Coupling system for direct air carbon capture and dual-alkali method carbon capture

Abstract

The invention provides a direct air carbon capture and dual-alkali method carbon capture coupling system, which comprises a DAC device and a dual-alkali method carbon capture device, the dual-alkali method carbon capture device performs primary capture on flue gas and then exhausts the gas into the DAC device through a fan, the dual-alkali method carbon capture device uses an alkaline solution as a CO2 absorption liquid, the CO2 absorption liquid is used as a CO2 absorption liquid, and the CO2 absorption liquid is used as a CO2 absorption liquid. CO2 absorption rich liquid absorbed by the dual-alkali method carbon capture device is conveyed to the DAC device through a pump to be sprayed, the CO2 absorption rich liquid generated by the DAC device flows back to the dual-alkali method carbon capture device to generate an alkaline solution, the exhausted flue gas in the implementation process of the dual-alkali method carbon capture technology serves as capture inlet gas of the DAC system, and the capture efficiency of CO2 is improved; cO2 absorption rich liquid in a dual-alkali method carbon capture technology is used as alkaline spray liquid required in a DAC system desorption process, so that the comprehensive utilization efficiency of alkaline raw materials is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture and utilization, in particular to a coupling system of direct air carbon capture and dual alkali carbon capture. Background Art

[0002] Direct air capture is a highly promising carbon capture technology that has attracted increasing attention due to its wide range of applications. Existing DAC technologies mostly use active amine components as absorbents to achieve CO2 removal through heating desorption or alkaline solution spray desorption. 2 Desorption separation and regeneration of absorbent. Due to the high energy consumption of the heating desorption process, the wet regeneration process represented by desorption alkali solution spraying will be one of the low-cost development directions of DAC technology.

[0003] Dual-alkali carbon capture technology is an economically feasible chemical absorption carbon capture technology that can achieve CO 2 In-situ mineralization. This technology uses caustic soda solutions such as NaOH to absorb CO in the flue gas of coal-fired power plants. 2 , through the causticization reaction to produce carbonate minerals, in order to achieve the regeneration of the absorbent and CO 2 mineralization.

[0004] Chinese patent CN116889790A discloses a system and method for direct air carbon capture coupled with microalgae carbon fixation by wet adsorption, which uses a wet adsorption process and uses desorption alkali solution spraying to desorb CO 2 , the formed HCO 3 - For microalgae cultivation. This technology focuses on CO 2 The utilization after desorption does not solve the problem of the source of raw materials for the desorption alkali solution.

[0005] Chinese patent CN118384871A discloses a renewable resin-based adsorbent for air carbon capture, and its preparation method and application, using weakly alkaline seawater as a desorption liquid to react with the absorbent to achieve CO 2 After desorption, an equal amount of NaOH or other strong alkaline solution must be added to regenerate the adsorbent. 2 After desorption, it dissolves into seawater to achieve CO 2 Sealing did not reduce the usage of desorption alkali solution.

[0006] Chinese patent CN118698277A discloses an air carbon dioxide capture and recovery system with resin regeneration function, using saturated alkali solution as desorption liquid to 2 The adsorbent is cleaned to achieve CO 2The desorption of saturated alkali solution requires water to clean the adsorbent before and after use. This technology uses a temperature control system to recover industrial waste heat and control CO 2 The adsorption and desorption rates are reduced and the consumption of alkali solution is increased. Summary of the invention

[0007] The present invention solves the problem of large consumption of desorption alkali solution in the spray desorption process of the existing DAC technology and the problem of inefficient utilization of capture alkali solution in the capture process of the dual-alkali carbon capture technology. A coupling system of direct air carbon capture and dual-alkali carbon capture is proposed. The exhaust flue gas in the implementation process of the dual-alkali carbon capture technology is used as the capture intake air of the DAC system to improve CO 2 capture efficiency; CO in dual alkali carbon capture technology 2 The absorbed rich liquid is used as the alkaline spray liquid required for the desorption process of the DAC system to improve the comprehensive utilization efficiency of the alkaline raw materials.

[0008] In order to achieve the above objectives, the following technical solutions are proposed: A coupling system of direct air carbon capture and dual alkali carbon capture, comprising a DAC device and a dual alkali carbon capture device, wherein the dual alkali carbon capture device performs initial capture on flue gas and then exhausts the gas into the DAC device through a fan, and the dual alkali carbon capture device uses an alkaline solution as a CO 2 Absorption liquid, CO absorbed by the double alkali carbon capture device 2 The absorbed rich liquid is pumped to the DAC device for spraying. The CO generated by the DAC device 2 The absorbed rich liquid is refluxed to the dual alkali carbon capture device to generate an alkaline solution.

