Method and apparatus for calcining limestone using a cement production line

Abstract

This invention discloses a method and apparatus for calcining limestone using a cement production line, thereby upgrading an existing cement production line to produce limestone products. The method involves at least some steps implemented in the existing cement production line, including: crushing limestone material to form limestone particles and limestone powder; conveying the limestone particles to a particle calcining device for calcination to generate calcium oxide particles; conveying the limestone powder to a powder calcining device for calcination to generate calcium oxide powder; and mixing the calcium oxide particles and calcium oxide powder in a predetermined ratio to produce the final product.

Description

Technical Field

[0001] This invention relates to the modification of cement production lines, and more specifically, to a method and apparatus for calcining limestone using a cement production line. Background Technology

[0002] By the end of the 20th century, the new dry-process cement production technology had matured, with single-line capacity increasing from 2,000 tons per day to tens of thousands of tons per day. Clinker heat consumption could be stabilized at approximately 700-800 kcal / kg, not only meeting the massive demand for cement from global modernization but also becoming a model of modern process industry. A cement production line mainly includes equipment for raw material crushing and blending, fuel homogenization and preparation, cement firing (kiln tail preheater, rotary kiln, grate cooler), tail gas treatment, and finished product storage and transportation.

[0003] With increasingly stringent environmental protection requirements, cement production lines that fail to meet energy efficiency and emission standards will face closure and elimination. There is a vast market demand for granular quicklime. How to upgrade the processes of aging cement production lines, fully utilize existing equipment, and meet market demands is a technical challenge for those skilled in the art. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and apparatus for calcining limestone using a cement production line, thereby transforming an existing cement production line to produce limestone products.

[0005] To solve the above-mentioned technical problems, the embodiments of the present invention adopt the following technical solutions: In a first aspect, embodiments of the present invention provide a method for calcining limestone using a cement production line, comprising: The limestone material is crushed to form limestone particles and limestone powder; Limestone particles are fed into a particle calcination device for calcination to produce calcium oxide particles; limestone powder is fed into a powder calcination device for calcination to produce calcium oxide powder. Calcium oxide granules and calcium oxide powder are mixed in a set ratio to produce the product.

[0006] As a preferred example, the step of conveying limestone particles to a particle calcination device for calcination includes: conveying limestone particles discharged from the vertical mill to a particle preheating furnace for preheating; conveying the preheated limestone particles to a rotary kiln for calcination and decomposition to form calcium oxide particles; and conveying the calcium oxide particles to a grate cooler, using a cooling fan to blow air and cool the material in the grate cooler to obtain the finished product. The high-temperature airflow after heat exchange with the material in the grate cooler is blown by a cooling fan. Part of the airflow enters the rotary kiln through the kiln head hood, and the other part is introduced into the particle preheating furnace through the tertiary air duct. It mixes with the hot air at the kiln tail of the rotary kiln to preheat the limestone particles together. The airflow discharged from the particle preheating furnace is introduced into the vertical mill by a second fan.

[0007] As a preferred example, the step of conveying limestone particles to the particle calcination device for calcination further includes: screening the limestone particles discharged from the vertical mill, feeding limestone particles of the target particle size into the particle calcination device for calcination, and returning limestone particles larger than the target particle size to the vertical mill for recycling and crushing.

[0008] As a preferred example, the step of conveying limestone powder to a powder calcination device for calcination includes: The limestone powder in the vertical mill is conveyed to the cyclone dust collector, which collects the limestone powder. The collected limestone powder is then conveyed to the preheating cyclone for preheating. The preheated limestone powder is then conveyed to the suspension furnace for calcination and decomposition to generate calcium oxide powder. The calcium oxide powder is then passed through the first cyclone for gas-solid separation. The separated calcium oxide powder is then conveyed to the cooling cyclone for cooling before being output as the finished product. The first blower creates negative pressure in the cooling cyclone, the first cyclone, the suspension furnace, and the preheating cyclone, allowing ambient air to enter the cooling cyclone and cool the material. The resulting airflow flows sequentially through the suspension furnace, the first cyclone, and the preheating cyclone before flowing into the first blower. The airflow from the first blower is divided into two paths: one path enters the vertical mill, and the other path enters the kiln tail dust removal device.

[0009] As a preferred example, the airflow discharged from the uppermost cooling cyclone is introduced into the suspension furnace, and the airflow discharged from the next uppermost cooling cyclone is introduced into the feed pipe of the first cyclone, with the material flowing towards the air inlet of the uppermost cooling cyclone.

[0010] As a preferred example, the airflow discharged from the cooling cyclone located at the second-highest level is also introduced into the preheating cyclone located at the topmost level.

[0011] As a preferred example, the airflow discharged from the preheating cyclone is cooled before being introduced into the first fan.

[0012] As a preferred example, the method further includes: passing a portion of the airflow separated by the cyclone dust collector back to the vertical mill via a circulating fan, and the other portion flowing into the kiln tail dust collector; transporting the limestone powder separated by the kiln tail dust collector to a powder calcination device for calcination; and discharging the airflow purified by the kiln tail dust collector through the kiln tail dust removal fan.

[0013] Secondly, embodiments of the present invention also provide an apparatus for calcining limestone using a cement production line, comprising a vertical mill, a cyclone dust collector, a first fan, a circulating fan, a powder calcination device, a granulation calcination device, and a kiln tail dust removal device. The first outlet of the vertical mill is connected to the inlet of the cyclone dust collector; the outlet of the cyclone dust collector is connected to the kiln tail dust removal device; the discharge port of the cyclone dust collector is connected to the feed port of the powder calcination device; and the outlet pipe of the powder calcination device is connected to the inlet of the first fan. The outlet of the first fan is divided into two paths: one path is connected to the inlet of the vertical mill via a valve, and the other path is connected to the inlet of the kiln tail dust removal device. The second outlet of the vertical mill is connected to the feed port of the granulation calcination device. The inlet of the circulating fan is connected to the outlet of the cyclone dust collector; and the outlet of the circulating fan is connected to the inlet of the kiln tail dust removal device.

[0014] As a preferred embodiment, the powder calcination apparatus includes N preheating cyclones, a suspension furnace, a first cyclone, and M cooling cyclones; N and M are integers greater than 1; among three adjacent preheating cyclones, the feed pipe of the upper preheating cyclone and the air outlet pipe of the lower preheating cyclone are connected to the air inlet of the middle preheating cyclone via hot air pipes; the feed pipe of the lowermost preheating cyclone is connected to the suspension furnace, and the air outlet pipe of the uppermost preheating cyclone is connected to the air inlet of the first blower; when two-stage cooling cyclones are provided, the feed pipe of the upper cooling cyclone is connected to the external environment air inlet pipe, and the external environment air inlet pipe is connected to the air inlet of the lower cooling cyclone. Connections: When three or more cooling cyclones are installed, the feed pipe of the upper cooling cyclone and the air outlet pipe of the lower cooling cyclone are connected to the air inlet of the middle cooling cyclone via air ducts. The external environment air inlet pipe is connected to the air inlet pipe of the lowermost cooling cyclone and the feed pipe of the next lower cooling cyclone. The air outlet pipe of the uppermost cooling cyclone is connected to the air inlet of the suspension furnace. The outlet of the suspension furnace is connected to the air inlet of the first cyclone. The feed pipe of the first cyclone is connected to the air inlet pipe of the uppermost cooling cyclone. The air outlet pipe of the first cyclone is connected to the air inlet of the lowermost preheating cyclone.

[0015] As a preferred example, the feed pipe of the first cyclone and the air outlet pipe of the second-highest cooling cyclone are connected by a pipe and connected to the air inlet pipe of the uppermost cooling cyclone.

