storage tank is connected to an amine solution inlet at the top of the amine liquid decarbonization tower. The bottom of the amine liquid decarbonization tower is provided with a carbon-rich flue gas inlet and a carbon-rich amine liquid outlet. The carbon-rich flue gas inlet is connected to a CO2-rich flue gas source. Inside the amine liquid decarbonization tower, the amine solution flowing from top to bottom reacts with the CO2-rich flue gas flowing from bottom to top to generate carbon-rich amine liquid, which flows out from the carbon-rich amine liquid outlet.

[0009] More preferably, the decarbonization energy-saving unit includes: an interstage cooling heat exchanger, a first side-line extraction pump, a rich liquid temporary storage tank, a vessel liquid circulation pump, and a vessel liquid cooler. The inlet of the first side-line extraction pump is connected to the inner cavity of the amine decarbonization tower at the upper side wall, and the outlet of the first side-line extraction pump is connected to the condenser end inlet of the interstage cooling heat exchanger. The condenser end outlet of the interstage cooling heat exchanger is connected to the inner cavity of the amine decarbonization tower at the lower side wall. The rich amine liquid outlet at the bottom of the amine decarbonization tower is connected to the inlet of the rich liquid temporary storage tank. One outlet of the rich liquid temporary storage tank is connected to the inlet of the vessel liquid cooler via the vessel liquid circulation pump. The outlet of the vessel liquid cooler is connected to the inner cavity of the amine decarbonization tower at the lower side wall. The other outlet of the rich liquid temporary storage tank is connected to a desorption unit or a desorption energy-saving unit.

[0010] More preferably, the operating temperature of the condenser end of the interstage cooling heat exchanger is set to 20-50°C, the operating pressure of the first side line extraction pump is set to 1-30 bar, the operating pressure of the reactor liquid circulation pump is set to 1-30 bar, and the operating temperature of the reactor liquid cooler is set to 20-50°C.

[0011] Preferably, the desorption unit includes: a rich liquid stream heat exchanger and a desorption tower. The evaporation end inlet of the rich liquid stream heat exchanger is connected to a rich amine liquid source, and the evaporation end outlet of the rich liquid stream heat exchanger is connected to the desorption tower. The top of the desorption tower is provided with a rich CO2 gas outlet, and the bottom of the desorption tower is provided with a hot lean liquid outlet. The hot lean liquid outlet is connected to the condensation end inlet of the rich liquid stream heat exchanger, and the condensation end outlet of the rich liquid stream heat exchanger is connected to an amine solution source.

[0012] More preferably, the desorption energy-saving unit includes: a rich liquid distributor, an interstage reheat heat exchanger, a second side-stream extraction pump, a negative pressure flash tank, and a heat pump. The inlet of the rich liquid distributor is connected to a rich amine liquid source, one outlet of the rich liquid distributor is connected to the evaporation end inlet of the rich liquid stream heat exchanger, and the other outlet of the rich liquid distributor connects from the upper part of the desorption tower to the inner cavity of the desorption tower. The upper inner cavity of the desorption tower is also connected to the inlet of the second side-stream extraction pump, the outlet of the second side-stream extraction pump is connected to the evaporation end inlet of the interstage reheat heat exchanger, and the evaporation end outlet of the interstage reheat heat exchanger connects from the middle of the desorption tower to the inner cavity of the desorption tower. The hot lean liquid outlet at the bottom of the desorption tower is connected to the inlet of the negative pressure flash tank, one outlet of the negative pressure flash tank connects from the middle of the desorption tower to the inner cavity of the desorption tower via the heat pump; the other outlet of the negative pressure flash tank connects to the condensation end inlet of the rich liquid stream heat exchanger.

[0013] More preferably, the flow ratio of the rich liquid distributor to the rich liquid stream heat exchanger and the self-desorption tower is 0.1 to 0.6, the operating temperature of the evaporator end of the interstage reheat heat exchanger is 90 to 120°C, the operating pressure of the second side line extraction pump is 1 to 30 bar, the operating pressure of the negative pressure flash tank is 0.1 to 0.9 bar, and the compression ratio of the heat pump is 1.1 to 10.

[0014] This invention first introduces CO2-rich flue gas into a decarbonization unit, where it reacts with a mixed amine absorbent to generate CO2-poor gas and CO2-rich amine liquid (carbon-rich amine liquid). The carbon-rich amine liquid then enters a desorption unit, where it releases high-purity CO2 gas through desorption and is regenerated into carbon-poor amine liquid, which is then returned to the decarbonization unit for recycling. By incorporating various structural forms of decarbonization and desorption energy-saving units, the system achieves tiered utilization of internal heat and precise control of stream temperatures. For example, interstage cooling of the amine liquid in the decarbonization tower optimizes the absorption temperature, while operations such as diversion, reheating, and heat pump flash evaporation of the amine liquid in the desorption tower reduce desorption energy consumption. Ultimately, the entire decarbonization system achieves efficient CO2 capture while significantly reducing system operating energy consumption.

