Lime grading cooling system

Abstract

A lime staged cooling system is characterized in that a lower cooling section of a combustion chamber is sequentially divided into a first-stage cooling area, a second-stage cooling area and a third-stage cooling area from bottom to top and is provided with a primary air cavity; and a central channel for materials to pass through is reserved in the primary air cavity on the axis of the combustion chamber. In the vertical direction, the bottom wall of the primary air cavity is located in the first-stage cooling area, and the top wall of the primary air cavity is located in the third-stage cooling area. Air holes are formed in the top wall and the bottom wall of the primary air cavity. And a primary air inlet mechanism is arranged at the bottom of the primary cooling area. A secondary air inlet mechanism is arranged on the inner side wall of the primary air cavity. According to the utility model, primary air is adopted to cool materials in the first-stage cooling area and the third-stage cooling area, and secondary air is adopted to cool materials in the second-stage cooling area, so that the primary air bypasses the second-stage cooling area in which CaO and CO2 are easy to react, and reverse reaction can be reduced or even avoided. And meanwhile, secondary air does not generate reverse reaction, so that the cooling efficiency and the yield of lime are ensured.

Description

Technical Field

[0001] The utility model relates to a cooling system, in particular to a lime classification cooling system, belonging to the technical field of limestone manufacturing. Background Art

[0002] Active lime is an important industrial raw material, which is widely used and in huge demand in industries such as the steel industry, calcium carbide industry and alumina industry. In the past decade, the lime production in China has been increasing continuously. In 2020, the domestic lime production reached 300 million tons, and the CO2 emissions generated reached more than 330 million tons, making it a key object for CO2 emission reduction and carbon capture in the industrial field.

[0003] The parallel-flow regenerative double-shaft lime shaft kiln, as shown in Figure 6 , is one of the most advanced industrial lime production equipment and the mainstream kiln type at present. It adopts the double-shaft reversing regenerative technology and has the advantages of high system energy efficiency, uniform product roasting and low pollution emissions compared with other kiln types such as rotary kilns and mechanized shaft kilns. However, the CO2 concentration in the tail gas generated by its current conventional lime production process is relatively low, generally below 20%. Since the carbon capture cost increases with the decrease in the carbon dioxide concentration in the capture source, the carbon capture cost is as high as more than 300 yuan / ton of carbon dioxide, resulting in most manufacturers directly discharging the tail gas into the atmosphere, causing great resource waste and environmental pollution. Therefore, the too low CO2 concentration at the tail end greatly restricts the large-scale application of carbon capture technology in lime kiln equipment.

[0004] In view of the above problems, the technical personnel in the industry proposed a carbon front enrichment technology, that is, by reducing or eliminating other gas components in the flue gas to obtain high-concentration CO2 flue gas, thereby greatly reducing the tail-end carbon capture cost and realizing near-zero emissions in lime production. The main technical feature of this method is to use recycled flue gas to replace the cooling air to cool the high-temperature lime, and at the same time use pure oxygen + recycled flue gas for calcination to obtain high-concentration CO2 flue gas. However, directly using high-concentration CO2 flue gas to cool high-temperature calcium oxide easily causes the reverse carbonization reaction between calcium oxide and CO2, regenerating calcium carbonate and reducing the quality and output of lime products.

[0005] CaO + CO2 → CaCO3 Equation (1)

[0006] In the existing patented technologies, an indirect cooling method is usually adopted to avoid the reaction between the cooling gas and the high-temperature material. However, indirect cooling has three main drawbacks: First, indirect cooling requires a large number of cooling pipes to shuttle and distribute in the material, which easily causes material accumulation, forms a bridging effect, hinders the downward movement of the material, and disrupts the continuity of production; Second, indirect cooling easily causes uneven local heating, that is, the material close to the cooling pipe cools faster, while the material farther away from the cooling pipe has a slower cooling rate, resulting in too high local temperature of the outlet material, or consuming more cooling resources to meet the temperature requirements of all outlet materials; Third, the cooling pipes in the furnace chamber are subjected to mechanical friction and thermal stress of the high-temperature material, and are prone to wear such as cracking and bending deformation, and need to be frequently replaced, resulting in forced interruption of production, reduced production efficiency, and high maintenance costs. Summary of the Utility Model

[0007] According to the test results of the weight curve during the cooling process of high-temperature CaO in a pure CO2 atmosphere, as Figure 5 shown, CaO and CO2 only have an obvious reaction in the temperature range of about 720-850°C in the furnace chamber. Therefore, the present utility model proposes a lime grading cooling system, which divides the lime cooling area in the lime shaft kiln into three temperature intervals. The primary cooling air is introduced from the bottom of the kiln. After cooling the lime in the primary cooling area, it bypasses the secondary cooling area and directly enters the tertiary cooling area. At the same time, secondary cooling air is introduced into the secondary cooling area to avoid the reverse carbonization reaction between calcium oxide and CO2, ensuring the cooling effect of CO2 and also having the effect of CO2 enrichment.