[0016] As a preferred example, the first cyclone is located below the lowest preheating cyclone, the first cyclone and N preheating cyclones are located on one side of the suspension furnace, and the M cooling cyclones are located on the other side of the suspension furnace.

[0017] As a preferred example, the apparatus for calcining limestone using a cement production line further includes a waste heat utilization device. The waste heat utilization device is located between the first blower and the uppermost preheating cyclone. The inlet of the waste heat utilization device is connected to the outlet pipe of the uppermost preheating cyclone through a pipe, and the outlet of the waste heat utilization device is connected to the inlet of the first blower.

[0018] As a preferred example, the waste heat utilization device includes a boiler, the boiler's air inlet being connected to the air outlet pipe of the uppermost preheating cyclone through pipes and valves, and the boiler's air outlet being connected to the inlet of the first fan.

[0019] As a preferred example, the waste heat utilization device further includes a first pipeline humidifier. The inlet of the first pipeline humidifier is connected to the air outlet pipe of the uppermost preheating cyclone through a pipe and a valve. The outlet of the first pipeline humidifier is connected to the inlet of the first fan through a pipe. The air outlet of the boiler is connected to the inlet of the first fan through the first pipeline humidifier.

[0020] As a preferred embodiment, the pellet calcination apparatus includes a pellet preheating furnace, a rotary kiln, a grate cooler, and a kiln head hood; the feed inlet of the pellet preheating furnace is connected to the second outlet of the vertical mill via a second lifting device, the discharge outlet of the pellet preheating furnace is connected to the feed inlet of the rotary kiln, the discharge outlet of the rotary kiln is connected to the feed inlet of the grate cooler via the kiln head hood, and the air outlet of the pellet preheating furnace is connected to the air inlet of the vertical mill.

[0021] As a preferred example, the pellet calcination device further includes a tertiary air duct, the air inlet of which is connected to the kiln head hood, and the air outlet of which is connected to the pellet preheating furnace.

[0022] As a preferred example, the granule calcination device further includes a screening device located between the second lifting device and the vertical mill. The inlet of the screening device is connected to the second outlet of the vertical mill, the first outlet of the screening device is connected to the inlet of the second lifting device, and the second outlet of the screening device is connected to the inlet of the vertical mill.

[0023] As a preferred example, the pellet calcination device further includes a second fan, and the air outlet of the pellet preheating furnace is connected to the air inlet of the vertical mill through the second fan.

[0024] As a preferred embodiment, the pellet calcination device further includes a second pipeline humidifier, the air inlet of which is connected to the air outlet of the pellet preheating furnace, and the air outlet of the second pipeline humidifier is connected to the air inlet of the second fan.

[0025] As a preferred example, the kiln tail dust removal device includes a kiln tail dust collector, a kiln tail dust removal chimney, and a kiln tail dust removal fan. The air inlet of the kiln tail dust collector is connected to the air outlet of the cyclone dust collector. The air outlet of the kiln tail dust collector is connected to the kiln tail dust removal chimney through the kiln tail dust removal fan. The discharge port of the kiln tail dust collector is connected to the feed port of the powder calcination device through a first lifting device.

[0026] As a preferred example, the outlet of the circulating fan is divided into two paths: one path is connected to the air inlet of the vertical mill through a valve, and the other path is connected to the air inlet of the kiln tail dust collector.

[0027] As a preferred example, the vertical mill, cyclone dust collector, first fan, other equipment in the powder calcination device except for the suspension furnace, and the kiln tail dust removal device adopt existing cement production line equipment; the rotary kiln, grate cooler, tertiary air duct, and kiln head hood in the particle calcination device adopt existing cement production line equipment; the particle preheating furnace in the particle calcination device or the suspension furnace in the powder calcination device adopts existing cement production line equipment.

[0028] Compared with existing technologies, the present invention provides a method and apparatus for calcining limestone in a cement production line, thereby transforming existing cement production lines to produce limestone products. At least some steps of this method are implemented in the existing cement production line. The method includes: crushing limestone material to form limestone particles and limestone powder; conveying the limestone particles to a particle calcining device for calcination to generate calcium oxide particles; conveying the limestone powder to a powder calcining device for calcination to generate calcium oxide powder; and mixing the calcium oxide particles and calcium oxide powder in a predetermined ratio to produce the final product. This apparatus fully utilizes the equipment on the existing cement production line, maximizing resource utilization. This method achieves 100% utilization of limestone raw materials, with no solid waste generated. Attached Figure Description

[0029] Figure 1 This is a flowchart of a method according to an embodiment of the present invention; Figure 2 This is a structural diagram of the device according to an embodiment of the present invention, wherein the dashed line represents gas flow and the solid line represents material flow.

[0030] The diagram shows: 1. Vertical mill; 2. Cyclone dust collector; 3. First fan; 4. Preheating cyclone; 5. Suspension furnace; 6. First cyclone; 7. Cooling cyclone; 8. First duct humidifier; 9. Boiler; 10. Particle preheating furnace; 11. Rotary kiln; 12. Grate cooler; 13. Second lifting device; 14. Tertiary air duct; 15. Kiln head hood; 16. Screening device; 17. Second duct humidifier; 18. Kiln tail dust collector; 19. Kiln tail dust removal chimney; 20. Kiln tail dust removal fan; 21. Circulating fan; 22. Cooling fan; 23. Detailed Implementation

[0031] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] This invention discloses a method for calcining limestone using a cement production line, implemented by modifying existing cement production line equipment. At least some steps of this method are performed on the original cement production line.

[0033] like Figure 1 As shown, an embodiment of the present invention provides a method for calcining limestone using a cement production line, comprising: Step 10: Crush the limestone material to form limestone particles and limestone powder; Step 20: Limestone particles are fed into a particle calcination device for calcination to generate calcium oxide particles; limestone powder is fed into a powder calcination device for calcination to generate calcium oxide powder; Step 30: Mix calcium oxide granules and calcium oxide powder in a set ratio to make the product.

[0034] In the above method, step 10 can be achieved using the existing vertical mill 1 in the cement production line. Step 20 can be achieved using some equipment in the existing cement production line for calcination, without the need to build all the new equipment to implement these two steps. This method makes full use of the equipment in the existing cement production line and calcines limestone through technological transformation. It not only makes full use of the existing cement production line but also produces products that meet market demand.

[0035] In the above method, step 10 involves crushing the limestone material to form two materials with different size ranges. The limestone particles have a diameter range greater than or equal to 200 μm, while the limestone powder (fine powder) has a diameter range of ≤200 μm. The two limestone materials with different size ranges are then calcined separately to produce calcium oxide particles and calcium oxide powder, respectively. According to product requirements, the calcium oxide particles and calcium oxide powder are mixed in a predetermined ratio. If only calcium oxide particles are needed in the final product, only the calcium oxide particles are retained, and no calcium oxide powder is added. Using the method of this embodiment, calcium oxide particles and calcium oxide powder can be mixed in any ratio to produce calcium oxide products with different requirements.

[0036] Preferably, the step of conveying limestone particles to a particle calcination device for calcination includes: The limestone particles discharged from the vertical mill 1 are conveyed to the particle preheating furnace 10 for preheating. The preheated limestone particles are then conveyed to the rotary kiln 11 for calcination and decomposition to form calcium oxide particles. The calcium oxide particles are then conveyed to the grate cooler 12, where the material is cooled by the cooling fan 23 to obtain the finished product. The high-temperature airflow after heat exchange with the material in the grate cooler 12 is blown by the cooling fan 23. Part of the airflow enters the rotary kiln 11 through the kiln head hood 15, and the other part of the airflow is introduced into the particle preheating furnace 10 through the tertiary air pipe 14, where it mixes with the hot air at the kiln tail of the rotary kiln 11 to preheat the limestone particles together. The airflow discharged from the particle preheating furnace 10 is introduced into the vertical mill 1 by the second fan 17.

