A vertical coating granulation equipment and a graphite negative electrode material coating granulation method

Abstract

The present invention discloses a vertical coating granulation equipment and a method for coating and granulating graphite negative electrode materials, and belongs to the technical field of preparation of graphite negative electrode materials for lithium batteries. The present invention includes an outer shell, a jacket, a rotating central cylinder and a stirring device arranged in sequence from the outside to the inside, a material channel is formed between the outer shell and the jacket, a heat source channel is formed between the jacket and the rotating central cylinder, the stirring device passes through the rotating central cylinder, and one end extends into the cavity of the outer shell, and the stirring device transports the material in the outer shell cavity to the next process through the rotating central cylinder. The present invention can not only realize the continuous coating and granulation of lithium battery negative electrode materials and improve production efficiency; at the same time, the length of the granulation area is only half of the traditional length, so the processing capacity of a single set of equipment is improved, and it can be applied to mass production. In addition, the material first exchanges heat with the high-temperature flue gas in the downstream, and then exchanges heat with the high-temperature flue gas in the countercurrent, thereby improving energy utilization.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of graphite negative electrode materials for lithium batteries, and more specifically, relates to a vertical coating and granulation device and a coating and granulation method for graphite negative electrode materials. Background Art

[0002] In the existing production process of lithium battery graphite negative electrode materials, granulation is a key step in the production of negative electrode materials. The coating granulation process is generally carried out in the kettle body. A resistance wire is installed outside the granulation kettle to transfer heat to the material in the kettle through the wall, so that the material is stirred and mixed below 650°C. The graphene powder and asphalt powder are repeatedly stirred and mixed by the stirring shaft to melt the asphalt powder and coat the outer surface of the graphene particles, thereby obtaining a semi-finished negative electrode material. The material is heated and stirred in the granulation kettle for a period of 8 to 10 hours. After the reaction time is reached, the material is discharged from the granulation kettle to the cooling kettle, and then the granulation kettle continues to feed a new round of granulation. During the granulation process of the granulation kettle, the loading and discharging processes of the granulation kettle need to stop the kettle. The granulation kettle works intermittently and has low production efficiency.

[0003] The above-mentioned lithium battery graphite negative electrode material coating granulation process has the following problems: 1. The granulation kettle is an intermittent equipment with low production efficiency; 2. The output of the single unit setting is low and is only suitable for small-batch intermittent production.

[0004] After searching, the Chinese patent authorization announcement number is CN 216224247 U, the authorization announcement date is April 8, 2022, and the name of the invention is continuous negative electrode material granulation production line, which includes a mixer, a granulation kettle and a cooling kettle; the mixer is provided with multiple discharge ports, and a discharger and a buffer silo are provided under each of the discharge ports; there are multiple granulation kettles, and the granulation kettle is long and cylindrical, and multiple granulation kettles are arranged in parallel, and a screw feeder is provided between each buffer silo and the granulation kettle; a cooling kettle is provided in series at the rear end of each granulation kettle, and the material is continuously fed through the spiral feeding device, and the granulation kettle continuously discharges the material, thereby realizing continuous production of the production line. However, although continuous production is achieved, the furnace diameter of the granulation kettle is 30-50cm, and the length of the granulation kettle does not exceed 10 meters, so the processing capacity of a single granulation kettle is limited and it is not suitable for mass production. Summary of the Invention

[0005] 1. Problems to be solved

[0006] To address the intermittent operation of existing granulation kettles, resulting in low production efficiency and relatively low capacity, the present invention provides a vertical coating granulation equipment and a method for coating and granulating graphite negative electrode materials. The technical solution of the present invention not only enables continuous coating and granulation of lithium battery negative electrode materials, improving production efficiency, but also reduces the length of the granulation area to only half that of conventional equipment, thereby increasing the processing capacity of a single unit and making it suitable for large-scale production.