[0015] The beneficial effects of this invention are: 1. This invention achieves tiered utilization and precise control of internal heat by setting up decarbonization and desorption energy-saving units. For example, interstage cooling of the amine liquid in the decarbonization tower optimizes the absorption temperature and improves the absorption efficiency; reheating or heat pump flash evaporation of the amine liquid in the desorption tower reduces the energy consumption of the regeneration process, thereby significantly reducing the operating cost of the entire system.

[0016] 2. This invention has high absorption and desorption efficiency, solving the problem of efficient CO2 absorption in the decarbonization unit, while achieving efficient CO2 release in the desorption unit, thus improving the CO2 capture purity and recovery rate.

[0017] 3. This invention allows for the flexible configuration and combination of various energy-saving units with different structural forms (such as interstage cooling, splitters, interstage reheat, heat pump flash evaporation, etc.) according to different operating conditions, amine liquid types and processing scales, making it widely applicable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a mixed amine decarbonization system according to the present invention; Figure 2 This is a flowchart of the decarbonization unit of the present invention; Figure 3 This is a flowchart of the decarbonization and energy-saving unit of the present invention.

[0019] Figure 4 This is a flowchart of the desorption unit of the present invention; Figure 5 This is a flowchart of the desorption energy-saving unit of the present invention; Figure 6 This is a flowchart of an implementation example of the present invention.

[0020] In the diagram, 1. Decarbonization unit; 2. Decarbonization energy-saving unit; 3. Desorption unit; 4. Desorption energy-saving unit; 5. Amine liquid storage tank; 6. Amine liquid decarbonization tower; 7. Interstage cooling heat exchanger; 8. First side-stream extraction pump; 9. Rich liquid temporary storage tank; 10. Reactor liquid circulation pump; 11. Reactor liquid cooler; 12. Rich liquid stream heat exchanger; 13. Desorption tower; 14. Rich liquid distributor; 15. Interstage reheat heat exchanger; 16. Second side-stream extraction pump; 17. Negative pressure flash tank; 18. Heat pump. Detailed Implementation

[0021] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] like Figures 1-6 As shown, a mixed amine decarbonization system includes a decarbonization unit 1, a decarbonization energy-saving unit 2, a desorption unit 3, and a desorption energy-saving unit 4. CO2-rich flue gas is introduced into the decarbonization unit 1 and reacts with the mixed amine. After being treated by the decarbonization unit 1, CO2-poor gas and carbon-rich amine liquid are generated. The carbon-rich amine liquid includes CO2 and various amine absorbents (not limited to aqueous solutions and organic mixtures of monoamines and mixed amines). The carbon-rich amine liquid is then introduced into the desorption unit 3.

[0023] There are two structures for the connection between decarbonization unit 1 and decarbonization energy-saving unit 2. In the first structure, the carbon-rich amine liquid from decarbonization unit 1 is introduced into decarbonization energy-saving unit 2. After being processed by decarbonization energy-saving unit 2, the carbon-rich amine liquid at a lower temperature is obtained. Part of the cooled carbon-rich amine liquid is output to decarbonization unit 1, and the remainder is output to desorption unit 3. In the second structure, part of the amine liquid inside decarbonization unit 1 is introduced into decarbonization energy-saving unit 2. After being processed by decarbonization energy-saving unit 2, the amine liquid at a lower temperature is obtained. The cooled amine liquid is then output to decarbonization unit 1.

[0024] There are two structures for the connection between the decarbonization energy-saving unit 2 and the desorption unit 3. In the first structure, the carbon-rich amine liquid from the decarbonization energy-saving unit 2 enters the desorption unit 3, and the desorption unit 3 outputs high-purity CO2 gas and carbon-lean amine liquid through desorption. After that, the carbon-lean amine liquid is cooled and returns to the decarbonization unit 1. In the second structure, the carbon-rich amine liquid from the decarbonization energy-saving unit 2 enters the desorption energy-saving unit 4, and the energy-saving unit 4 distributes the carbon-rich amine liquid into different parts of the desorption unit 3.

[0025] There are two structures for the connection between desorption unit 3 and desorption energy-saving unit 4. In the first structure, the carbon-rich amine liquid from desorption unit 3 is introduced into desorption energy-saving unit 4 and regulated to a certain temperature by desorption energy-saving unit 4; the temperature-controlled carbon-rich amine liquid returns to desorption unit 3. In the second structure, the carbon-poor amine liquid from desorption unit 3 is introduced into desorption energy-saving unit 4 and processed by desorption energy-saving unit 4 to obtain a high-temperature gas phase; the high-temperature gas phase returns to desorption unit 3, and the remaining liquid is cooled and returned to decarbonization unit 1.