[0037] In this preferred embodiment, the rotary kiln 11, grate cooler 12, tertiary air duct 14, kiln head hood 15, and cooling fan are all existing equipment from the original cement production line. The limestone particles are conveyed to the particle calcining unit for calcination. For the material... Limestone particles are discharged from the vertical mill 1 and conveyed to the particle preheating furnace 10 for preheating. The preheated limestone particles are then conveyed to the rotary kiln 11 for calcination and decomposition, forming calcium oxide particles. The calcium oxide particles are then conveyed to the grate cooler 12, where the material is cooled by the air blower 23 to obtain the finished product. The airflow during the calcination process originates from the air blower 23. Through the air blower 23, a portion of the high-temperature airflow after heat exchange with the material in the grate cooler 12 enters the rotary kiln 11 via the kiln head hood 15 as combustion air, while the other portion is introduced into the particle preheating furnace 10 through the tertiary air duct 14, mixing with the hot air from the kiln tail of the rotary kiln 11 to preheat the limestone particles. A second fan 17 introduces the airflow carrying a small amount of fine powder from the particle preheating furnace 10 into the vertical mill 1. The second fan 17 provides the airflow propulsion. When the second blower 17 is turned on, the pellet preheating furnace 10 is under negative pressure, causing the airflow from the grate cooler 12 to split into two paths: one flows to the tertiary air duct 14 and the pellet preheating furnace 10, and the other flows to the rotary kiln 11 and the pellet preheating furnace 10. The two airflows mix in the pellet preheating furnace 10. The airflow discharged from the pellet preheating furnace 10 is then introduced into the vertical mill 1 by the second blower 17. The vertical mill 1 requires hot air to dry the material inside and also needs to utilize the flow of hot air for screening. The hot air carries the powder material. The airflow discharged from the pellet preheating furnace 10 has a certain temperature, forming hot air.

[0038] Preferably, the step of conveying limestone particles to the calcining device for calcination further includes: screening the limestone particles discharged from the vertical mill 1, sending limestone particles of the target particle size into the calcining device for calcination, and returning limestone particles larger than the target particle size to the vertical mill 1 for recycling and crushing. In this preferred embodiment, the limestone material discharged from the vertical mill 1 consists of limestone particles and limestone powder. For limestone particles, if the particle size is within the target particle size range, it enters the calcining device for calcination; if the particle size is larger than the target particle size range, it is returned to the vertical mill 1 for recycling and crushing. This process ensures that the vertical mill 1 does not generate waste.

[0039] Preferably, the step of conveying limestone powder to the powder calcination device for calcination includes: conveying limestone powder in the vertical mill 1 to the cyclone dust collector 2, collecting limestone powder in the cyclone dust collector 2, conveying the collected limestone powder to the preheating cyclone 4 for preheating, conveying the preheated limestone powder to the suspension furnace 5 for calcination and decomposition to generate calcium oxide powder, separating the calcium oxide powder through the first cyclone 6 for gas-solid separation, and conveying the separated calcium oxide powder to the cooling cyclone 7 for cooling before outputting the finished product. The first blower 3 creates negative pressure in the cooling cyclone 7, the first cyclone 6, the suspension furnace 5, and the preheating cyclone 4, allowing ambient air to enter the cooling cyclone 7 to cool the material. The resulting airflow flows sequentially through the suspension furnace 5, the first cyclone 6, and the preheating cyclone 4, and then into the first blower 3. The airflow from the first blower 3 is divided into two paths: one path enters the vertical mill 1, and the other path enters the kiln tail dust removal device.

[0040] In this preferred embodiment, the vertical mill 1, cyclone dust collector 2, preheating cyclone 4, first cyclone 6, cooling cyclone 7, first blower 3, and kiln tail dust removal device all utilize existing equipment from the cement production line. Limestone powder is conveyed to the powder calcination device for calcination. For the material, the limestone powder is discharged from the vertical mill 1 and conveyed to the cyclone dust collector 2. The cyclone dust collector 2 collects the limestone powder and conveys it to the preheating cyclone 4 for preheating. The preheated limestone powder is then conveyed to the suspension furnace 5 for calcination and decomposition, generating calcium oxide powder. The calcium oxide powder undergoes gas-solid separation in the first cyclone 6, and the separated calcium oxide powder is conveyed to the cooling cyclone 7 for cooling before being output as the finished product. The first blower 3 provides the airflow power for this calcination process. The first blower 3 is turned on, creating negative pressure in the cooling cyclone 7, the first cyclone 6, the suspension furnace 5, and the preheating cyclone 4, allowing ambient air to enter the cooling cyclone 7 and cool the material. The airflow in the cooling cyclone 7 heats up after heat exchange with the material and flows out of the cooling cyclone 7, then sequentially through the suspension furnace 5, the first cyclone 6, and the preheating cyclone 4 before flowing back into the first blower 3. The airflow serves as secondary combustion air in the suspension furnace 5. The airflow that exits after gas-solid separation in the first cyclone 6 preheats the material in the preheating cyclone 4. The airflow from the first blower 3 is divided into two paths: one enters the vertical mill 1, and the other enters the kiln tail dust collector. Preferably, a valve is installed in the pipeline flowing into the vertical mill 1 to control the airflow flow rate. The kiln tail dust collector filters the fine powder carried by the airflow and sends the filtered fine powder to the powder calcination device for circulating calcination, achieving zero solid waste; the cleaned airflow is then discharged to the outside.

[0041] Preferably, the airflow discharged from the uppermost cooling cyclone 7 is introduced into the suspension furnace 5, and the airflow discharged from the next uppermost cooling cyclone 7 is introduced into the feed pipe of the first cyclone 6, with the material flowing towards the air inlet of the uppermost cooling cyclone 7. There are multiple cooling cyclones 7. The airflow discharged from the uppermost cooling cyclone 7 is introduced into the suspension furnace 5 as combustion air. The airflow discharged from the next uppermost cooling cyclone 7 mixes and exchanges heat with the material discharged from the feed pipe of the first cyclone 6, with the airflow carrying the material flowing towards the air inlet of the uppermost cooling cyclone 7.

[0042] Preferably, the airflow discharged from the second-highest cooling cyclone 7 is also introduced into the topmost preheating cyclone 4. This is a bypass air process. Most of the airflow discharged from the second-highest cooling cyclone 7 is introduced into the feed pipe of the first cyclone 6, where it mixes with the material discharged from the feed pipe of the first cyclone 6 and flows into the topmost cooling cyclone. When the air volume in the cooling cyclone is greater than the combustion air volume discharged from the topmost cooling cyclone into the suspension furnace, a small portion of the low-temperature airflow discharged from the second-highest cooling cyclone 7 is directly introduced into the topmost preheating cyclone 4. The remaining airflow exchanges heat with the high-temperature material in the feed pipe of the first cyclone 6 to obtain a higher-temperature airflow, which enters the topmost cooling cyclone and then serves as combustion air in the suspension furnace. This bypass air process avoids excessive low-temperature airflow entering the suspension furnace. This increases the temperature of the combustion air entering the furnace while controlling the airflow volume, providing the necessary conditions for stable calcination within the furnace. The reasonable excess air coefficient effectively reduces system heat consumption and nitrogen oxide generation. This bypass air process also lowers the temperature of the final product, protecting downstream conveying equipment from burn-out or reduced lifespan. It provides greater controllability to the entire calcination system and lays a solid foundation for achieving the most efficient and maximized heat recovery. The more ambient air enters the external environment air inlet duct, the lower the temperature of the final product. According to the process, the airflow in the external environment air inlet duct is controlled to obtain the desired final product temperature. The bypass air process introduces part of the airflow discharged from the uppermost cooling cyclone 7 into the uppermost preheating cyclone 4, while the remaining airflow exchanges heat with the high-temperature material in the discharge pipe of the first cyclone 6. A valve is installed in the pipe connecting the outlet pipe of the uppermost cooling cyclone 7 to the uppermost preheating cyclone 4 to control the airflow rate.

