Preheating calcining device and method for producing high-purity lime

Abstract

The application relates to a preheating calcining device and method for producing high-purity lime, and belongs to the technical field of lime production. The device comprises a preheater body and a calcining kiln. A limestone feeding tank is arranged at the top end of the preheater body. Eight discharge holes are arranged in an annular array at the bottom end of the limestone feeding tank. An independent limestone chute is connected to the bottom end of each discharge hole. Eight vertical first partition plates are fixed in the preheater body in an annular array. Adjacent two first partition plates are independent heat exchange bins. The device further comprises eight discharge mechanisms and eight material blocking mechanisms. The device adopts eight independent heat exchange bins in an annular array. Limestone raw materials are distributed to each bin through eight discharge holes and chutes, so that local accumulation and flow deviation of the raw materials are avoided. High-temperature tail gas discharged from the calcining kiln is forced to blow reversely by a fan, penetrates through bin layers from bottom to top, and forms sufficient countercurrent heat exchange with limestone, so that the preheating uniformity is improved.

Description

Technical Field

[0001] This invention belongs to the field of quicklime production technology, specifically relating to a preheating calcination device and method for producing high-purity quicklime. Background Technology

[0002] High-purity quicklime is a key basic raw material for industries such as metallurgy, building materials, and chemicals. Its purity, activity, and stability directly determine the quality of downstream products and the reliability of production system operation. At present, quicklime industrial production generally adopts limestone calcination process, and the supporting equipment is mostly a combination of traditional calcination kiln and simple preheating device.

[0003] Existing preheating structures mostly adopt a single-cavity design, where limestone is concentrated and thickly piled up inside the preheater with poor permeability. High-temperature gas struggles to penetrate the thick material layer, only forming shallow heat exchange on the material surface. This results in uneven preheating of the limestone, large temperature differences between the material layers, and some raw materials entering the kiln at lower temperatures. To ensure complete calcination and decomposition, the kiln requires a large amount of additional fuel, leading to high overall energy consumption and increased production costs. Furthermore, traditional preheating systems use an integrated feeding, preheating, and unloading mode. After each unloading, the entire batch of material must be preheated before feeding can resume, resulting in a highly intermittent and discontinuous calcination process, low equipment utilization, and limited production capacity. In addition, existing devices lack effective utilization of waste heat recovery from calcination exhaust gas. The low utilization rate of waste heat and the direct discharge of most high-temperature flue gas not only result in a large waste of thermal energy but also lead to the fugitive emission of dust, which easily pollutes the surrounding environment and fails to meet the current policy requirements for energy conservation, emission reduction, and environmental protection. With the continuous growth in demand for high-quality, high-purity quicklime due to industrial upgrading and increasingly stringent national control over energy consumption and environmental protection indicators, traditional preheating and calcining devices have significant shortcomings in terms of preheating uniformity, waste heat utilization rate, production continuity, and environmental performance, making them unsuitable for modern, large-scale, and green production needs. Therefore, this study aims to develop a preheating and calcining device and method that provides more uniform preheating, high waste heat utilization rate, and stable and continuous production of high-purity quicklime. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of uneven preheating, high energy consumption, poor production continuity, and low waste heat utilization rate, and to provide a preheating calcination device and method for producing high-purity quicklime with uniform preheating, high waste heat utilization rate, and continuous and stable production.

[0005] The present invention achieves the above objectives through the following technical solutions: This invention proposes a preheating and calcining device for producing high-purity quicklime, comprising a preheater body and a calcining kiln. The preheater body has a baffle wall in the middle. The discharge port at the bottom of the preheater body is connected to the feed port of the calcining kiln via a pipe. A limestone feed box is installed at the top of the preheater body. The bottom of the limestone feed box has eight discharge holes arranged in a circular array, and each discharge hole is connected to an independent limestone chute. Eight vertical first partitions are fixed in a circular array inside the preheater body. An independent heat exchange hopper is located between two adjacent first partitions. Each heat exchange hopper corresponds to a single limestone chute. Each heat exchange hopper is also equipped with an exhaust vent. The calcining kiln has a kiln tail chute that can return the high-temperature exhaust gas from calcination to the heat exchange hopper. The device also includes: Eight unloading mechanisms are provided, each corresponding to one of the eight heat exchange silos. The unloading mechanisms are used to independently push the preheated raw materials in the corresponding heat exchange silos into the calcining kiln. Eight material blocking mechanisms are provided, each corresponding to one of the eight heat exchange hoppers and installed at the bottom of the heat exchange hoppers. The material blocking mechanisms can be synchronized with the corresponding unloading mechanisms, releasing the obstruction and restriction on the raw materials when the unloading mechanisms are in operation, thereby realizing the unloading of the raw materials.