[0009] This embodiment proposes a coupling system of direct air carbon capture and dual alkali carbon capture, referring to Figure 1 , including a double alkali carbon capture device, a fan and a direct air carbon capture device (DAC device for short). After the flue gas from the coal-fired power plant is introduced into the double alkali carbon capture device, the double alkali carbon capture device performs initial capture on it, and after the initial capture is completed, it is emptied. During the emptying process, the remaining carbon enters the DAC device through the fan; in addition, the CO used in the double alkali carbon capture device 2 The absorption liquid is an alkaline solution. After being absorbed by the alkaline solution, the CO 2 The absorbed rich liquid is then pumped to the DAC device for spraying, and the CO generated by the DAC device 2 The absorbed rich liquid is finally returned to the dual-alkali carbon capture system for causticization to produce alkaline solution for the dual-alkali carbon capture device as CO 2 The present invention uses direct air capture technology to secondary capture the flue gas exhausted during the implementation of the dual-alkali carbon capture technology, and uses the CO2 Absorbing rich liquid replaces the alkaline spray liquid required in the direct air carbon capture process. The CO adsorbed in the DAC system 2 After desorption, it enters the rich liquid of the double alkali process system, and then undergoes mineralization regeneration to achieve CO 2 Efficient capture and utilization.

[0010] The present invention provides a large amount of cheap desorption alkali solution for DAC technology by coupling DAC technology and dual alkali carbon capture technology, thereby reducing the application cost of DAC technology and improving the comprehensive utilization efficiency of alkaline raw materials in dual alkali carbon capture technology. Conventional DAC desorption alkali solution raw materials need to be purchased separately, and there will be a loss of 1-2% of alkaline raw materials in dual alkali carbon capture technology. The present invention couples and integrates technologies, and the exhaust flue gas in the implementation process of dual alkali carbon capture technology is used as the capture intake gas of the DAC system to achieve CO 2 Multiple captures increase the CO 2 The capture efficiency of conventional dual-alkali carbon capture technology is only one-time capture, and the capture efficiency is about 95-97%. Conventional DAC captures low-concentration CO from the air. 2 , the capture efficiency is about 10-15%; Preferably, the dual alkali carbon capture device includes an absorption tower, a mineralization reactor and a filter press. A flue gas inlet is connected at the bottom of the absorption tower, a spray head is provided at the top of the absorption tower, and the spray head is connected to the filtrate outlet of the filter press through an alkaline liquid infusion pipe. A liquid outlet is provided at the bottom of the absorption tower, and the liquid outlet is connected to a DAC device through a pipeline. An exhaust port is provided at the top of the absorption tower, and the exhaust port is connected to a fan.

[0011] The dual alkali carbon capture device of the present invention comprises an absorption tower, a mineralization reactor and a filter press. A flue gas inlet is connected to the bottom of the absorption tower for inputting flue gas from a coal-fired power plant. A spray head is arranged above the absorption tower. The spray head is connected to an alkaline liquid infusion pipe. The alkaline liquid infusion pipe is connected to the filtrate outlet of the filter press. A liquid outlet is arranged at the bottom of the absorption tower. An exhaust port is arranged at the top of the absorption tower. The liquid outlet is connected to a DAC device through a pipeline.

[0012] Preferably, the concentration of the alkaline solution is 1.0-5.0 mol / L, and the liquid-gas ratio during the spraying process is 5-10 L / m 3 .

[0013] The alkaline solution of the present invention is a caustic soda such as sodium hydroxide or potassium hydroxide, and its concentration is 1.0 to 5.0 mol / L. During the spraying process, the liquid-gas ratio is 5 to 10 L / m 3 .

[0014] Preferably, the mineralization reactor is provided with a regeneration agent input pipe, a slurry output port and a liquid inlet, wherein the regeneration agent input pipe inputs the regeneration agent into the mineralization reactor and is connected to the CO2 transported by the DAC device through the liquid inlet. 2 Absorb the rich liquid to carry out mineralization reaction.

[0015] The mineralization reactor of the present invention is provided with a regeneration agent input pipe, a slurry output port and a liquid inlet. The regeneration agent input pipe is used for inputting the regeneration agent, and the liquid inlet is used for CO2 removal from the DAC device. 2 The rich liquid input is absorbed, and the slurry output port is used to transport the slurry after the mineralization reaction to the filter press.

[0016] CO adsorbed in DAC system 2 After desorption, it enters the rich solution of the dual alkali process system and then enters the mineralization regeneration step, which simplifies the steps of DAC technology and realizes CO 2 Direct use of the conventional DAC system requires CO 2 Distill, concentrate and store.

[0017] Preferably, the regeneration agent is an alkaline hydroxide with a concentration of 1.0 to 5.0 mol / L, the regeneration reaction temperature is 40 to 80° C., the stirring rate is 50 to 300 rpm, and the reaction time lasts 30 to 70 min.

[0018] The regeneration agent of the present invention is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2 The alkaline hydroxide has a concentration of 1.0-5.0 mol / L, a regeneration reaction temperature range of 40-80°C, a stirring rate of 50-300 rpm, and a reaction time of 30-70 min.