[0043] Preferably, the method further includes: cooling the airflow discharged from the preheating cyclone 4 before introducing it into the first fan 3. The airflow discharged from the preheating cyclone 4 has a high temperature, for example, reaching 300-400℃. By cooling the airflow discharged from the preheating cyclone 4, the heat in the airflow is utilized, and the airflow temperature is reduced, protecting downstream equipment such as the first fan 3.

[0044] Preferably, the method further includes: the airflow separated by the cyclone dust collector 2 is partially returned to the vertical mill 1 via the circulating fan 22, and the other part flows into the kiln tail dust collector 19; the limestone powder separated by the kiln tail dust collector 19 is transported to the powder calcination device for calcination; and the purified airflow from the kiln tail dust collector 19 is discharged through the kiln tail dust removal fan. In this preferred embodiment, the circulating fan 22 is the power source for both the vertical mill 1 and the cyclone dust collector 2. A portion of the airflow separated by the cyclone dust collector 2 is returned to the vertical mill 1, realizing the recycling of flue gas. This not only reduces the amount of exhaust gas and lowers power consumption, but the circulating airflow is also a precise temperature control method for the vertical mill. The utilization of the circulating airflow makes it possible to balance the airflow throughout the plant. The remaining airflow flows into the kiln tail dust collector 19 for filtration. The limestone powder separated by the kiln tail dust collector 19 is transported to the powder calcination device for calcination, achieving zero solid waste. The kiln tail dust collector 21 provides power to the kiln tail dust collector 19 and the kiln tail dust collector chimney 20.

[0045] like Figure 2 As shown, an embodiment of the present invention discloses an apparatus for calcining limestone in a cement production line, comprising a vertical mill 1, a cyclone dust collector 2, a first blower 3, a circulating blower 22, a powder calcination device, a granulation calcination device, and a kiln tail dust removal device. The first outlet of the vertical mill 1 is connected to the inlet of the cyclone dust collector 2; the outlet of the cyclone dust collector 2 is connected to the kiln tail dust removal device; the discharge port of the cyclone dust collector 2 is connected to the feed inlet of the powder calcination device; and the outlet pipe of the powder calcination device is connected to the inlet of the first blower 3. The outlet of the first blower 3 is divided into two paths: one path is connected to the inlet of the vertical mill 1 via a valve, and the other path is connected to the inlet of the kiln tail dust removal device. The second outlet of the vertical mill 1 is connected to the feed inlet of the granulation calcination device. The inlet of the circulating blower 22 is connected to the outlet of the cyclone dust collector 2; and the outlet of the circulating blower 22 is connected to the inlet of the kiln tail dust removal device.

[0046] In the apparatus described above, the vertical mill 1, cyclone dust collector 2, first fan 3, and kiln tail dust removal device all utilize equipment from the existing cement production line. Some components in the powder calcination device and granule calcination device also utilize equipment from the existing cement production line. During operation, limestone material is added to the vertical mill 1. The vertical mill 1 pulverizes the limestone material, forming two materials with different particle size ranges: limestone particles and limestone powder. The limestone particles discharged from the vertical mill 1 are conveyed to the granule calcination device for calcination, generating calcium oxide particles. The limestone powder discharged from the vertical mill 1 is conveyed to the cyclone dust collector 2. The limestone powder collected by the cyclone dust collector 2 is conveyed to the powder calcination device for calcination, generating calcium oxide powder. The airflow from the cyclone dust collector 2 enters the kiln tail dust removal device. The kiln tail dust removal device filters the airflow and conveys the collected limestone powder to the powder calcination device for calcination, generating calcium oxide powder. This achieves zero solid waste. The filtered airflow is discharged from the kiln tail dust collector. The first fan 3 provides power for the gas flow in the powder calcination unit. When the first fan 3 is turned on, the powder calcination unit is under negative pressure, allowing ambient air to enter and form an airflow that flows from the calcination unit to the first fan 3. One outlet of the first fan 3 is connected to the inlet of the vertical mill 1 via a valve, and the other is connected to the inlet of the kiln tail dust collector. The outlet of the first fan 3 ventilates the vertical mill 1, providing hot air for its operation. The airflow flowing from the outlet of the first fan 3 into the kiln tail dust collector is filtered, and the collected limestone powder is transported to the powder calcination unit for calcination, while the filtered clean gas is discharged. The circulating fan 22 provides power to the vertical mill 1 and the cyclone dust collector 2. When the circulating fan 22 is started, negative pressure is generated in the vertical mill 1 and the cyclone dust collector 2, which forces the airflow at the outlet of the first fan 3 (part of the airflow is controlled by a valve or the channel is closed according to process requirements) and the airflow at the outlet of the second fan 17 to flow through the vertical mill and the cyclone dust collector in sequence, and finally be introduced into the kiln tail dust removal device through the circulating fan 22.

[0047] Preferably, the powder calcination device includes N preheating cyclones 4, a suspension furnace 5, a first cyclone 6, and M cooling cyclones 7. N and M are both integers greater than 1. The N preheating cyclones 4, the first cyclone 6, and the M cooling cyclones 7 are all existing equipment from the cement production line. The preheating cyclones 4 are used to preheat the limestone powder discharged from the kiln tail dust collector and cyclone dust collector 2. The suspension furnace 5 is used to calcine the preheated limestone powder to produce calcium oxide powder. The first cyclone 6 is used for gas-solid separation of the calcium oxide powder. The M cooling cyclones 7 are used to cool the calcium oxide powder.

[0048] N preheating cyclones 4 are arranged in series, one above the other. In three adjacent preheating cyclones, the feed pipe of the upper preheating cyclone and the air outlet pipe of the lower preheating cyclone are connected to the air inlet of the middle preheating cyclone via a hot air pipe. The material discharged from the feed pipe of the upper preheating cyclone mixes with the hot air discharged from the air outlet pipe of the lower preheating cyclone in the hot air pipe. The hot air heats the material and carries it into the middle preheating cyclone. After gas-solid separation in the preheating cyclones, the material is discharged from the feed pipe at the bottom of the preheating cyclone, and the airflow is discharged from the air outlet pipe at the top of the preheating cyclone. The feed pipe of the lowermost preheating cyclone is connected to the suspension furnace 5. The air outlet pipe of the uppermost preheating cyclone is connected to the air inlet of the first blower 3. In N preheating cyclones 4, the material flows from top to bottom, that is, from the uppermost preheating cyclone downwards. After being preheated by all the preheating cyclones, it flows into the suspension furnace from the lowermost preheating cyclone. In the N preheating cyclones 4, the gas flows from bottom to top, passing through all the preheating cyclones in sequence. Preferably, N is 3, 4, or 5.

