Two-stage rotary kiln for granulating and pre-carbonizing negative electrode material

Abstract

The application discloses a two-stage rotary kiln for negative electrode material granulation and pre-carbonization, and belongs to the technical field of negative electrode material production. The application comprises a granulation rotary kiln and a pre-carbonization rotary kiln which are connected with each other. The discharge end of the granulation rotary kiln and the feeding end of the pre-carbonization rotary kiln are connected through an intermediate connecting cover, and a volatile outlet is arranged on the intermediate connecting cover. The feeding end of the granulation rotary kiln and the discharge end of the pre-carbonization rotary kiln are both provided with an inert gas inlet. The granulation rotary kiln and the pre-carbonization rotary kiln adopt two independent kiln bodies, so that the decoupling control of the granulation process and the pre-carbonization process can be realized. Meanwhile, the intermediate connecting cover is arranged between the two kiln bodies and is used for discharging volatiles, so that the risk of tar condensation and blockage is reduced, and the volatiles are prevented from being retained for a long time or from corroding the cylinder after entering the high-temperature carbonization section.

Description

Technical Field

[0001] This invention belongs to the field of negative electrode material production technology, and more specifically, relates to a two-stage rotary kiln for granulation and pre-carbonization of negative electrode materials. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage industries, artificial graphite has become the mainstream choice for lithium-ion battery anode materials due to its excellent cycle stability and cost advantages. Typical production processes for artificial graphite anode materials include raw material pretreatment, granulation, pre-carbonization, graphitization, and post-treatment. Among these, granulation and pre-carbonization are key steps that determine the microstructure, structural stability, and final electrochemical performance of the anode material.

[0003] In traditional industrial production, the granulation process often uses separate batch reactors, such as hot-drying reactors and cooling reactors. However, these reactors are intermittent and only suitable for small-batch, intermittent production, resulting in low production efficiency. The pre-carbonization process uses tunnel kilns, which have low thermal efficiency due to static heating, crucible losses, and large floor space requirements. Therefore, the industry has begun to explore integrated granulation and pre-carbonization kilns, combining granulation and pre-carbonization into a single rotary kiln system.

[0004] For example, patent CN115367746A discloses a continuous granulation / pre-carbonization method for graphite anode materials. In this application, the granulation and pre-carbonization processes are carried out in the same kiln. High-temperature flue gas is first pre-carbonized by heat exchange in the pre-carbonization zone. After heat exchange, the temperature of the flue gas decreases and it then flows to the granulation zone for granulation. This design not only achieves continuous production of granulation and pre-carbonization but also improves the utilization rate of high-temperature flue gas. At the same time, it avoids the traditional granulation process of cooling to room temperature before the pre-carbonization process of heating up, thus reducing energy loss. Direct heat transfer through the metal cylinder wall and dynamic heating improve thermal efficiency.

[0005] For example, patent CN118066847A discloses a new integrated production process for granulation and pre-carbonization using a rotary kiln. This application achieves granulation and pre-carbonization functions on a single rotary kiln by utilizing different settings of the lifting plates, thus realizing continuous material production and reducing energy consumption.

[0006] The aforementioned applications all involve the application of rotary kilns in the production of negative electrode materials, but they still have certain shortcomings. Firstly, it has poor process adaptability.

[0007] Granulation requires strong shear mixing to form dense secondary particles, while pre-carbonization requires high-temperature stable heat treatment. The single cylinder, uniform rotation speed, and continuous temperature zone of an integrated kiln make it difficult to meet both requirements, resulting in insufficient densification of the granules and low tap density, which affects the efficiency of subsequent graphitization and the quality of the negative electrode material.

[0008] Secondly, it is difficult to balance the emissions of volatile components.

[0009] If volatiles are discharged from the feed end, the low temperature in the granulation section can easily cause tar to condense and clog the pipes.

[0010] If volatiles are discharged from the discharge end, although the high temperature of the pre-carbonization section can be used to heat the volatiles and prevent them from condensing, the corrosive gases such as volatiles generated in the granulation section are prone to secondary pyrolysis, coking, and corrosion of the cylinder after entering the high-temperature section (carbonization kiln), leading to deposition, thinning, or even cylinder breakage on the inner wall; the exfoliated material mixed with the material will affect the stable operation of subsequent equipment.

[0011] Third, the high-temperature section of the cylinder has low reliability.

[0012] Pre-carbonization requires a high temperature of 1000℃~1150℃. The externally heated cylinder, under the combined effects of thermal load, material gravity, cylinder weight, multi-stage support eccentricity, and the coupling of sealing and transmission loads, endures alternating bending and torsional loads, representing a typical fatigue load condition. Existing single-metal materials rarely possess both high-temperature strength and corrosion resistance simultaneously. Especially for medium-sulfur coke feedstock, the cylinder is subjected to prolonged high-temperature, heavy-load, and corrosive conditions, making it prone to corrosion, insufficient strength, and even cracking, threatening equipment lifespan and safety. Summary of the Invention

[0013] The problem to be solved In view of at least some of the problems existing in the prior art, the present invention proposes a two-stage rotary kiln for pre-carbonization of negative electrode material granulation. The purpose is to solve the problems of poor process adaptability, difficulty in balancing volatile matter emissions, and low reliability of the high-temperature section cylinder of the existing integrated rotary kiln.

[0014] Technical solution To solve the above problems, the technical solution adopted by the present invention is as follows: The present invention provides a two-stage rotary kiln for granulation and pre-carbonization of negative electrode materials, comprising a granulation rotary kiln and a pre-carbonization rotary kiln connected to each other; wherein the first flue gas passage of the granulation rotary kiln and the second flue gas passage of the pre-carbonization rotary kiln are connected by a flue gas connecting pipe. The discharge end of the granulation rotary kiln and the feed end of the pre-carbonization rotary kiln are connected by an intermediate connecting cover, and the intermediate connecting cover is provided with a volatile matter outlet. Both the feed end of the granulation rotary kiln and the discharge end of the pre-carbonization rotary kiln are equipped with inert gas inlets. The granulation rotary kiln is connected to a feeding mechanism, the output end of which extends into the low-temperature feeding zone Q1 of the granulation rotary kiln, and a scraping mechanism is provided in the low-temperature feeding zone Q1. The scraping mechanism includes a rotating shaft and a connecting sleeve fixedly sleeved on the rotating shaft. The connecting sleeve is connected to a scraper assembly via a main connecting rod.

