A co2 capture method and system based on fuel staged conversion coupled with chemical looping combustion

Abstract

The application discloses a CO2 capture method and system based on fuel staged conversion coupled with chemical looping combustion, and the method comprises the following steps: flue gas is introduced into a carbonation tower filled with metal oxygen carriers MeO and adsorbents A, the adsorbents A adsorb CO2 in the flue gas, and then the solid in the tower is transported to a calciner; the adsorbents A after adsorption are decomposed into the adsorbents A and CO2 in the calciner, the MeO in the calciner reacts with the substances transported in a fuel pre-conversion reactor to generate a reduced metal oxygen carrier; the regenerated adsorbents A and the reduced metal oxygen carrier in the calciner are transported to an air reactor to generate MeO and regenerated adsorbents A which are returned to the carbonation tower; fuel and reactants are introduced into the fuel pre-conversion reactor, part of the fuel is converted, and the products are sent into the calciner. Through fuel partial conversion and chemical looping combustion, the application realizes grade matching of the fuel conversion and the adsorbent regeneration process, avoids air separation energy consumption of separated pure oxygen, and effectively reduces CO2 capture energy consumption after medium-high temperature adsorption combustion.

Description

Technical Field

[0001] This invention relates to the field of CO2 capture technology, specifically to a CO2 capture method and system based on fuel staged conversion coupled with chemical looping combustion. Background Technology

[0002] With the global climate problem caused by greenhouse gas emissions becoming increasingly serious, CO2 emission reduction has become a hot issue of concern in the international community. Carbon capture, utilization and storage (CCUS) is widely recognized as the only technology that can achieve low-carbon utilization of fossil fuels. Among them, post-combustion CO2 capture technology has received considerable attention due to its advantages such as ease of retrofitting existing plants.

[0003] In post-combustion CO2 capture technology, adsorption separation is considered a potential CO2 capture method due to its advantages such as high adsorption capacity, low regeneration cost, and no corrosion. Adsorbents can be classified into low, medium, and high temperatures based on their adsorption temperature. Currently, medium- and high-temperature adsorption typically uses oxygen-enriched combustion of fuel for adsorbent regeneration. This method requires a large amount of electrical energy to produce high-purity oxygen. Regarding this issue, patents CN201080041211.X and CN201510134158.2 propose a high-temperature adsorption method using CaO as the adsorbent, and using the direct reduction reaction of CuO and fuel as the heat source for adsorbent regeneration. In both of these cases, chemical looping combustion is introduced as the energy source for adsorbent regeneration, avoiding the energy consumption of air separation. However, due to the limitation of calcium carbonate calcination temperature, the temperature of the fuel chemical loop combustion heating process is around 850-950℃. This means that under this heating method, the chemical energy of the fuel is directly converted into thermal energy at 850-950℃. However, there is a large gap between the thermal energy grade corresponding to this temperature and the input fuel grade, resulting in a large waste of the fuel's ability to perform work, which requires further improvement.

[0004] In view of the above-mentioned technical problems, this invention proposes a post-combustion capture method using fuel staged conversion coupled with chemical looping combustion. After combustion, the flue gas is adsorbed to generate a CO2-rich adsorbent carrier. The heat released during the adsorption process can be used to drive the pre-conversion of fuel into syngas, with CO and H2 as the main products. The syngas and unconverted fuel provide energy for the medium- and high-temperature adsorbent regeneration process through chemical looping combustion. Through staged fuel conversion, the medium-temperature adsorption heat is converted into chemical energy through thermochemical recovery, while simultaneously reducing the grade difference between the fuel release process and the adsorbent regeneration process during calcination. This reduces irreversible losses in the fuel conversion process and avoids power consumption in the air separation unit. Summary of the Invention

[0005] To address the high energy consumption problem in medium- and high-temperature adsorption and capture CO2 processes, this invention provides a highly efficient CO2 capture method and system based on fuel staged conversion coupled with chemical looping combustion. This method can achieve grade matching between the fuel conversion process and the regeneration process through partial fuel conversion and chemical looping combustion, avoiding the energy consumption of air separation for separating pure oxygen, and effectively reducing the energy consumption of CO2 capture technology after medium- and high-temperature adsorption and combustion.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a CO2 capture method based on fuel staged conversion coupled with chemical looping combustion, comprising the following steps:

[0008] The flue gas to be treated is fed into a carbonation tower, which is filled with a metal oxygen carrier MeO and adsorbent A. Adsorbent A adsorbs CO2 in the flue gas. After adsorption is complete, the solid in the carbonation tower is transported to a calcining furnace. In the calcining furnace, the adsorbent A that adsorbed CO2 is decomposed into adsorbent A and CO2. In the calcining furnace, the metal oxygen carrier MeO reacts with the unconverted fuel and syngas transported from the fuel preconversion reactor to generate a reduced metal oxygen carrier. The regenerated adsorbent A and the reduced metal oxygen carrier in the calcining furnace are transported to an air reactor, where the reduced metal oxygen carrier is oxidized back to MeO. MeO and the regenerated adsorbent A are then returned to the carbonation tower for recycling.

[0009] Fuel and reactants are introduced into the fuel preconversion reactor, where part of the fuel is converted into syngas under the action of a catalyst; the syngas and unconverted fuel are then fed into a calcining furnace.

[0010] Preferably, the metal oxygen support MeO comprises at least one selected from copper-based, nickel-based, cobalt-based, iron-based, and manganese-based materials; the adsorbent A comprises at least one selected from MgO, CaO, and Li4SiO4. In some specific embodiments of the invention, the metal oxygen support MeO is CuO.

[0011] Preferably, the reaction pressure inside the carbonation tower is 0.1–4 MPa, and the reaction temperature is 250–650 °C.

[0012] Preferably, the reaction pressure inside the calcining furnace is atmospheric pressure, and the reaction temperature is 450–950°C.

[0013] Preferably, the reaction pressure inside the air reactor is 1-2 MPa, and the reaction temperature is 800-1300℃.

[0014] Preferably, the heat required for the reaction in the fuel preconversion reactor is provided by the heat released from the reaction in the carbonation tower, and the fuel conversion rate needs to be adjusted according to the heat released from the carbonation tower; the reaction pressure in the fuel preconversion reactor is 0.1-4 MPa, and the reaction temperature is 150-600℃.

[0015] Preferably, the heat released from the reaction in the air reactor is used to heat the calcining furnace.

[0016] Preferably, by adjusting the fuel input and reactant ratio of the fuel preconversion reactor, the heat utilization of the carbonate tower and the heat demand of the calciner can be achieved simultaneously.

[0017] Preferably, the reactants introduced into the fuel preconversion reactor include H2O, CO2, or a mixture of both; the catalyst includes a catalyst with at least one of cobalt, nickel, and copper as the active component.

[0018] A second aspect of the present invention provides a system for CO2 capture using the above-described CO2 capture method based on fuel staged conversion coupled with chemical looping combustion, comprising a carbonation tower, a fuel preconversion reactor, a calciner, and an air reactor; wherein the carbonation tower, the calciner, and the air reactor are connected in sequence; wherein the air reactor is also connected to the carbonation tower; and wherein the fuel preconversion reactor is connected to the calciner.

[0019] Preferably, the system further includes a combined cycle expansion power generation device, which generates electricity using the oxygen-deficient air discharged from the air reactor. More preferably, the top cycle of the combined cycle expansion power generation device includes, but is not limited to, a gas-fired Brayton cycle and a humid air turbine cycle, while the bottom cycle includes, but is not limited to, a steam Rankine cycle, a supercritical CO2 Brayton cycle, and an organic Rankine cycle. The combined cycle expansion power generation device is connected to the gas output terminal of the air reactor. The high-pressure oxygen-deficient air from the air reactor outlet expands and generates electricity in the combined cycle, and the sensible heat of the expanded gas is recovered and converted into electricity through the bottom cycle.

