Cooling system and method for calcining powdery active lime in rotary kiln

Abstract

The invention discloses a cooling system and method for calcining powdery active lime in a rotary kiln, and belongs to the technical field of lime processing, the system comprises a fluidized bed, the fluidized bed is connected with the rotary kiln, a first air pipe is connected between the fluidized bed and a first fan, and the fluidized bed is used for cooling the powdery active lime for the first time; a second air pipe is connected between the first cyclone cooler and the second fan, the fluidized bed is connected with a first smoke pipe, and the first smoke pipe is communicated with the second air pipe; a fourth air pipe is connected between the second cyclone cooler and the third fan, the first cyclone cooler is connected with a first discharging pipe, and the first discharging pipe is communicated with the fourth air pipe; a sixth air pipe is connected between the third cyclone cooler and the third fan, the second cyclone cooler is connected with a second discharging pipe, the second discharging pipe is communicated with the sixth air pipe, and the third cyclone cooler is connected with a third discharging pipe. Therefore, the effects of improving the cooling efficiency and enhancing the cooling through multi-stage cooling are achieved.

Description

Technical Field

[0001] This application relates to the field of lime processing technology, specifically to a cooling system and method for calcining powdered active lime in a rotary kiln. Background Technology

[0002] Quicklime, as a fundamental raw material for large-scale industrial production, possesses advantages over ordinary lime, including higher activity, lower bulk density, higher porosity, larger specific surface area, and higher chemical purity. It is widely used in various industrial fields such as steelmaking, alumina production, power plant flue gas desulfurization, and wastewater treatment. Rotary kiln calcination systems have gradually become the mainstream equipment for quicklime production. These systems mainly consist of three main components: preheating equipment, a rotary kiln, and cooling equipment. Cooling the quicklime is a crucial step in the production process. The temperature of the quicklime discharged from the rotary kiln is approximately 1200℃. Rapidly cooling this high-temperature lime will improve its activity and porosity, further enhancing its quality. Simultaneously, the heated cooling air is used as secondary air in the kiln, significantly reducing fuel consumption. Therefore, the cooling process is key to both quality improvement and energy conservation.

[0003] Currently, the types of cooling equipment used in rotary kiln calcination systems for cooling active lime include: single-cylinder coolers, KMAG-type vertical coolers, KVS-type vertical coolers, and beam coolers. However, all of these devices have shortcomings. For example, while single-cylinder coolers are simple, their cooling effect is poor, with finished product discharge temperatures reaching 250–300℃, placing high demands on the conveying and storage of the finished product. KMAG-type vertical coolers have complex system structures (including complex transmission devices and auxiliary equipment), resulting in high maintenance costs and low cooling efficiency. KVS-type vertical coolers have complex ventilation systems and are difficult to maintain, making them suitable only for cooling large materials. Beam coolers involve a large amount of on-site installation and welding work, making them only suitable for small to medium-sized production scales below 600t / d. Moreover, these devices are not suitable for cooling powdered active lime.

[0004] Furthermore, many existing cement clinker production lines face the risk of kiln dismantling due to capacity constraints. Converting them into powdered lime production lines would revitalize these assets. However, current mature lime cooling equipment is too tall to be easily installed near the clinker cooler. Therefore, converting the rotary kiln in a cement clinker production line into a rotary kiln for calcining lime requires a new cooling device that is suitable for cooling the powdered active lime after calcination in the rotary kiln, without the installation difficulties caused by excessive height. Summary of the Invention

[0005] Therefore, this application provides a cooling system and method for calcining powdered quicklime in a rotary kiln, in order to solve the technical problems of low cooling efficiency and poor effect of existing rotary kiln calcination systems for powdered quicklime.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] The first aspect of the present invention provides a cooling system for calcining powdered quicklime in a rotary kiln, comprising: a fluidized bed, wherein the feed inlet of the fluidized bed is connected to the discharge end of the rotary kiln, and a first air duct is connected between the air inlet at the lower part of the fluidized bed and the air outlet of a first blower, wherein the fluidized bed is used for the first cooling of the powdered quicklime.

[0008] The first cyclone cooler has a second air duct connected between its air inlet and the air outlet of the second fan. The flue gas outlet of the fluidized bed is connected to a first smoke duct, which is connected to the second air duct.