[0006] As a further optimization of the present invention, it also includes at least one fan, the air outlet of which is connected to an air supply pipe, the air outlet of which extends into the kiln tail chute and is inclined toward the feed end of the calcining kiln.

[0007] As a further optimization of the present invention, a second baffle is installed inside the calcining kiln, and the kiln tail chute is located above the second baffle.

[0008] As a further optimization of the present invention, a baffle ring is fixed at the upper part of the interior of the preheater body, and a vent hole is opened on the baffle ring corresponding to the position of each heat exchange hopper.

[0009] As a further optimization of the present invention, the exhaust component includes an exhaust pipe connected to the top of the exhaust port and extending to the outside of the preheater body, and the outlet ends of all the exhaust pipes are connected to an annular pipe, and an external exhaust pipe is connected to the annular pipe.

[0010] As a further optimization of the present invention, a support is installed at the bottom of the preheater body, and eight guide slopes are arranged in a ring array on the upper surface of the support, and a vertical receiving groove is provided at the bottom of the guide slope.

[0011] As a further optimization of the present invention, the bottom end of the barrier wall is higher than the upper end surface of the support, so that a feeding slot connecting each heat exchange hopper is formed between the barrier wall and the bottom end of each heat exchange hopper.

[0012] As a further optimization of the present invention, the unloading mechanism includes a first telescopic rod mounted on the preheater body via a mounting bracket, the inner end of the first telescopic rod being fitted with a push plate that conforms to the guide slope, and a retaining ring being fixed on the inner wall of the preheater body above the push plate.

[0013] As a further optimization of the present invention, the material blocking mechanism includes a baffle that is slidably disposed in the receiving groove, and a second telescopic rod is installed at the bottom end of the baffle.

[0014] This invention also proposes a preheating and calcining method for producing high-purity quicklime, employing the aforementioned preheating and calcining apparatus for producing high-purity quicklime, comprising the following steps: S1. The limestone raw material is conveyed into the limestone feed box through the feeding equipment. The raw material in the limestone feed box flows into the corresponding limestone chute through eight drop holes and is finally distributed into eight independent heat exchange bins. S2. The DCS control system independently controls each unloading mechanism and the corresponding blocking mechanism to work synchronously. The blocking mechanism releases the material obstruction, and the unloading mechanism pushes out the preheated limestone material in the corresponding heat exchange hopper. The material is then transported to the inside of the calcining kiln through pipelines. S3. The calcining kiln calcines the limestone raw material at high temperature, and the calcined product is discharged from the discharge end of the calcining kiln. The blower is started and air is sent to the kiln tail chute through the air supply pipe. The high temperature exhaust gas generated by the calcining kiln is blown in reverse to the interior of the preheater body and introduced into each heat exchange bin, so that the high temperature exhaust gas directly penetrates the material layer and fully convects and exchanges heat with the limestone raw material to achieve preheating of the raw material. S4. After the preheating operation, the exhaust gas is collected through the exhaust gas holes on the barrier ring and then into each exhaust gas pipe. After being collected through the ring pipe, it is transported to the inside of the raw material silo by the external exhaust pipe. The waste heat of the exhaust gas is used to preheat the limestone raw material to be preheated in the silo, so as to realize the waste heat recovery and recycling.