[0015] In some embodiments, the scraper assembly includes a first scraper and a second scraper disposed on one side of the first scraper; The first scraper extends along the axial direction of the granulation rotary kiln, and the second scraper is inclined relative to the first scraper.

[0016] In some embodiments, a movable ring is fitted onto the main connecting rod.

[0017] In some embodiments, chains are suspended on the sidewalls of the first scraper and the second scraper that are far apart from each other.

[0018] In some embodiments, the rotation direction of the scraper assembly is the same as the rotation direction of the granulation rotary kiln, and there is a speed difference between the two. Alternatively, the rotation direction of the scraper assembly may be opposite to that of the granulation rotary kiln.

[0019] In some embodiments, the granulation rotary kiln is provided with a stirring mechanism, one end of which is located in the low-temperature feeding zone Q1 of the granulation rotary kiln, and the other end extends away from the scraping mechanism and extends out of the low-temperature feeding zone Q1.

[0020] In some embodiments, the feeding mechanism and the scraping mechanism share a common rotating shaft, and the rotating shaft is connected to the rotating shaft of the stirring mechanism via a ball cage coupling.

[0021] In some embodiments, the granulation rotary kiln is further provided with a lifting plate mechanism, which is located on the side of the stirring mechanism away from the scraping mechanism, and a baffle plate is provided between the lifting plate mechanism and the stirring mechanism. The baffle plate is a horizontally arranged frustum structure, with the opening on the side facing the stirring mechanism being larger than the opening on the other side.

[0022] In some embodiments, the aspect ratio of the granulation rotary kiln is smaller than that of the pre-carbonization rotary kiln.

[0023] In some embodiments, the granulation rotary kiln and the pre-carbonization rotary kiln are both arranged at an inclination with the feed end higher and the discharge end lower, and the inclination angle of the granulation rotary kiln is greater than that of the pre-carbonization rotary kiln.

[0024] Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a two-stage rotary kiln for granulation and pre-carbonization of negative electrode materials. The granulation rotary kiln and the pre-carbonization rotary kiln are two independent kiln bodies, so that the granulation process and the pre-carbonization process are no longer limited to the same cylinder, the same rotation speed, and the same thermal regime, thereby achieving decoupled control of the granulation process and the pre-carbonization process. Moreover, since the high-temperature pre-carbonization operation can be completed independently in the pre-carbonization rotary kiln, the length of the high-temperature carbonization section cylinder, the load-bearing conditions, and the heat-affected zone can be designed separately according to the pre-carbonization requirements, so as to reduce the comprehensive thermomechanical load borne by the high-temperature carbonization section cylinder and improve the structural reliability and safety of the equipment in long-term operation. At the same time, the setting of the intermediate connecting cover reduces the risk of tar condensation and blockage, and avoids the long-term retention of volatiles or corrosion of the cylinder after entering the high-temperature carbonization section.

[0025] (2) The present invention provides a two-stage rotary kiln for pre-carbonization of anode material granulation. By setting a scraping mechanism in the low-temperature feeding zone Q1 of the granulation rotary kiln, the material adhering to the wall can be cleaned in a timely manner to prevent the material from accumulating or agglomerating in the low-temperature feeding zone Q1, thus ensuring continuous and stable feeding. On the other hand, it can further enhance the material turning, shearing, mixing and agglomeration process, which is beneficial to the formation of a more compact structure and more uniform particle size of the anode material raw material before entering the pre-carbonization.

[0026] (3) The present invention provides a two-stage rotary kiln for pre-carbonization of negative electrode material granulation. By optimizing the structure of the scraping mechanism, the material adhering to the main connecting rod can be cleaned in time by the up and down movement of the movable ring; the material adhering to the scraper wall can be cleaned by the impact and friction effect between the chain swinging and the scraper wall. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to the present invention; Figure 2 This is a schematic diagram of the granulation rotary kiln in this invention; Figure 3 This is a schematic diagram of the scraping mechanism in this invention; Figure 4 This is a schematic diagram of the baffle plate in this invention; Figure 5 This is a schematic diagram of the plate-flipping mechanism in this invention; Figure 6 This is a schematic diagram of the structure of the reverse board body in this invention; Figure 7 This is a schematic diagram of the pre-carbonization rotary kiln in this invention; Figure 8 for Figure 7 Sectional view along the middle AA direction; Figure 9 for Figure 7 Sectional view along the BB direction; Figure 10 for Figure 9 A magnified view of a section at point C.

[0028] In the picture: 100. Granulation rotary kiln; 110. First flue gas passage; 200. Pre-carbonization rotary kiln; 210. First cylinder; 211. Heat-resistant layer; 212. Transition layer; 213. Corrosion-resistant layer; 220. Second cylinder; 230. Second flue gas passage; 300. Intermediate connecting cover; 410. Feeding mechanism; 420. Scraping mechanism; 421. Connecting sleeve; 4221. Main connecting rod; 4222. Secondary connecting rod; 423. Scraper assembly; 4231. First scraper; 4232. Second scraper; 424. Moving ring; 425. Chain; 430. Mixing mechanism; 440. Lifting plate mechanism; 450. Baffle plate; 451. Discharge port; 441. First reverse engineering assembly; 442. Second reverse engineering assembly; 443. Third reverse engineering assembly; 4411. Reverse engineering body; 44111. Notch; 500. Flue gas connection pipe; 600, Support assembly; 610, Support component; 620, Adjusting screw; 630, Support plate; 640, Adjusting nut; 650, First elastic element; 660, Sealing component; 670, Heat insulation component; 700. Floating guide assembly; 710. Mounting rod; 720. Second elastic element; 730. Guide block; 740. Guide rod; 810. Flue gas inlet box; 820. Flue gas outlet box; 830. Discharge hood. Detailed Implementation

[0029] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] like Figure 1 As shown in this embodiment, a two-stage rotary kiln for granulation and pre-carbonization of negative electrode materials includes a granulation rotary kiln 100 and a pre-carbonization rotary kiln 200 that are interconnected. The flue gas passages of the granulation rotary kiln 100 and the pre-carbonization rotary kiln 200 are connected by a flue gas connecting pipe 500. High-temperature flue gas first flows in reverse through the flue gas passage of the pre-carbonization rotary kiln 200, and then flows in reverse through the flue gas connecting pipe 500 through the flue gas passage of the granulation rotary kiln 100, thereby completing the heating operation of the materials in the different kiln bodies.