[0020] Preferably, the system further includes a waste heat boiler power generation unit, which utilizes the heat from the decarbonized flue gas discharged from the carbonation tower and the CO2-rich gas discharged from the calcination furnace to generate electricity. More preferably, the waste heat boiler power generation unit can also utilize the oxygen-deficient air (mainly N2) after passing through the combined cycle expansion generator to further recover heat for power generation. The sensible heat carried by the decarbonized flue gas and calcination reaction gas products is recovered through the waste heat boiler, generating high-temperature steam to drive a steam turbine. The N2 discharged from the air reactor tower first enters the gas turbine through a pipeline, driving the gas turbine to generate electricity, and then is sent to the waste heat boiler through a pipeline at the gas turbine outlet to further release waste heat to heat the feedwater.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] This invention provides a highly efficient CO2 capture method and system based on fuel staged conversion coupled with chemical looping combustion. It can achieve grade matching between the fuel conversion process and the regeneration process through partial fuel conversion and chemical looping combustion, avoid the energy consumption of air separation to separate pure oxygen, and effectively reduce the energy consumption of CO2 capture technology after medium and high temperature adsorption combustion. Attached Figure Description

[0023] Figure 1 This is a flowchart of the CO2 capture method based on fuel staged conversion coupled with chemical looping combustion according to the present invention;

[0024] Figure 2 This is a process flow diagram of the CO2 capture system based on fuel staged conversion coupled with chemical looping combustion according to the present invention;

[0025] Figure 3 This is a typical process flow diagram of an embodiment of the present invention;

[0026] Figure 4 The above is a process flow diagram of the reference object selected in this invention, which is a calcium-cycle pure oxygen combustion process for CO2 capture. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0029] This invention provides a highly efficient CO2 capture method based on fuel staged conversion coupled with chemical looping combustion, such as... Figure 1 As shown, it includes the following steps:

[0030] (1) The flue gas to be treated is introduced into a carbonation tower and comes into contact with a medium-high temperature adsorbent A. The CO2 in the flue gas reacts with the adsorbent to form A-CO2, thus completing the adsorption of CO2 in the flue gas. The reaction pressure is atmospheric pressure, the reaction temperature range is 250-650℃, and the main chemical reaction is A+CO2→A-CO2. The high-temperature solid generated by the reaction is separated from the decarbonized flue gas through gas-solid separation. The solid is transported to a calcining furnace, and the decarbonized flue gas is directly discharged into the air after waste heat utilization.

[0031] (2) Fuel, reactants, and catalyst are introduced into the fuel preconversion reactor, where part of the fuel is converted into syngas, with H2 and CO as the main products. The reaction pressure is 0.1–4.0 MPa and the reaction temperature is 200–600 °C. The syngas and the remaining unconverted fuel are then fed into the calciner.

[0032] The reactants include H2O, CO2, or a mixture of both.

[0033] Optionally, the heat required for the reaction is provided by the heat released from the reaction occurring in the carbonation tower, and the fuel conversion rate needs to be adjusted according to the heat released from the carbonation tower.

[0034] Optionally, fuel preconversion reactions include processes such as cracking, pre-reforming, and gasification.

[0035] (3) In step (1), the A-CO2 transported is decomposed into A and CO2 in the calcining furnace, realizing the regeneration of the medium-high temperature absorbent A and the enrichment of CO2. The reaction pressure is atmospheric pressure, the reaction temperature range is 450~950℃, and the main chemical reaction is A-CO2→A+CO2. The regenerated A is recycled to the air reactor, and the enriched CO2 is discharged from the gas output end for subsequent compression or utilization. After the CO2 absorption capacity of the medium-high temperature adsorbent and the oxygen carrying capacity of the metal oxygen carrier decrease, a small amount of fresh material will be transported into the calcining furnace through pipeline.

[0036] In step (2), the syngas (H2, CO2, CO) from the fuel conversion process, along with the unconverted fuel, undergoes a reduction reaction with the metal oxygen carrier MeO in a calciner. The reaction pressure is atmospheric pressure, and the reaction temperature is 450–950 °C. The main chemical reaction that occurs is CH4. x O y +MeO→CO2+Me+H2O, H2+MeO→Me+H2O, CO+MeO→Me+CO2. The heat released by the reaction provides heat for the regeneration of the adsorbent, and the solid product is sent to the air reactor.

[0037] The metal oxygen support can be one or a mixture of copper-based, nickel-based, cobalt-based, iron-based, and manganese-based materials.