[0015] The beneficial effects of this invention are as follows: 1. This invention employs a ring-shaped array of eight independent heat exchange silos. Limestone raw materials are distributed to each silo through eight drop holes and chutes in the top feed box, avoiding local accumulation and uneven flow of raw materials. The high-temperature exhaust gas discharged from the calcining kiln penetrates the material layer of each silo from bottom to top under the forced reverse blowing action of the fan, forming a sufficient counter-current convection heat exchange with the limestone. This ensures that the preheating temperature of the limestone is stably controlled in the range of 850–950℃, improving the uniformity of preheating and solving the drawbacks of insufficient and uneven preheating in traditional processes.

[0016] 2. This invention designs a two-stage waste heat recovery closed loop: preheating limestone with high-temperature exhaust gas from calcination and preheating raw materials with low-temperature exhaust gas after heat exchange. This achieves efficient and tiered utilization of thermal energy. The high-temperature exhaust gas generated by the calcination kiln is forced back to the preheater by a fan, penetrating the material layer to preheat the limestone, significantly increasing the temperature of the raw materials entering the kiln and reducing the fuel consumption required for heating and decomposition in the calcination kiln. The low-temperature exhaust gas, whose temperature drops to 200–300℃ after heat exchange, is collected and transported to the raw material silo to preheat the limestone in the silo that has not yet entered the preheater, further recovering waste heat and reducing energy consumption in the preheating stage.

[0017] 3. This invention adopts an eight-bin independent operation, time-sharing unloading, and cyclic preheating mode. Each heat exchange bin can independently complete the entire process of feeding, preheating, and unloading. The DCS system precisely controls the unloading timing of each bin, realizing continuous operation of unloading from one bin, preheating in multiple bins, and continuous feeding. This avoids the drawbacks of traditional processes, such as waiting for overall preheating after a single unloading, strong production intermittency, and low efficiency. Moreover, the unloading mechanism and the baffle mechanism are synchronously linked and logically interlocked. During unloading, the baffle quickly releases its obstruction, and the pusher plate smoothly pushes the raw material. After resetting, the baffle immediately blocks, and the bin continues to preheat, ensuring continuous and stable material flow. The calcining kiln operating conditions fluctuate little and operate smoothly, shortening the production cycle and increasing capacity.

[0018] 4. The preheater body adopts a structure such as a barrier wall, a first baffle, and a barrier ring to achieve uniform airflow distribution, independent separation of the hopper, and independent exhaust gas discharge, effectively avoiding problems such as flue gas deviation and local pressure buildup; the bottom support is designed with a guide slope and a receiving groove, which, together with the baffle ring and push plate structure, makes the raw material push smooth and less prone to jamming, with low unloading resistance and low wear of the mechanism. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a front view of the present invention; Figure 3 This is a cross-sectional structural schematic diagram of the calcining kiln of the present invention; Figure 4 This is a cross-sectional structural schematic diagram of the preheater body of the present invention; Figure 5 This is the present invention. Figure 4 Side view; Figure 6 This is the present invention. Figure 4 A schematic diagram of the cross-sectional structure; Figure 7 This is a structural schematic diagram of the preheater body and support of the present invention in the separated state; Figure 8 This is a schematic diagram of the structure of the present invention with the support and the baffle mechanism separated. Figure 9This is a cross-sectional view of the preheater body of the present invention after the support is removed.