[0026] Furthermore, the decarbonization unit 1 includes an amine liquid storage tank 5 and an amine liquid decarbonization tower 6, wherein: CO2-rich flue gas enters the bottom of the amine liquid decarbonization tower 6 through a pipeline, and the flue gas entering the amine liquid decarbonization tower 6 reacts with the amine solution transported from the amine liquid storage tank 5 from bottom to top. After decarbonization, the flue gas is discharged from the top of the amine liquid decarbonization tower 6, and the amine solution from top to bottom becomes carbon-rich amine liquid and is output from the bottom of the tower.

[0027] Furthermore, the decarbonization energy-saving unit 2 has two structures. The first structure includes an interstage cooling heat exchanger 7 and a first side-line extraction pump 8. The liquid in the upper part of the amine decarbonization tower 6 is transported through the first side-line extraction pump 8 and then transported through the pipeline to the interstage cooling heat exchanger 7 for heat exchange and cooling. The cooled liquid returns to the lower part of the amine decarbonization tower 6 through the pipeline.

[0028] The second structure includes a rich liquid storage tank 9, a bottom liquid circulation pump 10, and a bottom liquid cooler 11; wherein: the bottom liquid of the amine decarbonization tower 6 is transported into the rich liquid storage tank 9 through a pipeline, a part of which enters the next unit, and the remaining part enters the bottom liquid cooler 11 through the bottom liquid circulation pump 10 and pipeline. After being cooled by the bottom liquid cooler 11, the bottom liquid returns to the lower part of the amine decarbonization tower 6 through a pipeline.

[0029] Furthermore, the desorption unit 3 includes a rich liquid stream heat exchanger 12 and a desorption tower 13; wherein: the rich amine liquid enters the rich liquid stream heat exchanger 12 through a conveying pipeline, the rich amine liquid exchanges heat with the hot lean liquid output from the bottom of the desorption tower 13 in the rich liquid stream heat exchanger 12 to become a hot rich liquid and enters the desorption tower 13, the hot rich liquid is desorbed by the desorption tower 13 to obtain CO2-rich gas, the gas is output from the top of the tower, and the hot lean liquid is output from the bottom of the desorption tower 13.

[0030] Furthermore, the desorption energy-saving unit 4 has three structures. The first structure includes a rich liquid distributor 14. In this structure, the rich amine liquid enters the rich liquid distributor 14 through a conveying pipeline. In the rich liquid distributor 14, a portion of the rich amine liquid is distributed in a certain proportion and directly enters the upper part of the desorption tower 13. The remaining portion enters the rich liquid stream heat exchanger 12.

[0031] The second structure includes an interstage reheat heat exchanger 15 and a second side-line extraction pump 16; wherein: the liquid inside the upper part of the desorption tower 13 is transported through the second side-line extraction pump 16 and then through the pipeline into the interstage reheat heat exchanger 15 for heating, and the heated liquid returns to the middle part of the desorption tower 13 through the pipeline.

[0032] The third structure includes a negative pressure flash tank 17 and a heat pump 18; wherein: the liquid in the desorption tower 13 is transported into the negative pressure flash tank 17 through a pipeline, and the gas enters the heat pump 18 through a pipeline for compression, and then the compressed hot gas returns to the bottom of the desorption tower 13.

[0033] The decarbonization unit 1 is equipped with an amine solution inlet, a carbon-rich flue gas inlet, a carbon-lean flue gas outlet, a carbon-rich amine liquid outlet, a side-extraction outlet, an interstage coolant inlet, and a bottom circulating liquid inlet. CO2-rich flue gas enters the decarbonization unit 1 through the carbon-rich flue gas inlet, and the amine solution enters the decarbonization unit 1 through the amine solution inlet. The decarbonization unit 1 generates carbon-lean flue gas and carbon-rich amine liquid. The carbon-lean flue gas exits from the carbon-lean flue gas outlet, and the carbon-rich amine liquid exits from the carbon-rich amine liquid outlet. Side-extraction liquid can exit from the side-extraction outlet of the decarbonization unit 1. This side-extraction liquid can enter the decarbonization energy-saving unit 2 and then return to the decarbonization unit 1 through the interstage coolant inlet. Carbon-rich amine liquid exiting the carbon-rich amine liquid outlet of the decarbonization unit 1 can also enter the decarbonization energy-saving unit 2. Afterward, a portion of the liquid is recycled back to the decarbonization unit 1, and the remaining portion is output to the desorption unit 3 or the desorption energy-saving unit 4.