[0007] 2. Technical solution

[0008] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0009] The present invention provides a vertical coating granulation equipment, comprising an outer shell, a jacket, a rotating central cylinder and a stirring device, wherein the stirring device passes through the rotating central cylinder, the jacket is arranged outside the rotating central cylinder, a material channel is formed between the outer shell and the jacket, and the material channel is connected to the interior of the rotating central cylinder; a heat source channel is formed between the jacket and the rotating central cylinder; and the stirring device outputs the material in the material channel through the rotating central cylinder.

[0010] Furthermore, a material inlet is provided on the shell, and a material outlet is provided on the top of the rotating central tube; a heat source inlet and a heat source outlet are provided on the jacket, and the heat source inlet is higher than the heat source outlet.

[0011] Furthermore, a fixed outer cover is provided on the top of the rotating central cylinder, a material outlet is arranged on the fixed outer cover, and a plurality of scrapers are provided on the outer wall of the rotating central cylinder located inside the fixed outer cover.

[0012] Furthermore, ribs are provided on the outer wall of the rotating central tube, and a plurality of ribs are provided at intervals along the axial direction of the rotating central tube.

[0013] Furthermore, cylinder stirring teeth are provided on the inner wall of the rotating central cylinder, and a plurality of cylinder stirring teeth are provided at intervals along the axial direction of the rotating central cylinder.

[0014] Furthermore, the stirring device includes a rotating shaft, on which a first spiral, a second spiral, a third spiral and a fourth spiral are provided, wherein the rotation direction of the first spiral, the third spiral and the fourth spiral is opposite to that of the second spiral, and the second spiral surrounds the first spiral.

[0015] Furthermore, the rotation direction of the rotating central cylinder is opposite to that of the rotating shaft.

[0016] Furthermore, a guide member is provided in the rotating center tube, and the guide member includes a guide ring and a fixed rod. One end of the fixed rod is connected to the wall of the rotating center tube, and the other end is connected to the guide ring, and the rotating shaft passes through the guide ring.

[0017] Furthermore, the contact point between the guide member and the rotating shaft is a polished rod section.

[0018] A method for coating and granulating a graphite negative electrode material of the present invention adopts the above-mentioned device for coating and granulating, comprising the following steps:

[0019] Step 1: The material enters the material channel and first exchanges heat with the heat source in the heat source channel to preheat the material at room temperature;

[0020] Step 2: The preheated material is transported into the rotating central cylinder through the stirring device, and the material and the heat source are countercurrently exchanged for coating and granulation;

[0021] Step 3: The coated and granulated material is transported out of the rotating central cylinder by the stirring device. The volatiles generated during the coating and granulation process are burned to become high-temperature flue gas and then re-enter the heat source channel.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention relates to a vertical coating granulation device, wherein a material channel for the material to pass through is formed between the shell and the jacket, a heat source channel is formed between the jacket and the rotating central cylinder, and a stirring device is located inside the rotating central cylinder and extends into the cavity of the shell. The material is first preheated in the material channel, and then the stirring device transports the material in the inner cavity of the shell to the rotating central cylinder for coating and granulation. Finally, the stirring device discharges the material from the rotating central cylinder, thereby realizing the continuous production of the coating and granulation process of the negative electrode material of the lithium battery. In addition, compared with the traditional granulation equipment, the vertical coating granulation equipment of the present invention has a coating and granulation area length of only half of the traditional length, so that the processing capacity of a single set of equipment is improved, and it can be suitable for mass production.

[0025] (2) In a vertical coating granulation equipment of the present invention, a plurality of scrapers are provided on the outer wall of the rotating central cylinder located in the fixed outer cover to ensure that the material transported from the rotating central cylinder can be discharged through the material outlet as quickly as possible to avoid the accumulation of the material in the fixed outer cover; in addition, a rib is provided on the outer wall of the rotating central cylinder located in the jacket, and a plurality of cylinder stirring teeth are provided on the inner wall of the rotating central cylinder, which not only improves the heat exchange effect, but also makes the relative movement between the materials more intense, thereby ensuring the intensity of mixing and stirring.