[0019] Preferably, the filter press is provided with a slurry inlet and a product outlet, the slurry inlet is connected to the slurry outlet of the mineralization reactor through a pump, and an infusion pump is provided between the alkaline liquid infusion pipe and the filtrate outlet of the filter press.

[0020] The filter press of the present invention is provided with a slurry inlet and a product outlet connected to the slurry outlet of the mineralization reactor through a pump, and an infusion pump is provided between the filtrate outlet of the filter press and the alkaline liquid infusion pipe. The slurry after the mineralization reaction enters the filter press, the separated calcium carbonate is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters the absorption tower to continue carbon capture.

[0021] Preferably, the by-product output at the product outlet is calcium carbonate.

[0022] Preferably, the DAC device is provided with a dehumidification module and an adsorption-desorption module. When the adsorption-desorption module is in an adsorption reaction, the gas is first dehumidified by the dehumidification module and then enters the adsorption-desorption module. When the adsorption-desorption module is in a desorption reaction, the alkaline liquid directly enters the adsorption-desorption module.

[0023] The DAC device of the present invention is provided with a dehumidification module and an adsorption-desorption module, the fan is connected to the dehumidification module through a pipeline, the dehumidification module is connected to the adsorption-desorption module through a pipeline, and the fan is also directly connected to the adsorption-desorption module through a pipeline. When the adsorption-desorption module is in an adsorption reaction, the gas is first dehumidified by the dehumidification module and then enters the adsorption-desorption module; when the adsorption-desorption module is in a desorption reaction, the alkaline liquid directly enters the adsorption-desorption module.

[0024] Preferably, the dehumidification module is provided with a water pipe, through which the collected water is transported to an external water storage tank, and the water storage tank is connected to the adsorption-desorption module via a water pump.

[0025] The dehumidification module of the present invention is also provided with a water pipe, which transports the moisture collected by the dehumidification module to an external water storage tank, and the water storage tank is connected to the adsorption-desorption module through a water pump. The desorbed adsorbent is sprayed and rinsed with the cleaning water in the water storage tank, and blown and dried with a fan, and the blowing time lasts for 0.5 to 1.5 hours, and then enters the next adsorption-desorption cycle.

[0026] Preferably, the adsorption-desorption module is provided with two independent first adsorption-desorption modules and second adsorption-desorption modules, and the first adsorption-desorption module and the second adsorption-desorption module perform adsorption-desorption process alternately.

[0027] The present invention has two independent adsorption-desorption modules, namely the first adsorption-desorption module and the second adsorption-desorption module, which perform the adsorption-desorption process alternately. The DAC system has two independent CO 2 The adsorption-desorption module is connected to the rich liquid pipeline and the fan air flow channel in the absorption tower respectively; the two modules alternately perform the adsorption-desorption process to realize the continuous operation of the DAC system and perform secondary carbon capture on the gas exhausted from the dual-alkali carbon capture system.

[0028] The beneficial effects of the present invention are: 1. By coupling DAC technology and dual-alkali carbon capture technology, a large amount of cheap desorption alkali solution is provided for DAC technology, which reduces the application cost of DAC technology and improves the comprehensive utilization efficiency of alkaline raw materials in dual-alkali carbon capture technology; 2. Through technical coupling integration, the exhaust flue gas during the implementation of the dual-alkali carbon capture technology is used as the capture air intake of the DAC system to achieve CO2 Multiple captures increase the CO 2 The capture efficiency; 3. CO adsorbed in DAC system 2 After desorption, it enters the rich solution of the dual alkali process system and then enters the mineralization regeneration step, which simplifies the steps of DAC technology and realizes CO 2 direct use of. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a system connection diagram of the present invention.

[0030] Figure 2 It is a schematic diagram of the working principle of the present invention.

[0031] Among them: 1. Flue gas inlet duct; 2. Absorption tower; 3. Alkaline liquid infusion pipe; 4. Fan; 5. DAC device; 6. Dehumidification module; 7. First adsorption-desorption module; 8. Second adsorption-desorption module; 9. Water storage tank; 10. Mineralization reactor; 11. Regeneration agent input pipe; 12. Filter press; 13. Product outlet. DETAILED DESCRIPTION

[0032] Embodiment 1: This embodiment proposes a coupling system of direct air carbon capture and dual alkali carbon capture, referring to Figure 1 , comprising a double alkali carbon capture device, a fan 4 and a direct air carbon capture device (DAC device for short) 5. After the flue gas from the coal-fired power plant is introduced into the double alkali carbon capture device, the double alkali carbon capture device performs initial capture on it. After the initial capture is completed, it is emptied. During the evacuation, the remaining carbon enters the DAC device through the fan 4. In addition, the CO used in the double alkali carbon capture device 2 The absorption liquid is an alkaline solution. After being absorbed by the alkaline solution, the CO 2 The absorbed rich liquid is then pumped to the DAC device for spraying, and the CO generated by the DAC device 2 The absorbed rich liquid is finally returned to the dual alkali carbon capture device to produce alkaline solution for the dual alkali carbon capture device as CO 2 Absorbent liquid use.

