A dual-cycle CO2 capture method and system

Abstract

This invention discloses a dual-cycle CO2 capture method and system. The method includes: providing fuel and flue gas to be treated; mixing the flue gas with CaO for decarbonization to obtain decarbonized gas and carbon-containing products, generating a first thermal energy; oxidizing a metal to obtain metal oxides, generating a second thermal energy; calcining and regenerating the carbon-containing products to obtain regenerated CaO, which is then allowed to react with the flue gas to be treated, with the heat required for calcination and regeneration provided by the second thermal energy; and mixing the metal oxides with fuel for reduction to obtain regenerated metal, CO2, and H2O, with the heat required for reduction provided by the first thermal energy. This invention couples the calcium cycle and chemical looping combustion in a dual-cycle heat coupling mode, utilizing the heat from the chemical looping reaction to heat the calcium cycle, while simultaneously utilizing the waste heat released from the calcium cycle to achieve the reduction reaction of the chemical looping metal oxides, reducing the temperature difference in the heat exchange process and achieving highly efficient CO2 capture.

Description

Technical Field

[0001] This invention relates to the field of CO2 capture technology, and in particular to a dual-cycle CO2 capture method and system. Background Technology

[0002] With the development of the national economy, the large amounts of CO2 emissions from the burning of fossil fuels in the power and industrial sectors pose a threat to the human living environment, making it urgent to reduce carbon emissions from these sectors. CO2 capture and storage is expected to be key to mitigating CO2 emissions and reducing environmental impact. Among different CO2 capture technologies, post-combustion CO2 capture is the only end-of-pipe method that can reduce carbon emissions from stationary sources without altering industrial plants.

[0003] Among post-combustion CO2 capture technologies, the calcium cycle process is a promising low-energy CO2 capture technology with advantages such as wide availability of raw materials, high reactivity, and low cost. The calcium cycle process mainly consists of two processes: carbonation and calcination. However, both processes occur at relatively high reaction temperatures and generate significant waste heat, including the reaction heat of 600-650℃ released by the carbonation reaction, the waste heat from the decarbonization gas products, and the waste heat from the calcination furnace products.

[0004] Existing research on carbon capture power plants faces certain challenges in utilizing the heat of carbonation. While they often employ thermodynamic cycles to utilize the medium-to-high-temperature waste heat released during carbonation, directly heating the working fluid at room temperature results in significant temperature differences during heat exchange, leading to substantial energy losses and low system efficiency. Furthermore, to prevent the dilution of enriched CO2 by atmospheric N2, calcium cycle processes typically employ oxygen-enriched combustion. However, the high-purity oxygen required for oxygen-enriched combustion consumes substantial air separation energy. These factors all contribute to increased costs and decreased efficiency in practical applications of calcium cycle processes, hindering their widespread adoption.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a dual-cycle CO2 capture method and system to solve the problems of low CO2 capture efficiency and unreasonable thermal energy utilization in the prior art.

[0007] The technical solution of the present invention is as follows:

[0008] A dual-cycle CO2 capture system includes a carbonation tower, a calciner, an air reactor, and a fuel reactor.

[0009] The carbonation tower and the calcining furnace are connected by a first pipe and a second pipe. The carbonation tower has a flue gas inlet and a decarbonized gas outlet. The first pipe is used to transport the generated carbon-containing products from the carbonation tower to the calcining furnace, and the second pipe is used to transport the obtained regenerated CaO to the carbonation tower.

[0010] The calcining furnace and the air reactor are connected by a third pipe. The calcining furnace has a CaO replenishment input end and a gas output end. The third pipe is used to transport the second heat energy to the calcining furnace.

[0011] The fuel reactor is equipped with a metal replenishment input terminal;

[0012] The fuel reactor and the air reactor are connected by a fourth pipe and a fifth pipe, the fourth pipe being used to transport recycled metal to the air reactor and the fifth pipe being used to transport metal oxide to the fuel reactor;

[0013] The fuel reactor is connected to the calcining furnace via a sixth pipe, which is used to transport gas to the calcining furnace;

[0014] The fuel reactor is connected to the carbonation tower via a seventh pipe, which is used to transfer the first thermal energy to the fuel reactor.

