Calcium carbonate cyclic decomposition and CO2 capture system

Abstract

The utility model discloses a calcium carbonate cyclic decomposition and CO2 capture system, which relates to the technical field of CO2 capture and comprises a decomposition furnace, a preheater component, a tertiary air pipe and a rotary kiln. The preheater assembly comprises four preheaters which are sequentially connected, namely C1, C2, C3 and C4, and the discharging end of the preheater C4 is connected with the feeding end of the decomposing furnace; the feeding end of the decomposing furnace extends downwards and is connected with an ultra-high-temperature circulating fan, and the kiln tail of the rotary kiln and a tertiary air pipe are both communicated with an air inlet pipe of the preheater C4. The outlet end of the decomposing furnace is connected with a preheater C5, the discharging end of the preheater C5 is communicated with the rotary kiln, an air outlet pipeline of the preheater C5 is divided into two paths, one path is connected with an ultrahigh-temperature circulating fan, and the other path is connected with a CO2 aftertreatment system. According to the utility model, the kiln tail decomposing furnace and the preheater of the existing cement production line are properly modified, so that the system can normally produce cement clinker and simultaneously co-produce high-concentration CO2, the high-concentration CO2 is captured, and the emission reduction of CO2 on the cement production line is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of CO2 capture, in particular to a system for cyclic decomposition of calcium carbonate and CO2 capture. Background Art

[0002] The cement industry is a major CO2 emitter, accounting for approximately 5% of all CO2 generated by human activities. The global cement industry must address CO2 emission reduction in its future development. Theoretical analysis shows that, based on the industry's current production levels, producing one ton of cement clinker emits approximately 940 kilograms of CO2. CO2 emissions from the cement industry account for approximately 20% of my country's total industrial CO2 emissions. With China's plan to include the cement industry in carbon neutrality management starting in 2025, the industry faces immense pressure to reduce CO2 emissions.

[0003] The cement industry needs to reduce carbon emissions through the following specific measures: ① Reducing excess production capacity: CO2 generated by limestone decomposition and coal combustion, which account for approximately 75% of the cement production process, is the primary source of carbon emissions. Based on my country's cement energy consumption levels, each ton of cement produced generates approximately 0.7 to 0.8 tons of CO2, making it the most fundamental and effective measure for reducing carbon emissions in my country's cement industry. ② Adopting alternative fuels: After over 30 years of exploration, alternative fuel technology and experience in the cement industry have matured, becoming a key tool for energy conservation and emission reduction in developed countries. Two-thirds of cement plants in developed countries use alternative fuels, and the average replacement rate for combustible waste in the cement industry reaches 20%. Extensive production practices and experimental results in developed countries demonstrate that the use of alternative fuels and waste disposal in the cement industry, recovering energy and materials from waste, aligns with the waste management model. The technological advantages of new dry process cement kilns determine their technological advantages. While producing qualified products, they utilize and dispose of waste, avoiding secondary pollution. This is an effective and technically and economically sound approach to achieving both product quality and environmental standards. ③ Reducing the amount of clinker in cement: Technologies such as the currently being promoted LC3 cement are examples. However, none of these methods effectively resolve the contradiction between cement production and carbon emissions. Only by achieving high-concentration capture of CO2 in cement companies, reducing the cost of subsequent purification processes, and processing it into another series of products, and allowing cement companies to produce a series of cement by-product CO2 products, can we truly achieve emission reduction and efficiency improvement.

[0004] CO2 is a valuable resource, recognized by global organizations as one of the most user-friendly gases. It is widely used in numerous fields, including chemistry, food, mechanical processing, and oil extraction. However, due to the high cost of capturing and purifying CO2, global annual CO2 utilization currently falls below 100 million tons, representing a significant waste.

[0005] Regarding CO2 capture in the cement industry, in October 2018, a domestic 5,000 t / d cement clinker production line completed and commissioned a project capable of capturing and purifying (reducing emissions) 50,000 tons of CO2 annually using conventional carbon capture and purification technology. This project directly captures CO2 from cement kiln exhaust gases. Due to the very low CO2 content in flue gas (18-20%), the project can only produce industrial-grade liquid CO2. Furthermore, the high production costs and investment mean that, aside from the CO2 reduction benefits, the investment returns are minimal. However, this project has set a precedent for CO2 capture and purification in the cement industry, achieving CO2 emission reduction goals.