[0033] It is worth mentioning that, in this embodiment, both the granulation rotary kiln 100 and the pre-carbonization rotary kiln 200 can be existing externally heated rotary kilns. For ease of description below, the flue gas passages of the granulation rotary kiln 100 and the pre-carbonization rotary kiln 200 will be referred to as the first flue gas passage 110 and the second flue gas passage 230, respectively.

[0034] In this embodiment, the discharge end of the granulation rotary kiln 100 and the feed end of the pre-carbonization rotary kiln 200 are connected by an intermediate connecting cover 300, which forms a material chute inside the kiln and collects the volatiles generated in the granulation rotary kiln 100 and the pre-carbonization rotary kiln 200. Of course, the intermediate connecting cover 300 is also provided with a volatiles outlet, and this volatiles outlet needs to be connected to a volatiles fan to promptly discharge the volatiles inside the intermediate connecting cover 300.

[0035] This design serves two purposes. First, it allows corrosive gases generated in the granulation rotary kiln 100 to be extracted, separated, or directionally discharged before entering the pre-carbonization rotary kiln 200, reducing the risk of secondary cracking and corrosion of the kiln body due to corrosive components entering the pre-carbonization rotary kiln 200. Second, the pre-carbonization rotary kiln 200 generates high-temperature volatiles, which can heat the low-temperature volatiles generated in the granulation rotary kiln 100. This ensures that the mixed volatiles entering the intermediate connecting shroud 300 maintain a high temperature, effectively preventing the risk of pipe blockage due to condensation and adhesion of volatiles. Furthermore, the intermediate connecting shroud 300 also serves as a heat-insulating buffer space to prevent excessive heat transfer from the pre-carbonization rotary kiln 200 to the granulation rotary kiln 100, avoiding abnormal temperature increases within the granulation rotary kiln 100 that could affect the quality of pellet formation.

[0036] Furthermore, in this embodiment, inert gas inlets are provided at the feed end of the granulation rotary kiln 100 and the discharge end of the pre-carbonization rotary kiln 200, so that the overall flow of inert gas in the two rotary kilns is towards the intermediate connecting hood 300, thereby accelerating the discharge of volatiles.

[0037] Compared to traditional integrated rotary kilns, where granulation and pre-carbonization occur within a single kiln, resulting in poor process adaptability and low reliability of the high-temperature section of the pre-carbonization rotary kiln 200, this embodiment employs two independent kiln bodies for granulation (100) and pre-carbonization (200), respectively. This eliminates the limitations of the same kiln body, rotational speed, and thermal regime for the granulation and pre-carbonization processes. Specifically, the granulation rotary kiln 100 can be configured with appropriate temperature, residence time, rotational speed, and mixing / shearing conditions based on the material's softening, agglomeration, and agglomeration characteristics; while the pre-carbonization rotary kiln 200 can be configured with higher temperatures and stable heat treatment conditions based on the material's devolatilization and carbonization solidification requirements, thus achieving decoupled control of the granulation and pre-carbonization processes.

[0038] In addition, in this embodiment, since the high-temperature pre-carbonization operation can be completed independently within the pre-carbonization rotary kiln 200, the length of the high-temperature carbonization section cylinder, the load-bearing conditions, and the heat-affected zone can be designed separately according to the pre-carbonization requirements, so as to reduce the comprehensive thermomechanical load borne by the high-temperature carbonization section cylinder and improve the structural reliability and safety of the equipment in long-term operation.

[0039] like Figure 2 As shown, in some embodiments, the granulation rotary kiln 100 is connected to a feeding mechanism 410. Meanwhile, a scraping mechanism 420, a stirring mechanism 430, and a lifting plate mechanism 440 are sequentially arranged inside the granulation rotary kiln 100 along the material's forward direction.

[0040] The main body of the feeding mechanism 410 is located outside the granulation rotary kiln 100, but the output end of the feeding mechanism 410 extends into the low-temperature feeding zone Q1 inside the granulation rotary kiln 100 to transport materials into the granulation rotary kiln 100; the scraping mechanism 420 is located in the low-temperature feeding zone Q1 to clean up the materials adhering to the wall in the low-temperature feeding zone Q1 in a timely manner; at the same time, it forcibly stirs the materials and continues to transport them forward; the starting end of the stirring mechanism 430 is located in the low-temperature feeding zone Q1 to stir and mix the materials transported by the scraping mechanism 420 and continue to transport them forward; and the lifting plate mechanism 440 is used to further mix the materials transported by the stirring mechanism 430 and continuously transport the materials to the discharge port.

[0041] It is worth mentioning that the aforementioned feeding mechanism 410, mixing mechanism 430 and lifting mechanism 440 can all adopt existing technologies, and no specific limitations are made here.

[0042] In the existing technology, after the material is fed into the granulation rotary kiln 100 by the feeding mechanism 410, it is directly conveyed by a conventional guide screw or lifting plates. Because the raw materials for granulation of negative electrode materials mostly contain binding components such as asphalt, and the volatiles generated in the kiln condense in the low-temperature feeding zone Q1, the material is prone to adhering to the inner wall of the granulation rotary kiln 100 cylinder, the guide screw, and the lifting plates, resulting in poor feeding or even blockage.