[0034] The decarbonization energy-saving unit 2 is equipped with a side-collected liquid inlet, an interstage coolant outlet, a carbon-rich amine liquid inlet, a tower bottom circulation outlet, and a rich liquid outlet. The side-collected liquid in the decarbonization unit 1 enters through the side-collected liquid inlet. After entering the decarbonization energy-saving unit 2, the side-collected liquid is output back to the decarbonization unit 1 through the interstage coolant outlet. Carbon-rich amine liquid may also exist in the decarbonization unit 1. It enters the decarbonization energy-saving unit 2 through the carbon-rich amine liquid inlet. Afterward, part of the liquid is output from the tower bottom circulation outlet and enters the decarbonization unit 1, and the remaining part is output from the rich liquid outlet and enters the desorption unit 3 or the desorption energy-saving unit 4.

[0035] Desorption unit 3 is equipped with a rich liquid inlet, an upper liquid inlet, a middle liquid inlet, a lower liquid inlet, a side-collected liquid outlet, an upper gas outlet, a lower gas inlet, and a lean amine liquid outlet. The rich amine liquid from decarbonization unit 1 or decarbonization energy-saving unit 2 is connected to the rich liquid inlet of desorption unit 3 through a pipeline. The rich amine liquid generates CO2-rich gas in desorption unit 3, which is output from the upper gas outlet, while the lean amine liquid is output from the lean amine liquid outlet. The rich amine liquid from decarbonization unit 1 or decarbonization energy-saving unit 2 can also be connected to the rich liquid inlet of desorption unit 3 through a pipeline. After the channel is connected to the desorption energy-saving unit 4, two liquid phase streams are output through the desorption energy-saving unit 4. One stream is connected to the upper liquid inlet of the desorption unit 3, and the other stream can be connected to the middle liquid inlet of the desorption unit 3. There may also be side sampled liquid output from the side sampled liquid outlet into the desorption energy-saving unit 4, and then the side sampled liquid can return to the desorption unit 3 through the lower liquid inlet. Finally, there may also be depleted amine liquid from the desorption unit 3 output from the depleted amine liquid outlet into the desorption energy-saving unit 4, and then the gas phase can return to the desorption unit 3 through the lower gas inlet.

[0036] The desorption energy-saving unit 4 is equipped with a rich liquid inlet, a rich liquid outlet 1, a rich liquid outlet 2, a side-sampled liquid inlet, a reheat liquid outlet, a lean amine liquid inlet, a recompression steam outlet, and a degassing liquid outlet. The rich amine liquid from the decarbonization unit 1 or the decarbonization energy-saving unit 2 enters the desorption energy-saving unit 4 through a pipeline connected to the rich liquid inlet. Two liquid phases are output from the rich liquid outlets 1-2 of the desorption energy-saving unit 4 and enter the desorption unit 3 through a pipeline. Side-sampled liquid may also enter the desorption energy-saving unit 4 from the side-sampled liquid inlet to generate reheat liquid, which is output from the reheat liquid outlet. Finally, lean amine liquid from the desorption unit 3 enters the desorption energy-saving unit 4 from the lean amine liquid inlet. Afterward, the gas phase can be output back to the desorption unit 3 through the recompression steam outlet, and the liquid is output through the degassing liquid outlet.

[0037] like Figure 2As shown, the decarbonization unit 1 includes an amine solution storage tank 5 and an amine solution decarbonization tower 6. The amine solution storage tank 5 is equipped with a lean amine solution circulation inlet and an amine solution outlet. The amine solution decarbonization tower 6 is equipped with an amine solution inlet, a carbon-rich flue gas inlet, a lean flue gas outlet, a carbon-rich amine solution outlet, a side-extraction outlet, an interstage coolant inlet, and a bottom circulating liquid inlet. CO2-rich flue gas enters the bottom of the amine solution decarbonization tower 6 through a pipeline connected to the carbon-rich flue gas inlet. The flue gas entering the amine solution decarbonization tower 6 reacts with the amine solution output from the amine solution outlet of the amine solution storage tank 5 from bottom to top. The amine solution outlet is connected to a pipeline... Connected to the amine solution inlet, the decarbonized flue gas is discharged from above the amine decarbonization tower 6, and the amine solution from top to bottom becomes carbon-rich amine solution and is output from the carbon-rich amine solution outlet at the bottom of the tower. Liquid can be side-collected from the amine decarbonization tower 6 and output from the side-collection outlet. The side-collected liquid can enter the decarbonization energy-saving unit 2 and then return to the amine decarbonization tower 6 through the interstage cooling liquid inlet. The carbon-rich amine solution output from the carbon-rich amine solution outlet of the amine decarbonization tower 6 can also enter the decarbonization energy-saving unit 2. After that, part of the liquid is recycled back to the amine decarbonization tower 6, and the remaining part is output into the desorption unit 3 or the desorption energy-saving unit 4.