[0006] If you want to obtain higher-purity CO2, you can also use technologies such as "external-fired rotary kiln", which requires deep transformation of the cement kiln system. Not only is the transformation cost high, but the "external-fired rotary kiln" technology mostly uses electromagnetic heating or gas heating, which has low heat transfer efficiency and high operating costs. Due to the limitations of the heat transfer method, this technology cannot achieve large-scale equipment.

[0007] In summary, it is necessary to develop a simple, applicable, stable, and reliable system that can not only decompose limestone to produce cement clinker but also capture high-concentration CO2. Furthermore, this system could utilize inexpensive fuels, or even industrial solid waste, instead of high-quality coal. This would be technically feasible and significantly reduce fuel costs for cement production. Furthermore, cement companies could simultaneously sell both cement and CO2, significantly increasing their profits while also making a significant contribution to environmental protection. Utility Model Content

[0008] The purpose of this utility model is to overcome the shortcomings of the existing technology and provide a system for the cyclic decomposition of calcium carbonate and the capture of CO2. The system is to appropriately modify the decomposition furnace and preheater at the kiln tail of the existing cement production line so that high-concentration CO2 is produced while decomposing and producing cement clinker, and the high-concentration CO2 is captured to achieve CO2 emission reduction on the cement production line.

[0009] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0010] A system for cyclic decomposition of calcium carbonate and CO2 capture comprises a decomposition furnace, a preheater assembly, a tertiary air duct, and a rotary kiln. The preheater assembly comprises four preheaters C1, C2, C3, and C4 connected in sequence, the discharge end of preheater C4 being connected to the feed end of the decomposition furnace. The feed end of the decomposition furnace extends downward and is connected to an ultra-high temperature circulation fan, and the kiln tail and tertiary air duct of the rotary kiln are both connected to the air inlet duct of preheater C4. The outlet end of the decomposition furnace is connected to a preheater C5, the discharge end of preheater C5 being connected to the rotary kiln, and the air outlet duct of preheater C5 being divided into two paths, one connected to the ultra-high temperature circulation fan, and the other connected to a CO2 post-treatment system.

[0011] Furthermore, the decomposition furnace is a double-layer external combustion circulating material decomposition furnace, including an outer layer and an inner tube made of steel plates, a hot air jacket is formed between the outer layer and the inner tube, one end of the hot air jacket is connected to the kiln tail of the rotary kiln, and the other end is connected to the preheater air inlet pipe; the tertiary air duct is connected to the hot air jacket.

[0012] Furthermore, the outer layer of the double-layer external combustion circulating material decomposition furnace is lined with thermal insulation material; a plurality of wind fins are welded on the outside of the inner tube, and a black body enhanced radiation heat transfer material is arranged inside the inner tube.

[0013] Furthermore, a plurality of CO gas internal combustion nozzles are arranged inside the inner cylinder of the double-layer external combustion circulating material decomposition furnace.

[0014] Furthermore, a multi-head spiral air guide device is provided in the hot air jacket.

[0015] Furthermore, a gangue hot blast furnace capable of providing an external combustion heat source is provided, and the air outlet of the gangue hot blast furnace is connected to the hot blast jacket.

[0016] Furthermore, a material distribution device and a circulating material pipe are provided at the discharge end of the preheater C5.

[0017] Furthermore, a cyclone is added between the preheaters C1 and C2, and the preheater C1 is a lower exhaust cyclone.

[0018] Furthermore, the CO2 post-processing system includes a heat exchanger and a high-temperature fan connected to the heat exchanger, and the high-temperature fan is connected to the external CO2 purification process.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) Compared with existing cement kiln CO2 capture technology, the device provided by this utility model increases the CO2 concentration in the decomposed gas from 18-20% in existing technology to 85-95%. Moreover, the capture equipment is synchronized with the capacity of the cement kiln system, fully realizing large-scale and scalable CO2 capture. The CO2 emission reduction rate of cement production lines can reach over 60%.

[0021] (2) The utility model not only realizes the high-concentration capture of carbon dioxide in cement kilns, but also realizes the “5 to 6” transformation of cement kiln preheaters, making the system more energy-efficient.

