Chemical looping air thermochemical deoxidation driven high-temperature direct air carbon capture method and system

Abstract

The invention relates to the technical field of direct air carbon capture, in particular to a chemical looping air thermochemical deoxidation driven high-temperature direct air carbon capture method and system. The method comprises the following steps: introducing air into an air reactor to react with a metal oxygen carrier to obtain an oxidation product and oxygen-deficient air, and generating heat energy to supply energy to a calcining furnace; an oxidation product enters a fuel reactor for reaction; oxygen-deficient air enters the first air contactor and the second air contactor to react and then passes through the particle reactor, the calcining furnace and the hydrator to complete air carbon capture. According to the invention, the chemical-looping metal oxygen carrier and the oxygen in the air are subjected to chemical reaction, so that the oxygen in the air is consumed in advance, the volume flow of the air entering the air contactor is greatly reduced, the CO2 concentration in the air is improved, and the decarburization process scale and decarburization energy consumption are remarkably reduced. Meanwhile, fuel is adopted to drive chemical looping combustion to supply energy to the calcination process, and efficient conversion and zero-energy-consumption carbon capture of energy supply fossil fuel are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct air carbon capture, and particularly to a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method and system. Background Art

[0002] Direct Air Capture (DAC) is an emerging technology for absorbing carbon dioxide from the air. This technology has the characteristics of efficiently capturing carbon dioxide from the atmosphere and flexible deployment, can operate in diverse environments, and can be effectively combined with renewable energy systems to achieve negative carbon emissions.

[0003] However, due to the extremely low concentration of CO2 in the air, compared with typical coal-fired power plant flue gas, for the same carbon capture amount, the air treatment volume of the DAC technology increases significantly, and the scale of the capture equipment is large. A typical high-temperature solution absorption DAC process uses NaOH / KOH and CaCO3 as circulating adsorbents, and the calcination process of CaCO3 is a high-energy density process, often using fossil fuel combustion to provide high-temperature heat energy of 900 - 1000 °C for it. To avoid the additional CO2 emissions brought by fossil fuel energy supply, an air separation device is required to prepare pure oxygen to avoid the carbon in the fuel being diluted by N2, and the high-purity oxygen required for oxy-fuel combustion consumes a huge air separation energy consumption. At the same time, to meet the electrical energy and heat energy requirements of the DAC process, the DAC technology often needs to be equipped with a natural gas carbon capture power plant by itself, which all lead to an increase in the cost and a decrease in the efficiency of this technology in practical applications, restricting the wide application of this technology.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the existing technology, the purpose of the present invention is to provide a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method and system, aiming to solve the problems of large-scale equipment, low CO2 concentration in the air, and high energy consumption for preparing pure oxygen by air separation in the existing DAC technology.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method is provided, which includes:

[0008] Step S1: Pass air into an air reactor to react with a metal oxygen carrier to obtain a metal oxygen carrier oxidation product and oxygen-depleted air, and generate heat energy;

[0009] Step S2: The metal oxygen carrier oxidation product obtained in Step S1 enters the fuel reactor and undergoes a reduction reaction with the fuel to obtain a regenerated metal oxygen carrier, CO2, and H2O. The regenerated metal oxygen carrier returns to the air reactor to continue reacting with air;

[0010] Step S3: The oxygen-depleted air obtained in Step S1 enters the first air contactor and reacts with the CO2 absorbent to obtain preliminarily decarbonized air and rich liquid. The preliminarily decarbonized air and fresh air enter the second air contactor and react with the CO2 absorbent to obtain decarbonized air and semi-rich liquid. The semi-rich liquid enters the first air contactor to continue reacting with the oxygen-depleted air;

[0011] Step S4: The rich liquid obtained in Step S3 enters the particle reactor and reacts with Ca(OH)2 to obtain CaCO3 and lean liquid. The lean liquid returns to the second air contactor to continue reacting with the preliminarily decarbonized air and fresh air;

[0012] Step S5: The CaCO3 obtained in Step S4 enters the calcination furnace and undergoes a calcination reaction to obtain CaO and CO2. The heat required for the calcination reaction is provided by the heat energy generated in the air reactor;

[0013] Step S6: The CaO obtained in Step S5 enters the hydrator and reacts with water vapor to obtain Ca(OH)2. Ca(OH)2 enters the particle reactor to continue reacting with the rich liquid.

[0014] Optionally, the first air contactor and the second air contactor are connected in series. The lean liquid first enters the second air contactor and reacts with the preliminarily decarbonized air and fresh air to obtain semi-rich liquid, and then the semi-rich liquid enters the first air contactor to react with the oxygen-depleted air.

[0015] Optionally, the metal oxygen carrier is one or more of Co, Cu, Mn, Ni, Fe, Ca, Ba, Pb, Ag, Pd, Cr, and Os.

[0016] Optionally, the CO2 absorbent is KOH or NaOH.

[0017] Optionally, the fuel is one or more of fossil fuels, hydrogen, biomass, and ammonia.

[0018] Optionally, the reaction pressure in the air reactor is 1 - 10 bar, and the reaction temperature in the air reactor is 900 - 1000 °C; the reaction pressure in the fuel reactor is atmospheric pressure, and the reaction temperature is 600 - 900 °C; the reaction conditions in the first air contactor and the second air contactor are normal temperature and pressure.