[0026] (3) In the present invention, a method for coating and granulating graphite negative electrode materials is provided. The room temperature material is preheated with the high temperature flue gas in the downstream direction, and then the material is coated and granulated in the countercurrent heat exchange with the high temperature flue gas. The material flow direction is reasonable, and the thermal energy of the high temperature flue gas is fully utilized, thereby reducing heat loss. In addition, the volatile matter precipitated during the coating and granulation process is converted into high temperature flue gas after incineration, and then re-enters the heat source channel to heat the material, which not only reduces the emission of waste gas, but also avoids energy waste and improves energy utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural schematic diagram of a vertical coating granulation equipment of the present invention;

[0028] Figure 2 for Figure 1 A partial enlarged view of the

[0029] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0030] Figure 4 Schematic diagram of the structure of the stirring device in the present invention;

[0031] Figure 5 It is an enlarged view of the local structure of the stirring device in the present invention;

[0032] Figure 6 It is a structural schematic diagram of the guide member in the present invention.

[0033] In the figure: 1, shell; 11, material inlet; 2, jacket; 21, heat source inlet; 22, heat source outlet;

[0034] 3. Rotating center cylinder; 31. Scraper; 32. Rib plate; 33. Cylinder stirring teeth;

[0035] 4. Stirring device; 41. Rotating shaft; 42. First spiral; 43. Second spiral; 44. Third spiral; 45. Fourth spiral; 46. Connecting rod; 47. Polished rod segment;

[0036] 5. Fixed outer cover; 51. Material outlet; 52. Volatile outlet;

[0037] 6. Guide member; 61. Guide ring; 62. Fixing rod;

[0038] 7. Fixed bracket; 8. Driving mechanism. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] like Figure 1As shown, a vertical coating granulation device of this embodiment includes a shell 1, a jacket 2, a rotating central cylinder 3 and a stirring device 4 arranged in sequence from the outside to the inside, all of which are concentrically arranged vertically.

[0042] The housing 1 is mounted on a fixed bracket 7. A material inlet 11 is located at the top of the housing 1, with an angle of 0-30° between the inlet 11 and the central axis of the housing 1 to facilitate material delivery. Specifically, in this embodiment, the housing 1 has a circular cross-section and a tapered bottom to facilitate material collection at the center. The jacket 2 is inserted into the housing 1, with one end protruding from the housing 1 and the other end extending into the cavity of the housing 1, forming a material channel between the housing 1 and the jacket 2.

[0043] The rotating central cylinder 3 passes through the jacket 2, with both ends extending outside the jacket 2, forming a sealed heat source channel between the jacket 2 and the rotating central cylinder 3. The stirring device 4 passes through the rotating central cylinder 3, with one end extending into the cavity of the outer shell 1. The stirring device 4 transports the material at the bottom of the outer shell 1 into the rotating central cylinder 3 for coating and granulation, and then outputs it from the rotating central cylinder 3.

[0044] The vertical coating granulation equipment of this embodiment uses high-temperature flue gas as a heat source. The high-temperature flue gas first exchanges heat with the material in the material channel in a downstream manner to preheat the material. It then exchanges heat in a countercurrent manner with the material in the rotating central cylinder 3 to coat and granulate the material, achieving continuous production of lithium battery negative electrode material coating granulation. Compared with traditional granulation equipment, the vertical coating granulation equipment of this embodiment has a coating granulation area that is only half the length of traditional granulation equipment, thereby improving the processing capacity of a single unit and making it suitable for large-scale production.

