Method and system for directly trapping carbon in air through solar-driven air thermochemical deoxidation

Abstract

The invention relates to the technical field of direct air carbon capture, in particular to a solar-driven air thermochemical deoxidation direct air carbon capture method and system.The chemical looping air separation technology is adopted, firstly, oxygen in air is removed through an oxidation reactor and a reduction reactor, and then the oxygen in the air is removed through the reduction reactor; then the oxygen-deficient air is fed into the DAC carbon capture unit for decarburization, so that the air handling capacity of the DAC unit can be greatly reduced; meanwhile, solar energy is adopted for supplying energy to the chemical looping reduction reactor, and clean and efficient energy supply of the DAC unit is achieved; therefore, the method and the system for directly capturing the air carbon through solar energy driven air thermochemical deoxidation adopt a mode of combining chemical looping air separation and DAC (Digital-to-Analog Converter), and the oxygen-deficient air at the outlet of the chemical looping air separation oxidation reactor acts on and drives the waste heat power generation unit to generate power, so that the supply of electric power and steam in the air decarbonization process is met; therefore, the problems of high energy consumption and high cost of the existing DAC technology are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct air carbon capture, and in particular to a solar-driven air thermochemical deoxidation direct air carbon capture method and system. Background Art

[0002] As an important technical means to address global climate change, direct air capture (DAC) technology is increasingly becoming a core component of emission reduction strategies in various countries. This technology has the characteristics of efficient capture of carbon dioxide from the atmosphere and flexible deployment. It can operate in a variety of environments and effectively combine with renewable energy systems to achieve negative carbon emissions.

[0003] Due to its effect, direct air capture technology has attracted much attention and research, such as the patent technology document CN115445384A, which discloses a wind-photovoltaic complementary drive direct air carbon capture system and method for greenhouses. The invention uses wind energy and solar energy to generate electricity, which can capture carbon dioxide from the air without generating additional carbon dioxide. While reducing the concentration of carbon dioxide in the air, it can also achieve on-site utilization of carbon dioxide and supply of carbon dioxide gas fertilizer in greenhouses, thereby reducing the energy consumption and cost of direct air carbon capture technology. The invention can also realize the continuous capture of carbon dioxide in the air and the continuous supply of carbon dioxide products through intermittent alternating operation of carbon dioxide adsorption-thermal regeneration reactors. The carbon dioxide capture efficiency is high, the adsorbent regeneration energy consumption is low, and the system scale can be flexibly adjusted according to demand. The invention closely combines air carbon capture with greenhouse gas fertilizer supply, which not only achieves air carbon reduction, but also realizes on-site utilization of carbon dioxide products, provides a new type of pollution-free greenhouse carbon dioxide gas fertilizer technology, improves greenhouse crop yields, and increases crop carbon sinks. Wind-photovoltaic complementary drive direct air carbon capture system and method for greenhouses.

[0004] However, the high energy consumption and high cost of these existing DAC technologies have seriously hindered their development and deployment. For low-temperature adsorption DAC technology, its energy consumption mainly occurs in the air compression process. However, due to the extremely low concentration of carbon dioxide in the air, compared with typical coal-fired flue gas, under the same carbon capture amount, the DAC technology has a larger air processing volume, and the corresponding air compression process consumes a lot of energy.

[0005] Therefore, according to the above-mentioned related technologies, it is urgent to develop a solar-driven air thermochemical deoxygenation direct air carbon capture method and system. Summary of the invention

[0006] In view of this, the purpose of the present invention is to propose a solar-driven air thermochemical deoxidation direct air carbon capture method and system to solve the problems of high energy consumption and high cost of the existing DAC technology.

[0007] Based on the above objectives, the present invention provides a solar-driven air thermochemical deoxygenation direct air carbon capture method and system.