[0019] Optionally, the reaction conditions in the particle reactor are normal temperature and pressure; the reaction pressure in the calciner is atmospheric pressure, and the reaction temperature is 850 - 950 °C; the reaction pressure in the hydrator is atmospheric pressure, and the reaction temperature is 250 - 350 °C.

[0020] Optionally, in step S2, the products CO2 and H2O in the fuel reactor are sent into the calciner to reduce the partial pressure of gaseous CO2 and promote the forward progress of the calcination reaction.

[0021] In the second aspect of the present invention, there is provided a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system prepared according to the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method of the present invention, which includes: an air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calciner, and a hydrator;

[0022] The air reactor and the fuel reactor are connected by a first pipeline and a second pipeline. The air reactor is loaded with a metal oxygen carrier, and the fuel reactor is loaded with fuel. The first pipeline is used to transport the oxidized product of the metal oxygen carrier obtained by oxidation in the air reactor to the fuel reactor, and the second pipeline is used to return the reduced metal oxygen carrier in the fuel reactor to the air reactor. The heat energy generated in the air reactor is transported to the calciner;

[0023] The air reactor and the first air contactor are connected by a third pipeline. The third pipeline is used to transport the oxygen-depleted air in the air reactor to the first air contactor. The first air contactor is loaded with a CO2 absorbent and is provided with a preliminary decarbonized air output end;

[0024] The first air contactor and the second air contactor are connected by a fourth pipeline and a fifth pipeline. The fourth pipeline is used to transport the preliminary decarbonized air in the first air contactor to the second air contactor, and the fifth pipeline is used to transport the semi-lean liquid in the second air contactor to the first air contactor. The second air contactor is loaded with a CO2 absorbent and is provided with a decarbonized air output end and an external air input end;

[0025] The first air contactor and the particle reactor are connected by a sixth pipeline. The sixth pipeline is used to transport the rich liquid obtained in the first air contactor to the particle reactor;

[0026] The second air contactor and the particle reactor are connected by a seventh pipeline. The seventh pipeline is used to return the lean liquid obtained in the particle reactor to the second air contactor;

[0027] The granular reactor and the calciner are connected by an eighth pipeline, and the eighth pipeline is used to transport the CaCO3 obtained in the granular reactor to the calciner;

[0028] The calciner and the hydrator are connected by a ninth pipeline. The calciner is provided with a CO2 output end, and the ninth pipeline is used to transport the CaO obtained in the calciner to the hydrator;

[0029] The hydrator and the granular reactor are connected by a tenth pipeline, and the tenth pipeline is used to transport the Ca(OH)2 obtained in the hydrator to the granular reactor.

[0030] Optionally, the air reactor and the calciner are arranged in an external combustion mode. The air reactor is placed inside the calciner, and the heat energy generated in the air reactor is transferred to the inside of the calciner through the metal wall.

[0031] Optionally, when the air reactor operates under normal pressure, the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system further includes an air preheater and a fuel preheater. The air preheater is connected to the air reactor to recover the waste heat of the oxygen-depleted air and preheat the air fed into the air reactor; the fuel preheater is connected to the calciner to recover the waste heat of the product at the outlet of the calciner, and the fuel preheater is also connected to the fuel reactor to preheat the fuel entering the fuel reactor.

[0032] Optionally, when the air reactor operates at a pressure higher than normal pressure, the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system further includes a gas turbine. The gas turbine is connected to the air reactor, and the gas turbine is used to receive the oxygen-depleted air in the air reactor to recover the pressure energy and heat energy of the oxygen-depleted air.

[0033] Optionally, when the air reactor operates at a pressure higher than normal pressure, the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system further includes an air compressor. The air compressor is connected to the air reactor, and the air compressor is used to pressurize the air and then feed it into the air reactor.

[0034] Optionally, the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system further includes a waste heat power generation cycle unit. The waste heat power generation cycle unit is respectively connected to the gas turbine, the fuel reactor and the calciner, and the waste heat power generation cycle unit is used to recover the waste heat of the products at the outlets of the gas turbine, the fuel reactor and the calciner.

[0035] Beneficial effects: The chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method and system provided by the present invention utilize the chemical-looping metal oxygen carrier to chemically react with the oxygen in the air. Before the air enters the air contactor to remove CO2, the oxygen in the air is consumed in advance, significantly reducing the air volume flow rate entering the air contactor and increasing the CO2 concentration in the air, and significantly reducing the scale of the decarbonization process and the decarbonization energy consumption. At the same time, fuel-driven chemical-looping combustion is used to supply energy for the calcination process, avoiding the high power consumption of using an air separation unit to prepare pure oxygen and a self-provided carbon capture power plant, and realizing the efficient conversion of the fossil fuel for energy supply and zero-energy carbon capture. Description of the Drawings

[0036] Figure 1 It is a flow chart of a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method provided by the present invention.

[0037] Figure 2 It is a schematic structural diagram of a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system provided by the present invention.

[0038] Figure 3 It is a schematic structural diagram of an atmospheric-pressure chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system provided in Example 1.