[0008] A lime grading cooling system, which includes a combustion chamber and a regenerative chamber. The combustion chamber includes an upper feeding and calcining section and a lower cooling section. A connection channel communicating with the regenerative chamber is provided at the top of the lower cooling section. The lower cooling section is sequentially divided into a primary cooling area, a secondary cooling area, and a tertiary cooling area from bottom to top, and a primary air cavity protruding inward is provided in the middle of the lower cooling section. A central channel for the material to pass through is reserved in the primary air cavity on the axis of the combustion chamber. In the vertical direction, the bottom wall of the primary air cavity is located in the primary cooling area, and its top wall is located in the tertiary cooling area. Vent holes are provided on both the top wall and the bottom wall of the primary air cavity. A primary air inlet mechanism is provided at the bottom of the primary cooling area. A secondary air inlet mechanism is provided on the inner side wall of the primary air cavity.

[0009] Preferably, the secondary air inlet mechanism includes a secondary air inlet pipe and a secondary air outlet pipe. The air inlet end of the secondary air inlet pipe is connected to an external air source, and its air outlet end is connected to the material cooling area corresponding to the secondary cooling area. The air inlet end of the secondary air outlet pipe is connected to the material cooling area corresponding to the secondary cooling area, and its air outlet end is connected to the outside of the combustion chamber.

[0010] Preferably, the secondary air inlet mechanism further includes a switching valve. A secondary air outlet branch communicating with the outside of the combustion chamber is branched from the secondary air inlet pipe, and a switching valve is provided at the branch. A secondary air inlet branch communicating with the secondary air source is branched from the secondary air outlet pipe, and a switching valve is provided at the branch.

[0011] Preferably, a secondary air inlet is provided on the inner side wall of the primary air cavity corresponding to the secondary cooling zone, and a secondary air outlet is provided on the side opposite to the secondary air inlet. The secondary air inlet pipe is connected to the secondary air inlet, and the secondary air outlet pipe is connected to the secondary air outlet.

[0012] Preferably, a secondary air inlet and a corresponding secondary air outlet form a secondary air passage. In the same horizontal plane, 1 to 8 secondary air passages are provided in total, preferably 4 to 5 secondary air passages.

[0013] Preferably, in the vertical direction, 2 to 8 rows of secondary air passages are provided in the secondary cooling zone in total, preferably 4 to 5 rows of secondary air passages.

[0014] Preferably, the diameter of the secondary air inlet pipe and / or the secondary air outlet pipe is 200 to 400 mm, preferably 250 to 350 mm.

[0015] Preferably, the temperature of the primary cooling zone is less than 700 °C, preferably less than 720 °C. The height of the primary cooling zone is 40% to 75% of the lime cooling zone, preferably 50% to 70%.

[0016] Preferably, the temperature of the secondary cooling zone is 700 °C to 850 °C, preferably 720 °C to 840 °C. The height of the secondary cooling zone is 10% to 25% of the lime cooling zone, preferably 12% to 20%.

[0017] Preferably, the temperature of the tertiary cooling zone is greater than 850 °C, preferably greater than 840 °C. The height of the tertiary cooling zone is 20% to 40% of the lime cooling zone, preferably 25% to 35%.

[0018] Preferably, the primary air mechanism includes a primary air diversion plate and a primary air pipe. The primary air diversion plate is arranged at the center of the bottom of the primary cooling zone and is a bottomless conical structure, and air permeable holes are provided on its plate body. The air inlet end of the primary air pipe is connected to the high CO2 concentration recycled flue gas source, and the air outlet end is connected to the bottom of the primary air diversion plate.

[0019] Preferably, the system further includes a temperature detection device. The temperature detection device is arranged on the inner wall at the lower end of the primary cooling zone and / or on the inner wall at the lower end of the secondary cooling zone and / or on the inner wall at the lower end of the tertiary cooling zone.