[0038] (4) The reduced metal oxygen carrier transported in step (3) undergoes an oxidation reaction with air in an air reactor, and the reduced metal oxygen carrier is oxidized back to MeO. The reaction pressure is 0.1-2.0 MPa, the reaction temperature is 800-1300℃, and the main chemical reaction is Air + Me → MeO. MeO and the recycled adsorbent A are sent back to the carbonation tower for the next cycle reaction.

[0039] Optionally, the heat released by the reaction can be used to heat the calcining furnace.

[0040] Medium and high temperature adsorbent A can be MgO, CaO and Li4SiO4, etc.; the catalysts used for fuel preconversion include, but are not limited to, catalysts with cobalt, nickel and copper as active components.

[0041] This invention also provides a highly efficient CO2 capture system based on fuel staged conversion coupled with chemical looping combustion, such as... Figure 2 As shown, it includes a carbonation tower, a fuel preconversion reactor, a calcining furnace, and an air reactor; the carbonation tower, calcining furnace, and air reactor are connected in sequence; the air reactor is also connected to the carbonation tower; the fuel preconversion reactor is connected to the calcining furnace.

[0042] Optionally, the capture system further includes a combined cycle expansion power generation unit, which generates electricity using the oxygen-deficient air discharged from the air reactor. The combined cycle expansion power generation unit is connected to the gas output terminal of the air reactor after the reaction. The high-pressure oxygen-deficient air at the air reactor outlet expands and generates electricity in the combined cycle, and the sensible heat of the expanded gas is recovered and converted into electricity through the bottom cycle. The top cycle in the combined cycle includes, but is not limited to, a gas-fired Brayton cycle and a humid air turbine cycle, while the bottom cycle includes, but is not limited to, a steam Rankine cycle, a supercritical CO2 Brayton cycle, and an organic Rankine cycle.

[0043] Optionally, the capture system also includes a waste heat boiler power generation unit, which generates electricity using the heat from the decarbonized flue gas discharged from the carbonation tower and the CO2-rich gas discharged from the calciner.

[0044] Example 1

[0045] Figure 3 This is a schematic diagram of a typical process flow for CO2 capture based on fuel staged conversion coupled with chemical looping combustion, as described in this invention. Figure 3 As shown, in this typical implementation case, CaO / CaCO3 was selected as the CO2 separation carrier, CuO / Cu as the oxygen carrier, natural gas as the typical fuel, and H2O as the fuel reforming reactant. The specific steps are as follows:

[0046] (1) The flue gas to be treated is introduced into the carbonation tower and comes into contact with the CaO adsorbent. The CO2 in the flue gas reacts with CaO to form CaCO3, thus reducing the CO2 emissions of the flue gas. The CaCO3 generated by the reaction is separated from the decarbonized flue gas. The solid is transported to the calcining furnace, and the decarbonized flue gas is directly discharged into the air after the waste heat is utilized.

[0047] (2) The fuel and H2O are fed into the fuel pre-conversion reactor together. Part of the fuel is reformed, and the conversion products H2, CO2, CO, etc., along with the remaining unconverted CH4, are sent to the calciner. The heat required for this reaction is provided by the heat released from the reaction in the carbonation tower.

[0048] (3) CaCO3 enters the calcining furnace to react and generate CaO and CO2, thereby regenerating the adsorbent and enriching CO2. The regenerated CaO is recycled to the air reactor, and the enriched CO2 is discharged from the gas output end. After the waste heat is utilized, it continues to be compressed or utilized in subsequent stages.

[0049] Since the adsorption capacity of regenerated CaO and the oxygen-carrying capacity of CuO decrease during the circulation process, a small amount of fresh CaCO3 and CuO are added to the calcining furnace to maintain the circulation.

[0050] Syngas from natural gas conversion and unconverted CH4 are fed into a calcining furnace to undergo a reduction reaction with CuO, providing heat for adsorbent regeneration. The product Cu is then sent to an air reactor.

[0051] (4) The Cu introduced into the air reactor undergoes an oxidation reaction with the air. The generated CuO and the recycled CaO are sent back to the carbonation tower for the next cycle reaction. The heat released by the reaction can be used to heat the calcining furnace.