[0020] In the diagram: 1. Preheater body; 11. Limestone feed box; 12. Guide plate; 13. Drop hole; 14. First baffle; 15. Heat exchange silo; 16. Limestone chute; 17. Barrier ring; 171. Exhaust vent; 18. Feeding trough; 19. Support; 191. Guide slope; 192. Receiving trough; 120. Baffle ring; 2. Calcination kiln; 21. Second partition; 22. Kiln tail chute; 3. Fan; 4. Feed pipe; 5. Conveying pipe; 6. Air supply pipe; 7. Unloading mechanism; 71. First telescopic rod; 72. Push plate; 8. Material blocking mechanism; 81. Second telescopic rod; 82. Baffle; 9. Mounting bracket; 10. Exhaust components; 101. Exhaust pipe; 102. Ring pipe. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0022] like Figures 1 to 9As shown, this invention proposes a preheating and calcining device for producing high-purity lime, comprising a preheater body 1 and a calcining kiln 2. A vertical baffle wall is installed in the middle of the preheater body 1 to separate the outer material bins and ensure uniform airflow distribution. The discharge port at the bottom of the preheater body 1 is connected to the feed port of the calcining kiln 2 via a pipe, enabling stable and continuous feeding of preheated limestone raw materials into the calcining kiln 2. A limestone feed box 11 is installed at the top of the preheater body 1, and a feed pipe 4 is connected to the top of the limestone feed box 11. The feed pipe 4 is directly connected to the upstream raw material conveying equipment, enabling automated and continuous feeding of limestone raw materials. A guide plate 12 is fixed to the bottom of the limestone feed box 11. The guide plate 12 has a streamlined conical structure that is high in the middle and low around the edges. After the raw material falls into the limestone feed box 11, it can be evenly distributed from the center to the periphery along the inclined surface of the guide plate 12 by its own gravity, avoiding the situation where the raw material accumulates in the center and there is empty material around the periphery. The bottom of the limestone feed box 11 is provided with eight dropping holes 13 in a circular array. The bottom of each dropping hole 13 is connected to an independent limestone chute 16 made of high-temperature resistant material. A high-temperature resistant electrically controlled valve can be installed on the limestone chute 16, which can independently control the material flow status and feed rate of a single chute through a DCS system. To achieve separate material distribution and adapt to the processing needs of different production loads, the preheater body 1 has eight vertical first partitions 14 fixed in a ring array inside. The first partitions 14 are made of high-temperature resistant and high-strength refractory materials. There is an independent heat exchange hopper 15 between two adjacent first partitions 14. Each heat exchange hopper 15 is set up one-to-one with a single limestone chute 16. Each heat exchange hopper 15 is equipped with a temperature sensor. The sensor can collect the preheating temperature of the limestone raw material inside each heat exchange hopper 15 in real time and accurately, and transmit the temperature data to the DCS control system in real time. The system can accurately judge the preheating temperature according to the preset process parameters. Each silo's raw material preheating status meets the standards, and the unloading timing of each silo is independently controlled. The heat exchange silo 15 is also equipped with an exhaust device 10 to achieve separate discharge of heat exchange waste gas. The calcining kiln 2 is equipped with a kiln tail chute 22 that can return the high-temperature exhaust gas from calcination to the heat exchange silo 15, avoiding the direct loss of high-temperature exhaust gas from the kiln tail and improving the waste heat utilization rate. Specifically, a second baffle 21 is installed in the calcining kiln 2, and the kiln tail chute 22 is located above the second baffle 21. The second baffle 21 plays the role of airflow separation and guidance, which can collect the high-temperature exhaust gas generated by the calcining kiln 2, reduce the disorderly diffusion of exhaust gas, and ensure that the exhaust gas flows back stably to the interior of the preheater body 1.

[0023] Secondly, the preheating and calcining device also includes eight unloading mechanisms 7 and eight blocking mechanisms 8. The eight unloading mechanisms 7 correspond one-to-one with the eight heat exchange hoppers 15. The function of the unloading mechanism 7 is to independently push the preheated limestone raw material in the corresponding heat exchange hopper 15 and smoothly transport the raw material into the calcining kiln 2. It can realize single hopper unloading and multiple hopper alternating unloading, flexibly adapting to the needs of continuous production. Compared with the traditional overall unloading method, it has stronger controllability and more uniform preheating effect. The eight blocking mechanisms 8 correspond one-to-one with the eight heat exchange hoppers 15 and are installed at the bottom of the heat exchange hoppers 15. Under normal conditions, they form a stable obstruction to the raw material. The blocking mechanism 8 can be linked synchronously with the corresponding unloading mechanism 7. When the unloading mechanism 7 is working, it releases the obstruction limit on the raw material to realize the unloading of the raw material.