[0038] like Figure 3 As shown, the decarbonization energy-saving unit 2 includes an interstage cooling heat exchanger 7 and a side-stream extraction pump 8; it also features two structural configurations: a temporary storage tank 9, a reactor liquid circulation pump 10, and a reactor liquid cooler 11. The cooling heat exchanger 7 has a pump outlet and an interstage cooling liquid outlet, while the side-stream extraction pump 8 has a side-collection liquid inlet and a pump outlet. Side-collection is possible in the amine decarbonization tower 6. The effluent enters the side-stream extraction pump 8 through the side-collection liquid inlet and exits through the pump outlet. The effluent then enters the cooling heat exchanger 7 through the pump outlet, cools, and exits through the interstage cooling liquid outlet. Afterward, it returns to the amine decarbonization tower 6 through the interstage cooling liquid inlet. The temporary storage tank 9 contains carbon-rich amine. The amine decarbonization tower 6 has a liquid inlet, a diversion outlet 1, and a diversion outlet 2. The reactor liquid circulation pump 10 is equipped with a reactor liquid inlet and a pumped liquid outlet. The reactor liquid cooler 11 is equipped with a pumped liquid inlet and a reactor circulating liquid outlet. The carbon-rich amine liquid from the amine decarbonization tower 6 is output from the carbon-rich amine liquid outlet and enters the temporary storage tank 9 from the carbon-rich amine liquid inlet. Then, part of the liquid in the temporary storage tank 9 is output from the diversion outlet 1, enters the reactor liquid circulation pump 10 through the reactor liquid inlet, is output from the pumped liquid outlet, enters the cooler 11 through the pumped liquid inlet, and then the cold liquid is output from the reactor circulating liquid outlet. Finally, it returns to the amine decarbonization tower 6 through the tower bottom circulation inlet. The remaining part is output from the diversion outlet 2 and enters the desorption unit 3 or the desorption energy-saving unit 4.

[0039] like Figure 4As shown, the desorption unit 3 includes a rich liquid stream heat exchanger 12 and a desorption tower 13. The rich liquid stream heat exchanger 12 has a rich liquid inlet, a hot lean amine liquid inlet, a cold lean amine liquid outlet, and a hot rich liquid outlet. The desorption tower 13 has an upper inlet, a middle inlet, a lower inlet, a side-collected liquid outlet, an upper gas outlet, a lower gas inlet, and a lean amine liquid outlet. The rich amine liquid from the decarbonization unit 1 or the decarbonization energy-saving unit 2 is connected to the rich liquid inlet of the rich liquid stream heat exchanger 12 via a pipeline for heat exchange with the hot lean amine liquid inlet. The cold lean amine liquid is then output from the cold lean amine liquid outlet, and the hot rich liquid is output from the hot rich liquid outlet. The hot rich liquid then enters the desorption tower 13 through the upper inlet. The carbon-rich amine liquid generates CO2-rich gas in the desorption tower 13, which is output from the upper gas outlet, while the carbon-lean amine liquid is output from the carbon-lean amine liquid outlet. The carbon-rich amine liquid can also be connected to the desorption energy-saving unit 4 through a pipeline, and the desorption energy-saving unit 4 outputs two liquid phase streams, one connected to the upper liquid inlet of the desorption tower 13 and the other connected to the middle liquid inlet of the desorption tower 13. There may also be side sample liquid output from the side sample liquid outlet into the desorption energy-saving unit 4, and then the side sample liquid can return to the desorption tower 13 through the lower liquid inlet. Finally, there may also be carbon-lean amine liquid from the desorption unit 3 output from the carbon-lean amine liquid outlet into the desorption energy-saving unit 4, and then the gas phase can return to the desorption tower 13 through the lower gas inlet.