[0022] (2) The system provided by this utility model is an improvement on existing technologies. It fully utilizes existing facilities and equipment, and with low system investment, it can achieve high-concentration carbon dioxide capture in cement kilns. The application of this utility model can achieve the co-production of carbon dioxide with cement production. Due to the ultra-low cost support, both products can be profitable. Carbon assets can also be sold for profit, achieving three goals at one stroke.

[0023] (3) During the use of the system provided by the utility model, due to the large-scale use of low calorific value coal or even coal gangue to replace high-quality coal, there is a large price difference, which achieves ultra-low cost for cement production and carbon dioxide capture.

[0024] (5) The utility model can realize the high-value utilization of low calorific value coal or coal gangue. The coal slag (coal-based kaolin) produced after the combustion of low calorific value coal or coal gangue can be used as a cement admixture to produce LC3 cement, further reducing the cost of cement.

[0025] (6) The system of the present invention can utilize the raw material system to grind limestone powder separately when not producing cement clinker, and the kiln system to produce active lime and co-produce carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a system structure diagram of calcium carbonate cyclic decomposition and CO2 capture in Example 1;

[0027] Figure 2 This is a system structure diagram for the calcium carbonate cyclic decomposition and CO2 capture in Example 2.

[0028] Among them, the names corresponding to the figure numbers are: 1-decomposition furnace, 2-coal gangue hot blast furnace, 3-cyclone, 4-lower exhaust cyclone, 5-high temperature fan, 6-circulation pipe, 7-material distribution device, 8-ultra-high temperature circulation fan, 9-CO gas internal combustion nozzle, 10-heat exchanger, 11-hot air jacket, 12-preheater assembly, 13-rotary kiln, 14-tertiary air duct. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. The present invention includes but is not limited to the following embodiments.

[0030] Example 1

[0031] This embodiment provides a system for the cyclic decomposition of calcium carbonate and the capture of CO2. The system is to appropriately modify the decomposition furnace and preheater at the tail end of the existing cement production line so that high-concentration CO2 is co-produced while decomposing to produce cement clinker, and the high-concentration CO2 is captured, thereby achieving CO2 emission reduction on the cement production line. The existing cement clinker production system includes a decomposition furnace 1, a preheater assembly 12, a tertiary air duct 14, and a rotary kiln 13. The preheater assembly 12 is a five-stage preheater, namely C1, C2, C3, C4, and C5. The feed end of the decomposition furnace 1 is connected to the discharge end of C4, the inlet end of C5 is connected to the outlet end of the decomposition furnace 1, and the discharge end of C5 is connected to the tail end of the rotary kiln 13. This embodiment makes the following improvements to the existing technology:

[0032] (1) Partial modification of the decomposition furnace: Cut off the C5 air outlet duct, and connect the C5 air outlet duct to the heat exchanger 10 and the air inlet of the high-temperature fan 5. Preferably, the high-temperature fan 5 is a high-temperature fan 5. The original decomposition furnace 1 is transformed into a double-layer external combustion circulating material decomposition furnace. The furnace has a double-layer structure. The outer layer is made of ordinary steel plates rolled and welded, and the inner layer is lined with thermal insulation materials, which are composed of thermal insulation and refractory materials. The inner layer (inner cylinder) is made of heat-resistant steel plates that can withstand 1100℃ and rolled and welded. Several wind fins are welded on the outside of the inner cylinder to increase the heat exchange area. A hot air jacket 11 is formed between the inner and outer layers. The kiln gas from the smoke chamber, part of the tertiary air, and the hot air generated by the offline coal gangue hot air furnace 2 are mixed and passed through the hot air jacket 11. The hot air temperature is controlled at about 1050℃. The high-temperature hot air transfers heat to the material by radiation heat transfer. At the same time, the inner cylinder has sufficient rigidity to maintain its shape. The exhaust gas after cooling by the jacket enters the C4 air inlet pipe. In order to ensure that the modified double-layer external combustion circulating material decomposition furnace has sufficient volume, the decomposition furnace is bent and extended downward.