[0052] (5) The sensible heat carried by the decarbonized flue gas and calcination reaction gas products is recovered by the waste heat boiler to generate high-temperature steam to drive the steam turbine to do work. The N2 discharged from the air reactor tower first enters the gas turbine through the pipeline to drive the gas turbine to generate electricity. Then, at the gas turbine outlet, it is sent to the waste heat boiler through the pipeline to further release waste heat to heat the feedwater.

[0053] Specifically, the main chemical reaction in the carbonation tower is: CaO + CO2 → CaCO3;

[0054] The main chemical reaction in the fuel preconversion reactor is CH4+H2O→H2+CO, as well as side reactions such as CO+H2O→CO2+H2 and CH4+CO2→CO+H2.

[0055] The main chemical reactions in the calcining furnace are: CaCO3→CaO+CO2, CH4+CuO→CO2+Cu+H2O, H2+CuO→Cu+H2O, and the reduction reaction of by-products of fuel reforming with CuO, including but not limited to CO+CuO→Cu+CO2.

[0056] The main chemical reaction in the air reactor is: Air + Cu → CuO.

[0057] In this typical case, the relevant reaction conditions were selected as follows: the temperature of the carbonation tower was 650℃, the pressure was atmospheric pressure, the molar ratio of CaO to CO2 was 4.5, and the CaO conversion rate was 20%; the pressure of the fuel preconversion reactor was atmospheric pressure, the reaction temperature was 600℃, and the molar ratio of H2O to methane was 1.5; the temperature of the calcining furnace was 900℃, the pressure was atmospheric pressure, and the calcining furnace was adiabatic; the temperature of the air reactor was 950℃, and the pressure was 6 bar; the waste heat boiler adopted triple reheat technology, namely 126 bar / 566℃, 26 bar / 566℃, and 5.5 bar / 305℃, the exhaust gas temperature of the waste heat boiler was 125℃, and the pressure was slightly positive pressure.

[0058] To further illustrate the beneficial effects of the present invention, Comparative Example 1 was selected as a reference. The process flow diagram of Comparative Example 1 is shown below. Figure 4 As shown.

[0059] Compare with Example 1

[0060] Traditional post-combustion capture technology was selected, with calcium-cycle pure oxygen combustion for CO2 capture as a reference.

[0061] The flue gas to be treated reacts with CaO adsorbent in the carbonation tower to remove CO2. The generated CaCO3 reacts in the calcination furnace to generate CaO and CO2, realizing the regeneration of the adsorbent and CO2 enrichment. The regenerated CaO is recycled back to the carbonation tower. The high-temperature heat required for the calcination process is provided by the combustion of fuel and pure oxygen. The pure oxygen is obtained by consuming electricity in the air separation unit. The sensible heat carried by the decarbonized flue gas and calcination reaction gas products, as well as the heat released by the carbonation reaction, are recovered through the waste heat boiler to generate high-temperature steam to drive the steam turbine to do work.

[0062] In this comparative example, the relevant reaction conditions were selected as follows: the temperature of the carbonation tower was 650℃, the pressure was atmospheric pressure, the molar ratio of CaO to CO2 was 4.25, and the CaO conversion rate was 20%; the temperature of the calcination furnace was 900℃, the fuel was natural gas, and the pressure was atmospheric pressure; the oxygen purity of the air separation unit was 95%, and the power consumption of the air separation unit was 180 kWh / t O2; the waste heat boiler adopted triple-pressure reheat technology, namely 126 bar / 566℃, 26 bar / 566℃, and 5.5 bar / 305℃, the exhaust gas temperature of the waste heat boiler was 125℃, and the pressure was slightly positive pressure.

[0063] Typical Example 1 and Comparative Example 1 used the same natural gas fuel and the same flue gas. The composition of the natural gas and flue gas is shown in Tables 1 and 2, and their performance comparison is shown in Table 3. Compared with the comparative examples, the typical example, under the same flue gas input and flue gas CO2 capture rate, has a unit CO2 capture energy consumption that is 0.35 MJ / kg lower than the reference, reducing energy consumption by 18.35 percentage points compared to the reference, demonstrating good energy utilization efficiency.