[0040] like Figure 5 As shown, the desorption energy-saving unit 4 includes a rich liquid distributor 14, a reheat heat exchanger 15, a side-stream extraction pump 16, a negative pressure flash tank 17, and a heat pump 18. The rich liquid distributor 14 has a rich liquid inlet, a first rich liquid outlet, and a second rich liquid outlet. The rich amine solution enters the rich liquid distributor 14 through a pipeline connected to the rich liquid inlet, and two liquid phases are output through the two rich liquid outlets of the rich liquid distributor 14. The first rich liquid outlet is connected to the upper inlet of the desorption tower 13, and the second rich liquid outlet is connected to the rich liquid inlet of the rich liquid stream heat exchanger 12. The reheat heat exchanger 15 has a circulating pump outlet and a reheat liquid outlet. The side-stream extraction pump 16 has a side-collection liquid inlet and a circulating pump outlet. The side-collection liquid from the desorption tower 13 enters the side-stream extraction pump 16 from the side-collection liquid inlet, and then flows out from... The liquid output from the circulating pump outlet enters the reheat heat exchanger 15 through the circulating pump outlet to generate reheat liquid. The reheat liquid is output through the reheat liquid outlet and passes through the desorption energy-saving unit 4 to generate reheat liquid. The reheat liquid is output from the reheat liquid outlet and returns to the desorption tower 13 through the lower inlet. The negative pressure flash tank 17 is equipped with a lean amine liquid inlet, a steam outlet, and a degassed liquid outlet. The heat pump 18 is equipped with a circulating steam inlet and a recompressed steam outlet. The lean amine liquid from the desorption tower 13 enters the negative pressure flash tank 17 through the lean amine liquid inlet. The liquid is output through the degassed liquid outlet, and the gas phase is output through the steam outlet. It enters the heat pump 18 through the circulating steam inlet and is compressed by the heat pump 18 to obtain compressed steam. The compressed steam is output through the recompressed steam outlet and returns to the desorption tower 13 through the lower inlet.

[0041] Example In this embodiment, the temperature of the interstage cooling heat exchanger 7 in the decarbonization energy-saving unit 2 is 20-50°C, the pressure of the first side-line extraction pump 8 is 1-30 bar, the pressure of the vessel liquid circulation pump is 1-30 bar, and the temperature of the vessel liquid cooler 11 is 20-50°C.

[0042] In this embodiment, the rich liquid distributor 14 in the desorption energy-saving unit 4 has a flow ratio of 0.1 to 0.6, the reheat heat exchanger 15 has a temperature of 90 to 120°C, the side-line extraction pump 16 has a pressure of 1 to 30 bar, the negative pressure flash tank 17 has a pressure of 0.1 to 0.9 bar, and the heat pump 18 has a compression ratio of 1.1 to 10.

[0043] The specific process flow of this embodiment is described below. The CO2-rich flue gas flow rate is 935.525 t / h. Table 1 shows the composition of the CO2-rich flue gas.

[0044]

[0045] In this embodiment, the mixed amine decarbonization system is described below. Figure 6 The CO2-rich flue gas enters the bottom of the amine decarbonization tower 6 through a pipeline connected to the carbon-rich flue gas inlet. The flue gas enters the amine decarbonization tower 6 from bottom to top and reacts with the amine solution output from the amine solution outlet of the amine solution storage tank 5. The amine solution outlet is connected to the amine solution inlet through a pipeline. After decarbonization, the flue gas is discharged from the top of the amine decarbonization tower 6, and the amine solution from top to bottom becomes carbon-rich amine solution and is output from the carbon-rich amine solution outlet at the bottom of the tower.

[0046] The carbon-rich amine liquid from the amine decarbonization tower 6 is discharged from the carbon-rich amine liquid outlet and enters the temporary storage tank 9 from the carbon-rich amine liquid inlet. Then, part of the liquid in the temporary storage tank 9 is discharged from the diversion outlet 1 and enters the bottom liquid circulation pump 10 through the bottom liquid inlet. It is discharged from the pump outlet and enters the cooler 11 through the pump outlet. Then, the cold liquid is discharged from the bottom circulation liquid outlet and finally returns to the amine decarbonization tower 6 through the bottom circulation inlet. The remaining part is discharged from the diversion outlet 2, which is connected to the rich liquid inlet of the rich liquid stream heat exchanger 12.

[0047] The rich liquid enters the rich liquid distributor 14 through the rich liquid distributor outlet 2 via a pipeline connected to the rich liquid inlet. Two liquid phases are output through the rich liquid distributor outlets 1-2. The rich liquid outlet 1 is connected to the upper inlet of the desorption tower 13, and the rich liquid outlet 2 is connected to the rich liquid inlet of the rich liquid stream heat exchanger 12 for heat exchange with the inlet of the hot lean amine liquid. Then, the cold lean amine liquid is output from the cold lean amine liquid outlet, and the hot rich liquid is output from the hot rich liquid outlet. The hot rich liquid then enters through the middle inlet of the desorption tower 13. The carbon-rich amine liquid generates CO2-rich gas in the desorption tower 13, and the gas is output from the upper outlet. The hot lean amine liquid is output from the lean amine liquid outlet and enters the rich liquid stream heat exchanger 12. After cooling, it enters the amine liquid storage tank 5.