[0020] Preferably, the system further includes an air volume regulating valve. The air volume regulating valve is arranged on the primary air duct and / or the secondary air inlet duct and / or the secondary air outlet duct.

[0021] Preferably, the cross-section of the primary air cavity in the horizontal direction is a continuous annular region arranged along the side wall of the secondary cooling zone.

[0022] Preferably, the cross-section of the primary air cavity in the horizontal direction is n sector-annular cavities distributed along the side wall of the secondary cooling zone, where the value range of n is 2 to 10.

[0023] In the present utility model, the lime cooling zone is sequentially divided into a primary cooling zone, a secondary cooling zone, and a tertiary cooling zone from bottom to top. Primary cooling air is introduced from the bottom of the primary cooling zone at the bottom of the kiln. After cooling the lime in the primary cooling zone, the primary cooling air passes through the bottom wall of the primary air cavity, passes through the primary air cavity, bypasses the secondary cooling zone, and then enters the tertiary cooling zone from the top wall of the primary air cavity to cool the lime in the tertiary cooling zone, bypassing the secondary cooling zone where CaO and CO2 are prone to react, which can reduce or even avoid the occurrence of reverse reactions. In addition, secondary air is introduced from the outside of the lime kiln, and the secondary air is directly introduced into the material cooling zone corresponding to the secondary cooling zone. Since there is no CO2 in the secondary air, no reverse reaction will occur, ensuring the cooling efficiency of the lime without affecting the output of the lime.

[0024] In the present utility model, the secondary air inlet mechanism includes a secondary air inlet duct and a secondary air outlet duct. The secondary air inlet duct is communicated with an external air source to introduce secondary air into the material cooling zone corresponding to the secondary cooling zone, and the secondary air outlet duct discharges the secondary air with an increased temperature after heat exchange from the secondary cooling zone. Among them, the material cooling zone corresponding to the secondary cooling zone is: in the secondary cooling zone, the material area except for the primary air cavity.

[0025] In the present utility model, a secondary air outlet branch pipe is connected to the secondary air inlet duct, and a secondary air inlet branch pipe is connected to the secondary air outlet duct, and a switching valve is provided so that the secondary air inlet and the secondary air outlet can be exchanged with each other, adopting an alternating air inlet method on both sides to improve the heat exchange uniformity between the air flow and the material. In addition, the cycle time of the alternating air inlet on both sides can be set as the cycle time of the lime kiln calcination and heat storage alternation to improve the cooling efficiency.

[0026] In the present utility model, a secondary air inlet and a secondary air outlet are called a secondary air passage. In the same plane, multiple (for example, 1 to 8, preferably 4 to 5) secondary air passages are arranged. Preferably, 2 to 8 rows of secondary air passages are also arranged in the vertical direction, preferably 4 to 5 rows of secondary air passages, to improve the uniformity of material cooling in the material cooling zone corresponding to the secondary cooling zone.

[0027] In the present utility model, a temperature detection device is provided on the inner wall at the lower end of the primary cooling zone and / or on the inner wall at the lower end of the secondary cooling zone and / or on the inner wall at the lower end of the tertiary cooling zone to monitor the temperature inside the kiln in real time. Preferably, a air volume regulating valve is provided on the primary air duct and / or the secondary air duct to adjust the air volumes of the primary air and the secondary air in real time according to the temperature inside the kiln and control the temperature inside the kiln.

[0028] In the present utility model, the primary air cavity may be a continuous annular region provided along the side wall of the secondary cooling zone. The secondary air inlet pipe enters the combustion chamber from the side wall of the secondary cooling zone of the combustion chamber, passes through the inner side wall of the primary air cavity and then communicates with the corresponding material cooling zone of the secondary cooling zone. The secondary air outlet pipe passes through the side wall of the secondary cooling zone of the combustion chamber from the inner side wall of the other primary air cavity and discharges the secondary air from the combustion chamber. Alternatively, the primary air cavity may be a plurality of discontinuous fan-shaped annular cavities (as Figure 3 shown) distributed along the side wall of the secondary cooling zone, and a secondary air inlet pipe or a secondary air outlet pipe is connected to the inner side wall of each fan-shaped annular cavity.