[0008] A solar-driven air thermochemical deoxygenation direct air carbon capture method comprises the following steps:

[0009] Step S1: After entering the oxidation reactor, the air reacts with the metal oxygen carrier Me to generate MeO, and the oxygen in the air is consumed to become oxygen-depleted air;

[0010] The MeO generated in the oxidation reactor enters the reduction reactor and is reduced to Me and pure oxygen under the heat drive of solar energy;

[0011] The pure oxygen produced by the reduction reactor can be sold or used to supply oxygen for other energy processes;

[0012] The Me reduced in the reduction reactor will return to the oxidation reactor to continue reacting with oxygen in the air;

[0013] The pure oxygen is discharged from the reduction reactor outlet;

[0014] Step S2: the oxygen-depleted air generated in the oxidation reactor enters the adsorption tower, contacts with the adsorbent to remove carbon dioxide from the oxygen-depleted air, and generates decarbonized air and an adsorbent that completes carbon dioxide adsorption;

[0015] The decarbonized air is discharged from the adsorption tower into the atmosphere;

[0016] Step S3: The adsorbent produced by the adsorption tower that has completed the carbon dioxide adsorption will enter the desorption tower to complete the desorption of carbon dioxide, and then return to the adsorption tower again to continue to react with carbon dioxide in the air.

[0017] Preferably, a MeO and Me storage tank is provided between the oxidation reactor and the reduction reactor to adjust the instability of solar energy supply, store excess solar energy in the metal oxygen carrier Me during the day, and react air with Me at night to provide energy for the air decarbonization process;

[0018] A waste heat power generation unit and a compressor are arranged in sequence between the oxidation reactor and the adsorption tower.

[0019] Preferably, the oxygen-depleted air is compressed when entering the adsorption tower from the outlet of the oxidation reactor.

[0020] Preferably, the oxygen-depleted air at the outlet of the oxidation reactor is used to drive the waste heat boiler to generate electricity, thereby providing electricity and steam for the oxygen-depleted air decarbonization process;

[0021] The compression work required for the oxygen-depleted air compression process is provided by the waste heat power generation unit; the pump work required for the desorption tower vacuuming process is provided by the waste heat power generation unit;

[0022] The heat energy required for the desorption process of the desorption tower is provided by steam extraction from the waste heat power generation unit.

[0023] Preferably, the adsorbent is an adsorbent prepared by loading an organic amine on a solid porous material as a carrier;

[0024] The solid porous material is any one of zeolite, activated carbon and MOF material;

[0025] The organic amine is obtained by mixing a primary amine and a tertiary amine;

[0026] The tertiary amine is any one of 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5,7-triazabicyclo[4.4.0]dec-5-ene;

[0027] The primary amine is any one of ethanolamine and 2-amino-2-methyl-1-propanol;

[0028] The adsorbent is prepared by a physical impregnation method.

[0029] Preferably, the metal oxygen carrier Me is any one of cobalt, copper and manganese.

[0030] Preferably, the reaction pressure in the oxidation reactor is 1-10 bar, and the reaction temperature is 900-1000° C.;

[0031] The reaction temperature in the reduction reactor is 500-600°C.

[0032] Preferably, the working pressure of the adsorption tower is 1.5-3 bar to achieve a higher carbon dioxide adsorption capacity;

[0033] The desorption tower has an operating pressure of 0.01-0.1 bar to achieve a carbon dioxide recovery rate of about 90% and a carbon dioxide purity of more than 95%.

[0034] A solar-driven air thermochemical deoxygenation direct air carbon capture system, the solar-driven air thermochemical deoxygenation direct air carbon capture system comprises a solar collector field, a reduction reactor, an oxidation reactor, an adsorption tower and a desorption tower connected in sequence; the system uses chemical chain air separation technology to first remove oxygen from the air, and then send the oxygen-depleted air into a DAC carbon capture unit for decarbonization, which can greatly reduce the air handling capacity of the DAC unit, and is expected to reduce the air compression work by about 20%-30%. At the same time, during the day, by using concentrated solar energy to provide energy for the chemical chain deoxygenation process, a part of the solar energy is stored as the chemical energy of the metal oxygen carrier, and the other part absorbs the oxygen in the air, and by recovering high-temperature waste heat to generate electricity and heat, heat consumption and compression work are provided for DAC, and then the oxygen-depleted air enters the DAC for decarbonization after heat recovery. At night, the metal oxygen carrier in the storage tank reacts with the air to provide energy for the DAC, thereby realizing stable energy supply. The technology of the present invention can achieve long-term stable operation while greatly reducing the capture energy consumption of the DAC technology by combining with solar energy technology.