[0024] Among them, see Figure 1 - Figure 3 As shown, it also includes at least one blower 3, preferably a Roots blower, which has stable air pressure and adjustable flow rate. The outlet end of the blower 3 is connected to an air supply pipe 6, and the outlet end of the air supply pipe 6 extends into the kiln tail chute 22 and is inclined towards the feed end of the calcining kiln 2. In use, the blower 3 generates a stable high-pressure airflow, which can forcefully purge the high-temperature exhaust gas inside the calcining kiln 2, forcibly driving the high-temperature exhaust gas to flow in the opposite direction, so that the high-temperature flue gas can stably flow back to the preheater through the kiln tail chute 22. Inside each heat exchange bin 15 of the main body 1, a counter-current circulation heat exchange system is formed between the calcination exhaust gas and the raw materials. Counter-current heat exchange allows the high-temperature exhaust gas and the low-temperature limestone raw materials to fully and comprehensively contact and exchange heat, raising the temperature of the raw materials to 850–950℃, which can improve heat exchange efficiency and reduce the heat energy consumption of the calcination process. At the same time, the inclined air supply structure can effectively increase the impact force and conveying distance of the exhaust gas back blowing, avoid exhaust gas stagnation and poor backflow, and ensure the continuity and stability of the exhaust gas circulation heat exchange.

[0025] See Figure 4 - Figure 7As shown, a baffle ring 17 is fixed to the upper part of the preheater body 1. The baffle ring 17 is sealed and fixed to the inner wall of the preheater body 1. A vent hole 171 is opened on the baffle ring 17 corresponding to the position of each heat exchange hopper 15, so as to realize independent venting of each hopper and allow the heat exchange exhaust gas of each heat exchange hopper 15 to be discharged separately. The exhaust component 10 consists of a vent pipe 101, an annular pipe 102 and an external exhaust pipe. One end of the vent pipe 101 is connected to the vent hole 171 and the other end extends to the outside of the preheater body 1, so as to discharge the exhaust gas after heat exchange of each hopper separately. All exhaust gases are discharged. The exhaust gas from pipe 101 is collected at the annular pipe 102 and then transported centrally through the external exhaust pipe. This effectively balances the exhaust resistance of each heat exchange silo 15, avoiding local pressure buildup and flue gas retention caused by poor exhaust in a single silo. It ensures that the flow velocity of high-temperature flue gas in each silo is basically the same, thus ensuring the uniformity of raw material preheating. At the same time, the centralized closed-loop collection and transportation of waste gas can realize the secondary recovery and utilization of waste heat, reduce production energy consumption, and prevent the overflow of fugitive waste gas, thus avoiding dust and high-temperature waste gas pollution of the production environment. It has the dual benefits of energy saving and emission reduction.

[0026] See Figure 6 - Figure 8 As shown, a support 19 is installed at the bottom of the preheater body 1. The upper surface of the support 19 has eight guide slopes 191 arranged in a ring. The guide slopes 191 are inclined from the outside to the inside and from the top to the bottom, forming a funnel-shaped guide structure. A vertical receiving groove 192 is opened at the bottom of the guide slope 191 for installing the material blocking mechanism 8. A discharge hole is opened in the middle of the support 19. A conveying pipe 5 is connected between the discharge hole and the calcining kiln 2. During the unloading operation, the unloading mechanism 7 can push the raw material along the smooth slope of the guide slope 191. The guide effect of the slope is used to smoothly guide the raw material to the central discharge hole, effectively reducing the resistance of the raw material pushing and avoiding problems such as the raw material getting stuck or accumulating at the bottom of the hopper, thus ensuring a smooth unloading process.

[0027] The bottom of the vertical barrier wall is higher than the upper surface of the support 19, so that the barrier wall and the bottom of each heat exchange hopper 15 form a feeding slot 18 that connects each heat exchange hopper 15. The feeding slot 18 can realize the interconnection of the bottom of each independent heat exchange hopper 15. On the one hand, it can effectively balance the material level and internal air pressure of each hopper, and avoid problems such as flue gas deviation, excessive heat exchange temperature difference, and uneven preheating of raw materials caused by excessive feeding, excessive material level, insufficient feeding, or excessively low material level in a single hopper. On the other hand, it can reserve a certain material buffer space, and under the condition of alternating unloading and continuous feeding of multiple hoppers, it can stabilize the material flow rhythm, ensure continuous and stable unloading operation, effectively stabilize the feeding condition of the calcining kiln 2, and thus ensure the stability of calcination temperature and finished product quality.