[0033] The dual alkali carbon capture device of the present invention comprises an absorption tower 2, a mineralization reactor 10 and a filter press 12. A flue gas inlet 1 is connected to the bottom of the absorption tower 2 for inputting flue gas from a coal-fired power plant. A spray head is arranged above the absorption tower 2. The spray head is connected to an alkaline liquid infusion pipe 3. The alkaline liquid infusion pipe is connected to the filtrate outlet of the filter press 12. A liquid outlet is arranged at the bottom of the absorption tower 2. An exhaust port is arranged at the top of the absorption tower 2. The liquid outlet is connected to the DAC device through a pipeline. The alkaline solution of the present invention is a caustic alkali such as sodium hydroxide and potassium hydroxide, and its concentration is 1.0 to 5.0 mol / L. During the spraying process, the liquid-gas ratio is 5 to 10 L / m 3 .

[0034] The mineralization reactor 10 of the present invention is provided with a regeneration agent input pipe 11, a slurry output port and a liquid inlet. The regeneration agent input pipe 11 is used for inputting the regeneration agent, and the liquid inlet is used for CO2 removal from the DAC device. 2 The rich liquid input is absorbed, and the slurry output port is used to transport the slurry after the mineralization reaction to the filter press 12.

[0035] CO adsorbed in DAC system 2 After desorption, it enters the rich solution of the dual alkali process system and then enters the mineralization regeneration step, which simplifies the steps of DAC technology and realizes CO 2 Direct use of the conventional DAC system requires CO 2 The regeneration agent of the present invention is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2 The alkaline hydroxide has a concentration of 1.0-5.0 mol / L, a regeneration reaction temperature range of 40-80°C, a stirring rate of 50-300 rpm, and a reaction time of 30-70 min.

[0036] The filter press 12 of the present invention is provided with a slurry inlet and a product outlet 13 connected to the slurry outlet of the mineralization reactor 10 through a pump, and an infusion pump is provided between the filtrate outlet of the filter press 12 and the alkaline liquid infusion pipe. The slurry after the mineralization reaction enters the filter press 12, the separated calcium carbonate is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters absorption tower 2 to continue carbon capture.

[0037] The present invention provides a large amount of cheap desorption alkali solution for DAC technology by coupling DAC technology and dual alkali carbon capture technology, thereby reducing the application cost of DAC technology and improving the comprehensive utilization efficiency of alkaline raw materials in dual alkali carbon capture technology. Conventional DAC desorption alkali solution raw materials need to be purchased separately, and there will be a loss of 1-2% of alkaline raw materials in dual alkali carbon capture technology. The present invention couples and integrates technologies, and the exhaust flue gas in the implementation process of dual alkali carbon capture technology is used as the capture intake gas of the DAC system to achieve CO 2 Multiple captures increase the CO 2 The capture efficiency of conventional dual-alkali carbon capture technology is only one-time capture, and the capture efficiency is about 95-97%. Conventional DAC captures low-concentration CO from the air. 2 , the capture efficiency is about 10-15%; The exhaust gas from the dual alkali carbon capture technology is drawn out by a fan and then enters the DAC system as the capture air. The DAC system dehumidifies the air and completes the CO 2 The water collected by adsorption and dehumidification is used as the subsequent cleaning water. The CO 2 The absorbed rich liquid is drawn out and enters the DAC adsorption-desorption module. The rich liquid is used as desorption alkali liquid to remove CO in the DAC system. 2 The adsorbent is sprayed and desorbed. After desorption, CO 2 The rich liquid enters the double alkali system and is then pumped into the mineralization regeneration module of the double alkali system. The desorbed adsorbent in the DAC system is sprayed and cleaned with the above-mentioned cleaning water, and then dried by a fan to enter the next absorption-desorption cycle.

[0038] Embodiment 2: This embodiment defines the DAC device 5 on the basis of the embodiment 1, and proposes a coupling system of direct air carbon capture and dual alkali carbon capture, referring to Figure 1 , comprising a double alkali carbon capture device, a fan 4 and a direct air carbon capture device (DAC device for short) 5. After the flue gas from the coal-fired power plant is introduced into the double alkali carbon capture device, the double alkali carbon capture device performs initial capture on it. After the initial capture is completed, it is emptied. During the evacuation, the remaining carbon enters the DAC device through the fan 4. In addition, the CO used in the double alkali carbon capture device 2 The absorption liquid is an alkaline solution. After being absorbed by the alkaline solution, the CO 2 The absorbed rich liquid is then pumped to the DAC device for spraying, and the CO generated by the DAC device 2 The absorbed rich liquid is finally returned to the dual alkali carbon capture device to produce alkaline solution for the dual alkali carbon capture device as CO 2 Absorbent liquid use.