[0015] Preferably, it also includes a heat recovery unit, which is connected to the carbonation tower and the air reactor to recover the waste heat from the outlet products of the carbonation tower and the air reactor.

[0016] A dual-cycle CO2 capture method using the above system includes the following steps:

[0017] S1, providing fuel and flue gas to be treated;

[0018] S2. The flue gas to be treated is mixed with CaO and decarbonized at the carbonization temperature to obtain decarbonized gas and carbon-containing products, and to generate the first heat energy. The chemical reactions that occur include: This process occurs in the carbonation tower;

[0019] S3. Oxidation treatment of metals at oxidation temperatures yields metal oxides and generates a second heat energy. The chemical reactions that occur include: This process takes place in an air reactor, and the metal is selected from one or both of nickel and cobalt.

[0020] S4. The carbon-containing product in S2 is calcined and regenerated at a calcination temperature to obtain regenerated CaO. The regenerated CaO is fed back into S2 to continue reacting with the flue gas to be treated, thereby decarbonizing the flue gas. The heat required for the calcination and regeneration is provided by the second thermal energy source. The chemical reactions that occur include: This process occurs in the calcining furnace;

[0021] S5. The metal oxide is mixed with fuel at a reduction temperature to reduce the metal oxide, yielding recycled metal, CO2, and H2O. The heat energy required for the reduction process is provided by a first heat energy source. The chemical reactions that occur include: This process occurs in the fuel reactor.

[0022] Specifically, this invention adds a chemical looping combustion process to the traditional carbon cycle, coupling the calcium cycle and the chemical looping combustion reaction together. The high-temperature heat from the chemical looping reaction is used to heat the calcium ring calcination process, while the medium-temperature waste heat released from the carbonation process of the calcium cycle is used to achieve the reduction reaction of the chemical looping metal oxide. This reduces the temperature difference in the heat exchange process, reduces irreversible losses in the heat exchange process, and achieves the upgrading of medium-grade heat (~650℃) to high-grade heat (~1000℃). It also avoids the power consumption of the air separation unit and achieves efficient CO2 capture after combustion.

[0023] Preferably, the recycled metal is fed into S3 for further oxidation treatment.

[0024] Specifically, the recycled metal obtained by this invention is further used for oxidation treatment and recycling, thus saving costs.

[0025] Preferably, CO2 and H2O in S5 are fed into S4 to reduce the partial pressure of CO2 in the gas phase and promote the forward progress of the CaO regeneration reaction.

[0026] Specifically, the present invention also feeds the CO2 and H2O generated by the reduction treatment of metal oxides into S4 to reduce the partial pressure of CO2 in the gas phase and promote the forward progress of the CaO regeneration reaction.

[0027] Preferably, a portion of the first and second thermal energy is used to generate steam, which is then used to generate electricity through a thermodynamic cycle.

[0028] Specifically, the present invention further improves the capture performance by recovering the remaining first and second thermal energy to generate steam to drive the external transmission of electricity.

[0029] Preferably, the carbonization temperature is 600~650℃, the oxidation temperature is 900~1000℃, the calcination temperature is 850~950℃, and the reduction temperature is 500~600℃.

[0030] Specifically, the present invention sets the carbonization temperature to 600~650℃, as a reaction temperature that is too low will result in a slow reaction rate; sets the oxidation temperature to 900~1000℃, as a reaction that is too low will not proceed easily, while a reaction temperature that is too high will cause CaCO3 to sinter easily; sets the calcination temperature to 850~950℃, thereby ensuring a heat exchange temperature difference of 50~100℃; and sets the reduction temperature to 500~600℃, thereby ensuring a heat exchange temperature difference of 50~100℃.

[0031] Preferably, the metal is selected from one or both of nickel and cobalt.