[0029] Compared with the prior art, the present utility model has the following beneficial effects:

[0030] 1. A lime grading cooling system provided by the present utility model uses primary air to cool the materials in the primary cooling zone and the tertiary cooling zone, and uses secondary air to cool the materials in the secondary cooling zone, so that the primary air bypasses the secondary cooling zone where CaO and CO2 are prone to react, which can reduce or even avoid the occurrence of reverse reactions. At the same time, no reverse reaction will occur to the secondary air, ensuring the cooling efficiency and output of lime.

[0031] 2. A lime grading cooling system provided by the present utility model is provided with multiple secondary air passages, which improves the cooling uniformity in the secondary cooling zone and has a good cooling effect. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of a lime grading cooling system provided by the present utility model.

[0033] Figure 2 It is a cross-sectional view of the primary air cavity and the central channel in the secondary cooling zone of a lime grading cooling system provided by the present utility model.

[0034] Figure 3 It is a cross-sectional view of the primary air cavity and the central channel with another structure in the secondary cooling zone of a lime grading cooling system provided by the present utility model

[0035] Figure 4 It is a vertical distribution diagram of the secondary air inlet or the secondary air outlet in the secondary cooling zone of a lime grading cooling system provided by the present utility model.

[0036] Figure 5 It is a test chart of the temperature range for the reaction of CaO with CO2 in a pure CO2 atmosphere.

[0037] Figure 6 It is a schematic structural diagram of a co-current regenerative double-chamber lime shaft kiln.

[0038] Reference numerals: A1: primary cooling zone; A2: secondary cooling zone; A3: tertiary cooling zone; 1: primary air cavity; 2: primary air inlet mechanism; 3: secondary air inlet mechanism; 301: secondary air inlet pipe; 302: secondary air outlet pipe; 4: secondary air inlet; 5: secondary air outlet. Detailed implementation manners

[0039] The technical solutions of the present utility model will be illustrated by way of example below. The scope of protection claimed by the present utility model includes but is not limited to the following embodiments.

[0040] A lime grading cooling system, which includes a combustion chamber and a regenerative chamber. The combustion chamber includes an upper feeding and calcining section and a lower cooling section. A connection channel communicating with the regenerative chamber is provided at the top of the lower cooling section. The lower cooling section is sequentially divided into a primary cooling zone A1, a secondary cooling zone A2, and a tertiary cooling zone A3 from bottom to top. And a primary air cavity 1 protruding inward is provided in the middle of the lower cooling section. A central passage for the material to pass through is reserved in the primary air cavity 1 on the axis of the combustion chamber. In the vertical direction, the bottom wall of the primary air cavity 1 is located in the primary cooling zone A1, and its top wall is located in the tertiary cooling zone A3. Vent holes are provided on both the top wall and the bottom wall of the primary air cavity 1. A primary air inlet mechanism 2 is provided at the bottom of the primary cooling zone A1. A secondary air inlet mechanism 3 is provided on the inner side wall of the primary air cavity 1.

[0041] Preferably, the secondary air inlet mechanism 3 includes a secondary air inlet pipe 301 and a secondary air outlet pipe 302. The air inlet end of the secondary air inlet pipe 301 is communicated with an external air source, and its air outlet end is communicated with the material cooling area corresponding to the secondary cooling zone A2. The air inlet end of the secondary air outlet pipe 302 is communicated with the material cooling area corresponding to the secondary cooling zone A2, and its air outlet end is communicated with the outside of the combustion chamber.

[0042] Preferably, the secondary air inlet mechanism 3 further includes a switching valve; a secondary air outlet branch pipe communicating with the outside of the combustion chamber is branched from the secondary air inlet pipe 301, and a switching valve is provided at the branch; a secondary air inlet branch pipe communicating with a secondary air source is branched from the secondary air outlet pipe 302, and a switching valve is provided at the branch.

[0043] Preferably, a secondary air inlet is provided on the inner side wall of the primary air cavity 1 corresponding to the secondary cooling zone A2, and a secondary air outlet is provided on the side opposite to the secondary air inlet. The secondary air inlet pipe 301 is connected to the secondary air inlet, and the secondary air outlet pipe 302 is connected to the secondary air outlet.

[0044] Preferably, a secondary air inlet 4 and a corresponding secondary air outlet 5 form a secondary air passage. In the same horizontal plane, 1 to 8 secondary air passages are provided, preferably 4 to 5 secondary air passages.