[0009] The second cyclone cooler has a fourth air duct connected between its air inlet and the air outlet of the third fan. The first cyclone cooler has a first discharge pipe connected to its discharge outlet, and the first discharge pipe is connected to the fourth air duct.

[0010] The third cyclone cooler has a sixth air duct connected between its air inlet and the air outlet of the third fan. The second cyclone cooler has a second discharge pipe connected to its discharge outlet, which is connected to the sixth air duct. The third cyclone cooler also has a third discharge pipe connected to its discharge outlet.

[0011] Optionally, the fluidized bed is provided with a first space, a second space, a third space, and a fourth space, with the second space located at the bottom and the fourth space located at the top. The first space and the third space are arranged side by side in the middle. The first space has a lower opening that communicates with the second space. The second space communicates with the third space and the third space communicates with the fourth space. The feed inlet of the fluidized bed is connected to the first space. The air inlet at the bottom of the fluidized bed is connected to the second space. The air inlet at the bottom of the fluidized bed is offset from the lower opening of the first space. The smoke outlet of the fluidized bed is connected to the fourth space.

[0012] Alternatively, the outer shell of the fluidized bed has a non-axisymmetric structure, and the first space is located inside the relatively outwardly protruding portion of the outer shell.

[0013] Optionally, the discharge port and the air outlet of the first cyclone cooler are both located at the lower part of the main body of the first cyclone cooler.

[0014] Further optionally, an air inlet pipe is provided above the fluidized bed, one end of the air inlet pipe passes through the fourth space and communicates with the first space, and the other end of the air inlet pipe is connected to the air outlet of the first cyclone cooler by a third air pipe.

[0015] Optionally, the outlet of the second cyclone cooler is connected to a fifth air duct, which is connected to the decomposition furnace.

[0016] Optionally, the air outlet of the third cyclone cooler is connected to a seventh air duct, and the seventh air duct is connected to the fourth air duct.

[0017] The second aspect of this invention provides a cooling method for calcining powdered quicklime in a rotary kiln, employing a cooling system for calcining powdered quicklime in a rotary kiln as provided in the first aspect. The specific method is as follows:

[0018] Powdered quicklime enters the fluidized bed for primary cooling; powdered quicklime calcined in the rotary kiln enters the fluidized bed, and the first blower delivers cooling air into the fluidized bed through the first air duct. The powdered quicklime is cooled by the cooling air, and the cooled powdered quicklime enters the second air duct through the first smoke pipe.

[0019] After primary cooling, the powdered quicklime enters the first cyclone cooler for secondary cooling. The second fan delivers cooling air into the first cyclone cooler through the second air duct. At the same time, the second air duct carries the powdered quicklime delivered by the first smoke pipe into the first cyclone cooler for cooling and separation. The air separated by the first cyclone cooler enters the fluidized bed through the third air duct. The powdered quicklime separated by the first cyclone cooler enters the fourth air duct through the first discharge pipe.

[0020] After secondary cooling, the powdered quicklime enters the second cyclone cooler for tertiary cooling. The third fan delivers cooling air into the second cyclone cooler through the fourth air duct. At the same time, the fourth air duct carries the powdered quicklime delivered by the first discharge pipe into the second cyclone cooler for cooling and separation. The air separated by the second cyclone cooler enters the fifth air duct, and the powdered quicklime separated by the second cyclone cooler enters the sixth air duct through the second discharge pipe.

[0021] After three cooling cycles, the powdered quicklime enters the third cyclone cooler for a fourth cooling cycle. The third fan delivers cooling air into the third cyclone cooler through the sixth air duct. At the same time, the sixth air duct carries the powdered quicklime delivered by the second discharge pipe into the third cyclone cooler for cooling and separation. The air separated by the third cyclone cooler enters the fourth air duct. The powdered quicklime separated by the third cyclone cooler enters the powdered quicklime finished product recycling process through the third discharge pipe.

[0022] Optionally, the cooling of the powdered quicklime in the fluidized bed includes: after entering the first space, the powdered quicklime enters the second space through the lower opening; the cooling air from the first fan also enters the second space through the first duct; the cooling air and the powdered quicklime are fully mixed in the second space; and the powdered quicklime moves in a fluid dynamic state under the action of the cooling air and enters the third space, then enters the fourth space and exits the fluidized bed through the first flue. During the fluid dynamic movement, the powdered quicklime and the cooling air undergo sufficient heat exchange, so that the powdered quicklime is cooled to below 800°C when it is discharged from the fluidized bed.