[0064] Table 1 Input Natural Gas Composition

[0065]

[0066]

[0067] Table 2 Input Smoke Composition

[0068]

[0069] Table 3 Performance Comparison

[0070]

[0071] *Total CO2 capture = Flue gas CO2 capture + Natural gas CO2 capture

[0072] **Equivalent CO2 capture energy consumption (MJ / kg) = (Fuel input - Electricity output / Conventional natural gas power generation efficiency) / Total CO2 captured; Conventional natural gas power generation efficiency is calculated using the benchmark value of 52.5% commonly used in the literature (De Lena E, Spinelli M, Martínez I, et al. Process integration study of tail-end Ca-Looping process for CO2 capture in cement plants[J]. International Journal of Greenhouse Gas Control, 2017, 67:71-92.).

[0073] This invention reduces the grade difference between the fuel release process and the adsorbent regeneration process during calcination by graded conversion of fuel, thereby significantly reducing irreversible losses in the fuel conversion process. At the same time, it avoids the power consumption of the air separation unit and effectively reduces the energy consumption of CO2 capture technology after medium- and high-temperature adsorption and combustion.

[0074] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A CO2 capture method based on fuel staged conversion coupled with chemical looping combustion, characterized in that, Includes the following steps: The flue gas to be treated is fed into a carbonation tower, which is filled with a metal oxygen carrier MeO and adsorbent A. Adsorbent A adsorbs CO2 in the flue gas. After adsorption is complete, the solid in the carbonation tower is transported to a calcining furnace. In the calcining furnace, the adsorbent A that adsorbed CO2 is decomposed into adsorbent A and CO2. In the calcining furnace, the metal oxygen carrier MeO reacts with the unconverted fuel and syngas transported from the fuel preconversion reactor to generate a reduced metal oxygen carrier. The regenerated adsorbent A and the reduced metal oxygen carrier in the calcining furnace are transported to an air reactor, where the reduced metal oxygen carrier is oxidized back to MeO. MeO and the regenerated adsorbent A are then returned to the carbonation tower for recycling. Fuel and reactants are introduced into the fuel preconversion reactor, where part of the fuel is converted into syngas under the action of a catalyst; the syngas and unconverted fuel are then fed into a calcining furnace. The heat required for the reaction in the fuel preconversion reactor is provided by the heat released from the reaction in the carbonation tower, and the fuel conversion rate needs to be adjusted according to the heat released from the carbonation tower; the reaction pressure in the fuel preconversion reactor is 0.1~4 MPa, and the reaction temperature is 150~600℃; The reactants include H2O, CO2, or a mixture of both; the catalyst includes a catalyst with at least one of cobalt, nickel, and copper as the active component.

2. The CO2 capture method based on fuel staged conversion coupled with chemical looping combustion according to claim 1, characterized in that, The metal oxygen support MeO includes at least one of copper-based, nickel-based, cobalt-based, iron-based, and manganese-based materials; the adsorbent A includes at least one of MgO, CaO, and Li4SiO4.

3. The CO2 capture method based on fuel staged conversion coupled with chemical looping combustion according to claim 1, characterized in that, The reaction pressure inside the carbonation tower is 0.1~4 MPa, and the reaction temperature is 250~650℃.

4. The CO2 capture method based on fuel staged conversion coupled with chemical looping combustion according to claim 1, characterized in that, The reaction pressure inside the calcining furnace is atmospheric pressure, and the reaction temperature is 450~950℃.

5. The CO2 capture method based on fuel staged conversion coupled with chemical looping combustion according to claim 1, characterized in that, The reaction pressure inside the air reactor is 1~2 MPa, and the reaction temperature is 800~1300℃.

6. A system using the CO2 capture method based on fuel staged conversion coupled with chemical looping combustion as described in any one of claims 1-5, characterized in that, It includes a carbonation tower, a fuel preconversion reactor, a calcining furnace, and an air reactor; the carbonation tower, calcining furnace, and air reactor are connected in sequence; the air reactor is also connected to the carbonation tower; and the fuel preconversion reactor is connected to the calcining furnace.

7. The system according to claim 6, characterized in that, It also includes a combined cycle expansion power generation unit, which generates electricity using oxygen-deficient air discharged from an air reactor.

8. The system according to claim 6, characterized in that, It also includes a waste heat boiler power generation device, which uses the heat from the decarbonized flue gas discharged from the carbonation tower and the CO2-rich gas discharged from the calciner to generate electricity.

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