[0039] Figure 4 It is a schematic structural diagram of a traditional high-temperature solution absorption direct air carbon capture system provided in Comparative Example 1.

[0040] Figure 5 It is a schematic structural diagram of a high-pressure chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system provided in Example 3. Detailed Embodiments

[0041] The present invention provides a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method and system. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] As Figure 1 shown, an embodiment of the present invention provides a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method, which includes:

[0043] Step S1: Pass air into an air reactor to chemically react with a metal oxygen carrier (Me) to obtain a metal oxygen carrier oxidation product and oxygen-depleted air, and generate heat energy;

[0044] Step S2: The metal oxide carrier oxidation product (MeO) obtained in step S1 enters the fuel reactor and undergoes a reduction reaction with the fuel to obtain a regenerated metal oxide carrier, CO2, and H2O. The regenerated metal oxide carrier returns to the air reactor to continue reacting with air;

[0045] Step S3: The oxygen-depleted air obtained in step S1 enters the first air contactor to react with the CO2 absorbent, obtaining preliminarily decarbonized air and rich liquid (carbon-rich solution). The preliminarily decarbonized air and fresh air enter the second air contactor to react with the CO2 absorbent, obtaining decarbonized air and semi-lean liquid. The semi-lean liquid enters the first air contactor to continue reacting with the oxygen-depleted air;

[0046] Step S4: The rich liquid obtained in step S3 enters the particle reactor and reacts with Ca(OH)2 to obtain CaCO3 and lean liquid (carbon-lean solution). The lean liquid returns to the second air contactor to continue reacting with the preliminarily decarbonized air and fresh air;

[0047] Step S5: The CaCO3 obtained in step S4 enters the calcination furnace and undergoes a calcination reaction to obtain CaO and CO2. The heat required for the calcination reaction is provided by the thermal energy generated in the air reactor;

[0048] Step S6: The CaO obtained in step S5 enters the hydrator and reacts with water vapor to obtain Ca(OH)2. The Ca(OH)2 enters the particle reactor to continue reacting with the rich liquid.

[0049] The embodiment of the present invention provides a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method. Air first enters the air reactor, and a chemical reaction occurs between the chemical-looping metal oxide carrier and the oxygen in the air. Before the air enters the air contactor to remove CO2, the oxygen in the air is consumed in advance, significantly reducing the volume flow rate of the air entering the air contactor and increasing the CO2 concentration in the air, and significantly reducing the scale of the decarbonization process and the decarbonization energy consumption. At the same time, fuel-driven chemical-looping combustion is used to supply energy for the calcination process, avoiding the high power consumption of using an air separation unit to prepare pure oxygen and a self-provided carbon capture power plant, and realizing the efficient conversion of the energy-providing fossil fuel and zero-energy carbon capture. By using the direct air carbon capture method of the embodiment of the present invention, the energy penalty of the DAC technology can be significantly reduced.

[0050] In some embodiments, the first air contactor and the second air contactor are connected in series. The lean liquid first enters the second air contactor to react with the preliminarily decarbonized air and fresh air to obtain semi-lean liquid, and then the semi-lean liquid enters the first air contactor to react with the oxygen-depleted air.

[0051] In some embodiments, the metal oxide carrier is one or more of Co, Cu, Mn, Ni, Fe, Ca, Ba, Pb, Ag, Pd, Cr, and Os.

[0052] In some embodiments, the fuel is one or more of fossil fuels, hydrogen, biomass, and ammonia. The reaction pressure in the fuel reactor is normal pressure, and the reaction temperature is 600 - 900 °C. The main chemical reaction occurring in the fuel reactor is the reduction reaction of the metal oxygen carrier oxidation product MeO with the fuel to obtain the metal oxygen carrier Me, CO2, and H2O.

[0053] In some embodiments, the reaction pressure in the air reactor is 1 - 10 bar, and the reaction temperature is 900 - 1000 °C. The main chemical reaction occurring in the air reactor is Air + Me → MeO, and the heat released by this reaction supplies heat to the calciner, with a heat exchange temperature difference of 50 - 100 °C. Therefore, the reaction temperature needs to be set to 900 - 1000 °C.

[0054] In some embodiments, the reaction conditions in the first air contactor and the second air contactor are normal temperature and normal pressure. The first air contactor and the second air contactor are loaded with a CO2 absorbent to absorb CO2 in the oxygen - depleted air. Preferably, the CO2 absorbent is KOH or NaOH. When the CO2 absorbent is KOH, the main chemical reaction occurring in the first air contactor and the second air contactor is KOH + CO2 → K2CO3 + H2O; a similar reaction occurs when the CO2 absorbent is NaOH.

[0055] In some embodiments, the reaction conditions in the particle reactor are normal temperature and normal pressure. The main chemical reaction occurring in the particle reactor is K2CO3 + Ca(OH)2 → KOH + CaCO3.

[0056] In some embodiments, the reaction pressure in the calciner is normal pressure, and the reaction temperature in the calciner is 850 - 950 °C. The main chemical reaction occurring in the calciner is CaCO3 → CaO + CO2. When the reaction temperature is too low, the reaction is not easy to proceed; when the reaction temperature is too high, CaCO3 is prone to sintering. Therefore, the reaction temperature in the calciner needs to be set to 850 - 950 °C.