[0039] The dual alkali carbon capture device of the present invention comprises an absorption tower 2, a mineralization reactor 10 and a filter press 12. A flue gas inlet 1 is connected to the bottom of the absorption tower 2 for inputting flue gas from a coal-fired power plant. A spray head is arranged above the absorption tower 2. The spray head is connected to an alkaline liquid infusion pipe 3. The alkaline liquid infusion pipe is connected to the filtrate outlet of the filter press 12. A liquid outlet is arranged at the bottom of the absorption tower 2. An exhaust port is arranged at the top of the absorption tower 2. The liquid outlet is connected to the DAC device through a pipeline. The alkaline solution of the present invention is a caustic alkali such as sodium hydroxide and potassium hydroxide, and its concentration is 1.0 to 5.0 mol / L. During the spraying process, the liquid-gas ratio is 5 to 10 L / m 3 .

[0040] The mineralization reactor 10 of the present invention is provided with a regeneration agent input pipe 11, a slurry output port and a liquid inlet. The regeneration agent input pipe 11 is used for inputting the regeneration agent, and the liquid inlet is used for CO2 removal from the DAC device. 2 The rich liquid input is absorbed, and the slurry output port is used to transport the slurry after the mineralization reaction to the filter press 12.

[0041] CO adsorbed in DAC system 2 After desorption, it enters the rich solution of the dual alkali process system and then enters the mineralization regeneration step, which simplifies the steps of DAC technology and realizes CO 2 Direct use of the conventional DAC system requires CO 2 The regeneration agent of the present invention is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2 The alkaline hydroxide has a concentration of 1.0-5.0 mol / L, a regeneration reaction temperature range of 40-80°C, a stirring rate of 50-300 rpm, and a reaction time of 30-70 min.

[0042] The filter press 12 of the present invention is provided with a slurry inlet and a product outlet 13 connected to the slurry outlet of the mineralization reactor 10 through a pump, and an infusion pump is provided between the filtrate outlet of the filter press 12 and the alkaline liquid infusion pipe. The slurry after the mineralization reaction enters the filter press 12, the separated calcium carbonate is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters absorption tower 2 to continue carbon capture.

[0043] The DAC device of the present invention is provided with a dehumidification module 6 and an adsorption-desorption module. The dehumidification module 6 and the fan 4 are connected to the dehumidification module 6 through a pipeline. The dehumidification module 6 is connected to the adsorption-desorption module through a pipeline. The fan 4 is also directly connected to the adsorption-desorption module through a pipeline. When the adsorption-desorption module is in an adsorption reaction, the gas is first dehumidified by the dehumidification module 6 and then enters the adsorption-desorption module; when the adsorption-desorption module is in a desorption reaction, the alkaline liquid directly enters the adsorption-desorption module.

[0044] The dehumidification module 6 of the present invention is also provided with a water pipe, which transports the moisture collected by the dehumidification module 6 to an external water storage tank 9, and the water storage tank 9 is connected to the adsorption-desorption module through a water pump. The desorbed adsorbent is sprayed and rinsed with the cleaning water in the water storage tank 9, and blown and dried with a fan, and the blowing time lasts for 0.5 to 1.5 hours, and then enters the next adsorption-desorption cycle.

[0045] The present invention provides a large amount of cheap desorption alkali solution for DAC technology by coupling DAC technology and dual alkali carbon capture technology, thereby reducing the application cost of DAC technology and improving the comprehensive utilization efficiency of alkaline raw materials in dual alkali carbon capture technology. Conventional DAC desorption alkali solution raw materials need to be purchased separately, and there will be a loss of 1-2% of alkaline raw materials in dual alkali carbon capture technology. The present invention couples and integrates technologies, and the exhaust flue gas in the implementation process of dual alkali carbon capture technology is used as the capture intake gas of the DAC system to achieve CO 2 Multiple captures increase the CO 2 The capture efficiency of conventional dual-alkali carbon capture technology is only one-time capture, and the capture efficiency is about 95-97%. Conventional DAC captures low-concentration CO from the air. 2 , the capture efficiency is about 10-15%; The exhaust gas from the dual alkali carbon capture technology is drawn out by a fan and then enters the DAC system as the capture air. The DAC system dehumidifies the air and completes the CO 2 The water collected by adsorption and dehumidification is used as the subsequent cleaning water. The CO 2 The absorbed rich liquid is drawn out and enters the DAC adsorption-desorption module. The rich liquid is used as desorption alkali liquid to remove CO in the DAC system. 2 The adsorbent is sprayed and desorbed. After desorption, CO 2 The rich liquid enters the double alkali system and is then pumped into the mineralization regeneration module of the double alkali system. The desorbed adsorbent in the DAC system is sprayed and cleaned with the above-mentioned cleaning water, and then dried by a fan to enter the next absorption-desorption cycle.