[0048] Ultimately, the unit energy consumption of the mixed amine decarbonization system in this embodiment is 2.62 GJ·tCO2-1, and the CO2 supply of the system is approximately 172.2 t / h.

[0049] In summary, this invention organically integrates a decarbonization unit, a decarbonization energy-saving unit, a desorption unit, and a desorption energy-saving unit to construct a highly efficient and flexible mixed amine decarbonization system. In this system, each unit works collaboratively. The decarbonization unit achieves full contact and reaction between CO2-rich flue gas and the amine solution, generating carbon-rich amine liquid and carbon-poor flue gas. The decarbonization energy-saving unit optimizes the decarbonization process and reduces energy consumption through interstage cooling and reactor liquid circulation cooling. The desorption unit desorbs the carbon-rich amine liquid, producing CO2-rich gas and carbon-poor amine liquid. The desorption energy-saving unit further improves desorption efficiency and recovers energy by utilizing technologies such as rich liquid diversion, side-stream reheating, negative pressure flash evaporation, and heat pump compression. The flexible configuration and combination of each energy-saving unit allows the system to adapt to different operating conditions, amine liquid types, and processing scales, effectively reducing unit energy consumption; for example, in this embodiment, the unit energy consumption is as low as 2.62 GJ·tCO2. -1 It ensures a high CO2 processing capacity, has significant economic and environmental benefits, and provides an efficient and feasible solution for industrial decarbonization.

[0050] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A mixed amine decarbonization system, characterized in that, include: The decarbonization unit (1) is used to react CO2-rich flue gas with mixed amine to generate CO2-poor gas and carbon-rich amine liquid. The decarbonization energy-saving unit (2) is used to perform interstage cooling or kettle liquid circulation cooling on the amine liquid in the decarbonization unit (1) in order to regulate the temperature of the decarbonization unit (1), improve CO2 absorption efficiency and recover energy. The desorption unit (3) is used to heat and regenerate the carbon-rich amine liquid, separate CO2 from the carbon-rich amine liquid, and obtain high-purity CO2 gas and carbon-poor amine liquid. The desorption energy-saving unit (4) is used to recover the heat of the desorption unit (3) and optimize the heat distribution to reduce the energy consumption of amine liquid regeneration. The decarbonization energy-saving unit (2) forms an internal circulation pipeline with the decarbonization unit (1) to draw out part of the amine liquid in the decarbonization unit (1), cool it, and send it back to the decarbonization unit (1); the decarbonization energy-saving unit (2) also forms an external circulation pipeline with the decarbonization unit (1) and the desorption unit (3) to cool the carbon-rich amine liquid discharged from the decarbonization unit (1), send part of it back to the decarbonization unit (1), and send the other part to the desorption unit (3). The desorption energy-saving unit (4) is connected to the decarbonization energy-saving unit (2), the desorption unit (3) and the decarbonization unit (1) respectively. It is used to regulate the feeding state of the carbon-rich amine liquid, recover the heat of the desorption unit (3), and transport the regenerated carbon-poor amine liquid back to the decarbonization unit (1).

2. The mixed amine decarbonization system according to claim 1, characterized in that, The decarbonization energy-saving unit (2) adopts both interstage cooling and kettle liquid circulation cooling: through interstage cooling, some of the amine liquid inside the decarbonization unit (1) is drawn out and cooled before returning to the decarbonization unit (1); through kettle liquid circulation cooling, the carbon-rich amine liquid discharged from the decarbonization unit (1) is cooled, and part of it flows back to the decarbonization unit (1) and part of it is transported to the desorption unit (3). The desorption energy-saving unit (4) regulates the temperature of the carbon-rich amine liquid from the decarbonization energy-saving unit (2) and sends it to different parts of the desorption unit (3); the desorption energy-saving unit (4) receives the carbon-poor amine liquid from the desorption unit (3), recovers heat to generate a high-temperature gas phase and sends it back to the desorption unit (3), and transports the cooled carbon-poor amine liquid to the decarbonization unit (1). The desorption energy-saving unit (4) uses one or more of the following methods to achieve heat recovery and distribution: rich liquid diversion, side-line reheat, negative pressure flash evaporation, or heat pump compression.

3. The mixed amine decarbonization system according to claim 1, characterized in that, The decarbonization unit (1) includes: an amine liquid storage tank (5) and an amine liquid decarbonization tower (6). The inlet of the amine liquid storage tank (5) is connected to an amine solution source, and the outlet of the amine liquid storage tank (5) is connected to the amine solution inlet at the top of the amine liquid decarbonization tower (6). The bottom of the amine liquid decarbonization tower (6) is provided with a carbon-rich flue gas inlet and a carbon-rich amine liquid outlet. The carbon-rich flue gas inlet is connected to a CO2-rich flue gas source. Inside the amine liquid decarbonization tower (6), the amine solution from top to bottom reacts with the CO2-rich flue gas from bottom to top to generate carbon-rich amine liquid, which flows out from the carbon-rich amine liquid outlet.