[0057] In some embodiments, the reaction pressure in the hydrator is normal pressure, and the reaction temperature is 250 - 350 °C, preferably 300 °C. The main chemical reaction occurring in the hydrator is CaO + H2O → Ca(OH)2.

[0058] In some embodiments, in step S2, the products CO2 and H2O in the fuel reactor are sent into the calciner to reduce the partial pressure of gaseous CO2 and promote the forward progress of the calcination reaction.

[0059] As Figure 2As shown in the figure, an embodiment of the present invention provides a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system prepared according to the aforementioned chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method, which includes: an air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calciner, and a hydrator;

[0060] The air reactor and the fuel reactor are connected by a first pipeline and a second pipeline. The air reactor is loaded with a metal oxygen carrier, and the fuel reactor is loaded with fuel. The first pipeline is used to transport the oxidized metal oxygen carrier product in the air reactor to the fuel reactor, and the second pipeline is used to return the reduced metal oxygen carrier in the fuel reactor to the air reactor. The heat energy generated in the air reactor is transported to the calciner;

[0061] The air reactor and the first air contactor are connected by a third pipeline. The third pipeline is used to transport the oxygen-depleted air in the air reactor to the first air contactor. The first air contactor is loaded with a CO2 absorbent and is provided with a preliminary decarbonized air output end;

[0062] The first air contactor and the second air contactor are connected by a fourth pipeline and a fifth pipeline. The fourth pipeline is used to transport the preliminary decarbonized air in the first air contactor to the second air contactor, and the fifth pipeline is used to transport the semi-lean liquid in the second air contactor to the first air contactor. The second air contactor is loaded with a CO2 absorbent and is provided with a decarbonized air output end and an external air input end;

[0063] The first air contactor and the particle reactor are connected by a sixth pipeline. The sixth pipeline is used to transport the rich liquid obtained in the first air contactor to the particle reactor;

[0064] The second air contactor and the particle reactor are connected by a seventh pipeline. The seventh pipeline is used to return the lean liquid obtained in the particle reactor to the second air contactor;

[0065] The particle reactor and the calciner are connected by an eighth pipeline. The eighth pipeline is used to transport the CaCO3 obtained in the particle reactor to the calciner;

[0066] The calciner and the hydrator are connected by a ninth pipeline. The calciner is provided with a CO2 output end. The ninth pipeline is used to transport the CaO obtained in the calciner to the hydrator;

[0067] The hydrator and the particle reactor are connected by a tenth pipeline, and the tenth pipeline is used to transport Ca(OH)2 obtained in the hydrator to the particle reactor.

[0068] The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system provided by the embodiment of the present invention consists of an air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calciner, and a hydrator. This system uses a chemical-looping metal oxygen carrier to chemically react with oxygen in the air to remove the oxygen in the air before it enters the air contactor, reducing the volumetric flow rate of the air entering the air contactor and shrinking the scale of the DAC device. Moreover, the pre-air deoxygenation increases the CO2 concentration in the air, achieving a reduction in the energy consumption for carbon capture. At the same time, fuel-driven chemical-looping combustion is used to supply energy for the calcination process, avoiding the high power consumption of using an air separation unit to prepare pure oxygen and a self-provided carbon capture power plant, and realizing the efficient conversion of the supplied fossil fuel and zero-energy carbon capture. The direct air carbon capture system provided by the embodiment of the present invention can provide new ideas and methods for reducing the energy consumption of DAC capture.

[0069] The working principle of the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system provided by the embodiment of the present invention is as follows: As shown in Figure 2 the figure, air first enters the air reactor, where the oxygen in the air and the metal oxygen carrier undergo an oxidation reaction to obtain a metal oxygen carrier oxidation product and oxygen-depleted air. The metal oxygen carrier oxidation product enters the fuel reactor through a first pipeline and reacts with fuel to obtain a regenerated metal oxygen carrier, CO2, and H2O. The regenerated metal oxygen carrier returns to the air reactor through a second pipeline to continue reacting with the oxygen in the air; the oxygen-depleted air enters the first air contactor through a third pipeline and reacts with the semi-lean liquid transported from the second air contactor through a fifth pipeline to obtain a preliminarily decarbonized air with CO2 removed and a carbon-rich solution. The preliminarily decarbonized air enters the second air contactor through a fourth pipeline; the carbon-rich solution obtained in the first air contactor enters the particle reactor through a sixth pipeline and reacts with Ca(OH)2 to form CaCO3. The carbon-depleted solution obtained by removing CO2 in the particle reactor returns to the second air contactor through a seventh pipeline to continue reacting with the oxygen-depleted air; the product CaCO3 obtained in the particle reactor enters the calciner through an eighth pipeline and undergoes a calcination reaction to obtain CaO and CO2. The heat required for the calcination reaction is provided by the heat energy generated in the air reactor, and the obtained CO2 is discharged through the CO2 output end provided on the calciner; the product CaO obtained in the calciner enters the hydrator through a ninth pipeline and reacts with water vapor to obtain Ca(OH)2, and Ca(OH)2 returns to the particle reactor through a tenth pipeline to continue reacting with the carbon-rich solution.