[0035] Preferably, the solar-driven air thermochemical deoxygenation direct air carbon capture system also includes a MeO storage tank, a Me storage tank and a waste heat recovery power generation unit, wherein the MeO storage tank and the Me storage tank are connected to the oxidation reactor and the reduction reactor, the MeO storage tank is used to store the metal oxide MeO at the outlet of the oxidation reactor, and the Me storage tank is used to store the metal Me at the outlet of the reduction reactor, so as to smooth the volatility of solar energy and achieve long-term stable carbon capture.

[0036] Beneficial effects of the present invention:

[0037] The present invention provides a method and system for direct air carbon capture by solar-driven air thermochemical deoxygenation. The present invention adopts chemical chaining air separation technology, first removes oxygen from the air through an oxidation reactor and a reduction reactor, and then sends the oxygen-depleted air to a DAC carbon capture unit for decarbonization, which can greatly reduce the air processing capacity of the DAC unit; at the same time, the present invention adopts solar energy to power the chemical chaining reduction reactor, thereby achieving clean and efficient power supply of the DAC unit; therefore, the method and system for direct air carbon capture by solar-driven air thermochemical deoxygenation adopts a combination of chemical chaining air separation and DAC, and the oxygen-depleted air at the outlet of the chemical chaining air separation oxidation reactor is used to drive the waste heat power generation unit to generate electricity, so as to meet the supply of electricity and steam in the air decarbonization process, thereby solving the problems of high energy consumption and high cost of the existing DAC technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A diagram of the direct air carbon capture method by solar-driven air thermochemical deoxidation in the present invention;

[0040] Figure 2 This is a diagram of a conventional low temperature adsorption direct air carbon capture system;

[0041] Figure 3 This is a diagram of the solar-driven air thermochemical deoxygenation direct air carbon capture system of the present invention. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0043] Example 1: A solar-driven air thermochemical deoxygenation direct air carbon capture method is as follows:

[0044] S1: According to the attached Figure 3 The solar collector field, reduction reactor, MeO storage tank, Me storage tank, oxidation reactor, waste heat power generation unit, adsorption tower and desorption tower are assembled into a solar-driven air thermochemical deoxygenation direct air carbon capture system; compared with the traditional low-temperature adsorption DAC system, this system adopts chemical chaining air separation technology, and the air is first passed into the chemical chaining oxidation reactor to react with metal Me to remove oxygen from the air, and then compressed and sent to the adsorption tower for decarbonization. At the same time, during the day, concentrated solar energy is used to provide energy for the chemical chaining deoxygenation process, part of the solar energy is stored as chemical energy of metal oxygen carriers, and the other part absorbs oxygen in the air, and generates electricity and heat by recovering high-temperature waste heat, providing heat consumption and compression work for DAC. At night, the metal oxygen carriers in the storage tank react with air to provide energy for DAC, achieving stable energy supply;

[0045] S2: 30 g of 1,8-diazabicyclo[5.4.0]undec-7-ene and 10 g of ethanolamine were mixed evenly, and then zeolite was impregnated therein to obtain an adsorbent;

[0046] S3: placing the adsorbent into an adsorption tower;

[0047] S4: placing cobalt into an oxidation reactor and setting the reaction pressure in the oxidation reactor to 1 bar and the reaction temperature to 900° C.;

[0048] S5: setting the reaction temperature in the reduction reactor to 500° C.;

[0049] S6: Set the working pressure of the adsorption tower to 1.5 bar;