[0049] M cooling cyclones 7 are arranged in series, one above the other. When two-stage cooling cyclones are installed, the discharge pipe of the upper cooling cyclone is connected to the external environment air inlet pipe, and the external environment air inlet pipe is connected to the air inlet of the lower cooling cyclone. When three or more cooling cyclones are installed, in the three adjacent cooling cyclones, the discharge pipe of the upper cooling cyclone and the air outlet pipe of the lower cooling cyclone are connected to the air inlet of the middle cooling cyclone through a duct. The external environment air inlet pipe is connected to the air inlet pipe of the lowermost cooling cyclone and the discharge pipe of the next lowermost cooling cyclone. The high-temperature material discharged from the discharge pipe of the upper cooling cyclone mixes with the airflow discharged from the air outlet pipe of the lower cooling cyclone in the duct. The airflow cools the material and carries the material into the middle cooling cyclone. After gas-solid separation in the cooling cyclones, the material is discharged from the discharge pipe at the bottom of the cooling cyclone, and the airflow is discharged from the air outlet pipe at the top of the cooling cyclone. The outlet pipe of the uppermost cooling cyclone is connected to the inlet of the suspension furnace 5. The high-temperature airflow exiting from the outlet pipe of the uppermost cooling cyclone enters the suspension furnace 5 as combustion air. Preferably, M is 2, 3, or 4. For example... Figure 2As shown, M is 3. In the original cement production line, an equal number of cyclones are arranged on both sides of the suspension furnace 5. In this embodiment, of the five cyclones located on one side of the suspension furnace, the upper four cyclones are used as preheating cyclones, and the lowermost cyclone is used as the first cyclone 6. Of the five cyclones located on the other side of the suspension furnace, the lower three are selected as cooling cyclones, and the upper two are discarded. Of course, other solutions can be adopted by making appropriate modifications according to the cooling air volume, such as using the upper cyclones on the other side of the suspension furnace as cooling cyclones.

[0050] The outlet of the suspension furnace 5 is connected to the inlet of the first cyclone 6. The discharge pipe of the first cyclone 6 is connected to the air inlet pipe of the uppermost cooling cyclone, and the outlet pipe of the first cyclone 6 is connected to the air inlet of the lowermost preheating cyclone. The material generated after calcination in the suspension furnace 5 (i.e., calcium oxide powder) enters the first cyclone 6 with the airflow. The first cyclone 6 performs gas-solid separation; the separated material enters the cooling cyclone, and the separated gas enters the preheating cyclone.

[0051] In the powder calcination apparatus of the above embodiment, the material flows with the gas. The first blower 3 provides power for the flow of material and gas. When the first blower 3 is turned on, a negative pressure is formed in the cooling cyclone 7, the first cyclone 6, the suspension furnace 5, and the preheating cyclone 4, allowing ambient air to enter the cooling cyclone 7 to cool the material. The airflow in the cooling cyclone 7 heats up after exchanging heat with the material, flows out of the cooling cyclone 7, and then flows sequentially through the suspension furnace 5, the first cyclone 6, and the preheating cyclone 4 before flowing back into the first blower 3. The airflow from the first blower 3 is divided into two paths: one path enters the vertical mill 1, and the other path enters the kiln tail dust removal device.

[0052] Preferably, the discharge pipe of the first cyclone 6 and the outlet pipe of the second-highest cooling cyclone are connected by a pipe and communicate with the inlet pipe of the uppermost cooling cyclone. The first cyclone 6 performs gas-solid separation, and the material enters the discharge pipe of the first cyclone 6. The airflow discharged from the outlet pipe of the second-highest cooling cyclone causes the material discharged from the discharge pipe of the first cyclone 6 to flow into the inlet pipe of the uppermost cooling cyclone. By setting a pipe to connect the discharge pipe of the first cyclone 6 and the outlet pipe of the second-highest cooling cyclone, the flow of material discharged from the discharge pipe of the first cyclone 6 is realized.

[0053] Preferably, the first cyclone 6 is located below the lowest preheating cyclone 4, the first cyclone 6 and N preheating cyclones 4 are located on one side of the suspension furnace 5, and the M cooling cyclones 7 are located on the other side of the suspension furnace 5. This preferred embodiment utilizes the first cyclone 6, preheating cyclone 4, and cooling cyclones 7 from the existing hydraulic production line. When implementing this preferred embodiment, the first cyclone 6, preheating cyclone 4, and cooling cyclones 7 maintain their original positions in the cement production line and are not relocated. This significantly saves equipment production costs and makes full use of existing resources.

[0054] Preferably, the apparatus for calcining limestone using a cement production line further includes a waste heat recovery device. This waste heat recovery device is located between the first blower 3 and the uppermost preheating cyclone 4. The inlet of the waste heat recovery device is connected to the outlet pipe of the uppermost preheating cyclone 4 via a pipe, and the outlet of the waste heat recovery device is connected to the inlet of the first blower 3. The preheating cyclone 4 is used to preheat the material before it enters the suspension furnace 5. The airflow exiting the outlet pipe of the preheating cyclone 4 still has a certain temperature. By setting up the waste heat recovery device, the high temperature in the airflow exiting the preheating cyclone 4 is absorbed, reducing the airflow temperature. The waste heat recovery device is existing equipment from the original water conservancy production line, making full use of existing resources.

[0055] Preferably, the waste heat utilization device includes a boiler 9. The air inlet of the boiler 9 is connected to the air outlet of the uppermost preheating cyclone 4 via a pipe and a valve. The air outlet of the boiler 9 is connected to the inlet of the first fan 3. The airflow from the preheating cyclone 4 is introduced into the boiler 9, where the high-temperature airflow exchanges heat with the steam boiler 9, and the high-temperature airflow is cooled down.

[0056] In emergency situations such as boiler 9 malfunction, to utilize waste heat, preferably, the waste heat utilization device also includes a first pipeline humidifier 8. The inlet of the first pipeline humidifier 8 is connected to the outlet pipe of the uppermost preheating cyclone 4 via a pipe and valve, and the outlet of the first pipeline humidifier 8 is connected to the inlet of the first fan 3 via a pipe. The outlet of the boiler 9 is connected to the inlet of the first fan 3 via the first pipeline humidifier 8. The first pipeline humidifier 8 serves as a bypass channel in emergency situations such as boiler 9 malfunction. The flow rate of gas in the first pipeline humidifier 8 is controlled by adjusting the valve. When the airflow flows from the preheating cyclone 4 into the first pipeline humidifier 8, the temperature of the flue gas is reduced by water spraying, greatly reducing the load and air temperature of the downstream first fan 3. In the above preferred embodiment, during the calcination process to produce calcium oxide powder: The material flow process is as follows: Limestone enters the vertical mill through the three-way airlock valve, undergoes coarse grinding by the grinding device, and fine powder is carried by hot air to the classifier of vertical mill 1 for separation. The coarse powder returns to the grinding disc through the conical hopper for regrinding, while the fine powder is carried away to the subsequent cyclone dust collector 2 and kiln tail dust collector 19 for dust collection. The collected fine powder enters the first lifting device through the air chute. The powder is fed from the first lifting device into the preheating cyclone 4, and undergoes multi-stage preheating ( Figure 1 After four stages of preheating, the material reaches a certain temperature and then enters the suspension furnace 5 for high-temperature calcination. It remains in the suspension furnace 5 for a certain reaction time to complete the calcination or decomposition, producing calcium oxide powder. The calcium oxide powder enters the cooling cyclone 7 through the first cyclone 6, where it undergoes staged heat exchange and cooling with cold air. Finally, the finished calcium oxide powder is discharged from the cooling cyclone 7. The suspension furnace 5 can be a modified and utilized decomposition furnace of the original cement preheater, or it can be a newly added suspension furnace.