[0043] Therefore, in this embodiment, the scraping mechanism 420 in the low-temperature feeding zone Q1 can, on the one hand, promptly clean up the material adhering to the wall, preventing the material from accumulating or agglomerating in the low-temperature feeding zone Q1 and ensuring continuous and stable feeding. On the other hand, it can further enhance the material turning, shearing, mixing and agglomeration processes, which is beneficial for the negative electrode material raw materials to form granules with a denser structure and more uniform particle size before entering the pre-carbonization stage.

[0044] Specifically, refer to Figure 2 As shown, the aforementioned low-temperature feeding zone Q1 refers to the area of ​​the granulation rotary kiln 100 near the feed inlet that is not covered by the first flue gas passage 110.

[0045] Meanwhile, for the convenience of the following description, the area of ​​the granulation rotary kiln 100 covered by the first flue gas channel 110 is defined as the heating area Q2; the area of ​​the granulation rotary kiln 100 near the discharge port and not covered by the first flue gas channel 110 is defined as the discharge area Q3.

[0046] It is easy to understand that the heating area Q2 mentioned above is the area where the negative electrode material raw material actually undergoes heat exchange and granulation.

[0047] refer to Figure 3 As shown, in one specific embodiment of the scraping mechanism 420, the scraping mechanism 420 includes a rotating shaft and a connecting sleeve 421 fixedly sleeved on the rotating shaft. The connecting sleeve 421 is connected to a scraper assembly 423 via a main connecting rod 4221. The rotating shaft extends axially along the granulation rotary kiln 100 and is located on the central axis of the granulation rotary kiln 100. The scraper assembly 423 also extends axially along the granulation rotary kiln 100.

[0048] Furthermore, the scraper assembly 423 includes a first scraper 4231 and a second scraper 4232 disposed on one side of the first scraper 4231; wherein the second scraper 4232 is inclined relative to the first scraper 4231. That is, the distance from one end of the second scraper 4232 to the first scraper 4231 is greater than the distance from the other end of the second scraper 4231, and the end with the larger distance faces the feeding mechanism 410.

[0049] In this embodiment, the scraper assembly 423 serves two purposes: firstly, it allows for timely cleaning of materials adhering to the wall, and secondly, it enhances the mixing of the materials. Furthermore, the overall inclined arrangement of the scraper assembly 423 facilitates material propulsion and reduces the risk of material accumulation at the feed inlet.

[0050] In some embodiments, the scraper assembly 423 rotates in the same direction as the granulation rotary kiln 100, but there must be a speed difference between them. The scraper assembly 423 uses this speed difference to complete the mixing, conveying, and wall cleaning operations of the material.

[0051] In other embodiments, the rotation direction of the scraper assembly 423 is opposite to that of the granulation rotary kiln 100, which can also achieve the mixing, conveying and wall cleaning of materials.

[0052] It is easy to understand that, in this embodiment, although the scraper assembly 423 can effectively clean the material adhering to the cylinder wall, the scraper assembly 423 and the main connecting rod 4221 themselves are also at risk of material adhesion due to the low temperature of the low-temperature feeding zone Q1 and the material's tendency to stick.

[0053] Therefore, in this embodiment, a movable ring 424 is fitted on the main connecting rod 4221. When the main connecting rod 4221 rotates synchronously with the rotating shaft, the movable ring 424 will continuously move up and down on the main connecting rod 4221 under its own gravity, thereby cleaning the adhesive material on the main connecting rod 4221 in a timely manner.

[0054] Furthermore, a secondary connecting rod 4222 is provided between the main connecting rod 4221 and the scraper assembly 423 to ensure the connection stability of the scraper assembly 423, and a movable ring 424 is also sleeved on the secondary connecting rod 4222.

[0055] In other embodiments, a chain 425 is suspended on the sidewalls of the two scrapers that are far apart from each other. The impact and friction between the chain 425 and the scraper wall when it swings can be used to clean the adhesive material on the scraper wall.

[0056] It is understandable that, since there is a gap between the first scraper 4231 and the second scraper 4232, material may also stick to this gap. Therefore, in this embodiment, a sealing plate (not shown in the figure) is also provided on the first scraper 4231 and the second scraper 4232 to seal the gap between the first scraper 4231 and the second scraper 4232, so as to prevent material from sticking to the area between the two scrapers.

[0057] It is easy to understand that in this embodiment, the rotating shafts of the feeding mechanism 410, the scraping mechanism 420 and the stirring mechanism 430 are all located on the central axis of the granulation rotary kiln 100, that is, the rotating shafts of the three are collinear.

[0058] Specifically, the feeding mechanism 410, the scraping mechanism 420, and the stirring mechanism 430 can share a single rotating shaft. That is, the rotating shaft of the feeding mechanism 410 extends all the way into the granulation rotary kiln 100, and both the scraping mechanism 420 and the stirring mechanism 430 are mounted on this rotating shaft. Alternatively, each of the three mechanisms may have its own rotating shaft, or two of them may share a single rotating shaft.

[0059] It is worth mentioning that when the feeding mechanism 410, scraping mechanism 420, and stirring mechanism 430 do not share a single rotating shaft, adjacent rotating shafts can be connected by a coupling. Preferably, the coupling is a ball cage coupling with strong angle compensation capability, which can maintain relatively stable constant-speed transmission even when there is an angle between the two shafts.

[0060] In this specific embodiment, the feeding mechanism 410 and the scraping mechanism 420 share a common rotating shaft, and the rotating shaft is connected to the rotating shaft of the stirring mechanism 430 through a ball cage coupling.

[0061] Meanwhile, one end of the stirring mechanism 430 is located in the low-temperature feeding zone Q1, and the other end extends 2-4 meters into the heating zone Q2. Specifically, the stirring mechanism 430 has an inner and outer double spiral ribbon structure, with the inner and outer spiral ribbons rotating in opposite directions, ensuring that the material is fully stirred and mixed in the heating zone, rapidly dispersing and mixing the material evenly, ensuring uniform nucleation starting point for granulation, and ensuring the product's tap density.

[0062] like Figure 2 , Figure 4 As shown, in some optional embodiments, a baffle plate 450 is provided between the stirring mechanism 430 and the lifting plate mechanism 440. Specifically, the baffle plate 450 is generally a horizontally arranged frustum structure, and the opening on the side facing the stirring mechanism 430 is larger than the opening on the other side.