[0046] The working principle of the present invention is as follows: refer to Figure 2, the flue gas 1 of the coal-fired power plant is introduced into the absorption tower 2, and the flue gas flow rate is 100~500m 3 / h; at the same time, alkaline solution 3 is used as the absorption liquid to spray the CO in the flue gas 2 The alkali solution is caustic alkali such as sodium hydroxide and potassium hydroxide, the concentration of the alkali solution is 1.0-5.0 mol / L, and the liquid-gas ratio of the spraying process is 5-10 L / m 3 .

[0047] The flue gas is initially captured in the absorption tower and then discharged. The discharged gas is introduced into the DAC system 5 through the fan 4. The fan flow rate is 100-500m 3 / h; the airflow first passes through the dehumidification module 6 to remove moisture and then enters the CO 2 The first adsorption-desorption module 7 or the second adsorption-desorption module 8 has an adsorption time of 0.5 to 2.5 hours. The water collected by the dehumidification module is sent to the water storage tank 9 for recycling to remove CO 2 The air is then exhausted.

[0048] DAC system in CO 2 After the adsorption is completed, desorption is performed to remove the CO 2 The absorbed rich liquid is pumped into the first adsorption-desorption module 7 or the second adsorption-desorption module 8 of DAC for spray desorption. The desorbed CO 2 Mainly CO 3 2- Enter CO in the form of 2 In the absorption rich liquid, the desorption process lasts for 0.5 to 2.5 hours; the desorbed adsorbent is sprayed and rinsed with the cleaning water in the water storage tank 9, and blown and dried with a fan, the blowing time lasts for 0.5 to 1.5 hours, and then enters the next adsorption-desorption cycle.

[0049] CO 2 The absorbed rich liquid is pumped into the mineralization reactor 10, and the absorbed liquid is regenerated by a causticizing reaction with the regeneration agent 11, and the regeneration agent is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2 The alkaline hydroxide is used, the regeneration agent concentration is 1.0-5.0 mol / L, the regeneration reaction temperature is 40-80°C, the stirring rate is 50-300 rpm, and the reaction time is 30-70 min.

[0050] The slurry after the mineralization reaction enters the filter press 12, and the separated calcium carbonate 13 is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters absorption tower 2 to continue carbon capture.

[0051] Embodiment 3: This embodiment optimizes the DAC device 5 on the basis of embodiment 2, and provides a pair of independent adsorption-desorption modules, and proposes a coupling system of direct air carbon capture and dual alkali carbon capture, referring to Figure 1 , including a double alkali carbon capture device, a fan 4 and a direct air carbon capture device also known as a DAC device 5. After the flue gas from the coal-fired power plant is introduced into the double alkali carbon capture device, the double alkali carbon capture device performs initial capture on it. After the initial capture is completed, it is emptied. During the evacuation, the rest enters the DAC device through the fan 4. In addition, the CO used in the double alkali carbon capture device 2 The absorption liquid is an alkaline solution. After being absorbed by the alkaline solution, the CO 2 The absorbed rich liquid is then pumped to the DAC device for spraying, and the CO generated by the DAC device 2 The absorbed rich liquid is finally returned to the dual alkali carbon capture device to produce alkaline solution for the dual alkali carbon capture device as CO 2 Absorbent liquid use.

[0052] The dual alkali carbon capture device of the present invention comprises an absorption tower 2, a mineralization reactor 10 and a filter press 12. A flue gas inlet 1 is connected to the bottom of the absorption tower 2 for inputting flue gas from a coal-fired power plant. A spray head is arranged above the absorption tower 2. The spray head is connected to an alkaline liquid infusion pipe 3. The alkaline liquid infusion pipe is connected to the filtrate outlet of the filter press 12. A liquid outlet is arranged at the bottom of the absorption tower 2. An exhaust port is arranged at the top of the absorption tower 2. The liquid outlet is connected to the DAC device through a pipeline. The alkaline solution of the present invention is a caustic alkali such as sodium hydroxide and potassium hydroxide, and its concentration is 1.0 to 5.0 mol / L. During the spraying process, the liquid-gas ratio is 5 to 10 L / m 3 .

[0053] The mineralization reactor 10 of the present invention is provided with a regeneration agent input pipe 11, a slurry output port and a liquid inlet. The regeneration agent input pipe 11 is used for inputting the regeneration agent, and the liquid inlet is used for CO2 removal from the DAC device. 2 The rich liquid input is absorbed, and the slurry output port is used to transport the slurry after the mineralization reaction to the filter press 12.

[0054] CO adsorbed in DAC system 2 After desorption, it enters the rich solution of the dual alkali process system and then enters the mineralization regeneration step, which simplifies the steps of DAC technology and realizes CO 2 Direct use of the conventional DAC system requires CO 2 The regeneration agent of the present invention is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2The alkaline hydroxide has a concentration of 1.0-5.0 mol / L, a regeneration reaction temperature range of 40-80°C, a stirring rate of 50-300 rpm, and a reaction time of 30-70 min.