[0032] Beneficial effects:

[0033] This invention discloses a dual-cycle CO2 capture method and system. The method employs a dual-cycle heat matching mode combining calcium cycle and chemical looping combustion, which fully utilizes the waste heat between units. This not only avoids waste heat but also achieves the conversion of medium-grade heat (~650℃) to high-grade heat (~1000℃), avoiding the energy consumption of the air separation unit compared to the traditional oxy-fuel combustion calcium cycle process. Furthermore, since chemical looping combustion can achieve high-concentration CO2 enrichment while efficiently converting fuel (without separation energy consumption), it can effectively improve capture energy efficiency. Process waste heat can also be recovered through Rankine cycle / combined cycle, further improving the performance of the capture system. Specifically, under the same flue gas input and 90% CO2 capture rate, the energy efficiency of the traditional oxy-fuel combustion calcium cycle is approximately 31.7%, the energy efficiency of the Ni-based dual-cycle + Rankine cycle is 37.1%, and the energy efficiency of the Ni-based dual-cycle + combined cycle is 41.4%. Attached Figure Description

[0034] Figure 1 This is a flowchart of the dual-cycle CO2 capture method of the present invention.

[0035] Figure 2 This is a schematic diagram of the capture system in Embodiment 2 of the present invention.

[0036] Figure 3 This is a schematic diagram of the capture system in Embodiment 3 of the present invention.

[0037] Figure 4 This is a schematic diagram of the capture system in Comparative Example 1 of the present invention. Detailed Implementation

[0038] This invention provides a dual-cycle CO2 capture method and system. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the reference numerals for sequence in the method of this invention do not refer to a specific order, but are merely for ease of description.

[0039] This invention provides a dual-cycle CO2 capture method, comprising the following steps:

[0040] S1, providing fuel and flue gas to be treated;

[0041] S2. The flue gas to be treated is mixed with CaO and decarbonized at the carbonization temperature to obtain decarbonized gas and carbon-containing products, and to generate the first heat energy. The chemical reactions that occur include: ;

[0042] S3. Oxidation treatment of metals at oxidation temperatures yields metal oxides and generates a second heat energy. The chemical reactions that occur include: The metal is selected from one or both of nickel and cobalt;

[0043] S4. The carbon-containing product in S2 is calcined and regenerated at a calcination temperature to obtain regenerated CaO. The regenerated CaO is fed back into S2 to continue reacting with the flue gas to be treated, thereby decarbonizing the flue gas. The heat required for the calcination and regeneration is provided by the second thermal energy source. The chemical reactions that occur include: ;

[0044] S5. The metal oxide is mixed with fuel at a reduction temperature to reduce the metal oxide, yielding recycled metal, CO2, and H2O. The heat energy required for the reduction process is provided by a first heat energy source. The chemical reactions that occur include: ;

[0045] In some embodiments, the recycled metal is fed into S3 for further oxidation treatment.

[0046] In some embodiments, CO2 and H2O in S5 are fed into S4 to reduce the partial pressure of CO2 in the gas phase and promote the forward progress of the CaO regeneration reaction.

[0047] In some implementations, a portion of the first and second thermal energy is used to generate steam, which is then used to generate electricity through a thermodynamic cycle.

[0048] In some embodiments, the carbonization temperature is 600~650℃, the oxidation temperature is 900~1000℃, the calcination temperature is 850~950℃, and the reduction temperature is 500~600℃.

[0049] In some embodiments, the metal is selected from one or both of nickel and cobalt.

[0050] The present invention also provides a dual-cycle CO2 capture system prepared by the method described above, comprising a carbonation tower, a calcining furnace, an air reactor, and a fuel reactor.

[0051] The carbonation tower and the calcining furnace are connected by a first pipe and a second pipe. The carbonation tower has a flue gas inlet and a decarbonized gas outlet. The first pipe is used to transport the generated carbon-containing products from the carbonation tower to the calcining furnace, and the second pipe is used to transport the obtained regenerated CaO to the carbonation tower.

[0052] The calcining furnace and the air reactor are connected by a third pipe. The calcining furnace has a CaO replenishment input end and a gas output end. The third pipe is used to transport the second heat energy to the calcining furnace.

[0053] The fuel reactor is equipped with a metal replenishment input terminal;

[0054] The fuel reactor and the air reactor are connected by a fourth pipe and a fifth pipe, the fourth pipe being used to transport recycled metal to the air reactor and the fifth pipe being used to transport metal oxide to the fuel reactor;

[0055] The fuel reactor is connected to the calcining furnace via a sixth pipe, which is used to transport gas to the calcining furnace;

[0056] The fuel reactor is connected to the carbonation tower via a seventh pipe, which is used to transfer the first thermal energy to the fuel reactor.