[0070] An embodiment of the present invention provides a chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system, which is different from the traditional high-temperature solution absorption direct air carbon capture system. The innovation points of the system of the present invention are at least as follows: (1) An air reactor is used to pre-remove oxygen from the air, and then it enters the first air contactor for carbon removal; (2) The heat released by the reaction of the air reactor with the metal oxygen carrier is used to supply heat to the calciner; (3) A first air contactor and a second air contactor are set at the same time. The oxygen-depleted air coming out of the air reactor first passes through the first air contactor and then enters the second air contactor for carbon removal, realizing the gradual enrichment of the carbon components in the air; (4) The fuel reactor products CO2 and H2O are sent to the calciner to reduce the partial pressure of gaseous CO2 and promote the forward progress of the calcination reaction.

[0071] In some embodiments, the air reactor and the calciner are arranged in an external combustion mode, the air reactor is placed inside the calciner, and the heat energy generated in the air reactor is transferred to the inside of the calciner through the metal wall.

[0072] In some embodiments, the fuel reactor and the calciner are connected by an eleventh pipeline, and the eleventh pipeline is used to transport the reduced products CO2 and H2O in the fuel reactor to the calciner.

[0073] In some embodiments, when the air reactor operates under normal pressure, the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system further includes an air preheater and a fuel preheater. The air preheater is connected to the air reactor to recover the waste heat of the oxygen-depleted air and preheat the air introduced into the air reactor; the fuel preheater is connected to the calciner to recover the waste heat of the products at the outlet of the calciner, and the fuel preheater is also connected to the fuel reactor to preheat the fuel entering the fuel reactor.

[0074] In some embodiments, the fuel preheater and the fuel reactor are connected by a twelfth pipeline, and the twelfth pipeline is used to send the fuel preheated by the fuel preheater into the fuel reactor.

[0075] In some embodiments, the air preheater and the air reactor are connected by a thirteenth pipeline, and the thirteenth pipeline is used to send the air preheated by the air preheater into the air reactor.

[0076] In some embodiments, when the air reactor operates at a pressure higher than normal pressure, the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system further includes an air compressor, and the air compressor is connected to the air reactor to pressurize the air and send it into the air reactor.

[0077] In some embodiments, when the air reactor operates at a pressure higher than atmospheric pressure, the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system further includes a gas turbine connected to the air reactor, and the gas turbine is configured to receive the oxygen-depleted air in the air reactor to recover the pressure energy and thermal energy of the oxygen-depleted air.

[0078] In some embodiments, the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system may further include a waste heat power generation cycle unit, which is respectively connected to the gas turbine, the fuel reactor, and the calciner, and the waste heat power generation cycle unit is configured to recover the waste heat of the outlet products in the gas turbine, the fuel reactor, and the calciner.

[0079] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention and in no way limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0080] Example 1

[0081] This embodiment provides a normal-pressure chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system, as Figure 3 shown, including an air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calciner, a hydrator, an air preheater, and a fuel preheater;

[0082] The air reactor and the fuel reactor are connected by a first pipeline and a second pipeline. The air reactor is loaded with a metal oxygen carrier, and the fuel reactor is loaded with fuel. The first pipeline is used to transport the metal oxygen carrier oxidation product obtained by oxidation in the air reactor to the fuel reactor, and the second pipeline is used to return the metal oxygen carrier reduced in the fuel reactor to the air reactor;

[0083] The air reactor and the first air contactor are connected by a third pipeline. The third pipeline is used to transport the oxygen-depleted air in the air reactor to the first air contactor. The first air contactor is loaded with a CO2 absorbent and is provided with a preliminary decarbonized air output end;

[0084] The first air contactor and the second air contactor are connected by a fourth pipeline and a fifth pipeline. The fourth pipeline is used to transport the preliminarily decarbonized air in the first air contactor to the second air contactor, and the fifth pipeline is used to transport the semi-lean liquid in the second air contactor to the first air contactor. The second air contactor is loaded with a CO2 absorbent and is provided with a decarbonized air output end and an external fresh air input end;

[0085] The first air contactor and the particle reactor are connected by a sixth pipeline, and the sixth pipeline is used to transport the rich liquid obtained in the first air contactor to the particle reactor;

[0086] The second air contactor and the particle reactor are connected by a seventh pipeline, and the seventh pipeline is used to return the lean liquid obtained in the particle reactor to the second air contactor;

[0087] The particle reactor and the calciner are connected by an eighth pipeline, and the eighth pipeline is used to transport the CaCO3 obtained in the particle reactor to the calciner;

[0088] The calciner and the hydrator are connected by a ninth pipeline. The calciner is provided with a CO2 output end, and the ninth pipeline is used to transport the CaO obtained in the calciner to the hydrator;

[0089] The hydrator and the particle reactor are connected by a tenth pipeline, and the tenth pipeline is used to transport the Ca(OH)2 obtained in the hydrator to the particle reactor;

[0090] The air reactor and the calciner are arranged in an external combustion type. The air reactor is placed inside the calciner, and the heat released by the air reactor is transferred to the inside of the calciner through the metal wall;

[0091] The fuel reactor and the calciner are connected by an eleventh pipeline, and the eleventh pipeline is used to transport the products CO2 and H2O reduced in the fuel reactor to the calciner;

[0092] The fuel preheater is connected to the calciner to recover the waste heat of the product at the outlet of the calciner, and the fuel preheater and the fuel reactor are connected by a twelfth pipeline. The twelfth pipeline is used to send the fuel preheated by the fuel preheater into the fuel reactor;

[0093] The air preheater is connected to the air reactor to recover the waste heat of the oxygen-depleted air, and the air preheater and the air reactor are connected by a thirteenth pipeline. The thirteenth pipeline is used to send the air preheated by the air preheater into the air reactor.