[0050] S7: setting the working pressure of the desorption tower to 0.1 bar;

[0051] S8: introducing air into the oxidation reactor;

[0052] S9: collecting the decarbonized air discharged from the adsorption tower and the carbon dioxide discharged from the desorption tower;

[0053] Example 2: A solar-driven air thermochemical deoxygenation direct air carbon capture method is as follows:

[0054] S1: According to the attached Figure 3 Assemble a solar energy-driven air thermochemical deoxygenation direct air carbon capture system by assembling a solar energy collection field, a reduction reactor, a MeO storage tank, a Me storage tank, an oxidation reactor, a waste heat power generation unit, an adsorption tower, and a desorption tower;

[0055] S2: 30 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene and 13 g of ethanolamine were mixed evenly, and then activated carbon was impregnated therein to obtain an adsorbent;

[0056] S3: placing the adsorbent into an adsorption tower;

[0057] S4: placing copper into an oxidation reactor and setting the reaction pressure in the oxidation reactor to 5 bar and the reaction temperature to 950° C.;

[0058] S5: setting the reaction temperature in the reduction reactor to 550° C.;

[0059] S6: Set the working pressure of the adsorption tower to 2.5 bar;

[0060] S7: setting the working pressure of the desorption tower to 0.05 bar;

[0061] S8: introducing air into the oxidation reactor;

[0062] S9: collecting the decarbonized air discharged from the adsorption tower and the carbon dioxide discharged from the desorption tower;

[0063] Example 3: A solar-driven air thermochemical deoxygenation direct air carbon capture method is as follows:

[0064] S1: According to the attached Figure 3 Assemble a solar energy-driven air thermochemical deoxygenation direct air carbon capture system by assembling a solar energy collection field, a reduction reactor, a MeO storage tank, a Me storage tank, an oxidation reactor, a waste heat power generation unit, an adsorption tower, and a desorption tower;

[0065] S2: 30 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene and 15 g of 2-amino-2-methyl-1-propanol were mixed evenly, and then the MOF material was impregnated therein to obtain an adsorbent;

[0066] S3: placing the adsorbent into an adsorption tower;

[0067] S4: placing manganese into an oxidation reactor and setting the reaction pressure in the oxidation reactor to 10 bar and the reaction temperature to 1000° C.;

[0068] S5: setting the reaction temperature in the reduction reactor to 600° C.;

[0069] S6: Set the working pressure of the adsorption tower to 3 bar;

[0070] S7: setting the working pressure of the desorption tower to 0.01 bar;

[0071] S8: introducing air into the oxidation reactor;

[0072] S9: collecting the decarbonized air discharged from the adsorption tower and the carbon dioxide discharged from the desorption tower;

[0073] Comparative Example 1:

[0074] Compared with Example 1, this comparative example only replaces the "1,8-diazabicyclo[5.4.0]undec-7-ene and ethanolamine" used in the adsorbent preparation process with "1,8-diazabicyclo[5.4.0]undec-7-ene", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally carbon dioxide and decarbonized air are obtained;

[0075] Comparative Example 2:

[0076] Compared with Example 1, this comparative example only replaces the "1,8-diazabicyclo[5.4.0]undec-7-ene and ethanolamine" used in the adsorbent preparation process with "ethanolamine", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally carbon dioxide and decarbonized air are obtained;

[0077] Comparative Example 3:

[0078] Compared with Example 1, this comparative example only replaces the "1,8-diazabicyclo[5.4.0]undec-7-ene and ethanolamine" used in the adsorbent preparation process with "polyethyleneimine", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally obtains carbon dioxide and decarbonized air;

[0079] Comparative Example 4:

[0080] Compared with Example 1, this comparative example does not have MeO and Me storage tanks between the oxidation reactor and the reduction reactor, and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally carbon dioxide and decarbonized air are obtained;

[0081] Comparative Example 5:

[0082] Compared with Example 1, this comparative example only replaces the working pressure of the adsorption tower from "1.5 bar" to "0.5 bar", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally obtains carbon dioxide and decarbonized air;

[0083] Comparative Example 6:

[0084] Compared with Example 1, this comparative example only replaces the working pressure of the desorption tower from "0.1 bar" to "1 bar", and the remaining steps and parameters are the same, which will not be repeated in this comparative example. Finally, carbon dioxide and decarbonized air are obtained.