[0045] Specifically, the jacket 2 has a heat source inlet 21 at its top and a heat source outlet 22 at its bottom. The heat source outlet 22 is connected to the outer shell 1 via a pipe, with the pipe positioned at an angle of 0 to 40 degrees relative to the axis of the outer shell 1 to facilitate the proper descent of the material within the material channel. An expansion joint or metal hose is also provided on the pipe to compensate for the axial expansion of the pipe caused by heating. Furthermore, to further enhance the heat exchange of the high-temperature flue gas, ribs 32 are provided on the outer wall of the rotating central tube 3 within the jacket 2. Blades may also be provided.

[0046] During the movement of the material, it first flows downstream with the flue gas, and then flows in the countercurrent direction. The material can be preheated while flowing downstream. The material at room temperature is preheated to 200-250°C before entering the granulation zone. Since the flue gas entering the zone has a high temperature of 750-800°C, the preheated material exchanges heat with the flue gas in the countercurrent direction. At this time, the material temperature is concentrated at 300-600°C. Under the forced stirring action of the stirring device 4, the material is coated and granulated. This material flow fully utilizes the thermal energy of the high-temperature flue gas and reduces heat loss.

[0047] like Figure 2 As shown, the rotating central tube 3 is connected to a fixed outer cover 5, and the fixed outer cover 5 is provided with a material outlet 51 and a volatile outlet 52. Among them, the angle between the material outlet 51 and the central axis of the rotating central tube 3 is 0-30°, which is convenient for the falling of the material. The outer wall of the rotating central tube 3 located in the fixed outer cover 5 is provided with a plurality of scrapers 31 to ensure that the material transported from the rotating central tube 3 can be discharged through the material outlet 51 as soon as possible, so as to avoid the accumulation of material in the fixed outer cover 5, thereby affecting the continuity of production. In addition, the rotating central tube 3 is connected to a driving mechanism 8, which is located between the jacket 2 and the fixed outer cover 5, and the rotating central tube 3 rotates in the opposite direction to the rotating shaft 41 of the stirring device 4 to enhance the stirring and heat exchange effect.

[0048] During use, the material enters the material channel from the material inlet 11, falls to the bottom of the cone under the action of gravity, enters the rotating central cylinder 3 under the transportation of the stirring device 4, continues to be transported upward in the rotating central cylinder 3, and after reaching the fixed outer cover 5, enters the subsequent process section through the material outlet 51.

[0049] In this embodiment of a vertical coating granulation apparatus, material must fall through a material channel to the bottom of the outer cylinder, where it is then conveyed upward by a stirring device 4 into the rotating central cylinder 3. As the material ascends, it is squeezed together with the material descending under the action of gravity, which can easily lead to poor material delivery and even blockage of the material channel, thus affecting the continuous conveyance of the material. To address this issue, the structure of the stirring device 4 in this embodiment has been further optimized.

[0050] Specifically, combined Figure 1 、 Figure 4 、 Figure 5 As shown, the stirring device 4 includes a rotating shaft 41, which extends to the outside of the housing 1 and is connected to a motor. The motor is in a low temperature section, which is conducive to protecting it.

[0051] The portion of the rotating shaft 41 extending into the housing 1 is provided with a first spiral 42 and a second spiral 43 having opposite rotation directions, and the portion located within the rotating center tube 3 is provided with a third spiral 44 and a fourth spiral 45. The first spiral 42, the third spiral 44, and the fourth spiral 45 have the same rotation direction, the starting position of the first spiral 42 is slightly lower than the starting position of the second spiral 43, and the two have the same pitch, and the starting angles are staggered. The hollow cone formed by the rotation of the second spiral 43 contains the cone formed by the rotation of the first spiral 42. Specifically in this embodiment, the first spiral 42 is a spiral sheet, and the second spiral 43 is a spiral ribbon, which is connected to the rotating shaft 41 by a connecting rod 46.

[0052] In this embodiment, the design of the first spiral 42 and the second spiral 43 can effectively reduce the impact of the falling material on the upward material, ensuring that the material falls more smoothly; at the same time, the second spiral 43 can transport the falling material to the bottom of the outer cylinder as quickly as possible, which can effectively prevent the blockage of the material and thus ensure the continuity of material transportation.