[0033] (2) Adding a circulating material pipe 6 and an ultra-high temperature circulating fan 8: An adjustable material distributor 7 and a circulating material pipe 6 are added to the C5 flap valve project. The regulating range of the circulating material is between 0% and 300%. The ultra-high temperature circulating fan 8 is used to move the material in the decomposition furnace cylinder. It is a high-volume, low-pressure fan.

[0034] (3) CO gas internal combustion nozzles 9 are installed to enhance the heat transfer performance of the double-layer external combustion circulating material decomposition furnace. Multiple CO gas internal combustion nozzles 9 are installed inside the inner tube. Pure oxygen is used to assist the combustion of CO, achieving oxygen-enriched combustion. The reaction formula is CO + O2 = CO2. The CO2 generated by combustion enters the C5 and is captured.

[0035] (4) Preheater Partial Renovation: Due to the increase in the temperature of the hot air entering the C4 cyclone separator after the renovation, the temperature of the cement raw material leaving the preheater C4 is between 800-830°C before entering the double-layer external combustion circulating material decomposition furnace. In order to reduce the outlet temperature of C1, a new cyclone 3 was added and the original C1 was replaced with a lower exhaust cyclone 4 to facilitate connection to the original exhaust duct.

[0036] (5) A large amount of "blackbody enhanced radiation heat transfer material" is installed inside the inner tube of the double-layer external combustion circulating material decomposition furnace, which can save energy by 10-15%. In addition, when the circulating material reaches 300%, the following effects can be achieved:

[0037] 1. At the same system temperature, the decomposition rate can be increased by 8%. Increasing the system temperature by 100°C can increase the decomposition rate by another 10%;

[0038] 2. System heat consumption: can be reduced by 12%;

[0039] 3. System power consumption: can be reduced by 12%;

[0040] 4. System exhaust volume: can be reduced by 10%, thereby further reducing system heat consumption.

[0041] (6) A multi-head spiral air guide device is installed in the jacket of the double-layer external combustion circulating material decomposition furnace, allowing the hot air to run in a spiral trajectory in the jacket, thereby increasing the heat exchange time between it and the lining.

[0042] (7) Since the decomposition heat source of the kiln tail decomposition furnace is provided by the coal gangue hot blast furnace 2 (external combustion heat source), there is no need to provide combustion-supporting air, so the opening of the tertiary air duct can be adjusted to a relatively low position. In addition, the utilization rate of the coal mill system is greatly reduced, which greatly increases the heat for cooling the clinker at the kiln head, and can increase the steam production of the AQC boiler. The power generation of the system is greatly increased to more than 60kwh / t clinker; the coal gangue hot blast furnace 2 is a circulating fluidized bed hot blast furnace for coal gangue or low calorific value coal.

[0043] (8) A high-temperature fan 5 is installed at the outlet of C5, and an ultra-high-temperature circulating fan 8 is connected to the C5 outlet duct. The high-concentration CO2 flue gas discharged from the C5 outlet duct is divided into two paths. One path is cooled by the heat exchanger 10, and then enters the CO2 purification process through the high-temperature fan 5 to be processed into various carbon dioxide products. After chemical absorption process, CO2 can be directly used in the food, oil extraction, chemical and other industries. The other path is directly sent to the cement plant's recycling fuel system, where it reacts with the carbon in the low calorific value coal under the action of high temperature and catalyst to generate CO gas for recycling in the cement kiln system.

[0044] In this embodiment, in the double-layer external combustion circulating material decomposition furnace, the concentration of CO2 generated by the decomposition of calcium carbonate is as high as 85-95%.

[0045] In this embodiment, the cement raw meal is preheated to 800-830°C in the cement kiln preheaters C1-C4 before entering the double-layer external-fired circulating material precalciner. The heat source for the double-layer external-fired circulating material precalciner is provided by the coal gangue hot blast furnace 2. The hot air from the double-layer external-fired circulating material precalciner, after heat exchange and cooling, is fed into the cement kiln preheater through the C4 air inlet pipe for thermal energy reuse. The gas-solid mixture exiting the double-layer external-fired circulating material precalciner is separated into gas and solids by the cyclone separator C5. The high-concentration CO2 gas (85-95% CO2 concentration) produced by calcium carbonate decomposition is cooled by the heat exchanger 10 and then delivered to the CO2 purification system by a high-temperature CO2 blower. A portion of the mixture, including calcium oxide, produced by calcium carbonate decomposition enters the rotary kiln for calcination to form cement clinker (the remaining portion passes through the distribution valve and circulating material pipe 6 and returns to the precalciner). The circulating air is extracted at the C5 outlet pipe and delivered upstream of the double-layer external-fired circulating material precalciner by an ultra-high-temperature circulating blower.