[0023] Compared with the prior art, this application has at least the following beneficial effects:

[0024] 1. Improved Cooling Efficiency. This application utilizes a fluidized bed in the cooling process, leveraging its unique heat transfer mechanism to achieve a breakthrough in efficiency. The intense mixing of cooling air and powdered quicklime particles within the fluidized bed enables instantaneous thermal equilibrium between gas and particles, and between particles themselves. Continuously replenished cooling air further enhances heat transfer between the bed and its walls, allowing the hot powdered quicklime to quickly reach temperature equilibrium and achieve rapid cooling. Compared to traditional cooling equipment, this multi-dimensional heat transfer-based cooling method significantly shortens the material cooling cycle, substantially improving the cooling efficiency of the entire rotary kiln calcination system from the very beginning of the cooling process.

[0025] 2. Multi-stage cooling enhances temperature reduction. This application adopts a multi-stage cooling architecture of "fluidized bed + three-stage cyclone cooler" to construct a progressively cooling system. After initial rapid cooling by the fluidized bed, the material enters the second air duct through the first smoke pipe, where it undergoes secondary cooling under the action of cooling air delivered by the second fan. It then enters the first cyclone cooler to complete gas-solid separation and further cooling. The material separated by the first cyclone cooler enters the fourth air duct, where it undergoes a third cooling by cooling air supplemented by the third fan, and is then separated by the second cyclone cooler. Finally, the material enters the sixth air duct, where it undergoes a fourth cooling by the cooling air from the second fan, and is finally separated by the third cyclone cooler. Attached Figure Description

[0026] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0027] Figure 1 A schematic diagram of a cooling system for calcining powdered quicklime in a rotary kiln, provided for an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the structure of a fluidized bed provided in an embodiment of this application;

[0029] Figure 3 This is a schematic diagram of the structure of the first cyclone cooler provided in the embodiment of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Fluidized bed; 2. First cyclone cooler; 3. Second cyclone cooler; 4. Third cyclone cooler; 5. Rotary kiln; 6. First blower; 7. Second blower; 8. Third blower; 9. First air duct; 10. Second air duct; 11. Third air duct; 12. Fourth air duct; 13. Fifth air duct; 14. Sixth air duct; 15. Seventh air duct; 16. First smoke pipe; 17. First discharge pipe; 18. Second discharge pipe; 19. Third discharge pipe; 20. First space; 21. Second space; 22. Third space; 23. Fourth space; 24. Lower air outlet pipe; 25. Air inlet of the first cyclone cooler; 26. Discharge outlet of the first cyclone cooler; 27. Outer shell. Detailed Implementation

[0032] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Currently, grate coolers are commonly used in cement clinker production. However, since cement clinker is granular, they are not suitable for powdery materials (such as powdered quicklime). This is mainly because powdery materials are easily blown away by the strong airflow of the grate cooler, resulting in low heat exchange efficiency. Additionally, some material can easily enter the air chamber through the grate openings, affecting ventilation and cooling. Many cement companies, during capacity replacement or technological upgrades, hope to utilize existing rotary kilns to burn powdered quicklime. Using the original grate cooler results in poor cooling effect and low efficiency. If a vertical cooler is used, either the entire rotary kiln needs to be raised, or the vertical cooler must be installed underground, leading to high civil engineering costs. Therefore, there is an urgent need for a new cooling solution for powdered quicklime that can utilize existing rotary kilns, overcome the shortcomings of grate coolers, and eliminate the need for deep underground excavation. Based on the background technology and the above considerations, this invention proposes a highly efficient cooling system and method for powdered quicklime without altering the existing rotary kiln structure.

[0034] The following is in conjunction with the appendix Figure 1-3 The present application will be further described in detail through specific embodiments.