[0057] Airflow process flow: Ambient air is drawn into the cooling system from the bottom cooling cyclone 7 due to the negative pressure environment created by the operation of the first fan 3. After rapid heat exchange with calcium oxide powder in stages, the airflow is drawn out from the outlet of the second-upper cooling cyclone 7 and directed to the feed pipe of the first cyclone 6. After carrying the material, the airflow returns to the top cooling cyclone 7. After gas-solid separation, the airflow is discharged from the outlet pipe of the top cooling cyclone 7 and introduced into the bottom of the suspension furnace 5 through a pipeline as combustion air, maximizing the utilization of waste heat. If it is necessary to ensure the temperature of the combustion air entering the furnace and the finished material at the same time, a portion of the hot air from the outlet of the second-upper cooling cyclone 7 can be directed to the inlet of the top preheating cyclone 7. This process adjustment is a very effective control method. After calcination in the suspension furnace 5, the high-temperature hot air is separated by the first cyclone separator 6. The airflow enters the preheating cyclone separator 4 from bottom to top. Finally, the exhaust gas enters the waste heat utilization device due to the negative pressure provided by the first fan, realizing waste heat utilization. After the exhaust gas passes through the first fan, it supplies hot air to the vertical mill 1. The hot air carries the powder material into the classifier of the vertical mill for classification. Then, the finished product exits the vertical mill 1 and enters the cyclone dust collector 2. It then enters the kiln tail dust collector through the circulating fan 22. After purification, it passes through the kiln tail dust removal fan 21 and is discharged through the kiln tail dust removal chimney 20 after passing the test.

[0058] Preferably, the pellet calcination apparatus includes a pellet preheating furnace 10, a rotary kiln 11, a grate cooler 12, and a kiln head hood 15; the feed inlet of the pellet preheating furnace 10 is connected to the second outlet of the vertical mill 1 through a second lifting device 13, the discharge outlet of the pellet preheating furnace 10 is connected to the feed inlet of the rotary kiln 11, the discharge outlet of the rotary kiln 11 is connected to the feed inlet of the grate cooler 12 through the kiln head hood 15; and the air outlet of the pellet preheating furnace 10 is connected to the air inlet of the vertical mill 1.

[0059] In this preferred embodiment, the rotary kiln 11, grate cooler 12, and kiln head hood 15 are all existing equipment in the original cement production line, making full use of existing resources and reducing equipment construction costs. The pellet preheating furnace 10 and the second lifting device 13 are newly added equipment to the original cement production line. Limestone particles discharged from the vertical mill 1 enter the pellet preheating furnace 10 for preheating through the second lifting device 13. The preheated limestone particles then enter the rotary kiln 11 for calcination, producing calcium oxide particles. The calcium oxide particles enter the grate cooler 12 through the kiln head hood 15, where they are cooled by the airflow from the cooling fan 23. The airflow blown into the grate cooler 12 by the cooling fan 23 is cooled and then enters the rotary kiln 11 and the pellet preheating furnace 10, and is introduced into the vertical mill 1 from the outlet of the pellet preheating furnace 10.

[0060] Preferably, the granulation calcination device further includes a tertiary air duct 14, the air inlet of which is connected to the kiln head hood 15, and the air outlet of which is connected to the granulation preheating furnace 10. The tertiary air duct 14 is existing equipment in the cement production line. The cooling fan 23 blows ambient air into the grate cooler 12, where the airflow exchanges heat with the high-temperature material. Part of the heated airflow enters the granulation preheating furnace 10 through the tertiary air duct 14 to preheat the material in the granulation preheating furnace 10, while another part of the heated airflow enters the rotary kiln 11 as high-temperature combustion air to participate in the calcination of the material. Then, it enters the granulation preheating furnace 10 with the flue gas from the kiln tail to preheat the material in the granulation preheating furnace 10.

[0061] Preferably, the granulation calcination apparatus further includes a screening device 16, located between the second lifting device 13 and the vertical mill 1. The inlet of the screening device 16 is connected to the second outlet of the vertical mill 1, the first outlet of the screening device 16 is connected to the inlet of the second lifting device 13, and the second outlet of the screening device 16 is connected to the inlet of the vertical mill 1. If the material discharged from the second outlet of the vertical mill 1 has a particle size that is too large, it is difficult to calcine into calcium oxide particles. The screening device 16 filters out materials within the target particle size range and conveys them to the second lifting device 13, while materials larger than the target particle size range are returned to the vertical mill 1 for re-crushing. This helps improve the product quality calcined by the granulation calcination apparatus.

[0062] Preferably, the pellet calcination device further includes a second fan 17, and the air outlet of the pellet preheating furnace 10 is connected to the air inlet of the vertical mill 1 through the second fan 17. The second fan 17 provides power for the airflow in the pellet calcination device. In the pellet calcination device, ambient air is blown into the grate cooler 12 by the cooling fan 23 to form an airflow. When the second fan 17 is turned on, a negative pressure is formed in the pellet preheating furnace 10, the tertiary air duct 14, the rotary kiln 11, and the grate cooler 12, causing the airflow to flow from the grate cooler 12 to the pellet preheating furnace 10 and into the second fan 17. The airflow from the second fan 17 is introduced into the vertical mill 1 as a source of hot air for the vertical mill, realizing processes such as material drying and sorting.

[0063] Preferably, the pellet calcination apparatus further includes a second duct humidifier 18, the air inlet of which is connected to the air outlet of the pellet preheating furnace 10, and the air outlet of the second duct humidifier 18 is connected to the air inlet of the second fan 17. The airflow exiting from the air outlet of the pellet preheating furnace 10 still has a certain temperature. By reducing the temperature of the flue gas through spray humidification before flowing through the second fan 17, the second fan 17 can be effectively protected and its service life extended.

[0064] Preferably, the kiln tail dust removal device includes a kiln tail dust collector 19, a kiln tail dust removal chimney 20, and a kiln tail dust removal fan 21. The air inlet of the kiln tail dust collector 19 is connected to the air outlet of the cyclone dust collector 20; the air outlet of the kiln tail dust collector 19 is connected to the kiln tail dust removal chimney 20 via the kiln tail dust removal fan 21; and the discharge port of the kiln tail dust collector 19 is connected to the feed port of the powder calcining device via a first lifting device. The airflow entering the kiln tail dust removal device includes the airflow flowing out of the powder calcining device and the airflow flowing out of the cyclone dust collector 2. These airflows carry a small amount of fine limestone powder. The kiln tail dust collector 19 collects the material in the airflow and conveys the material to the feed port of the powder calcining device via the first lifting device. The gas separated by the kiln tail dust collector 19 (i.e., clean gas) enters the kiln tail dust removal chimney 20 and is discharged via the kiln tail dust removal fan 21. The kiln tail dust collector fan 21 provides the power for the airflow in the kiln tail dust collector. When the kiln tail dust collector fan 21 is turned on, a negative pressure is formed in the kiln tail dust collector 19, causing the gas separated by the kiln tail dust collector 19 to flow towards the kiln tail dust collector fan 21.

[0065] Preferably, the outlet of the circulating fan 22 is divided into two paths: one path is connected to the air inlet of the vertical mill 1 through a valve, and the other path is connected to the air inlet of the kiln tail dust collector 19. A portion of the airflow separated by the cyclone dust collector 2 is returned to the vertical mill 1, realizing the recycling of flue gas. This not only reduces the amount of exhaust gas and lowers power consumption, but also serves as a precise temperature control method for the vertical mill.

[0066] Preferably, the vertical mill 1, cyclone dust collector 2, first fan 3, other equipment in the powder calcination device except for the suspension furnace 5, and the kiln tail dust removal device are all existing cement production line equipment; the rotary kiln 11, grate cooler 12, tertiary air duct 14, and kiln head hood 15 in the particle calcination device are all existing cement production line equipment; the particle preheating furnace 10 in the particle calcination device or the suspension furnace 5 in the powder calcination device is a decomposition furnace from the existing cement production line. When a decomposition furnace is used, it can be modified according to process requirements. According to process requirements, the decomposition furnace in the existing cement production line is modified into a particle preheating furnace 10 or a suspension furnace 5. In this preferred embodiment, most of the components used are equipment from the existing cement production line. This makes full use of the existing cement production line equipment, reduces modification costs, and allows the existing cement production line to produce calcium oxide products.