[0085] Performance Test:

[0086] Referring to the test standard of "GB / T18204.24 Public Place Hygiene Inspection Method, Part II: Chemical Pollutants", the purity and carbon dioxide recovery rate of the carbon dioxide processed by Examples 1 to 3 of the present invention and Comparative Examples 1 to 6 at 00:00 and 12:00 every day were measured; the average value of the measurement results for 30 days was taken as the measurement result, and it was finally found that the solar-driven air thermochemical deoxidation direct air carbon capture method and system of the present invention has a better carbon dioxide recovery capacity and recovery stability; this may be because the adsorbent provided by the present invention is prepared by compounding tertiary amines and primary amines, and the tertiary amines and primary amines have a stronger carbon dioxide affinity after compounding; and when the MeO storage tank and the Me storage tank of the present invention are connected to the oxidation reactor and the reduction reactor, the MeO storage tank can be used to store the metal oxide MeO at the outlet of the oxidation reactor, and the Me storage tank can be used to store the metal Me at the outlet of the reduction reactor, so as to smooth the volatility of solar energy and achieve long-term stable carbon capture; the working pressure of the adsorption tower and the desorption tower of the present invention is also the optimal working pressure adjusted by the present invention, which can make the present invention have a better carbon dioxide recovery capacity;

[0087] Figure 2 This is a traditional low-temperature adsorption DAC process flow chart, which consists of an adsorption tower and a desorption tower. The air is first compressed by a compressor and then enters the adsorption tower to contact the adsorbent. The CO2 in the air is removed and the decarbonized air is discharged from the top of the adsorption tower. Subsequently, the adsorbent that has adsorbed CO2 enters the desorption tower for regeneration. After regeneration, the adsorbent returns to the adsorption tower to continue to react with the air. The desorption tower maintains a vacuum environment through a vacuum pump to ensure a high CO2 desorption rate. The electricity and steam required for regeneration are provided externally.

[0088] Figure 3 The system of the direct air carbon capture method of solar-driven air thermochemical deoxygenation provided by the present invention is composed of a solar collector field, a reduction reactor, a MeO storage tank, a Me storage tank, an oxidation reactor, a waste heat power generation unit, an adsorption tower and a desorption tower. Compared with the traditional low-temperature adsorption DAC system, this system adopts chemical chain air separation technology. The air is first passed into the chemical chain oxidation reactor to react with the metal Me, and the oxygen in the air is removed, and then it is compressed and sent to the adsorption tower for decarbonization. At the same time, during the day, concentrated solar energy is used to provide energy for the chemical chain deoxygenation process, part of the solar energy is stored as the chemical energy of the metal oxygen carrier, and the other part absorbs the oxygen in the air, and the high-temperature waste heat is recovered to generate electricity and heat, providing heat consumption and compression work for DAC. At night, the metal oxygen carrier in the storage tank reacts with the air to provide energy for DAC, thereby achieving stable energy supply.

[0089] Combination Figure 1 and Figure 2 It can be seen that compared with the prior art, the present invention solves the problems of high energy consumption and high cost of the prior DAC technology, and also has better carbon dioxide recovery capacity and recovery stability;

[0090] This may be because the present invention adopts chemical chaining air separation technology to first remove oxygen from the air and then send the oxygen-depleted air to the DAC carbon capture unit for decarbonization, which can greatly reduce the air processing volume of the DAC unit, and is expected to reduce the air compression work by about 20%-30%, while increasing the carbon dioxide concentration in the captured air and reducing the capture energy consumption; the present invention adopts solar energy to power the chemical chaining reduction reactor, thereby achieving clean and efficient power supply for the DAC unit, and at the same time adding storage tanks to store energy to achieve long-term stable operation of the DAC capture technology; the present invention adopts a combination of chemical chaining air separation and DAC, and uses the oxygen-depleted air at the outlet of the chemical chaining air separation oxidation reactor to drive the waste heat power generation unit to generate electricity, which can meet the supply of electricity and steam in the air decarbonization process, achieve self-sufficiency in the system energy demand, and can also export electricity and steam to the outside.