[0035] This embodiment provides a cooling system for calcining powdered quicklime in a rotary kiln, including: a fluidized bed 1, a first cyclone cooler 2, a second cyclone cooler 3, and a third cyclone cooler 4. The feed inlet of the fluidized bed 1 is connected to the discharge end of the rotary kiln 5. A first air duct 9 connects the air inlet at the bottom of the fluidized bed 1 to the air outlet of the first blower 6. The fluidized bed 1 is used for the first cooling of the powdered quicklime. A second air duct 10 connects the air inlet 25 of the first cyclone cooler to the air outlet of the second blower 7. A first smoke pipe 16 connects the smoke outlet of the fluidized bed 1. A smoke pipe 16 is connected to a second air duct 10; a fourth air duct 12 is connected between the air inlet of the second cyclone cooler 3 and the air outlet of the third fan 8; a first discharge pipe 17 is connected to the discharge port 26 of the first cyclone cooler, and the first discharge pipe 17 is connected to the fourth air duct 12; a sixth air duct 14 is connected between the air inlet of the third cyclone cooler 4 and the air outlet of the third fan 8; a second discharge pipe 18 is connected to the discharge port of the second cyclone cooler 3, and the second discharge pipe 18 is connected to the sixth air duct 14; and a third discharge pipe 19 is connected to the discharge port of the third cyclone cooler 4.

[0036] This application employs a fluidized bed 1 for rapid cooling of materials, resulting in a rapid decrease in material temperature. The fluidized bed 1 used for cooling relies primarily on the heat transfer and cooling process within it, including heat transfer between cooling air and hot particles, between hot and cold particles, and between the bed layer and heat exchange surfaces through which cooling air is continuously supplied. The heat transfer between the bed layer and heat exchange surfaces is mainly between the bed layer and the bed wall, where the particles primarily refer to powdered quicklime. Due to the intense mixing of gas (cooling air) and particles within the fluidized bed 1, thermal equilibrium can be reached instantaneously between the gas and particles, and between particles themselves, rapidly achieving temperature equilibrium between the particles and the bed layer. This achieves a rapid cooling effect on the powdered quicklime, thereby improving the cooling efficiency of the powdered quicklime in the rotary kiln 5 calcination system. Typically, the temperature of the powdered quicklime discharged from the rotary kiln outlet is approximately 1200°C; after fluidized bed cooling, the temperature can rapidly decrease to below 800°C.

[0037] Powdered quicklime, rapidly cooled within the fluidized bed 1, enters the second air duct 10 through the first flue duct 16 for further cooling and then proceeds to the first cyclone cooler 2 for separation. The material separated by the first cyclone cooler 2 (powdered quicklime) enters the fourth air duct 12 for further cooling and then enters the second cyclone cooler 3 for further separation. The temperature of the material separated by the second cyclone cooler 3 drops to approximately 450℃. This material then enters the sixth air duct 14 for further cooling and then enters the third cyclone cooler 4 for further separation. Through multiple cyclone cooler cycles, the temperature of the discharged material (powdered quicklime) is effectively cooled, reaching below 100℃. If an even lower temperature is required for the discharged product, the material separated by the third cyclone cooler 4 can be further cooled and separated by the fourth cyclone cooler.

[0038] The outlet of the second cyclone cooler 3 is connected to the fifth air duct 13, which is connected to the decomposition furnace. The air temperature at the outlet of the second cyclone cooler 3 is approximately 400°C. The heat entering the decomposition furnace is reused. The decomposition furnace is the process before the material enters the rotary kiln 5, and will not be described in detail here.

[0039] The outlet of the third cyclone cooler 4 is connected to the seventh air duct 15, which is connected to the fourth air duct 12.

[0040] In one embodiment, the fluidized bed 1 of this application is improved from the prior art, such as... Figure 2 As shown, the outer shell 27 of the fluidized bed 1 has a non-axisymmetric structure, with the portion opposite to the rotary kiln 5 protruding more than the overall outer shell 27. The fluidized bed 1 is divided into a first space 20, a second space 21, a third space 22, and a fourth space 23. The first space 20 is located at the protruding portion of the outer shell 27, i.e., the first space 20 is located inside the outwardly protruding portion of the outer shell 27. The second space 21 is located in the lower part of the fluidized bed 1, and the fourth space 23 is located within the fluidized bed 1. In the upper part of the fluidized bed 1, the first space 20 and the third space 22 are arranged side by side in the middle. The first space 20 has a lower opening that communicates with the second space 21. The second space 21 communicates with the third space 22. The third space 22 communicates with the fourth space 23. The feed inlet of the fluidized bed 1 is connected to the first space 20. The air inlet at the bottom of the fluidized bed 1 is connected to the second space 21. The air inlet at the bottom of the fluidized bed 1 is staggered from the lower opening of the first space 20. The flue gas outlet of the fluidized bed 1 is connected to the fourth space 23. The first space 20 is completely isolated from the third space 22 and the fourth space 23, meaning that the material exiting the rotary kiln 5 can only enter the second space 21 through the first space 20.