[0067] In the above embodiments, the limestone particles calcination process in the rotary kiln includes: Material flow process: After coarse grinding, the material on the grinding disc of vertical mill 1 is discharged from the vertical mill through the second outlet and enters a screening device (e.g., a vibrating screen) for sorting. Particles within the target particle size range are considered qualified and are conveyed to the particle preheating furnace 10 via the second lifting device. Coarse particles larger than the target particle size range are returned to vertical mill 1 for regrinding. The entire processing system produces no waste, maximizing resource utilization. In the particle preheating furnace 10, the material undergoes material-air contact heat exchange. The preheated material enters the rotary kiln on the original cement production line for calcination. After calcination and decomposition, calcium oxide particles are generated. The calcium oxide particles enter the grate cooler through the kiln head hood, where a cooling fan continuously blows air to cool the material, finally obtaining the cooled finished product.

[0068] Airflow process flow: The cooling air of the grate cooler is provided by multiple cooling fans. After passing through the granular material layer, the material and air exchange heat is achieved. Part of the high-temperature air enters the rotary kiln through the kiln head hood as combustion air to reduce the system heat consumption. The other part is introduced into the granular preheater through the tertiary air duct of the original cement production line. It mixes with the hot air at the kiln tail of the rotary kiln to preheat the limestone particles together. Then the gas is introduced into the newly added second pipeline humidifier for cooling treatment. After passing through the second fan 17, it is sent into the air inlet of the vertical mill 1. The hot air carries the powder into the classifier of the vertical mill 1 for classification. Then the finished product is discharged from the vertical mill 1 and enters the cyclone dust collector 2. It then enters the kiln tail dust collector 19 through the circulating fan 22. After purification, it passes through the kiln tail dust removal fan 21. After passing the test, it is discharged through the kiln tail dust removal chimney 20.

[0069] The method and apparatus of the above embodiments adopt staged combined calcination, making the most of the existing equipment on the cement production line, with a utilization rate of over 80%, maximizing resource utilization, and the transformation cost is far lower than the new construction cost, which is a process transformation with multiple benefits.

[0070] In the methods and apparatus of the above embodiments, calcium oxide particles and calcium oxide powder are produced independently. No solid waste is generated throughout the entire production process, and the materials are 100% utilized.

[0071] In the methods and apparatus of the above embodiments, the ratio between calcium oxide particles and calcium oxide powder can be flexibly adjusted according to product grade requirements to mix the desired product. It can also be sold as an independent product with a very wide market.

[0072] In the methods and apparatus of the above embodiments, the particle size of the raw material discharged from the vertical mill is the particle size of the finished product. It is not necessary to grind, calcin, granulate, or press the raw material into balls after grinding. This eliminates the ineffective processes of grinding and granulation, reduces ineffective processes, lowers the energy consumption of the product, and thus reduces the production cost of the finished lime product.

[0073] In the methods and apparatus of the above embodiments, the calcination of granular materials and powder materials achieves maximum heat recovery and utilization, resulting in low overall system energy consumption.

[0074] In the methods and apparatus of the above embodiments, the powder calcination system is equipped with a bypass air process arrangement to avoid excessive low-temperature airflow entering the suspension furnace, which effectively reduces system heat consumption and nitrogen oxide generation. At the same time, it also reduces the temperature of the finished product, protects the downstream conveying equipment of the finished product, provides more controllability to the entire calcination system, and provides a solid foundation for achieving the most efficient and maximized heat recovery and utilization.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for calcining limestone using a cement production line, characterized in that, The method is implemented in at least some steps of the existing cement production line; the method includes: The limestone material is crushed to form limestone particles and limestone powder; Limestone particles are fed into a particle calcination device for calcination to produce calcium oxide particles; limestone powder is fed into a powder calcination device for calcination to produce calcium oxide powder. Calcium oxide granules and calcium oxide powder are mixed in a set ratio to produce the product.

2. The method for calcining limestone using a cement production line according to claim 1, characterized in that, The process of conveying limestone particles to a particle calcination device for calcination includes: The limestone particles discharged from the vertical mill (1) are transported to the particle preheating furnace (10) for preheating. The preheated limestone particles are then transported to the rotary kiln (11) for calcination and decomposition to form calcium oxide particles. The calcium oxide particles are then transported to the grate cooler (12), and the material in the grate cooler (12) is cooled by blowing air with the cooling fan (23) to obtain the finished product. Using the cooling fan (23) to blow air, the high-temperature airflow after heat exchange with the material in the grate cooler (12) enters the rotary kiln (11) through the kiln head hood (15), and the other part of the airflow is introduced into the particle preheating furnace (10) through the tertiary air pipe (14) and mixed with the hot air at the kiln tail of the rotary kiln (11) to preheat the limestone particles together; the airflow discharged from the particle preheating furnace (10) is introduced into the vertical mill (1) through the second fan (17).

3. The method for calcining limestone using a cement production line according to claim 2, characterized in that, The process of conveying limestone particles to a particle calcination device for calcination further includes: The limestone particles discharged from the vertical mill (1) are screened, and the limestone particles with the target particle size are fed into the particle calcination device for calcination. The limestone particles larger than the target particle size are returned to the vertical mill (1) for recycling and crushing.

4. The method for calcining limestone using a cement production line according to claim 1, characterized in that, The process of conveying limestone powder to a powder calcination device for calcination includes: The limestone powder in the vertical mill (1) is transported to the cyclone dust collector (2), the cyclone dust collector (2) collects the limestone powder, the collected limestone powder is transported to the preheating cyclone (4) for preheating, the preheated limestone powder is transported to the suspension furnace (5) for calcination and decomposition to generate calcium oxide powder, the calcium oxide powder is passed through the first cyclone (6) for gas-solid separation, the separated calcium oxide powder is transported to the cooling cyclone (7) for cooling and then output as finished product; The first blower (3) creates negative pressure in the cooling cyclone (7), the first cyclone (6), the suspension furnace (5) and the preheating cyclone (4), so that the ambient air enters the cooling cyclone (7) to cool the material. The resulting airflow flows through the suspension furnace (5), the first cyclone (6) and the preheating cyclone (4) in sequence and flows into the first blower (3). The airflow from the first blower (3) is divided into two paths. One path enters the vertical mill (1) and the other path enters the kiln tail dust removal device.

5. The method for calcining limestone using a cement production line according to claim 4, characterized in that, The airflow discharged from the uppermost cooling cyclone (7) is introduced into the suspension furnace (5), and the airflow discharged from the next uppermost cooling cyclone (7) is introduced into the feed pipe of the first cyclone (6), and the material flows to the air inlet of the uppermost cooling cyclone (7).

6. The method for calcining limestone using a cement production line according to claim 5, characterized in that, The airflow discharged from the cooling cyclone (7) located at the second highest level is also introduced into the preheating cyclone (4) located at the highest level.

7. The method for calcining limestone using a cement production line according to claim 5, characterized in that, The airflow discharged from the preheating cyclone (4) is cooled and then introduced into the first fan (3).

8. The method for calcining limestone using a cement production line according to claim 4, characterized in that, The method further includes: The airflow separated by the cyclone dust collector (2) is returned to the vertical mill (1) by a part of it through the circulating fan (22), and the other part flows into the kiln tail dust collector (19); the limestone powder separated by the kiln tail dust collector (19) is transported to the powder calcination device for calcination, and the airflow purified by the kiln tail dust collector (19) is discharged through the kiln tail dust removal fan.