[0055] The filter press 12 of the present invention is provided with a slurry inlet and a product outlet 13 connected to the slurry outlet of the mineralization reactor 10 through a pump, and an infusion pump is provided between the filtrate outlet of the filter press 12 and the alkaline liquid infusion pipe. The slurry after the mineralization reaction enters the filter press 12, the separated calcium carbonate is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters absorption tower 2 to continue carbon capture.

[0056] The DAC device of the present invention is provided with a dehumidification module 6 and an adsorption-desorption module. The dehumidification module 6 and the fan 4 are connected to the dehumidification module 6 through a pipeline. The dehumidification module 6 is connected to the adsorption-desorption module through a pipeline. The fan 4 is also directly connected to the adsorption-desorption module through a pipeline. When the adsorption-desorption module is in an adsorption reaction, the gas is first dehumidified by the dehumidification module 6 and then enters the adsorption-desorption module; when the adsorption-desorption module is in a desorption reaction, the gas directly enters the adsorption-desorption module.

[0057] The dehumidification module 6 of the present invention is also provided with a water pipe, which transports the moisture collected by the dehumidification module 6 to an external water storage tank 9, and the water storage tank 9 is connected to the adsorption-desorption module through a water pump. The desorbed adsorbent is sprayed and rinsed with the cleaning water in the water storage tank 9, and blown and dried with a fan, and the blowing time lasts for 0.5 to 1.5 hours, and then enters the next adsorption-desorption cycle.

[0058] The present invention has two independent adsorption-desorption modules, namely the first adsorption-desorption module 7 and the second adsorption-desorption module 8, which perform the adsorption-desorption process alternately. 2 The adsorption-desorption module is connected to the rich liquid pipeline and the fan air flow channel in the absorption tower 2 respectively; the two modules alternately perform the adsorption-desorption process, which can realize the continuous operation of the DAC system and perform secondary carbon capture on the gas exhausted from the dual-alkali carbon capture system.

[0059] The present invention provides a large amount of cheap desorption alkali solution for DAC technology by coupling DAC technology and dual alkali carbon capture technology, thereby reducing the application cost of DAC technology and improving the comprehensive utilization efficiency of alkaline raw materials in dual alkali carbon capture technology. Conventional DAC desorption alkali solution raw materials need to be purchased separately, and there will be a loss of 1-2% of alkaline raw materials in dual alkali carbon capture technology. The present invention couples and integrates technologies, and the exhaust flue gas in the implementation process of dual alkali carbon capture technology is used as the capture intake gas of the DAC system to achieve CO 2 Multiple captures increase the CO2 The capture efficiency of conventional dual-alkali carbon capture technology is only one-time capture, and the capture efficiency is about 95-97%. Conventional DAC captures low-concentration CO from the air. 2 , the capture efficiency is about 10-15%; The exhaust gas from the dual alkali carbon capture technology is drawn out by a fan and then enters the DAC system as the capture air. The DAC system dehumidifies the air and completes the CO 2 The water collected by adsorption and dehumidification is used as the subsequent cleaning water. The CO 2 The absorbed rich liquid is drawn out and enters the DAC adsorption-desorption module. The rich liquid is used as desorption alkali liquid to spray and desorb the CO2 adsorbent in the DAC system. 2 The desorbed CO2 enters the rich liquid of the dual alkali system and is then pumped into the mineralization regeneration module of the dual alkali system. The desorbed CO2 in the DAC system is sprayed and cleaned with the above-mentioned cleaning water, and then dried by a fan and enters the next absorption-desorption cycle. Two independent adsorption-desorption modules can realize the continuous operation of the DAC system. 2 Without going through the separation, distillation and concentration steps of traditional DAC, the exhaust air of the dual-alkali carbon capture system can achieve secondary carbon capture.

[0060] The working principle of the present invention is as follows: refer to Figure 2 , the flue gas 1 of the coal-fired power plant is introduced into the absorption tower 2, and the flue gas flow rate is 100~500m 3 / h; at the same time, alkaline solution 3 is used as the absorption liquid to spray the CO in the flue gas 2 The alkali solution is caustic alkali such as sodium hydroxide and potassium hydroxide, the concentration of the alkali solution is 1.0-5.0 mol / L, and the liquid-gas ratio of the spraying process is 5-10 L / m 3 .

[0061] The flue gas is initially captured in the absorption tower and then discharged. The discharged gas is introduced into the DAC system 5 through the fan 4. The fan flow rate is 100-500m 3 / h; the airflow first passes through the dehumidification module 6 to remove moisture and then enters the CO 2 The first adsorption-desorption module 7 or the second adsorption-desorption module 8 has an adsorption time of 0.5 to 2.5 hours. The water collected by the dehumidification module is sent to the water storage tank 9 for recycling to remove CO 2 The air is then exhausted.