[0046] Example 2

[0047] This embodiment provides a system for the cyclic decomposition of calcium carbonate and CO2 capture. By appropriately modifying the precalciner and preheater at the kiln tail of an existing cement production line, the system produces high-concentration CO2 while decomposing and producing cement clinker. This high-concentration CO2 is then captured, thereby reducing CO2 emissions from the cement production line. The improvements include:

[0048] (1) Partial modification of the decomposition furnace: The C5 outlet duct is cut off and connected to the heat exchanger 10 and the air inlet of the high-temperature blower 5. Preferably, the high-temperature blower 5 is a CO2 high-temperature blower. The original decomposition furnace 12 is retained. The kiln gas from the smoke chamber and some hot tertiary air are mixed and fed into the C4 air inlet duct. To ensure sufficient volume for the modified decomposition furnace, the decomposition furnace is bent and extended downward.

[0049] (2) Adding a circulating material pipe 6 and an ultra-high temperature circulating fan 8: An adjustable material distributor 7 and a circulating material pipe 6 are added to the C5 flap valve project. The regulating range of the circulating material is between 0% and 300%. The ultra-high temperature circulating fan (serial number 8) is used to move the material in the decomposition furnace cylinder. It is a high-volume, low-pressure fan.

[0050] (3) Installing CO gas internal combustion nozzles: Multiple CO gas internal combustion nozzles 9 are installed in the modified decomposition furnace 12. The combustion of CO is assisted by pure oxygen, achieving oxygen-enriched combustion. The reaction formula is CO + O2 = CO2. The CO2 produced by combustion enters C5 and is captured.

[0051] (4) Partial modification of the preheater: Due to the increase in the temperature of the hot air entering the C4 cyclone separator after the modification, the temperature of the cement raw material leaving the preheater C4 is between 800 and 830°C before entering the modified decomposition furnace 12. In order to reduce the outlet temperature of C1, a new cyclone 3 is added and the original C1 is replaced with a lower exhaust cyclone 4 to facilitate connection with the original exhaust duct.

[0052] (5) The modified decomposition furnace is equipped with a large amount of "blackbody enhanced radiation heat transfer material", which can save energy by 10-15%. In addition, when the recycled material reaches 300%, the following effects can be achieved:

[0053] 1. At the same system temperature, the decomposition rate can be increased by 8%. Increasing the system temperature by 100°C can increase the decomposition rate by another 10%;

[0054] 2. System heat consumption: can be reduced by 12%;

[0055] 3. System power consumption: can be reduced by 12%;

[0056] 4. System exhaust volume: can be reduced by 10%, thereby further reducing system heat consumption.

[0057] (6) Since the decomposition heat source of the modified decomposition furnace is CO gas plus pure oxygen to achieve oxygen-enriched combustion, the reaction formula is CO+O2=CO2, and no combustion air is required. Therefore, the opening of the tertiary air duct can be adjusted to a very low position. In addition, the utilization rate of the coal mill system is greatly reduced, which greatly increases the heat for cooling the clinker at the kiln head. The steam production of the AQC boiler can be increased, and the power generation of the system is greatly increased to more than 60kwh / t clinker.

[0058] (7) In the modified decomposition furnace, the CO2 concentration produced by the decomposition of calcium carbonate is as high as 85-95%.

[0059] (8) A high-temperature fan 5 is installed at the outlet of C5, and the ultra-high-temperature circulating fan 8 is connected to the C5 outlet duct. The high-concentration CO2 flue gas discharged from the C5 outlet duct is divided into two paths. One path is cooled by the heat exchanger 10, and then enters the CO2 purification process through the high-temperature fan 5 to be processed into various carbon dioxide products. After chemical absorption process, CO2 can be directly used in the food, oil extraction, chemical and other industries. The other path directly enters the recycled fuel system sent to the cement plant, and reacts with the carbon in the low calorific value coal under the action of high temperature and catalyst to generate CO gas for recycling in the cement kiln system.