[0091] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0092] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A solar-driven air thermochemical deoxygenation direct air carbon capture method, characterized in that: The following steps are involved: Step S1: After the air enters the oxidation reactor, it reacts with the metal oxygen carrier Me to generate MeO, and the oxygen in the air is consumed to become oxygen-depleted air; Step S2: the oxygen-depleted air generated in the oxidation reactor enters the adsorption tower, contacts with the adsorbent to remove carbon dioxide from the oxygen-depleted air, and generates decarbonized air and an adsorbent that completes carbon dioxide adsorption; Step S3: The adsorbent produced by the adsorption tower that has completed carbon dioxide adsorption will enter the desorption tower to complete the desorption of carbon dioxide, and then return to the adsorption tower again to continue to react with carbon dioxide in the air.

2. The solar-driven air thermochemical deoxidation direct air carbon capture method according to claim 1, characterized in that: The MeO generated in the oxidation reactor enters the reduction reactor and is reduced to Me and pure oxygen under the heat drive of solar energy; The Me reduced in the reduction reactor will return to the oxidation reactor to continue reacting with oxygen in the air; The pure oxygen is discharged from the reduction reactor outlet; The oxygen-depleted air will be compressed when entering the adsorption tower from the outlet of the oxidation reactor; The decarbonized air is discharged from the adsorption tower into the atmosphere.

3. The solar-driven air thermochemical deoxidation direct air carbon capture method according to claim 1, characterized in that: The adsorbent is prepared by using a solid porous material as a carrier and loading an organic amine; The solid porous material is any one of zeolite, activated carbon and MOF material; The organic amine is obtained by mixing a primary amine and a tertiary amine; The tertiary amine is any one of 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; The primary amine is any one of ethanolamine and 2-amino-2-methyl-1-propanol; The mass ratio of the primary amine to the tertiary amine is 3:1-1.

5.

4. The solar-driven air thermochemical deoxidation direct air carbon capture method according to claim 1, characterized in that: The metal oxygen carrier Me is any one of cobalt, copper and manganese.

5. The solar-driven air thermochemical deoxidation direct air carbon capture method according to claim 1, characterized in that: The reaction pressure in the oxidation reactor is 1-10 bar; The reaction temperature in the oxidation reactor is 900-1000°C; The reaction temperature in the reduction reactor is 500-600°C.

6. The solar-driven air thermochemical deoxidation direct air carbon capture method according to claim 1, characterized in that: The working pressure of the adsorption tower is 1.5-3 bar; the working pressure of the desorption tower is 0.01-0.1 bar.

7. A solar-driven air thermochemical deoxygenation direct air carbon capture system according to any one of claims 1 to 6, characterized in that: The solar-driven air thermochemical deoxidation direct air carbon capture system comprises a solar collector field, a reduction reactor, an oxidation reactor, an adsorption tower and a desorption tower connected in sequence; A MeO storage tank and a Me storage tank are provided between the oxidation reactor and the reduction reactor; A waste heat power generation unit and a compressor are arranged in sequence between the oxidation reactor and the adsorption tower.

8. The solar-driven air thermochemical deoxidation direct air carbon capture system according to claim 7, characterized in that: The compression work required for the compression process of oxygen-depleted air is provided by the waste heat power generation unit; The pump work required for the vacuuming process of the desorption tower is provided by the waste heat power generation unit; The heat energy required for the desorption process of the desorption tower is provided by steam extraction from the waste heat power generation unit.

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