[0028] See Figure 4 - Figure 9As shown, the unloading mechanism 7 includes a first telescopic rod 71 mounted on the preheater body 1 via a mounting bracket 9. The first telescopic rod 71 is preferably a hydraulic telescopic rod. A push plate 72 is mounted on the inner end of the first telescopic rod 71. The bottom surface of the push plate 72 is in contact with the guide slope 191 to ensure uniform force and smooth movement during the pushing process. A retaining ring 120 is fixed to the inner wall of the preheater body 1 and above the push plate. The upper surface of the retaining ring 120 has an inclined surface that slopes towards the center. During the material falling process, the inclined surface of the retaining ring 120 can guide the scattered material, causing it to fall to the front side of the retracted push plate 72. In the processing area, it effectively avoids the accumulation of raw materials on the back side and in the gaps of the push plate 72, and prevents the push plate 72 from jamming, deforming under force, and structural damage during the extension and retraction process. This improves the operational stability and service life of the unloading mechanism 7. In specific use, the first telescopic rod 71 extends outward, driving the push plate 72 to slide smoothly along the guide slope 191, and smoothly pushes the preheated raw materials in the hopper to the central discharge hole. After unloading, the first telescopic rod 71 retracts, the push plate 72 returns to the initial position, the raw materials fall to replenish, and a new round of preheating process begins, realizing the automated cycle of raw material preheating and unloading.

[0029] Considering that if the push plate 72 is not long enough, the back of the push plate 72 may push back the falling material when it retracts, causing some material to remain and affecting the unloading efficiency and material level stability, in order to improve the thoroughness of unloading, this device can use an extended push plate 72. At the same time, an extended bottom stroke space is set for the heat exchange hopper 15, which can fully accommodate the retracted push plate 72. In addition, a baffle plate inclined towards the center of the equipment is added above the push plate 72. The upper end of the push plate 72 and the lower end of the baffle plate are kept in a sliding fit. During the entire process of the push plate 72 extending outward to push the material, the upper end of its back is always in close contact with the baffle plate and sealed, with no exposed gaps. This can avoid the drawbacks of dragging and pushing back the material when the push plate 72 retracts, and ensure that each unloading operation is thorough.

[0030] The material blocking mechanism 8 includes a baffle 82 slidably disposed within the receiving trough 192. A second telescopic rod 81 is installed at the bottom end of the baffle 82. The second telescopic rod 81 is preferably a hydraulic telescopic rod. During unloading, the second telescopic rod 81 receives a command from the DCS control system and drives the baffle 82 to retract downward into the receiving trough 192, completely releasing the material blocking limit and making way for the unloading mechanism 7 to push the material. After a single unloading is completed, the second telescopic rod 81 immediately resets, and the baffle 82 extends upward to re-seal the discharge channel. The synchronous linkage and logical interlock between the material blocking mechanism 8 and the unloading mechanism 7 are achieved through electrical programs, ensuring that each heat exchange silo 15 operates independently and that the preheating time and temperature of each batch of raw materials are uniform. This ensures the production quality of high-purity lime from the perspective of process structure.

[0031] It should also be noted that the adjustment, control and alarm of the production operation of this device are centrally controlled in the main control room using DCS, and are equipped with screen display of each control point and necessary interlock monitoring. The operating parameters used in the production process are automatically recorded and can be printed at any time.