[0060] In this embodiment, the cement raw meal is preheated to 800-830°C in the cement kiln preheaters C1-C4 before entering the modified circulating material decomposition furnace 12. The heat source of the modified circulating material decomposition furnace 12 is provided by the combustion of CO gas and pure oxygen; the kiln gas and part of the tertiary air are directly introduced into the cement kiln preheater from the C4 air inlet pipe for heat energy recycling. The gas-solid mixture exiting the modified circulating material decomposition furnace 12 is separated into gas and solid by the newly added cyclone separator C5. The high-concentration CO2 gas (CO2 concentration 85-95%) obtained by the decomposition of calcium carbonate is cooled by a heat exchanger and then sent to the CO2 purification system by a high-temperature CO2 blower. A portion of the mixture of calcium oxide and other substances obtained by the decomposition of calcium carbonate enters the rotary kiln for calcination to form cement clinker (the other portion passes through the distributing valve and the circulating material pipe 6 and returns to the decomposition furnace). The circulating air is extracted at the C5 outlet pipe and sent to the upstream of the modified circulating material decomposition furnace by an ultra-high-temperature circulating blower.

[0061] The above embodiment is only one of the preferred implementation methods of the present invention and should not be used to limit the scope of protection of the present invention. Any changes or modifications that have no substantive meaning made to the main design concept and spirit of the present invention, as long as the technical problems they solve are still consistent with the present invention, should be included in the scope of protection of the present invention.

Claims

1. A system for cyclic decomposition of calcium carbonate and capture of CO2, comprising a decomposition furnace (1), a preheater assembly (12), a tertiary air duct (14), and a rotary kiln (13); the preheater assembly (12) comprises four preheaters C1, C2, C3, and C4 connected in sequence, and the discharge end of the preheater C4 is connected to the feed end of the decomposition furnace (1); characterized in that: The feed end of the decomposition furnace (1) extends downward and is connected to an ultra-high temperature circulation fan (8); the kiln tail and the tertiary air duct (14) of the rotary kiln (13) are both connected to the air inlet pipe of the preheater C4; the outlet end of the decomposition furnace (1) is connected to the preheater C5, the discharge end of the preheater C5 is connected to the rotary kiln (13), and the air outlet duct of the preheater C5 is divided into two paths, one path is connected to the ultra-high temperature circulation fan (8), and the other path is connected to the CO2 post-treatment system.

2. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 1, characterized in that: The decomposition furnace (1) is a double-layer external combustion circulating material decomposition furnace, comprising an outer layer and an inner cylinder made of steel plates, a hot air jacket (11) being formed between the outer layer and the inner cylinder, one end of the hot air jacket (11) being connected to the kiln tail of the rotary kiln (13), and the other end being connected to the air inlet pipe of the preheater C4; a tertiary air duct (14) being connected to the hot air jacket (11).

3. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 2, characterized in that: The outer layer of the double-layer external combustion circulating material decomposition furnace is lined with thermal insulation materials; a number of wind fins are welded on the outside of the inner tube, and black body enhanced radiation heat transfer materials are arranged inside the inner tube.

4. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 3, characterized in that: A plurality of CO gas internal combustion nozzles (9) are arranged inside the inner cylinder of a double-layer external combustion type circulating material decomposition furnace.

5. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 4, characterized in that: A multi-head spiral air guide device is arranged in the hot air jacket (11).

6. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 5, characterized in that: A gangue hot blast furnace (2) capable of providing an external combustion heat source is provided, and an air outlet of the gangue hot blast furnace (2) is connected to a hot blast jacket (11).

7. A system for cyclic decomposition of calcium carbonate and CO2 capture according to any one of claims 1 to 6, characterized in that: A material distribution device (7) and a circulating material pipe (6) are provided at the discharge end of the preheater C5.

8. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 7, characterized in that: A cyclone (3) is newly installed between the preheaters C1 and C2, and the preheater C1 is a lower exhaust cyclone (4).

9. A system for calcium carbonate cyclic decomposition and CO2 capture according to claim 8, characterized in that: The CO2 post-processing system comprises a heat exchanger (10) and a high-temperature blower (5) connected to the heat exchanger, and the high-temperature blower (5) is connected to an external CO2 purification process.

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