[0053] The third spiral 44 is located above the first spiral 42, and the two are connected to each other and have the same rotation direction. The fourth spiral 45 is located above the third spiral 44, and is connected to the third spiral 44 and has the same rotation direction. The third spiral 44 is composed of a plurality of stirring teeth, which are distributed on the rotating shaft 41 along the spiral line, and the number of stirring teeth per turn is not less than P / B, wherein B is the axial length of a single stirring tooth along the rotating shaft 41, and P is the pitch of the spiral line. Specifically in this embodiment, the fourth spiral 45 is a spiral sheet, and the stirring teeth are round steel, in which case B is the diameter of the round steel. In addition, a spiral belt is provided on the third spiral 44, so that, on the premise of ensuring the strength of the third spiral 44 itself, it is further ensured that the material can obtain sufficient stirring intensity and sufficient conveying capacity.

[0054] To further enhance the agitation of materials within the rotating central cylinder 3, a number of agitating teeth 33 are installed on the inner wall of the rotating central cylinder 3. The presence of these teeth not only enhances heat transfer but also intensifies the relative motion of the materials. The spacing between the outer edges of the third and fourth spirals 44 and 45 and the agitating teeth 33 must be strictly controlled, ensuring a close fit while ensuring non-contact during heating. Typically, this spacing is set between 10 and 40 mm.

[0055] Combine Figure 1 、 Figure 6 As shown, the rotating center cylinder 3 is provided with a guide member 6 comprising a guide ring 61 and a fixing rod 62. One end of the fixing rod 62 is connected to the wall of the rotating center cylinder 3, and the other end is connected to the guide ring 61. The rotating shaft 41 passes through the guide ring 61. The provision of the guide member 6 ensures the concentricity of the rotating shaft 41 with the rotating center cylinder 3 during rotation. To facilitate replacement of the rotating shaft 41, the guide member 6 is positioned as close as possible to the end of the rotating shaft 41.

[0056] The contact point between the guide member 6 and the rotating shaft 41 is the polished rod section 47. The polished rod section 47 is not provided with spiral blades, stirring teeth and other components. On the one hand, it is convenient for the installation of the rotating shaft 41 and the guide member 6; on the other hand, considering the thermal expansion of the rotating shaft 41, a certain axial expansion space must be left between the guide ring 61 and the spiral blades or the third spiral 44, so as to improve the operating stability of the device.

[0057] Example 2

[0058] A method for coating and granulating a graphite negative electrode material in this embodiment uses the apparatus in Example 1 to perform coating and granulation, comprising the following steps:

[0059] Step 1: The material enters the material channel and first exchanges heat with the high-temperature flue gas in the heat source channel to preheat the room temperature material;

[0060] Step 2: The material in the material channel is concentrated to the bottom of the housing 1 under the action of its own gravity and the conveyance of the second screw 43;

[0061] Step 3: The material at the bottom of the shell 1 is transported by the first screw 42 and rotates in the central cylinder 3; at the same time, the material continues to move upward under the transport of the third screw 44. During the upward movement, the material exchanges heat with the high-temperature flue gas in a countercurrent manner to be coated and granulated;

[0062] Step 4: The coated and granulated material is output from the rotating central cylinder 3 by the fourth screw 45;

[0063] Step 5: The volatile matter generated during the coating and granulation process is burned to become high-temperature flue gas and then re-enters the heat source channel.

[0064] The present embodiment provides a method for coating and granulating a graphite negative electrode material. The room-temperature material is first preheated in a downstream manner with high-temperature flue gas, and then subjected to countercurrent heat exchange with the high-temperature flue gas for coating and granulation. The material flow is reasonable, and while ensuring continuous production, the thermal energy of the high-temperature flue gas is fully utilized, thereby reducing heat loss. In addition, the volatile matter released during the coating and granulation process is burned to become high-temperature flue gas, and then re-enters the heat source channel to heat the material, which not only reduces exhaust gas emissions, but also avoids energy waste and improves energy utilization.