[0032] This invention also proposes a preheating and calcining method for producing high-purity quicklime, employing the aforementioned preheating and calcining apparatus for producing high-purity quicklime, comprising the following steps: S1. The limestone raw material that has been crushed and screened to meet the standards and has qualified impurity content is conveyed to the limestone feed box 11 through the feed pipe 4 via the upstream conveying equipment. After the raw material enters the feed box, it is evenly dispersed to the surrounding area under the guiding action of the guide plate 12. Then, it flows into the corresponding independent limestone chute 16 through eight evenly distributed drop holes 13, and is finally sent to the interior of eight independent heat exchange bins 15. S2. The DCS control system independently controls each group of unloading mechanisms 7 and corresponding blocking mechanisms 8 to work synchronously. The blocking mechanism 8 releases the material obstruction, and the unloading mechanism 7 pushes out the preheated limestone material (850–950℃) in the corresponding heat exchange hopper 15. The material is then transported to the inside of the calcining kiln 2 through pipelines. S3. The calcining kiln 2 receives the preheated limestone raw material and performs high-temperature calcination to decompose the raw material, completing the conversion reaction of limestone into quicklime. The high-purity quicklime product after calcination is automatically discharged from the discharge end of the calcining kiln 2 and enters the subsequent process. Simultaneously with the calcination operation, the blower 3 is started. The blower 3 outputs a stable high-pressure airflow, which is blown at an angle through the air supply pipe 6 to the kiln tail chute 22. The high-temperature calcination exhaust gas generated inside the calcining kiln 2 is forced to be blown in the reverse direction into the preheater body 1 and introduced into eight independent heat exchange bins 15. The high-temperature exhaust gas penetrates the material layer from bottom to top and forms a sufficient counter-current convection heat exchange with the low-temperature limestone raw material in the bin, which quickly raises the temperature of the raw material, completes the preheating operation of the raw material, maximizes the recovery of calcination waste heat, and reduces the fuel consumption of the calcination process. S4. After heat exchange, the temperature of the low-temperature exhaust gas drops to 200-300℃. The low-temperature exhaust gas in each silo is introduced into the respective exhaust pipe 101 through the corresponding independent exhaust port 171 on the isolation ring 17. All exhaust gas is collected in the ring pipe 102 through the exhaust pipe 101, and then transported to the inside of the raw material storage silo through the external exhaust pipe. The residual heat of the exhaust gas is used to preheat the room temperature limestone raw materials to be processed in the silo, realizing the secondary recycling of the waste heat, further reducing the overall production energy consumption. At the same time, the closed exhaust gas collection method can avoid fugitive emissions, realizing energy saving and environmental protection.

[0033] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A preheating and calcining apparatus for producing high-purity quicklime, comprising a preheater body (1) and a calcining kiln (2), wherein a partition wall is provided in the middle of the interior of the preheater body (1), and the discharge port at the bottom of the preheater body (1) and the feed port of the calcining kiln (2) are connected by a pipe, characterized in that, The top of the preheater body (1) is equipped with a limestone feed box (11). The bottom of the limestone feed box (11) is provided with eight dropping holes (13) in a circular array. The bottom of each dropping hole (13) is connected to an independent limestone chute (16). Inside the preheater body (1), eight vertical first partitions (14) are fixed in a circular array. Between two adjacent first partitions (14) is an independent heat exchange silo (15). Each heat exchange silo (15) is arranged in a one-to-one correspondence with a single limestone chute (16). The heat exchange silo (15) is also provided with an exhaust device (10). The calcining kiln (2) is provided with a kiln tail chute (22) that can return the high-temperature exhaust gas of calcination to the heat exchange silo (15). It also includes: Eight unloading mechanisms (7) are provided, and each of the eight unloading mechanisms (7) corresponds to one of the eight heat exchange bins (15). The unloading mechanism (7) is used to independently push the preheated raw materials in the corresponding heat exchange bins (15) so that the raw materials are sent into the calcining kiln (2). Eight material blocking mechanisms (8) are provided, each corresponding to one of the eight heat exchange silos (15), and installed at the bottom of the heat exchange silos (15). The material blocking mechanisms (8) can be linked synchronously with the corresponding unloading mechanism (7). When the unloading mechanism (7) is in operation, the obstruction and restriction on the raw material are released, and the raw material is unloaded.