[0045] Preferably, in the vertical direction, 2 to 8 rows of secondary air passages are provided in the secondary cooling zone A2, preferably 4 to 5 rows of secondary air passages.

[0046] Preferably, the diameter of the secondary air inlet pipe 301 and / or the secondary air outlet pipe 302 is 200 to 400 mm, preferably 250 to 350 mm.

[0047] Preferably, the height of the primary cooling zone A1 is 40% to 75% of the lime cooling zone, preferably 50% to 70%. Preferably, the temperature of the primary cooling zone A1 is less than 700 °C, preferably less than 720 °C.

[0048] Preferably, the height of the secondary cooling zone A2 is 10% to 25% of the lime cooling zone, preferably 12% to 20%. Preferably, the temperature of the secondary cooling zone A2 is 700 °C to 850 °C, preferably 720 °C to 840 °C.

[0049] Preferably, the height of the tertiary cooling zone A3 is 20% to 40% of the lime cooling zone, preferably 25% to 35%. Preferably, the temperature of the tertiary cooling zone A3 is greater than 850 °C, preferably greater than 840 °C.

[0050] Preferably, the primary air inlet mechanism 2 includes a primary air diversion plate 201 and a primary air duct 202. The primary air diversion plate 201 is provided at the center of the bottom of the primary cooling zone A1 and is a bottomless conical structure with ventilation holes on its plate body. The intake end of the primary air duct 202 is connected to the high CO2 concentration recycled flue gas source, and the outlet end is connected to the bottom of the primary air diversion plate 201.

[0051] Preferably, the system further includes a temperature detection device. The temperature detection device is provided on the inner wall at the lower end of the primary cooling zone A1 and / or the inner wall at the lower end of the secondary cooling zone A2 and / or the inner wall at the lower end of the tertiary cooling zone A3.

[0052] Preferably, the system further includes an air volume regulating valve. The air volume regulating valve is provided on the primary air duct 202 and / or the secondary air inlet pipe 301 and / or the secondary air outlet pipe 302.

[0053] Preferably, the cross-section of the primary air cavity 1 in the horizontal direction is a continuous annular region arranged along the side wall of the secondary cooling zone A2.

[0054] Preferably, the cross-section of the primary air cavity 1 in the horizontal direction is n sector-annular cavities distributed along the side wall of the secondary cooling zone A2, where the value range of n is 2 to 10. Embodiment 1

[0055] A lime classification cooling system, which includes a combustion chamber and a regenerative chamber. The combustion chamber includes an upper feeding and calcining section and a lower cooling section. A connection channel communicating with the regenerative chamber is provided at the top of the lower cooling section. The lower cooling section is sequentially divided into a primary cooling zone A1, a secondary cooling zone A2, and a tertiary cooling zone A3 from bottom to top. And a primary air cavity 1 protruding inward is provided in the middle of the lower cooling section. A central channel for the material to pass through is reserved in the primary air cavity 1 on the axis of the combustion chamber. In the vertical direction, the bottom wall of the primary air cavity 1 is located in the primary cooling zone A1, and its top wall is located in the tertiary cooling zone A3. Air-permeable holes are provided on both the top wall and the bottom wall of the primary air cavity 1. A primary air inlet mechanism 2 is provided at the bottom of the primary cooling zone A1. A secondary air inlet mechanism 3 is provided on the inner side wall of the primary air cavity 1. Embodiment 2

[0056] Repeat Embodiment 1, except that the secondary air inlet mechanism 3 includes a secondary air inlet pipe 301 and a secondary air outlet pipe 302. The air inlet end of the secondary air inlet pipe 301 is communicated with an external air source, and its air outlet end is communicated with the material cooling zone corresponding to the secondary cooling zone A2. The air inlet end of the secondary air outlet pipe 302 is communicated with the material cooling zone corresponding to the secondary cooling zone A2, and its air outlet end is communicated with the outside of the combustion chamber. Embodiment 3

[0057] Repeat Embodiment 2, except that the secondary air inlet mechanism 3 further includes a switching valve. A secondary air outlet branch communicating with the outside of the combustion chamber is branched from the secondary air inlet pipe 301, and a switching valve is provided at the branch. A secondary air inlet branch communicating with a secondary air source is branched from the secondary air outlet pipe 302, and a switching valve is provided at the branch. Embodiment 4