[0094] Example 2

[0095] This example provides a carbon capture method using the high-temperature direct air carbon capture system driven by atmospheric pressure chemical looping air thermochemical deoxidation in Example 1. The steps are as follows:

[0096] 251000 t / h of air (corresponding to an annual CO2 capture scale of 1 million tons) enters the air reactor through an induced draft fan. The oxygen in the air and the metal oxygen carrier Ni undergo an oxidation reaction at 1000 °C and atmospheric pressure to obtain the metal oxygen carrier oxidation product NiO and oxygen-depleted air. The metal oxygen carrier oxidation product NiO enters the fuel reactor through the first pipeline and undergoes a reduction reaction with the fuel natural gas at 900 °C and atmospheric pressure to obtain the regenerated metal oxygen carrier Ni, CO2, and H2O. The regenerated metal oxygen carrier Ni returns to the air reactor through the second pipeline to continue reacting with the oxygen in the air, and the CO2 and H2O are input into the calciner; among them, the input fuel natural gas is first preheated by a fuel preheater and then sent into the fuel reactor. The volume fractions of each component in the fuel natural gas are: CH4 - 79.75%, C2H6 - 9.68%, C3H8 - 4.45%, C4H 10 - 2.37%, CO2 - 2.92%, N2 - 0.83%.

[0097] The oxygen-depleted air obtained in the air reactor enters the first air contactor through the third pipeline after passing through the air preheater, and reacts with the KOH solution at normal temperature and atmospheric pressure to obtain the preliminarily decarbonized air and the rich liquid. The preliminarily decarbonized air is transported through the fourth pipeline to the second air contactor and mixed with fresh air for further decarbonization, and the decarbonized air is discharged from the decarbonized air output end at the top of the second air contactor;

[0098] The rich carbon solution obtained in the first air contactor enters the particle reactor through the sixth pipeline and reacts with Ca(OH)2 at normal temperature and atmospheric pressure to generate CaCO3, realizing the migration of CO2. The poor liquid obtained by removing CO2 in the particle reactor returns to the second air contactor through the seventh pipeline to continue reacting with the preliminarily decarbonized air and fresh air;

[0099] The product CaCO3 obtained in the particle reactor enters the calciner through the eighth pipeline and undergoes a calcination reaction at 900 °C and atmospheric pressure to obtain CaO and CO2. The heat required for the calcination reaction is provided by the heat energy generated in the air reactor through heat transfer of the metal wall, and the obtained CO2 is discharged through the CO2 output end provided on the calciner;

[0100] The product CaO obtained in the calciner enters the hydrator through the ninth pipeline and reacts with 7 t / h of water vapor at 300 °C and atmospheric pressure to obtain Ca(OH)2, and the Ca(OH)2 returns to the particle reactor through the tenth pipeline to continue reacting with the rich carbon solution.

[0101] Comparative Example 1

[0102] A traditional high-temperature solution absorption direct air carbon capture system, as Figure 4 shown, is composed of an air contactor, a particle reactor, a calciner, an air separation unit, and a hydrator. The carbon capture method of the system is as follows: Air enters the air contactor to contact with the CO2 absorbent, and CO2 in the air reacts with the CO2 absorbent to form a carbonate solution (rich solution). The air from which CO2 has been removed is then discharged into the atmospheric environment; the carbonate solution enters the particle reactor to react with Ca(OH)2, removing CO2 from the carbonate solution to form CaCO3 and generating a lean solution that returns to the air contactor. The CaCO3 enters the calciner and undergoes a calcination reaction to become CaO, and the heat energy for this reaction is provided by the combustion of fuel and pure oxygen prepared by the air separation unit; the CaO regenerated by the calciner enters the hydrator to react with water vapor to form Ca(OH)2, and the Ca(OH)2 then enters the particle reactor to continue the next cycle; the power consumption of the air separation unit and auxiliary equipment is provided by the power grid.

[0103] Performance detection test:

[0104] A carbon capture performance comparison test was carried out on Example 2 and Comparative Example 1, and the results are shown in Table 1 below.

[0105] Table 1

[0106]

[0107] As can be seen from Table 1, the performance of the novel chemical looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system of the present invention has been greatly improved compared to the traditional high-temperature solution absorption direct air carbon capture system. The CO2 capture energy consumption of the system of the present invention has decreased significantly compared to the reference system, from 6.3 GJ / t CO2 to 4.5 GJ / t CO2. This is mainly because in the system of the present invention, methane-driven chemical looping is used to supply energy for the high-temperature calcination process of direct air carbon capture. On the one hand, it avoids the power consumption of air separation (14.8 MW) required for preparing pure oxygen. On the other hand, considering the utilization of waste heat, the system of the present invention saves 25.9% of natural gas input compared to the reference system.