9. An apparatus for calcining limestone using a cement production line, characterized in that, It includes a vertical mill (1), a cyclone dust collector (2), a first fan (3), a circulating fan (22), a powder calcination device, a granule calcination device, and a kiln tail dust removal device, among which, The first outlet of the vertical mill (1) is connected to the inlet of the cyclone dust collector (2), the air outlet of the cyclone dust collector (2) is connected to the kiln tail dust removal device, the discharge port of the cyclone dust collector (2) is connected to the feed port of the powder calcining device, and the air outlet pipe of the powder calcining device is connected to the inlet of the first blower (3). The outlet of the first blower (3) is divided into two paths, one path is connected to the air inlet of the vertical mill (1) through a valve, and the other path is connected to the air inlet of the kiln tail dust removal device. The second outlet of the vertical mill (1) is connected to the feed inlet of the granulation calcination device; The air inlet of the circulating fan (22) is connected to the air outlet of the cyclone dust collector (2); the air outlet of the circulating fan (22) is connected to the air inlet of the kiln tail dust removal device.

10. The apparatus for calcining limestone using a cement production line according to claim 9, characterized in that, The powder calcination device includes N preheating cyclones (4), a suspension furnace (5), a first cyclone (6), and M cooling cyclones (7); N and M are integers greater than 1. Among the three adjacent preheating cyclones, the feed pipe of the upper preheating cyclone and the air outlet pipe of the lower preheating cyclone are connected to the air inlet of the middle preheating cyclone through a hot air pipe; the feed pipe of the lowermost preheating cyclone is connected to the suspension furnace (5), and the air outlet pipe of the uppermost preheating cyclone is connected to the air inlet of the first blower (3); When two-stage cooling cyclones are set, the discharge pipe of the upper cooling cyclone is connected to the external environment air inlet pipe, and the external environment air inlet pipe is connected to the air inlet of the lower cooling cyclone. When three or more cooling cyclones are set, among the three adjacent cooling cyclones, the discharge pipe of the upper cooling cyclone and the air outlet pipe of the lower cooling cyclone are connected to the air inlet of the middle cooling cyclone through air pipes. The external environment air inlet pipe is connected to the air inlet pipe of the lowermost cooling cyclone and the discharge pipe of the next lower cooling cyclone. The air outlet pipe of the uppermost cooling cyclone is connected to the air inlet of the suspension furnace (5). The outlet of the suspension furnace (5) is connected to the air inlet of the first cyclone (6), the discharge pipe of the first cyclone (6) is connected to the air inlet of the uppermost cooling cyclone, and the outlet pipe of the first cyclone (6) is connected to the air inlet of the lowermost preheating cyclone.

11. The apparatus for calcining limestone using a cement production line according to claim 10, characterized in that, The discharge pipe of the first cyclone (6) and the air outlet pipe of the second highest cooling cyclone are connected by a pipe and connected to the air inlet pipe of the uppermost cooling cyclone.

12. The apparatus for calcining limestone using a cement production line according to claim 10, characterized in that, The first cyclone (6) is located below the lowest preheating cyclone (4). The first cyclone (6) and N preheating cyclones (4) are located on one side of the suspension furnace (5), and M cooling cyclones (7) are located on the other side of the suspension furnace (5).

13. The apparatus for calcining limestone using a cement production line according to claim 10, characterized in that, It also includes a waste heat utilization device, which is located between the first fan (3) and the uppermost preheating cyclone (4). The inlet of the waste heat utilization device is connected to the air outlet pipe of the uppermost preheating cyclone (4) through a pipe, and the outlet of the waste heat utilization device is connected to the inlet of the first fan (3).

14. The apparatus for calcining limestone using a cement production line according to claim 13, characterized in that, The waste heat utilization device includes a boiler (9), the air inlet of the boiler (9) is connected to the air outlet of the preheating cyclone (4) located at the top through pipes and valves, and the air outlet of the boiler (9) is connected to the inlet of the first fan (3).

15. The apparatus for calcining limestone using a cement production line according to claim 14, characterized in that, The waste heat utilization device also includes a first pipeline humidifier (8), the inlet of which is connected to the air outlet of the preheating cyclone (4) located at the top through a pipe and a valve, and the outlet of which is connected to the inlet of the first fan (3) through a pipe; the air outlet of the boiler (9) is connected to the inlet of the first fan (3) through the first pipeline humidifier (8).

16. The apparatus for calcining limestone using a cement production line according to claim 9, characterized in that, The pellet calcination device includes a pellet preheating furnace (10), a rotary kiln (11), a grate cooler (12), and a kiln head hood (15); the feed inlet of the pellet preheating furnace (10) is connected to the second outlet of the vertical mill (1) through the second lifting device (13), the discharge outlet of the pellet preheating furnace (10) is connected to the feed inlet of the rotary kiln (11), the discharge outlet of the rotary kiln (11) is connected to the feed inlet of the grate cooler (12) through the kiln head hood (15); the air outlet of the pellet preheating furnace (10) is connected to the air inlet of the vertical mill (1).

17. The apparatus for calcining limestone using a cement production line according to claim 16, characterized in that, The pellet calcination device also includes a tertiary air duct (14), the air inlet of which is connected to the kiln head hood (15), and the air outlet of which is connected to the pellet preheating furnace (10).

18. The apparatus for calcining limestone using a cement production line according to claim 16, characterized in that, The granule calcination device also includes a screening device (16), which is located between the second lifting device (13) and the vertical mill (1). The inlet of the screening device (16) is connected to the second outlet of the vertical mill (1), the first outlet of the screening device (16) is connected to the inlet of the second lifting device (13), and the second outlet of the screening device (16) is connected to the inlet of the vertical mill (1).

19. The apparatus for calcining limestone using a cement production line according to claim 16, characterized in that, The pellet calcination device also includes a second blower (17), and the air outlet of the pellet preheating furnace (10) is connected to the air inlet of the vertical mill (1) through the second blower (17).

20. The apparatus for calcining limestone using a cement production line according to claim 19, characterized in that, The pellet calcination device also includes a second pipeline humidifier (18), the air inlet of which is connected to the air outlet of the pellet preheating furnace (10), and the air outlet of the second pipeline humidifier (18) is connected to the air inlet of the second fan (17).

21. The apparatus for calcining limestone using a cement production line according to claim 9, characterized in that, The kiln tail dust removal device includes a kiln tail dust collector (19), a kiln tail dust removal chimney (20), and a kiln tail dust removal fan (21). The air inlet of the kiln tail dust collector (19) is connected to the air outlet of the cyclone dust collector (2). The air outlet of the kiln tail dust collector (19) is connected to the kiln tail dust removal chimney (20) through the kiln tail dust removal fan (21). The discharge port of the kiln tail dust collector (19) is connected to the feed port of the powder calcination device through the first lifting device.

22. The apparatus for calcining limestone using a cement production line according to claim 21, characterized in that, The outlet of the circulating fan (22) is divided into two paths. One path is connected to the air inlet of the vertical mill (1) through a valve, and the other path is connected to the air inlet of the kiln tail dust collector (19).

23. The apparatus for calcining limestone using a cement production line according to claim 16, characterized in that, The vertical mill (1), cyclone dust collector (2), first fan (3), powder calcination device (excluding suspension furnace (5) and other equipment and kiln tail dust removal device are all from the original cement production line equipment. The rotary kiln (11), grate cooler (12), tertiary air duct (14), and kiln head hood (15) in the granulation calcination device are based on existing cement production line equipment. The granule preheating furnace (10) in the granule calcination device or the suspension furnace (5) in the powder calcination device adopts the existing cement production line equipment.

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