[0063] In this embodiment, the baffle plate 450 is used to stop the material conveyed by the mixing mechanism 430. Only when the material accumulation height exceeds the outlet height of the baffle plate 450 can it enter the working area of ​​the lifting mechanism 440. This design can extend the residence time of the material in the working area of ​​the mixing mechanism 430, thereby further ensuring that the material is fully sheared and mixed.

[0064] In this embodiment, although the baffle plate 450 can extend the residence time of the material in the working area of ​​the mixing mechanism 430, the material at the bottom will be blocked by the baffle plate 450, which will cause the material to be unable to be discharged completely, especially when the material type needs to be changed.

[0065] Therefore, in some alternative embodiments, to facilitate the material discharge operation, several small discharge ports 451 are provided in the area where the baffle plate 450 contacts the inner wall of the granulation rotary kiln 100.

[0066] Preferably, the discharge port 451 is a small through hole of 50~200mm*50~100mm, so as to ensure that during the non-material discharge stage, most of the material can be stopped by the baffle plate 450 and accumulated before entering the working area of ​​the lifting mechanism 440, and only a small part of the material can enter the working area of ​​the lifting mechanism 440 through the discharge port 451.

[0067] like Figure 5 As shown, in one specific embodiment of the lifting plate mechanism 440, the lifting plate mechanism 440 includes a first lifting plate assembly 441, a second lifting plate assembly 442, and a third lifting plate assembly 443 arranged sequentially. Each of the first lifting plate assembly 441, the second lifting plate assembly 442, and the third lifting plate assembly 443 includes several lifting plate groups axially distributed along the inner wall of the granulation rotary kiln 100, and each lifting plate group includes several lifting plate bodies 4411 arranged in a ring.

[0068] Specifically, the first lifting plate assembly 441 is located at the outlet of the baffle plate 450, and the lifting plate bodies 4411 in the first lifting plate assembly 441 and the second lifting plate assembly 442 have the same rotation direction, which is called the reverse return lifting plate; while the lifting plate body 4411 in the third lifting plate assembly 443 has the opposite rotation direction to the second lifting plate assembly 442, which is called the forward push lifting plate.

[0069] Specifically, in this embodiment, observing from the feed end of the granulation rotary kiln 100 as the discharge end, the first lifting plate assembly 441 and the second lifting plate assembly 442 have the lifting plate body 4411 arranged in a left-handed manner, while the lifting plate body 4411 in the third lifting plate assembly 443 has the lifting plate body 4411 arranged in a right-handed manner.

[0070] For ease of description below, the area of ​​heating zone Q2 located behind baffle plate 450 is divided into first heating zone Q21 and second heating zone Q22. Among them, the first lifting plate assembly 441, the second lifting plate assembly 442 and the third lifting plate assembly 443 are respectively located in the first heating zone Q21, the second heating zone Q22 and the discharge zone Q3.

[0071] At the same time, it is easy to understand that since the flue gas in the first flue gas passage 110 flows in the opposite direction, the actual temperature of the first heating zone Q21 is lower than that of the second heating zone Q22.

[0072] In this embodiment, within the first heating zone Q21, the asphalt is in the initial stage of pyrolysis and cross-linking curing, with a flue gas temperature of approximately 400–550°C. Within the second heating zone Q22, the asphalt is in the main stage of cross-linking curing and carbonization, with a flue gas temperature of approximately 550–850°C. Therefore, the first lifting plate assembly 441 and the second lifting plate assembly 442 are arranged in a reverse spiral pattern, primarily to extend the residence time of the material within their respective zones and ensure granulation effect.

[0073] The discharge area Q3 is located in the non-flue gas heating zone. When the second lifting plate assembly 442 pushes the granulated material into this area, the third lifting plate assembly 443 is arranged in a positive spiral, which can output the granulated material as soon as possible, avoid the material from accumulating at the discharge end and causing heat waste, and at the same time reduce the temperature at the discharge end support device.

[0074] refer to Figure 6 As shown, in some optional embodiments, the lifting plate bodies 4411 of the first lifting plate assembly 441 and the second lifting plate assembly 442 are provided with notches 44111 on the side facing the inner wall of the granulation rotary kiln 100.

[0075] In this embodiment, by setting the notch 44111, on the one hand, the mixing efficiency of the material layers on both sides of the lifting plate body 4411 can be enhanced, and the heat transfer efficiency can be improved; on the other hand, it also helps to reduce dust and improve the adhesion of materials on the back of the lifting plate body 4411.

[0076] To further reduce material adhesion to the lifting plate body 4411 and the cylinder wall, in this embodiment, a chain 425 is provided at the notch 44111. Specifically, one end of the chain 425 is located on the front of the lifting plate body 4411, and the other end passes obliquely through the notch 44111 and is located on the back of the lifting plate body 4411. The chain 425 must be in a free-suspension state, rather than a taut state.

[0077] During operation, the impact and friction between the chain 425 and the lifting plate body 4411 and the cylinder wall during its swing can clean up the adhered materials. At the same time, the continuous contact between the chain 425 and the materials can also enhance the mixing effect.

[0078] In some alternative embodiments, the height of the lifting plate body 4411 of the second lifting plate assembly 442 needs to be lower than that of the first lifting plate assembly 441; or, the number of lifting plate bodies 4411 of the second lifting plate assembly 442 distributed on the same cross section is less than that of the first lifting plate assembly 441; or, both of the above are taken into account at the same time, so as to reduce the stirring intensity of the material by the second lifting plate assembly 442.

[0079] The rationale for this design is that the first heating zone, Q21, is in the initial stage of cross-linking and curing, requiring strong stirring to ensure that the asphalt and coke powder particles are in full contact and uniformly coated, preventing asphalt agglomeration into large particles. In the second heating zone, Q22, the secondary particle blanks are basically solidified and formed. While ensuring the continuous and stable release of volatiles, the stirring intensity needs to be controlled to prevent the secondary particles that are solidifying from breaking.