[0058] Repeat Embodiment 3, except that a secondary air inlet is provided on the inner side wall of the primary air cavity 1 corresponding to the secondary cooling zone A2, and a secondary air outlet is provided on the side opposite to the secondary air inlet. The secondary air inlet pipe 301 is connected to the secondary air inlet, and the secondary air outlet pipe 302 is connected to the secondary air outlet. Embodiment 5

[0059] Repeat Example 4, except that one secondary air inlet 4 and one corresponding secondary air outlet 5 form a secondary air passage. In the same horizontal plane, a total of 4 secondary air passages are provided. Example 6

[0060] Repeat Example 5, except that in the vertical direction, a total of 5 rows of secondary air passages are provided in the secondary cooling zone A2. Secondary air outlet branches communicating with the outside of the lime shaft kiln are branched from the secondary air inlet pipe 301, and a switching valve is provided at the branch. Secondary air inlet branches communicating with the secondary air source are branched from the secondary air outlet pipe 302, and a switching valve is provided at the branch. Example 7

[0061] Repeat Example 6, except that the diameters of the secondary air inlet pipe 301 and the secondary air outlet pipe 302 are 300 mm.

[0062] The height of the primary cooling zone A1 is 60% of the lime cooling zone. The temperature of the primary cooling zone A1 is less than 720 °C.

[0063] The height of the secondary cooling zone A2 is 15% of the lime cooling zone. The temperature of the secondary cooling zone A2 is 720 °C to 840 °C.

[0064] The height of the tertiary cooling zone A3 is 25% of the lime cooling zone. The temperature of the tertiary cooling zone A3 is greater than 840 °C. Example 8

[0065] Repeat Example 7, except that the primary air inlet mechanism 2 includes a primary air diversion plate 201 and a primary air duct 202. The primary air diversion plate 201 is arranged at the center of the bottom of the primary cooling zone A1 and is a bottomless conical structure, and air-permeable holes are provided on its plate body. The air inlet end of the primary air duct 202 is connected to a high CO2 concentration recycled flue gas source, and the air outlet end is connected to the bottom of the primary air diversion plate 201. Example 9

[0066] Repeat Example 8, except that the system further includes a temperature detection device. The temperature detection device is arranged on the inner wall of the lower end of the primary cooling zone A1, the inner wall of the lower end of the secondary cooling zone A2, and the inner wall of the lower end of the tertiary cooling zone A3. Example 10

[0067] Repeat Example 9, except that the system further includes an air volume regulating valve. The air volume regulating valve is arranged on the primary air duct 202 and the secondary air inlet pipe 301. Example 11

[0068] Repeat Example 10, except that the cross-section of the primary air cavity 1 in the horizontal direction is a continuous annular area arranged along the side wall of the secondary cooling zone A2. Example 12

[0069] Repeat Example 10, except that the cross-section of the primary air cavity 1 in the horizontal direction is five fan-shaped ring cavities distributed along the side walls of the secondary cooling zone A2.

Claims

1. A lime classification cooling system, characterized in that: The system includes a combustion chamber and a heat storage chamber. The combustion chamber includes an upper feeding and calcining section and a lower cooling section. A connecting channel communicating with the heat storage chamber is provided at the top of the lower cooling section. The lower cooling section is sequentially divided into a primary cooling zone (A1), a secondary cooling zone (A2), and a tertiary cooling zone (A3) from bottom to top. And a primary air cavity (1) protruding inward is provided in the middle of the lower cooling section. A central channel for the material to pass through is reserved in the primary air cavity (1) on the axis of the combustion chamber. In the vertical direction, the bottom wall of the primary air cavity (1) is located in the primary cooling zone (A1), and its top wall is located in the tertiary cooling zone (A3). Vent holes are provided on both the top wall and the bottom wall of the primary air cavity (1). A primary air inlet mechanism (2) is provided at the bottom of the primary cooling zone (A1). A secondary air inlet mechanism (3) is provided on the inner side wall of the primary air cavity (1).

2. The system according to claim 1, wherein: The secondary air inlet mechanism (3) includes a secondary air inlet pipe (301) and a secondary air outlet pipe (302). The air inlet end of the secondary air inlet pipe (301) is communicated with an external air source, and its air outlet end is communicated with the material cooling zone corresponding to the secondary cooling zone (A2). The air inlet end of the secondary air outlet pipe (302) is communicated with the material cooling zone corresponding to the secondary cooling zone (A2), and its air outlet end is communicated with the outside of the combustion chamber.