4. The mixed amine decarbonization system according to claim 3, characterized in that, The decarbonization energy-saving unit (2) includes: an interstage cooling heat exchanger (7), a first side-line extraction pump (8), a rich liquid temporary storage tank (9), a kettle liquid circulation pump (10), and a kettle liquid cooler (11). The inlet of the first side-line extraction pump (8) is connected to the inner cavity of the amine decarbonization tower (6) at the upper side wall of the amine decarbonization tower (6). The outlet of the first side-line extraction pump (8) is connected to the condensing end inlet of the interstage cooling heat exchanger (7). The condensing end outlet of the interstage cooling heat exchanger (7) is connected to the inner cavity of the amine decarbonization tower (6) at the lower side wall of the amine decarbonization tower (6). The carbon-rich amine liquid outlet at the bottom of the amine decarbonization tower (6) is connected to the inlet of the rich liquid storage tank (9). One outlet of the rich liquid storage tank (9) is connected to the inlet of the kettle liquid cooler (11) via the kettle liquid circulation pump (10). The outlet of the kettle liquid cooler (11) is connected to the inner cavity of the amine decarbonization tower (6) at the lower side wall of the amine decarbonization tower (6). The other outlet of the rich liquid storage tank (9) is connected to the desorption unit (3) or the desorption energy-saving unit (4).

5. A mixed amine decarbonization system according to claim 4, characterized in that, The working temperature of the condenser end of the interstage cooling heat exchanger (7) is set to 20-50℃, the working pressure of the first side line extraction pump (8) is set to 1-30 bar, the working pressure of the reactor liquid circulation pump (10) is set to 1-30 bar, and the working temperature of the reactor liquid cooler (11) is set to 20-50℃.

6. The mixed amine decarbonization system according to claim 1, characterized in that, The desorption unit (3) includes: a rich liquid stream heat exchanger (12) and a desorption tower (13). The evaporation end inlet of the rich liquid stream heat exchanger (12) is connected to a rich amine liquid source, and the evaporation end outlet of the rich liquid stream heat exchanger (12) is connected to the desorption tower (13). The top of the desorption tower (13) is provided with a rich CO2 gas outlet, and the bottom of the desorption tower (13) is provided with a hot lean liquid outlet. The hot lean liquid outlet is connected to the condensation end inlet of the rich liquid stream heat exchanger (12), and the condensation end outlet of the rich liquid stream heat exchanger (12) is connected to an amine solution source.

7. A mixed amine decarbonization system according to claim 6, characterized in that, The desorption energy-saving unit (4) includes: a rich liquid distributor (14), an interstage reheat heat exchanger (15), a second side-line extraction pump (16), a negative pressure flash tank (17), and a heat pump (18). The inlet of the rich liquid distributor (14) is connected to the rich amine liquid source, one outlet of the rich liquid distributor (14) is connected to the evaporation end inlet of the rich liquid stream heat exchanger (12), and the other outlet of the rich liquid distributor (14) is connected from the upper part of the desorption tower (13) to the inner cavity of the desorption tower (13). The upper inner cavity of the desorption tower (13) is also connected to the inlet of the second side line extraction pump (16), the outlet of the second side line extraction pump (16) is connected to the evaporation end inlet of the interstage reheat heat exchanger (15), and the evaporation end outlet of the interstage reheat heat exchanger (15) is connected from the middle of the desorption tower (13) to the inner cavity of the desorption tower (13). The hot lean liquid outlet at the bottom of the desorption tower (13) is connected to the inlet of the negative pressure flash tank (17). One outlet of the negative pressure flash tank (17) is connected from the middle of the desorption tower (13) to the inner cavity of the desorption tower (13) via the heat pump (18). The other outlet of the negative pressure flash tank (17) is connected to the condenser end inlet of the rich liquid stream heat exchanger (12).

8. A mixed amine decarbonization system according to claim 7, characterized in that, The flow ratio of the rich liquid distributor (14) to the rich liquid stream heat exchanger (12) and the self-desorption tower (13) is 0.1 to 0.

6. The operating temperature of the evaporation end of the interstage reheat heat exchanger (15) is 90 to 120°C. The operating pressure of the second side line extraction pump (16) is 1 to 30 bar. The operating pressure of the negative pressure flash tank (17) is 0.1 to 0.9 bar. The compression ratio of the heat pump (18) is 1.1 to 10.

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