[0108] Example 3

[0109] A high-pressure chemical looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system, as Figure 5 shown, the system includes an air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calciner, a hydrator, a fuel preheater, an air compressor, a gas turbine, and a waste heat power generation unit.

[0110] The carbon capture method of the system is as follows: 251,000 t / h of air (corresponding to an annual CO2 capture scale of 1 million tons) enters the air compressor through the induced draft fan, is pressurized and then enters the air reactor. The oxygen in the air and the metal oxygen carrier Ni undergo an oxidation reaction at 1,000 °C under conditions higher than atmospheric pressure to obtain the metal oxygen carrier oxidation product NiO and oxygen-depleted air. The metal oxygen carrier oxidation product NiO enters the fuel reactor through the first pipeline and undergoes a reduction reaction with the fuel natural gas at 900 °C under atmospheric pressure to obtain the regenerated metal oxygen carrier Ni, CO2, and H2O. The regenerated metal oxygen carrier Ni returns to the air reactor through the second pipeline to continue reacting with the oxygen in the air, and the CO2 and H2O are input into the calciner; the volume fractions of the components in the fuel natural gas are: CH4 - 79.75%, C2H6 - 9.68%, C3H8 - 4.45%, C4H 10 - 2.37%, CO2 - 2.92%, N2 - 0.83%.

[0111] The oxygen-depleted air obtained in the air reactor enters the first air contactor through the third pipeline after recovering the pressure energy and heat energy through the gas turbine and the waste heat power generation unit, reacts with the KOH solution under normal temperature and pressure conditions to obtain the preliminarily decarbonized air and the rich liquid. The preliminarily decarbonized air is transported through the fourth pipeline to the second air contactor, mixed with fresh air, and further decarbonized. The decarbonized air is discharged from the decarbonized air output end at the top of the second air contactor;

[0112] The carbon-rich solution obtained in the first air contactor enters the particle reactor through the sixth pipeline and reacts with Ca(OH)2 under normal temperature and pressure conditions to generate CaCO3, realizing the migration of CO2. The lean liquid obtained by removing CO2 in the particle reactor returns to the second air contactor through the seventh pipeline to continue reacting with the preliminarily decarbonized air and fresh air;

[0113] The product CaCO3 obtained in the particle reactor enters the calciner through the eighth pipeline and undergoes a calcination reaction at 900 °C under atmospheric pressure to obtain CaO and CO2. The heat required for the calcination reaction is provided by the heat energy generated in the air reactor through heat transfer by the metal wall. The obtained CO2 is discharged through the CO2 output end provided on the calciner;

[0114] The product CaO obtained in the calciner enters the hydrator through the ninth pipeline and reacts with 7 t / h of water vapor at 300 °C under atmospheric pressure to obtain Ca(OH)2. The Ca(OH)2 returns to the particle reactor through the tenth pipeline to continue reacting with the carbon-rich solution.

[0115] In summary, for the chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method and system provided by the present invention, by using a chemical-looping metal oxygen carrier to chemically react with oxygen in the air, before the air enters the air contactor to remove CO2, the oxygen in the air is consumed in advance, significantly reducing the air volume flow rate entering the air contactor and increasing the CO2 concentration in the air, and significantly reducing the scale of the decarbonization process and the decarbonization energy consumption. At the same time, fuel-driven chemical-looping combustion is used to supply energy for the calcination process, avoiding the high power consumption of using an air separation unit to prepare pure oxygen and a self-provided carbon capture power plant, and realizing the efficient conversion of the energy-supplying fossil fuel and zero-energy carbon capture. The carbon capture provided by the present invention can significantly reduce the energy penalty of the DAC technology.

[0116] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A chemical looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method, characterized in that Comprising: Step S1: Introduce air into the air reactor to react with the metal oxygen carrier through an oxidation reaction, obtaining a metal oxygen carrier oxidation product and oxygen-depleted air, and generating heat energy; Step S2: The metal oxygen carrier oxidation product obtained in Step S1 enters the fuel reactor to react with the fuel through a reduction reaction, obtaining a regenerated metal oxygen carrier, CO2, and H2O. The regenerated metal oxygen carrier returns to the air reactor to continue reacting with air; Step S3: The oxygen-depleted air obtained in Step S1 enters the first air contactor to react with the CO2 absorbent, obtaining preliminarily decarbonized air and rich liquid. The preliminarily decarbonized air and fresh air enter the second air contactor to react with the CO2 absorbent, obtaining decarbonized air and semi-rich liquid. The semi-rich liquid enters the first air contactor to continue reacting with the oxygen-depleted air; Step S4: The rich liquid obtained in Step S3 enters the particle reactor to react with Ca(OH)2, obtaining CaCO3 and lean liquid. The lean liquid returns to the second air contactor to continue reacting with the preliminarily decarbonized air and fresh air; Step S5: The CaCO3 obtained in Step S4 enters the calcination furnace and undergoes a calcination reaction to obtain CaO and CO2. The heat required for the calcination reaction is provided by the heat energy generated in the air reactor; Step S6: The CaO obtained in Step S5 enters the hydrator to react with water vapor to obtain Ca(OH)2, and the Ca(OH)2 enters the particle reactor to continue reacting with the rich liquid.