[0065] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs a structure and embodiment similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A vertical coating granulation device, comprising a housing (1), characterized in that: It also includes a jacket (2), a rotating central cylinder (3) and a stirring device (4), wherein the stirring device (4) passes through the rotating central cylinder (3), the jacket (2) is arranged outside the rotating central cylinder (3), a material channel is formed between the shell (1) and the jacket (2), and the material channel is communicated with the interior of the rotating central cylinder (3); a heat source channel is formed between the jacket (2) and the rotating central cylinder (3); the stirring device (4) outputs the material in the material channel through the rotating central cylinder (3); wherein, The housing (1) is provided with a material inlet (11), and the top of the rotating central cylinder (3) is provided with a material outlet (51); The stirring device (4) includes a rotating shaft (41) extending outside the housing (1); the portion of the rotating shaft (41) extending into the housing (1) is provided with a first spiral (42) and a second spiral (43) having opposite rotation directions, and the portion located inside the rotating central cylinder (3) is provided with a third spiral (44) and a fourth spiral (45); and the second spiral (43) surrounds the first spiral (42); The third spiral (44) is located above the first spiral (42), and the fourth spiral (45) is located above the third spiral (44); and the first spiral (42), the third spiral (44), and the fourth spiral (45) have the same rotation direction.

2. A vertical coating granulation equipment according to claim 1, characterized in that: A heat source inlet (21) and a heat source outlet (22) are provided on the jacket (2), and the heat source inlet (21) is higher than the heat source outlet (22).

3. A vertical coating granulation equipment according to claim 2, characterized in that: A fixed outer cover (5) is provided on the top of the rotating central cylinder (3), a material outlet (51) is provided on the fixed outer cover (5), and a plurality of scrapers (31) are provided on the outer wall of the rotating central cylinder (3) located inside the fixed outer cover (5).

4. A vertical coating granulation equipment according to claim 3, characterized in that: Ribs (32) are provided on the outer wall of the rotating central cylinder (3), and a plurality of ribs (32) are provided at intervals along the axial direction of the rotating central cylinder (3).

5. The vertical coating granulation equipment according to claim 4, characterized in that: Cylinder stirring teeth (33) are provided on the inner wall of the rotating central cylinder (3), and a plurality of cylinder stirring teeth (33) are provided at intervals along the axial direction of the rotating central cylinder (3).

6. The vertical coating granulation equipment according to claim 5, characterized in that: The rotating central cylinder (3) rotates in the opposite direction to the rotating shaft (41).

7. The vertical coating granulation equipment according to claim 6, characterized in that: A guide member (6) is provided in the rotating central cylinder (3), and the guide member (6) includes a guide ring (61) and a fixing rod (62). One end of the fixing rod (62) is connected to the wall of the rotating central cylinder (3), and the other end is connected to the guide ring (61). The rotating shaft (41) passes through the guide ring (61).

8. The vertical coating granulation equipment according to claim 7, characterized in that: The contact point between the guide member (6) and the rotating shaft (41) is the polished rod section (47).

9. A method for coating and granulating a graphite negative electrode material, characterized in that: The coating granulation is carried out using the device according to any one of claims 1 to 8, comprising the following steps: Step 1: The material enters the material channel and first exchanges heat with the heat source in the heat source channel to preheat the material at room temperature; Step 2: The preheated material is transported through the stirring device (4) into the rotating central cylinder (3), where the material and the heat source undergo countercurrent heat exchange to form a coated granule; Step 3: The coated and granulated material is transported out of the rotating central cylinder (3) by the stirring device (4). The volatile matter generated during the coating and granulation process is burned to become high-temperature flue gas and then re-enters the heat source channel.

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