[0041] The first space 20 is connected to the discharge port of the rotary kiln 5, and the first space 20 includes the entire kiln door cover.

[0042] The material flowing out of the rotary kiln 5 enters the second space 21 through the first space 20, and achieves fluidization and boiling under the action of cooling air, thereby rapidly exchanging heat. After heat exchange, the material enters the third space 22 and the fourth space 23 with the air.

[0043] In this process, a small amount of large-particle lime in fluidized bed 1 is screened out through a slag removal hole in the middle of fluidized bed 1. A large amount of small-particle lime is lifted by the cooling air into the first cyclone cooler 2.

[0044] An air inlet pipe is provided above the fluidized bed 1. One end of the air inlet pipe passes through the fourth space 23 and connects to the first space 20. The other end of the air inlet pipe is connected to the air outlet of the first cyclone cooler 2 by a third air pipe 11.

[0045] The air temperature after separation by the first cyclone cooler 2 is about 600℃. It enters the fourth space 23 through the third air duct 11 and the air inlet pipe, and can be re-entered into the rotary kiln 5 as secondary combustion air to reuse the heat.

[0046] In one specific embodiment, the discharge port 26 of the first cyclone cooler and the air outlet of the first cyclone cooler 2 are both located at the lower part of the main body of the first cyclone cooler 2. The second cyclone cooler 3 and the third cyclone cooler 4 are common structures in the prior art, where the air inlet is located on the side of the main body, the air outlet is located on the top surface of the main body, and the discharge port is located on the bottom surface of the main body. The first cyclone cooler 2 is an improvement upon the prior art, such as... Figure 3 As shown, the first cyclone cooler 2 of this application blocks the air outlet located above the main body in the prior art. A lower air outlet pipe 24 is set at the lower axis of the first cyclone cooler 2. The upper end of the lower air outlet pipe 24 extends from bottom to top into the interior of the main body to the center of the cyclone cylinder. The lower end of the lower air outlet pipe 24 (the air outlet of the first cyclone cooler 2) extends to the outside of the main body and connects with the third air pipe 11. The discharge port 26 of the first cyclone cooler is set on the side of the lower air outlet pipe 24. In specific use, the cooling air from the second fan 7 enters the first cyclone cooler 2 from the air inlet 25 of the first cyclone cooler. Through cyclone separation, the air enters the lower air outlet pipe 24 in the center and is discharged. The material enters the discharge port 26 of the first cyclone cooler along the conical inner wall of the first cyclone cooler 2 and is discharged.

[0047] The first cyclone cooler 2 adopts a downward exhaust cyclone separator structure (i.e., downward exhaust duct 24). Compared with the traditional upward exhaust cyclone cooler structure, the downward exhaust duct 24 is much shorter, and its overall resistance loss is reduced. At the same time, the discharge port 26 and the air outlet of the first cyclone cooler are both arranged downward, reducing the height of the device system.

[0048] This embodiment also provides a cooling method for calcining powdered quicklime in a rotary kiln, which employs the aforementioned cooling system for calcining powdered quicklime in a rotary kiln. The specific method is as follows:

[0049] S1. Powdered quicklime enters fluidized bed 1 for primary cooling;

[0050] The powdered active lime produced by calcination in the rotary kiln 5 enters the fluidized bed 1, and the first blower 6 delivers cooling air into the fluidized bed 1 through the first air duct 9. The powdered active lime is cooled by the cooling air, and the cooled powdered active lime enters the second air duct 10 through the first smoke pipe 16.

[0051] S2. The powdered quicklime after the first cooling enters the first cyclone cooler 2 for a second cooling;

[0052] The second fan 7 delivers cooling air to the first cyclone cooler 2 through the second air duct 10. At the same time, the second air duct 10 carries the powdered quicklime delivered by the first smoke pipe 16 into the first cyclone cooler 2 for cooling and separation. The air separated by the first cyclone cooler 2 enters the fluidized bed 1 through the third air duct 11. The powdered quicklime separated by the first cyclone cooler 2 enters the fourth air duct 12 through the first discharge pipe 17.