2. The chemical looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture method according to claim 1, wherein The first air contactor and the second air contactor are connected in series. The lean liquid first enters the second air contactor to react with the preliminarily decarbonized air and fresh air to obtain semi-rich liquid, and the semi-rich liquid then enters the first air contactor to react with the oxygen-depleted air.

3. The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture method according to claim 1, wherein, The metal oxygen carrier is one or more of Co, Cu, Mn, Ni, Fe, Ca, Ba, Pb, Ag, Pd, Cr, and Os. The fuel is one or more of fossil fuels, hydrogen, biomass, and ammonia. The CO2 absorbent is KOH or NaOH.

4. The chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture method according to claim 1, characterized in that, The reaction pressure in the air reactor is 1 - 10 bar, and the reaction temperature is 900 - 1000 °C; the reaction pressure in the fuel reactor is atmospheric pressure, and the reaction temperature is 600 - 900 °C; the reaction conditions in the first air contactor and the second air contactor are normal temperature and atmospheric pressure; the reaction conditions in the particle reactor are normal temperature and atmospheric pressure; the reaction pressure in the calcination furnace is atmospheric pressure, and the reaction temperature is 850 - 950 °C; the reaction pressure in the hydrator is atmospheric pressure, and the reaction temperature is 250 - 350 °C.

5. The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture method according to claim 1, wherein In Step S2, the products CO2 and H2O in the fuel reactor are sent to the calcination furnace to reduce the partial pressure of gaseous CO2 and promote the forward progress of the calcination reaction.

6. A chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system prepared according to the chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture method described in claim 1, characterized in that, Comprising: An air reactor, a fuel reactor, a first air contactor, a second air contactor, a particle reactor, a calcination furnace, and a hydrator; The air reactor and the fuel reactor are connected by a first pipeline and a second pipeline. The air reactor is loaded with a metal oxygen carrier, and the fuel reactor is loaded with fuel. The first pipeline is used to transport the metal oxygen carrier oxidation product obtained by oxidation in the air reactor to the fuel reactor, and the second pipeline is used to return the metal oxygen carrier obtained by reduction in the fuel reactor to the air reactor. The heat energy generated in the air reactor is transported to the calciner; The air reactor and the first air contactor are connected by a third pipeline. The third pipeline is used to transport the oxygen-depleted air in the air reactor to the first air contactor. The first air contactor is loaded with a CO2 absorbent and is provided with a preliminary decarbonized air output end; The first air contactor and the second air contactor are connected by a fourth pipeline and a fifth pipeline. The fourth pipeline is used to transport the preliminary decarbonized air in the first air contactor to the second air contactor, and the fifth pipeline is used to transport the semi-lean liquid in the second air contactor to the first air contactor. The second air contactor is loaded with a CO2 absorbent and is provided with a decarbonized air output end and an external air input end; The first air contactor and the particle reactor are connected by a sixth pipeline. The sixth pipeline is used to transport the rich liquid obtained in the first air contactor to the particle reactor; The second air contactor and the particle reactor are connected by a seventh pipeline. The seventh pipeline is used to return the lean liquid obtained in the particle reactor to the second air contactor; The particle reactor and the calciner are connected by an eighth pipeline. The eighth pipeline is used to transport the CaCO3 obtained in the particle reactor to the calciner; The calciner and the hydrator are connected by a ninth pipeline. The calciner is provided with a CO2 output end. The ninth pipeline is used to transport the CaO obtained in the calciner to the hydrator; The hydrator and the particle reactor are connected by a tenth pipeline. The tenth pipeline is used to transport the Ca(OH)2 obtained in the hydrator to the particle reactor.

7. The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system according to claim 6, wherein The air reactor and the calciner adopt an external combustion arrangement. The air reactor is placed inside the calciner, and the heat energy generated in the air reactor is transferred to the inside of the calciner through the metal wall.

8. The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system according to claim 6, wherein The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system further includes an air preheater and a fuel preheater. The air preheater is connected to the air reactor to recover the waste heat of the oxygen-depleted air and preheat the air introduced into the air reactor; the fuel preheater is connected to the calciner to recover the waste heat of the calciner outlet product, and the fuel preheater is also connected to the fuel reactor to preheat the fuel entering the fuel reactor.

9. The chemical looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system according to claim 6, wherein The chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system further includes an air compressor and a gas turbine. The air compressor is connected to the air reactor for pressurizing air and feeding it into the air reactor; the gas turbine is connected to the air reactor for recovering the pressure energy and thermal energy of the oxygen-depleted air.

10. The chemical-looping air thermochemical deoxygenation-driven high-temperature direct air carbon capture system according to claim 9, wherein The chemical-looping air thermochemical deoxidation-driven high-temperature direct air carbon capture system further includes a waste heat power generation cycle unit. The waste heat power generation cycle unit is respectively connected to the gas turbine, the fuel reactor, and the calciner, and the waste heat power generation cycle unit is used to recover the waste heat of the outlet products in the gas turbine, the fuel reactor, and the calciner.

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