[0057] In some embodiments, a heat recovery unit is also included, which is connected to the carbonation tower and the air reactor to recover the waste heat from the outlet products of the carbonation tower and the air reactor.

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are intended only to illustrate the present invention and not to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0059] Example 1

[0060] A dual-cycle CO2 capture system includes a carbonation tower, a calcining furnace, an air reactor, a fuel reactor, and a heat recovery unit.

[0061] The carbonation tower and the calcining furnace are connected by a first pipe and a second pipe. The carbonation tower has a flue gas inlet and a decarbonized gas outlet. The calcining furnace and the air reactor are connected by a third pipe. The calcining furnace has a CaO replenishment inlet and a gas outlet. The fuel reactor and the air reactor are connected by a fourth pipe and a fifth pipe. The fuel reactor has a metal replenishment inlet. The fuel reactor and the calcining furnace are connected by a sixth pipe. The fuel reactor and the carbonation tower are connected by a seventh pipe. The heat recovery unit is connected to the carbonation tower and the air reactor to recover the first and second heat energy.

[0062] The first pipeline is used to transport the generated carbon-containing product from the carbonation tower to the calcination furnace; the second pipeline is used to transport the obtained regenerated CaO to the carbonation tower; the third pipeline is used to transport the second heat energy to the calcination furnace. The fourth pipeline is used to transport the regenerated metal to the air reactor; the fifth pipeline is used to transport the metal oxide to the fuel reactor; the sixth pipeline is used to transport the gas to the calcination furnace; and the seventh pipeline is used to transport the first heat energy to the fuel reactor.

[0063] Example 2

[0064] A dual-cycle CO2 capture method, using the system of Example 1, is described below. Figure 2 As shown, the steps are as follows:

[0065] S1. Provide flue gas to be treated and metallic Ni, wherein the CO2 concentration in the flue gas to be treated is 17.8% and the flue gas molar flow rate is 14716.1 kmol / h;

[0066] S2. The flue gas to be treated is mixed with CaO adsorbent in a carbonation tower and decarbonized at 650°C and atmospheric pressure to obtain decarbonized gas and carbon-containing product CaCO3, and generate the first heat energy. The decarbonized gas is discharged to the atmosphere from the decarbonized gas output end of the carbonation tower.

[0067] S3. The carbon-containing product CaCO3 is fed from the carbonation tower into the calcination furnace through the first pipe, where it is calcined and regenerated at 900°C and atmospheric pressure to obtain CaO and CO2. The CaO is then fed back into the above reaction through the second pipe to continue reacting with the CO2 in the flue gas to be treated. The CO2 obtained in the calcination furnace is discharged from the gas output end for further compression or utilization.

[0068] The pure oxygen required for the regeneration reaction in the calcining furnace is provided by an air separation device, which consists of an air compressor, a cooler, and a distillation column. The air is pressurized and cooled by the air compressor and cooler. Due to the difference in boiling points of the components, O2 is separated and purified in the distillation column. Since the adsorption capacity of regenerated CaO decreases during the cycle, a small amount of fresh CaO needs to be added from the CaO replenishment input end of the calcining furnace into the carbonization furnace to maintain the CO2 adsorption capacity of the CaO cycle.

[0069] S4. In an air reactor, at 1000°C and 1~10 bar pressure, metallic Ni is oxidized to obtain metallic oxide NiO, generating a second heat energy. This second heat energy is then transported to a calcining furnace through a third pipe, maintaining the calcination and regeneration process at 900°C. Unreacted N2 is released into the atmosphere from the top pipe of the air reactor tower.

[0070] S5. The metal oxide NiO is reduced with natural gas in a fuel reactor at 600°C and atmospheric pressure to obtain recycled metal Ni and gases CO2 and H2O. The recycled metal Ni is transported to the air reactor through the fourth pipe for oxidation treatment. The heat energy required for this process is provided by the first heat energy source, which is transported to the fuel reactor through the seventh pipe. Gases CO2 and H2O are used to promote the positive reaction of the calcination regeneration process. Gases CO2 and H2O are transported to the calcination furnace through the sixth pipe. After the oxygen-carrying capacity of the metal decreases, a small amount of fresh metal is introduced into the fuel reactor through the metal replenishment input. The volume fractions of the components in the input natural gas are: CH4 - 79.75%, C2H6 - 9.68%, C3H8 - 4.45%, C4H... 10 -2.37%, CO2-2.92%, N2-0.83%.