[0080] It is worth mentioning that the front side of the aforementioned lifting plate body 4411 refers to the side that is mainly used to contact and scatter the material during the rotation of the granulation rotary kiln 100; while the other side is the back side. Meanwhile, the height of the lifting plate body 4411 refers to the dimension by which the lifting plate body 4411 protrudes from the inner cylinder wall.

[0081] This embodiment describes a two-stage rotary kiln for the granulation and pre-carbonization of negative electrode materials. Because the granulation rotary kiln 100 relies on reverse lifting plates to repeatedly retract, tumble, and mix the material, it can achieve a longer actual movement path within a relatively short cylinder, thus allowing for a relatively small aspect ratio. In contrast, the pre-carbonization rotary kiln 200 primarily relies on its cylinder length and outer wall temperature to ensure residence time, heat transfer area, and volatile matter removal; therefore, its aspect ratio is typically larger. That is, the aspect ratio of the granulation rotary kiln 100 can actually be smaller than that of the pre-carbonization rotary kiln 200.

[0082] Meanwhile, the tilt angle of the granulation rotary kiln 100 is usually greater than that of the pre-carbonization rotary kiln 200. This is because the lifting mechanism 440 in the granulation rotary kiln 100 is equipped with reverse return lifting plates. The larger tilt angle can overcome the material backflow effect caused by the reverse lifting plates and maintain the material being slowly conveyed to the discharge end. On the other hand, the pre-carbonization rotary kiln 200 has no baffle structure, and the smaller tilt angle can constrain the axial flow velocity of the material, prevent the material from passing through quickly, and ensure the pre-carbonization time.

[0083] Furthermore, the granulation rotary kiln 100 should adopt a higher rotation speed to enhance material mixing. The rotation speed of the pre-carbonization rotary kiln 200 is designed to form a continuous and stable rolling bed of materials, and is generally slightly lower than that of the pre-carbonization rotary kiln 200, thereby extending the residence time.

[0084] It is worth mentioning that in this embodiment, both the granulation rotary kiln 100 and the pre-carbonization rotary kiln 200 are arranged in an inclined manner with the feed end higher and the discharge end lower. At the same time, the temperature zone inside the granulation rotary kiln 100 is generally 350~850℃, and the temperature zone inside the pre-carbonization rotary kiln 200 is generally 850~1150℃.

[0085] Traditional externally heated rotary kilns have a separate structure for the inner and outer cylinders, meaning their movements are relatively independent. Specifically, the outer cylinder is rotatably fitted onto the inner cylinder at both ends via dynamic sealing structures. Simultaneously, both ends of the inner cylinder extend beyond the inner cylinder by a certain distance; these extended sections are used to mount the power unit and support devices. The power unit independently drives the rotation of the inner cylinder, while the outer cylinder remains essentially stationary.

[0086] While the traditional split-type external heating kiln structure has the advantage of simple construction, it also has many significant drawbacks: Firstly, only the extended sections at both ends of the inner cylinder can be effectively supported. When the inner cylinder is long and is in a high-temperature condition for a long time, the inner cylinder is prone to bending deformation.

[0087] Secondly, the excessively large outward extensions at both ends of the inner cylinder exceed the coverage area of ​​the flue gas passage, constituting ineffective cylinder sections and resulting in redundant equipment length. This not only hinders cost reduction but also exacerbates the risk of flexural deformation due to the increased cylinder length. Furthermore, the excessively long outward extensions of the inner cylinder increase heat loss.

[0088] Thirdly, because the power unit and support unit are directly assembled on the inner cylinder, they are subjected to high temperatures for a long time, which greatly shortens the service life of the equipment.

[0089] Fourth, due to the relative movement between the inner and outer cylinders, the connection between them places stringent requirements on the sealing performance of the dynamic seal, resulting in a high risk of seal failure.

[0090] Specifically, in this embodiment, the granulation rotary kiln 100 has a relatively low overall operating temperature and a short cylinder length, making it suitable for use with a traditional split-type external heating kiln. However, the pre-carbonization rotary kiln 200 has a higher operating temperature and a longer overall cylinder length. If the traditional split-type structure is continued, the aforementioned problems are likely to occur, resulting in poor applicability. Therefore, this embodiment further optimizes and improves the structure of the pre-carbonization rotary kiln 200.

[0091] Specifically, refer to Figure 7 As shown, the pre-carbonization rotary kiln 200 includes a first cylinder 210 and a second cylinder 220 sleeved on the first cylinder 210. A second flue gas passage 230 is formed between the two cylinders, and the first cylinder 210 can rotate synchronously with the second cylinder 220.

[0092] The second cylinder 220 is equipped with a driving component and a supporting component. The driving component is used to drive the second cylinder 220 to rotate, thereby driving the first cylinder 210 to rotate. The supporting component is used to provide rolling support for the second cylinder 220. At the same time, a number of supporting assemblies 600 are provided in the second flue gas passage 230. Multiple sets of supporting assemblies 600 are provided along the axial direction of the pre-carbonization rotary kiln 200, and each set includes multiple assemblies distributed in a ring.

[0093] It should be noted that the aforementioned driving and supporting components are all existing technologies and are not specifically limited herein. The difference lies in the fact that in traditional kiln structures, the driving and supporting components are mounted on the extended portion of the first cylinder 210. In this embodiment, however, the driving and supporting components are directly mounted on the second cylinder 220.

[0094] like Figure 8 As shown, in one embodiment of the support assembly 600, the support assembly 600 includes a support member 610. One end of the support member 610 passes through the second cylinder 220 and contacts the outer wall of the first cylinder 210, while the other end is disposed on the second cylinder 220. Of course, an assembly hole for the support member 610 to pass through needs to be provided on the second cylinder 220.

[0095] It is understood that the support member 610 is directly used to provide radial support for the first cylinder 210. Therefore, the support member 610 should have good high-temperature strength and wear resistance, suitable for high-temperature flue gas and high-temperature cylinder environments. Preferably, the support member 610 can be made of silicon carbide or silicon nitride.