[0062] DAC system in CO 2 After the adsorption is completed, desorption is performed to remove the CO 2The absorbed rich liquid is pumped into the first adsorption-desorption module 7 or the second adsorption-desorption module 8 of DAC for spray desorption. The desorbed CO 2 Mainly CO 3 2- Enter CO in the form of 2 In the absorption rich liquid, the desorption process lasts for 0.5 to 2.5 hours; the desorbed adsorbent is sprayed and rinsed with the cleaning water in the water storage tank 9, and blown and dried with a fan, the blowing time lasts for 0.5 to 1.5 hours, and then enters the next adsorption-desorption cycle.

[0063] CO 2 The absorbed rich liquid is pumped into the mineralization reactor 10, and the absorbed liquid is regenerated by a causticizing reaction with the regeneration agent 11, and the regeneration agent is Ca(OH) 2 Mg(OH) 2 、Ba(OH) 2 The alkaline hydroxide is used, the regeneration agent concentration is 1.0-5.0 mol / L, the regeneration reaction temperature is 40-80°C, the stirring rate is 50-300 rpm, and the reaction time is 30-70 min.

[0064] The slurry after the mineralization reaction enters the filter press 12, and the separated calcium carbonate 13 is recovered as a by-product, and the filtrate is used as CO 2 The absorption liquid enters absorption tower 2 to continue carbon capture.

[0065] The DAC system is equipped with two independent CO 2 The adsorption-desorption module is connected to the rich liquid pipeline and the fan air flow channel in the absorption tower 2 respectively; the two modules alternately perform the adsorption-desorption process, which can realize the continuous operation of the DAC system and perform secondary carbon capture on the gas exhausted from the dual-alkali carbon capture system.

Claims

1. A coupling system of direct air carbon capture and dual alkali carbon capture, characterized in that: The invention comprises a DAC device (5) and a double alkali carbon capture device. The double alkali carbon capture device performs initial capture on flue gas and then discharges the gas into the DAC device through a fan (4). The double alkali carbon capture device uses an alkaline solution as a CO2 absorption liquid. The CO2 absorption rich liquid absorbed by the double alkali carbon capture device is transported to the DAC device through a pump for spraying. The CO2 absorption rich liquid generated by the DAC device flows back to the double alkali carbon capture device to generate an alkaline solution.

2. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 1, characterized in that: The dual alkali carbon capture device comprises an absorption tower (2), a mineralization reactor (10) and a filter press (12); a flue gas inlet duct (1) is connected to the bottom of the absorption tower (2); a spray head is provided on the top of the absorption tower (2); the spray head is connected to the filtrate outlet of the filter press (12) through an alkaline liquid infusion pipe (3); a liquid outlet is provided at the bottom of the absorption tower (2); the liquid outlet is connected to a DAC device through a pipeline; an exhaust port is provided at the top of the absorption tower (2); the exhaust port is connected to a fan (4).

3. The coupling system of direct air carbon capture and dual alkali carbon capture according to claim 1, characterized in that: The concentration of the alkaline solution is 1.0-5.0 mol / L, and the liquid-gas ratio during the spraying process is 5-10 L / m 3 .

4. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 2, characterized in that: The mineralization reactor (10) is provided with a regeneration agent input pipe (11), a slurry output port and a liquid inlet. The regeneration agent input pipe (11) inputs the regeneration agent into the mineralization reactor (10) to carry out a mineralization reaction with the CO2 absorption rich liquid transported by the DAC device through the liquid inlet.

5. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 4, characterized in that: The regeneration agent is alkaline hydroxide with a concentration of 1.0-5.0 mol / L, a regeneration reaction temperature of 40-80° C., a stirring rate of 50-300 rpm, and a reaction time of 30-70 min.

6. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 4, characterized in that: The filter press (12) is provided with a slurry inlet and a product outlet (13); the slurry inlet is connected to the slurry outlet of the mineralization reactor (10) through a pump; an infusion pump is provided between the alkaline liquid infusion pipe and the filtrate outlet of the filter press (12).

7. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 6, characterized in that: The by-product outputted from the product outlet (13) is calcium carbonate.

8. A coupling system of direct air carbon capture and dual alkali carbon capture according to any one of claims 1 to 7, characterized in that: The DAC device is provided with a dehumidification module (6) and an adsorption-desorption module. When the adsorption-desorption module is in an adsorption reaction, the gas first passes through the dehumidification module (6) for dehumidification and then enters the adsorption-desorption module. When the adsorption-desorption module is in a desorption reaction, the alkaline liquid directly enters the adsorption-desorption module.

9. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 8, characterized in that: The dehumidification module (6) is provided with a water pipe, through which the collected moisture is transported to an external water storage tank (9), and the water storage tank (9) is connected to the adsorption-desorption module via a water pump.

10. A coupling system of direct air carbon capture and dual alkali carbon capture according to claim 8, characterized in that: The adsorption-desorption module is provided with two independent first adsorption-desorption modules (7) and second adsorption-desorption modules (8), and the first adsorption-desorption module (7) and the second adsorption-desorption module (8) perform adsorption-desorption processes alternately.

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