2. The preheating and calcining apparatus for producing high-purity quicklime according to claim 1, characterized in that: It also includes at least one fan (3), the air outlet of which is connected to an air supply pipe (6), the air outlet of which extends into the kiln tail chute (22) and is inclined toward the feed end of the calcining kiln (2).

3. The preheating and calcining apparatus for producing high-purity quicklime according to claim 2, characterized in that: The calcining kiln (2) is equipped with a second partition (21), and the kiln tail chute (22) is located above the second partition (21).

4. The preheating and calcining apparatus for producing high-purity quicklime according to claim 1, characterized in that: The upper part of the preheater body (1) is fixed with a baffle ring (17), and a vent hole (171) is opened on the baffle ring (17) corresponding to the position of each heat exchange hopper (15).

5. The preheating and calcining apparatus for producing high-purity quicklime according to claim 4, characterized in that: The exhaust component (10) includes an exhaust pipe (101) connected to the top of the exhaust port (171) and extending to the outside of the preheater body (1). The outlet ends of all the exhaust pipes (101) are connected to an annular pipe (102), and an external exhaust pipe is connected to the annular pipe (102).

6. The preheating and calcining apparatus for producing high-purity quicklime according to claim 1, characterized in that: The bottom end of the preheater body (1) is equipped with a support (19), and the upper end surface of the support (19) is provided with eight guide slopes (191) in a ring array. The bottom end of the guide slopes (191) is provided with a vertical receiving groove (192).

7. The preheating and calcining apparatus for producing high-purity quicklime according to claim 1, characterized in that: The bottom of the barrier wall is higher than the upper surface of the support (19), so that a feeding slot (18) connecting the barrier wall and the bottom of each heat exchange hopper (15) is formed.

8. A preheating and calcining apparatus for producing high-purity quicklime according to claim 6, characterized in that: The unloading mechanism (7) includes a first telescopic rod (71) mounted on the preheater body (1) via a mounting bracket (9). The inner end of the first telescopic rod (71) is fitted with a push plate (72) that conforms to the guide slope (191). A retaining ring (120) is fixed on the inner wall of the preheater body (1) and above the push plate (72).

9. A preheating and calcining apparatus for producing high-purity quicklime according to claim 6, characterized in that: The material blocking mechanism (8) includes a baffle (82) that is slidably disposed in the receiving groove (192), and a second telescopic rod (81) is installed at the bottom end of the baffle (82).

10. A preheating and calcining method for producing high-purity quicklime, comprising the preheating and calcining apparatus for producing high-purity quicklime as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. The limestone raw material is transported to the limestone feed box (11) through the feeding equipment. The raw material in the limestone feed box (11) flows into the corresponding limestone chute (16) through eight drop holes (13) and is finally sent to the interior of eight independent heat exchange bins (15). S2. The DCS control system independently controls each unloading mechanism (7) and the corresponding blocking mechanism (8) to work synchronously. The blocking mechanism (8) releases the material blockage, and the unloading mechanism (7) pushes out the preheated limestone material in the corresponding heat exchange bin (15). The material is transported to the inside of the calcining kiln (2) through the pipeline. S3. The calcining kiln (2) calcines the limestone raw material at high temperature. The calcined product is discharged from the discharge end of the calcining kiln (2). The blower (3) is started and air is sent to the kiln tail chute (22) through the air supply pipe (6). The high temperature tail gas generated by the calcining kiln (2) is blown in the opposite direction to the interior of the preheater body (1) and introduced into each heat exchange bin (15) so that the high temperature tail gas can directly penetrate the material layer and fully convect and exchange heat with the limestone raw material to achieve the preheating of the raw material. S4. After the preheating operation, the exhaust gas is collected through the exhaust gas hole (171) on the barrier ring (17) and then into each exhaust gas pipe (101). After being collected through the ring pipe (102), it is transported to the inside of the raw material silo by the external exhaust pipe. The waste heat of the exhaust gas is used to preheat the limestone raw material to be preheated in the silo, so as to realize the recycling of waste heat.

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