[0053] S3. The powdered quicklime after secondary cooling enters the second cyclone cooler 3 for a third cooling;

[0054] The third blower 8 delivers cooling air to the second cyclone cooler 3 through the fourth air duct 12. At the same time, the fourth air duct 12 carries the powdered quicklime delivered by the first discharge pipe 17 into the second cyclone cooler 3 for cooling and separation. The air separated by the second cyclone cooler 3 enters the fifth air duct 13, and the powdered quicklime separated by the second cyclone cooler 3 enters the sixth air duct 14 through the second discharge pipe 18.

[0055] S4. The powdered quicklime, after being cooled three times, enters the third cyclone cooler 4 for a fourth cooling process.

[0056] The third blower 8 delivers cooling air to the third cyclone cooler 4 through the sixth air duct 14. At the same time, the sixth air duct 14 carries the powdered quicklime delivered by the second discharge pipe 18 into the third cyclone cooler 4 for cooling and separation. The air separated by the third cyclone cooler 4 enters the fourth air duct 12. The powdered quicklime separated by the third cyclone cooler 4 enters the powdered quicklime finished product recycling process through the third discharge pipe 19.

[0057] Specifically, the cooling process of powdered quicklime entering fluidized bed 1 includes: after entering the first space 20, the powdered quicklime enters the second space 21 through the lower opening of the first space 20; the cooling air from the first fan 6 also enters the second space 21 through the first air duct 9; the cooling air and the powdered quicklime are fully mixed in the second space 21; and the powdered quicklime moves in a fluid dynamic state under the action of the cooling air and enters the third space 22; and then enters the first smoke pipe 16 through the fourth space 23 and is discharged from fluidized bed 1. During the fluid dynamic movement of the powdered quicklime, the powdered quicklime and the cooling air undergo sufficient heat exchange, so that the powdered quicklime is rapidly cooled to below 800℃ when it is discharged from fluidized bed 1.

[0058] In this method, a fluidized bed 1 is used to cool the material, which rapidly reduces the temperature of the material. Due to the intense mixing between the gas (cooling air) and the particles in the fluidized bed 1, the gas and particles, and the particles themselves, can reach thermal equilibrium instantly, which quickly brings the temperature between the particles and the bed to achieve the effect of rapid cooling of powdered quicklime, thereby improving the cooling efficiency of powdered quicklime in the rotary kiln calcination system.

[0059] The technical features of the above embodiments can be combined in any way (as long as there is no contradiction in the combination of these technical features). For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A cooling system for calcining powdered quicklime in a rotary kiln, characterized in that, include: Fluidized bed (1), the feed inlet of the fluidized bed (1) is connected to the discharge end of the rotary kiln (5), and a first air duct (9) is connected between the air inlet at the bottom of the fluidized bed (1) and the air outlet of the first blower (6). The fluidized bed (1) is used for the first cooling of powdered active lime. The first cyclone cooler (2) is connected to the air inlet (25) of the first cyclone cooler and the air outlet of the second fan (7) by a second air duct (10). The flue gas outlet of the fluidized bed (1) is connected to the first smoke pipe (16), and the first smoke pipe (16) is connected to the second air duct (10). The second cyclone cooler (3) has a fourth air duct (12) connected between its air inlet and the air outlet of the third fan (8). The first cyclone cooler (2) has a first discharge pipe (17) connected to its discharge outlet. The first discharge pipe (17) is connected to the fourth air duct (12). The third cyclone cooler (4) has a sixth air duct (14) connected between its air inlet and the air outlet of the third fan (8). The discharge port of the second cyclone cooler (3) is connected to a second discharge pipe (18), which is connected to the sixth air duct (14). The discharge port of the third cyclone cooler (4) is connected to a third discharge pipe (19).

2. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 1, characterized in that, The fluidized bed (1) is provided with a first space (20), a second space (21), a third space (22) and a fourth space (23) isolated within it. The second space (21) is located at the bottom and the fourth space (23) is located at the top. The first space (20) and the third space (22) are arranged side by side in the middle. The first space (20) has a lower opening that communicates with the second space (21). The second space (21) communicates with the third space (22). The third space (22) communicates with the fourth space (23). The feed inlet of the fluidized bed (1) is connected to the first space (20). The air inlet at the bottom of the fluidized bed (1) is connected to the second space (21). The air inlet at the bottom of the fluidized bed (1) is offset from the lower opening of the first space (20). The smoke outlet of the fluidized bed (1) is connected to the fourth space (23).

3. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 2, characterized in that, The outer shell (27) of the fluidized bed (1) is a non-axisymmetric structure, and the first space (20) is located inside the relatively outwardly protruding part of the outer shell (27).

4. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 1, characterized in that, The discharge port (26) of the first cyclone cooler and the air outlet of the first cyclone cooler (2) are both located at the lower part of the main body of the first cyclone cooler (2).

5. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 2, characterized in that, An air inlet pipe is provided above the fluidized bed (1). One end of the air inlet pipe passes through the fourth space (23) and communicates with the first space (20). The other end of the air inlet pipe is connected to the air outlet of the first cyclone cooler (2) by a third air pipe (11).

6. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 1, characterized in that, The outlet of the second cyclone cooler (3) is connected to a fifth air duct (13), which is connected to the decomposition furnace.

7. The cooling system for calcining powdered quicklime in a rotary kiln according to claim 1, characterized in that, The outlet of the third cyclone cooler (4) is connected to the seventh air duct (15), which is connected to the fourth air duct (12).

8. A cooling method for calcining powdered quicklime in a rotary kiln, characterized in that, The cooling system for calcining powdered quicklime in a rotary kiln according to any one of claims 1-7 is described in the following specific method: Powdered quicklime enters the fluidized bed (1) for a first cooling; the powdered quicklime generated by calcination in the rotary kiln (5) enters the fluidized bed (1), and the first blower (6) delivers cooling air into the fluidized bed (1) through the first air duct (9). The powdered quicklime is cooled by the cooling air, and the cooled powdered quicklime enters the second air duct (10) through the first smoke pipe (16). After the first cooling, the powdered quicklime enters the first cyclone cooler (2) for secondary cooling; the second fan (7) delivers cooling air into the first cyclone cooler (2) through the second air duct (10), and at the same time, the second air duct (10) carries the powdered quicklime delivered by the first smoke pipe (16) into the first cyclone cooler (2) for cooling and separation. The air separated by the first cyclone cooler (2) enters the fluidized bed (1) through the third air duct (11), and the powdered quicklime separated by the first cyclone cooler (2) enters the fourth air duct (12) through the first discharge pipe (17). After secondary cooling, the powdered quicklime enters the second cyclone cooler (3) for tertiary cooling. The third fan (8) delivers cooling air into the second cyclone cooler (3) through the fourth air duct (12). At the same time, the fourth air duct (12) carries the powdered quicklime delivered by the first discharge pipe (17) into the second cyclone cooler (3) for cooling and separation. The air separated by the second cyclone cooler (3) enters the fifth air duct (13). The powdered quicklime separated by the second cyclone cooler (3) enters the sixth air duct (14) through the second discharge pipe (18). After three cooling cycles, the powdered quicklime enters the third cyclone cooler (4) for four cooling cycles. The third fan (8) delivers cooling air into the third cyclone cooler (4) through the sixth air duct (14). At the same time, the sixth air duct (14) carries the powdered quicklime delivered by the second discharge pipe (18) into the third cyclone cooler (4) for cooling and separation. The air separated by the third cyclone cooler (4) enters the fourth air duct (12). The powdered quicklime separated by the third cyclone cooler (4) enters the powdered quicklime finished product recycling process through the third discharge pipe (19).

9. A cooling method for calcining powdered quicklime in a rotary kiln according to claim 8, characterized in that, The powdered active lime entering the fluidized bed (1) for one cooling includes: after entering the first space (20), the powdered active lime enters the second space (21) through the lower opening. The cooling air from the first fan (6) also enters the second space (21) through the first air duct (9). The cooling air and the powdered active lime are fully mixed in the second space (21). Under the action of the cooling air, the powdered active lime moves in a fluid dynamic and enters the third space (22). It then enters the first smoke pipe (16) through the fourth space (23) and is discharged from the fluidized bed (1). During the fluid dynamic movement, the powdered active lime and the cooling air exchange heat fully, so that the powdered active lime is cooled to below 800°C when it is discharged from the fluidized bed (1).

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