[0096] In this embodiment, the pre-carbonization rotary kiln 200 adopts an integrated structure with two cylinders rotating synchronously, which has the following advantages compared to the traditional split structure: Firstly, by setting a support member 610 between the two cylinders, the first cylinder 210 located inside can be supported at multiple points, thereby effectively reducing the risk of the first cylinder 210 bending and deforming due to excessive length and high temperature. Secondly, the drive components and support components can be directly mounted on the external second cylinder 220, which can greatly reduce the length of the extended section of the first cylinder 210, thereby significantly reducing the size of the ineffective cylinder section and avoiding redundant equipment length; at the same time, it also helps to reduce heat loss. Thirdly, the drive components and support components do not need to be installed on the high-temperature first cylinder 210, which can mitigate the adverse effects of high temperature on them.

[0097] Fourth, since there is not much relative movement between the two cylinders, the sealing performance at the joint is easier to ensure.

[0098] In some embodiments, one end of the support member 610 extends outside the second cylinder 220 and is connected to a pressure regulating assembly. The pressure regulating assembly includes an adjusting screw 620 disposed on the outer wall of the second cylinder 220, on which a support plate 630 is sleeved and equipped with an adjusting nut 640. One end of the support member 610 is connected to the support plate 630 via a first elastic member 650.

[0099] In this embodiment, the first elastic element 650 can apply an elastic supporting force to the support element 610, so that the first cylinder 210 can obtain elastic compensation when it expands due to heat or undergoes slight deformation, avoiding local thermal stress caused by rigid support after expansion. At the same time, by adjusting the setting of the adjusting nut 640, the preload of the first elastic element 650 can be adjusted, thereby flexibly adjusting the support state of the first cylinder 210.

[0100] In other embodiments, a sealing component 660, such as ceramic fiber packing, is provided between the support member 610 and the inner wall of the mounting hole on the second cylinder 220 to improve the sealing performance between the two and also to provide a certain heat insulation effect.

[0101] Furthermore, a heat insulation component 670 is provided between the first elastic member 650 and the support member 610 to reduce the transmission of high temperature from the first cylinder 210 to the first elastic member 650.

[0102] This embodiment describes a two-stage rotary kiln for pre-carbonization of negative electrode material granulation. The second cylinder 220 is a steel shell with an inner lining. The inner lining can be heat-insulating bricks + refractory bricks or ceramic fiber boards + refractory castables, which are used to improve the heat insulation performance of the second cylinder 220 and reduce the temperature rise of the outer cylinder metal structure, as well as reduce the temperature of the supporting components and driving components.

[0103] Meanwhile, one end of the first cylinder 210 is fixedly and sealed to the corresponding end of the second cylinder 220, and reinforcing ribs are provided to fix the axial positioning of the first cylinder 210 and transmit torque. The other end of the first cylinder 210 is provided with a packing seal assembly for dynamic sealing connection to the corresponding end of the second cylinder 220 to accommodate the difference in axial expansion between the first cylinder 210 and the second cylinder 220.

[0104] In this embodiment, a two-stage rotary kiln for pre-carbonization of negative electrode material granulation is provided. To ensure that the inner and outer cylinders of the pre-carbonization rotary kiln 200 can rotate synchronously and that the first cylinder 210 expands axially without jamming, several floating guide components 700 are also provided in the second flue gas channel 230. Multiple sets of these floating guide components 700 are provided along the axial direction of the pre-carbonization rotary kiln 200, each set including multiple components arranged in a ring. Furthermore, the floating guide components 700 and the support components 600 are arranged alternately along the axial direction of the pre-carbonization rotary kiln 200.

[0105] refer to Figure 9 As shown, the floating guide assembly 700 includes a mounting rod 710 disposed on the second cylinder 220. The mounting rod 710 is connected to a guide block 730 via a second elastic member 720. The end of the guide block 730 extends into the second flue gas passage 230 of the pre-carbonization rotary kiln 200. Meanwhile, a guide rod 740 is provided on the outer peripheral wall of the first cylinder 210, which engages with the guide block 730. The guide rod 740 extends axially along the first cylinder 210.

[0106] Specifically, the guide block 730 is stepped in shape, and the second cylinder 220 has stepped holes for mounting the guide block 730. At the same time, a slot is provided on the side of the guide block 730 near the guide rod 740 for the guide rod 740 to be inserted into, so as to complete the engagement between the two.

[0107] Furthermore, a flexible sealing material is provided on the contact surface between the guide block 730 and the stepped hole.

[0108] In this embodiment, a sufficient expansion gap can be reserved between the guide rod 740 and the guide block 730 in the cold state; during hot operation, the gap between the two shrinks, which can be used to limit the circumferential offset range of the first cylinder 210. At the same time, the second elastic element 720 not only provides a guiding path for the guide block 730, but also ensures the sealing performance between the guide block 730 and the stepped hole.

[0109] In summary, in this embodiment, by setting the floating guide component 700, it is possible to restrict the circumferential free movement of the first cylinder 210 relative to the second cylinder 220, and to allow the first cylinder 210 to undergo differential thermal expansion under high temperature conditions, thereby preventing the guide part from getting stuck.

[0110] This embodiment describes a two-stage rotary kiln for the pre-carbonization of negative electrode materials. Since the pre-carbonization rotary kiln 200 needs to withstand temperatures exceeding 1000℃, especially for medium-sulfur coke feedstock, the first cylinder 210 is subjected to prolonged high-temperature, heavy-load, and corrosive conditions, making it prone to corrosion, insufficient strength, and even cracking, threatening equipment lifespan and safety. Therefore, in this embodiment, the first cylinder 210 of the pre-carbonization rotary kiln 200 adopts a composite cylinder structure to increase its structural strength and improve its corrosion resistance.

[0111] Specifically, refer to Figure 10 As shown, the first cylinder 210 includes, from the outside to the inside, a heat-resistant layer 211, a transition layer 212, and a corrosion-resistant layer 213. Among them, the heat-resistant layer 211 constitutes the main load-bearing structure of the first cylinder 210, which is used to provide the mechanical strength required for rotational operation.