3. The system according to claim 2, wherein: The secondary air inlet mechanism (3) further includes a switching valve. A secondary air outlet branch communicating with the outside of the combustion chamber branches from the secondary air inlet pipe (301), and a switching valve is provided at the branching point. A secondary air inlet branch communicating with a secondary air source branches from the secondary air outlet pipe (302), and a switching valve is provided at the branching point.

4. The system according to claim 2, wherein: A secondary air inlet is provided on the inner side wall of the primary air cavity (1) corresponding to the secondary cooling zone (A2), and a secondary air outlet is provided on the side opposite to the secondary air inlet. The secondary air inlet pipe (301) is connected to the secondary air inlet, and the secondary air outlet pipe (302) is connected to the secondary air outlet.

5. The system according to claim 4, characterized in that: One secondary air inlet (4) and a corresponding secondary air outlet (5) form a secondary air passage. In the same horizontal plane, a total of 1 to 8 secondary air passages are provided.

6. The system according to claim 5, characterized in that: In the same horizontal plane, a total of 4 to 5 secondary air passages are provided.

7. The system according to claim 5, wherein: In the vertical direction, a total of 2 to 8 rows of secondary air passages are provided in the secondary cooling zone (A2).

8. The system according to claim 7, wherein: In the vertical direction, a total of 4 to 5 rows of secondary air passages are provided in the secondary cooling zone (A2).

9. The system according to any one of claims 2-8, characterized in that: The diameter of the secondary air inlet pipe (301) and / or the secondary air outlet pipe (302) is 200 - 400 mm; and / or The height of the primary cooling zone (A1) is 40% - 75% of the lime cooling zone; and / or The height of the secondary cooling zone (A2) is 10% - 25% of the lime cooling zone; and / or The height of the tertiary cooling zone (A3) is 20% - 40% of the lime cooling zone.

10. The system according to claim 9, characterized in that: The diameter of the secondary air inlet pipe (301) and / or the secondary air outlet pipe (302) is 250 - 350 mm; and / or The height of the primary cooling zone (A1) is 50% - 70% of the lime cooling zone; and / or The height of the secondary cooling zone (A2) is 12% - 20% of the lime cooling zone; and / or The height of the tertiary cooling zone (A3) is 25% - 35% of that of the lime cooling zone.

11. The system according to claim 9, characterized in that: The temperature of the primary cooling zone (A1) is less than 700 °C; and / or The temperature of the secondary cooling zone (A2) is 700 °C - 850 °C; and / or The temperature of the tertiary cooling zone (A3) is greater than 850 °C.

12. The system according to claim 11, characterized in that: The temperature of the primary cooling zone (A1) is less than 720 °C; and / or The temperature of the secondary cooling zone (A2) is 720 °C - 840 °C; and / or The temperature of the tertiary cooling zone (A3) is greater than 840 °C.

13. The system according to any one of claims 2-8, 10-12, characterized in that: The primary air inlet mechanism (2) includes a primary air diversion plate (201) and a primary air duct (202); the primary air diversion plate (201) is arranged at the center of the bottom of the primary cooling zone (A1) and is of a bottomless conical structure, and air-permeable holes are provided on its plate body; the air inlet end of the primary air duct (202) is connected to a high CO2 concentration recycled flue gas source, and the air outlet end is connected to the bottom of the primary air diversion plate (201).

14. The system according to any one of claims 2-8, 10-12, characterized in that: The system further includes a temperature detection device; the temperature detection device is arranged on the inner wall of the lower end of the primary cooling zone (A1) and / or on the inner wall of the lower end of the secondary cooling zone (A2) and / or on the inner wall of the lower end of the tertiary cooling zone (A3).

15. The system according to any one of claims 2-8, 10-12, characterized in that: The system further includes an air volume regulating valve; the air volume regulating valve is arranged on the primary air duct (202) and / or on the secondary air inlet pipe (301) and / or on the secondary air outlet pipe (302).

16. The system according to any one of claims 2-8, 10-12, characterized in that: The cross-section of the primary air cavity (1) in the horizontal direction is a continuous annular area arranged along the side wall of the secondary cooling zone (A2); or The cross-section of the primary air cavity (1) in the horizontal direction is n sector-shaped cavities distributed along the side wall of the secondary cooling zone (A2), and the value range of n is 2 - 10.

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