[0071] S6, the decarbonized gas discharged from the carbonation tower, the CO2 discharged from the calcining furnace, and the N2 discharged from the air reactor tower are all piped into the waste heat boiler to release heat, heat the Rankine cycle working fluid water, and generate steam. The steam generated by the waste heat boiler is piped into the turbine to drive the turbine to generate electricity. The low-temperature and low-pressure steam at the outlet is piped into the condenser to condense into water, and then piped into the pump for pressurization, and then piped back into the waste heat boiler to absorb heat. The steam pressure is 126 / 26 / 5.5 bar, the steam temperature is 566℃, and the entropy efficiency of the steam turbine is 0.88 / 0.89 / 0.87.

[0072] Specifically, the main chemical reaction in the carbonation tower is: CaO + CO2 → CaCO3;

[0073] The main chemical reaction in the calcining furnace is: CaCO3 → CaO + CO2;

[0074] The chemical reaction in the air reactor is: Air + Ni → NiO;

[0075] The main chemical reaction in the fuel reactor is: CH4 + NiO → Ni + CO2 + H2O.

[0076] Example 3

[0077] A dual-cycle CO2 capture method, such as Figure 3 As shown, this embodiment is basically the same as embodiment 2, except that in step S6, the N2 discharged from the air reactor tower first enters the gas turbine through the pipeline to drive the gas turbine to generate electricity, and then is sent to the waste heat boiler through the pipeline at the gas turbine outlet to further release waste heat to heat the feedwater.

[0078] Comparative Example 1

[0079] The difference from Example 2 is that a conventional oxygen-enriched combustion calcium cycle is used, such as... Figure 4 As shown, CO2 is removed from the flue gas in the carbonation tower. The adsorbent after CO2 adsorption is sent to the calcination furnace for regeneration. The high-temperature heat required for the calcination process is provided by the combustion of fuel and pure oxygen. The unit oxygen production power consumption is 180 kWh / t. The waste heat from each process is used to drive the Rankine cycle. The waste heat boiler power generation unit is a triple-pressure reheat unit with a steam pressure of 126 / 26 / 5.5 bar, a steam temperature of 566℃, and entropy efficiencies of steam permeability of 0.88 / 0.89 / 0.87.

[0080] Performance testing

[0081] The CO2 capture capacity and energy efficiency of Examples 2, 3 and Comparative Example 1 are compared as shown in Table 1 below, where energy efficiency = (electricity output - electricity input) / natural gas input.

[0082] Table 1

[0083]

[0084] As shown in the table above, the performance of the novel Ni-based dual-cycle CO2 capture system (Examples 2 and 3) is significantly improved compared to the traditional oxy-fuel combustion calcium ring (Comparative Example 1). When using a Rankine cycle to recover waste heat from the Ni-based dual-cycle system (Example 2), the system efficiency increases from 31.7% for the traditional oxy-fuel combustion calcium ring to 37.1%, and when combined with a combined cycle (Example 3), it further increases to 41.4%. This is mainly because, compared to the traditional oxy-fuel combustion calcium ring, the novel dual-cycle system fully utilizes the waste heat of each unit by introducing efficient, low-carbon chemical looping combustion, achieving heat matching, upgrading medium-grade heat to high-grade heat for utilization, improving energy efficiency, and saving energy consumption in air separation. Therefore, this method can provide a highly efficient CO2 capture solution for power plant flue gas capture.