[0112] The corrosion-resistant layer 213 is disposed on the side of the first cylinder 210 closest to the material, directly facing the high-temperature negative electrode material particles and corrosive volatiles. The transition layer 212 is disposed between the heat-resistant layer 211 and the corrosion-resistant layer 213, and the coefficient of thermal expansion of the transition layer 212 must be between that of the heat-resistant layer 211 and the corrosion-resistant layer 213, so as to buffer the difference in thermal expansion between the heat-resistant layer 211 and the corrosion-resistant layer 213, and reduce the risk of cracking and peeling of the corrosion-resistant layer 213 during heating and cooling.

[0113] It is worth mentioning that the specific materials of the heat-resistant layer 211, transition layer 212, and corrosion-resistant layer 213 can be selected from existing technologies and are not specifically limited here. For example, the heat-resistant layer 211 can be made of heat-resistant alloy steel or other metal materials suitable for high-temperature conditions, such as iron-nickel based alloys, nickel-based alloys, cobalt-based alloys, etc.; the transition layer 212 can be made of MCrAlY alloy; and the corrosion-resistant layer 213 can be made of YSZ (yttrium-stabilized zirconium oxide), etc.

[0114] In this embodiment, through the composite design of heat-resistant layer 211, transition layer 212 and corrosion-resistant layer 213, the first cylinder 210 simultaneously possesses high load-bearing capacity, high corrosion resistance and thermal expansion buffering function, and can perfectly adapt to the high-temperature pre-carbonization process of 850~1150℃.

[0115] like Figure 7 As shown, to facilitate the flow of flue gas within the second flue gas passage 230, in this embodiment, a flue gas inlet box 810 is connected to the flue gas inlet of the pre-carbonization rotary kiln 200, and a flue gas outlet box 820 is connected to the flue gas outlet. Simultaneously, a discharge hood 830 is provided at the discharge port of the pre-carbonization rotary kiln 200.

[0116] Specifically, the flue gas inlet box 810 and the flue gas outlet box 820 are rotatably sleeved on the second cylinder 220; the flue gas outlet box 820 is interconnected with the first flue gas channel 110 via a flue gas connecting pipe 500. The discharge hood 830 is rotatably sleeved on the end of the first cylinder 210, and the discharge hood 830 is provided with an inert gas inlet. Furthermore, dynamic sealing structures are required at the connections between the flue gas inlet box 810, the flue gas outlet box 820 and the second cylinder 220, and at the connection between the discharge hood 830 and the first cylinder 210 to ensure the sealing performance of the connections.

[0117] It is worth mentioning that the sealing structures mentioned in this embodiment are all existing technologies and are not specifically limited here.

[0118] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A two-stage rotary kiln for granulation and pre-carbonization of negative electrode materials, comprising a granulation rotary kiln (100) and a pre-carbonization rotary kiln (200) connected to each other; wherein, The first flue gas passage (110) of the granulation rotary kiln (100) and the second flue gas passage (230) of the pre-carbonization rotary kiln (200) are connected by a flue gas connecting pipe (500); The feature is that the discharge end of the granulation rotary kiln (100) and the feed end of the pre-carbonization rotary kiln (200) are connected by an intermediate connecting cover (300), and the intermediate connecting cover (300) is provided with a volatile matter outlet. The feed end of the granulation rotary kiln (100) and the discharge end of the pre-carbonization rotary kiln (200) are both equipped with inert gas inlets; The granulation rotary kiln (100) is connected to a feeding mechanism (410), the output end of which extends into the low-temperature feeding zone Q1 of the granulation rotary kiln (100), and a scraping mechanism (420) is provided in the low-temperature feeding zone Q1. The scraping mechanism (420) includes a rotating shaft and a connecting sleeve (421) fixedly sleeved on the rotating shaft. The connecting sleeve (421) is connected to a scraper assembly (423) via a main connecting rod (4221).

2. The two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 1, characterized in that: The scraper assembly (423) includes a first scraper (4231) and a second scraper (4232) disposed on one side of the first scraper (4231); The first scraper (4231) extends along the axial direction of the granulation rotary kiln (100), and the second scraper (4232) is inclined relative to the first scraper (4231).

3. The two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 2, characterized in that: A movable ring (424) is fitted on the main connecting rod (4221).

4. The two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 3, characterized in that: Chains (425) are suspended on the sidewalls of the first scraper (4231) and the second scraper (4232) that are far apart from each other.

5. A two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to any one of claims 1-4, characterized in that: The rotation direction of the scraper assembly (423) is the same as that of the granulation rotary kiln (100), and there is a speed difference between the two. Alternatively, the rotation direction of the scraper assembly (423) is opposite to that of the granulation rotary kiln (100).

6. The two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 5, characterized in that: The granulation rotary kiln (100) is equipped with a stirring mechanism (430). One end of the stirring mechanism (430) is located in the low-temperature feeding zone Q1 of the granulation rotary kiln (100), and the other end extends away from the scraping mechanism (420) and extends out of the low-temperature feeding zone Q1.

7. A two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 6, characterized in that: The feeding mechanism (410) and scraping mechanism (420) share a common rotating shaft, and the rotating shaft is connected to the rotating shaft of the stirring mechanism (430) through a ball cage coupling.

8. A two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 6, characterized in that: The granulation rotary kiln (100) is also provided with a lifting plate mechanism (440), which is located on the side of the stirring mechanism (430) away from the scraping mechanism (420), and a baffle plate (450) is provided between the lifting plate mechanism (440) and the stirring mechanism (430). The baffle plate (450) is a horizontally arranged frustum structure, and the opening on the side facing the stirring mechanism (430) is larger than the opening on the other side.

9. A two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 5, characterized in that: The aspect ratio of the granulation rotary kiln (100) is smaller than that of the pre-carbonization rotary kiln (200).

10. A two-stage rotary kiln for pre-carbonization of negative electrode material granulation according to claim 9, characterized in that: The granulation rotary kiln (100) and the pre-carbonization rotary kiln (200) are both arranged at an inclination with the feed end higher and the discharge end lower, and the inclination angle of the granulation rotary kiln (100) is greater than that of the pre-carbonization rotary kiln (200).

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