[0085] In summary, the present invention provides a dual-cycle CO2 capture method and system, the method comprising:

[0086] S1. Provide fuel and flue gas to be treated; S2. Mix the flue gas to be treated with CaO, and perform decarbonization treatment at the carbonization temperature to obtain decarbonized gas and carbon-containing products, and generate the first heat energy. The chemical reactions that occur include: S3. The metal is oxidized at an oxidation temperature to obtain a metal oxide, generating a second heat energy. The chemical reactions that occur include: S4. The carbon-containing product in S2 is calcined and regenerated at a calcination temperature to obtain regenerated CaO. The regenerated CaO is fed back into S2 to continue reacting with the flue gas to be treated, thereby decarbonizing the flue gas. The heat required for the calcination and regeneration is provided by the second thermal energy source. The chemical reactions that occur include: S5. The metal oxide is mixed with fuel at a reduction temperature to reduce the metal oxide, yielding recycled metal, CO2, and H2O. The heat energy required for the reduction process is provided by a first heat energy source. The chemical reactions that occur include: This method employs a dual-cycle heat matching approach combining calcium cycling and chemical looping combustion. This not only fully utilizes waste heat from each stage but also elevates the medium-temperature heat (~650℃) released in the carbonation tower to the high-temperature reaction heat (~1000℃) released in the air reactor through chemical looping combustion, providing the necessary heat for the calcination process and improving energy quality. Furthermore, by utilizing Rankine / combined cycle to recover waste heat from each material / unit, it significantly reduces CO2 capture energy consumption, achieving highly efficient CO2 capture. In addition, using external chemical looping combustion to heat the calciner avoids power consumption in the air separation unit, saving power in that area.

[0087] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A dual-cycle CO2 capture method, characterized in that, Including the following steps: S1, providing fuel and flue gas to be treated; S2. The flue gas to be treated is mixed with CaO and decarbonized at the carbonization temperature to obtain decarbonized gas and carbon-containing products, and to generate the first heat energy. The chemical reactions that occur include: ; S3. Oxidation treatment of metals at oxidation temperatures yields metal oxides and generates a second heat energy. The chemical reactions that occur include: The metal is selected from one or both of nickel and cobalt; S4. The carbon-containing product in S2 is calcined and regenerated at a calcination temperature to obtain regenerated CaO. The regenerated CaO is fed back into S2 to continue reacting with the flue gas to be treated, thereby decarbonizing the flue gas. The heat required for the calcination and regeneration is provided by the second thermal energy source. The chemical reactions that occur include: ; S5. The metal oxide is mixed with fuel at a reduction temperature to reduce the metal oxide, yielding recycled metal, CO2, and H2O. The heat energy required for the reduction process is provided by a first heat energy source. The chemical reactions that occur include: ; The CO2 and H2O in S5 are fed into S4 to reduce the partial pressure of CO2 in the gas phase and promote the forward progress of the CaO regeneration reaction. The carbonization temperature is 600~650℃, the oxidation temperature is 900~1000℃, the calcination temperature is 850~950℃, and the reduction temperature is 500~600℃.

2. The dual-cycle CO2 capture method according to claim 1, characterized in that, The recycled metal is fed into S3 for further oxidation treatment.

3. The dual-cycle CO2 capture method according to claim 1, characterized in that, A portion of the first and second thermal energy is used to generate steam, which is then used to generate electricity through a thermodynamic cycle.

4. A dual-cycle CO2 capture system prepared according to the dual-cycle CO2 capture method according to claim 1, characterized in that, Includes carbonation towers, calcining furnaces, air reactors, and fuel reactors. The carbonation tower and the calcining furnace are connected by a first pipe and a second pipe. The carbonation tower has a flue gas inlet and a decarbonized gas outlet. The first pipe is used to transport the generated carbon-containing products from the carbonation tower to the calcining furnace, and the second pipe is used to transport the obtained regenerated CaO to the carbonation tower. The calcining furnace and the air reactor are connected by a third pipe. The calcining furnace has a CaO replenishment input end and a gas output end. The third pipe is used to transport the second heat energy to the calcining furnace. The fuel reactor is equipped with a metal replenishment input terminal; The fuel reactor and the air reactor are connected by a fourth pipe and a fifth pipe, the fourth pipe being used to transport recycled metal to the air reactor and the fifth pipe being used to transport metal oxide to the fuel reactor; The fuel reactor is connected to the calcining furnace via a sixth pipe, which is used to transport gas to the calcining furnace; The fuel reactor is connected to the carbonation tower via a seventh pipe, which is used to deliver the first thermal energy to the fuel reactor.

5. The dual-cycle CO2 capture system according to claim 4, characterized in that, It also includes a heat recovery unit, which is connected to the carbonation tower and the air reactor to recover the waste heat from the outlet products of the carbonation tower and the air reactor.

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