Pre-carbonization system and method for graphite materials

Abstract

The present disclosure relates to the technical field of graphite material pre-carbonization. Provided are a pre-carbonization system and method for graphite materials. The pre-carbonization system comprises a kiln body, a positive-electrode rail, a negative-electrode rail, a kiln car, and a crucible, wherein the kiln body is provided with a tunnel cavity extending in a first direction and an oxygen-free gas inlet and an exhaust gas outlet that are in communication with the tunnel cavity, the tunnel cavity comprises a heating zone and a cooling zone that are in communication with each other, and the heating zone and the cooling zone are arranged along a direction from the head of the kiln body to the tail of the kiln body; the heating zone is provided with the positive-electrode rail and the negative-electrode rail that are spaced apart along a second direction, and both the positive-electrode rail and the negative-electrode rail extend along the first direction and are connected to a power supply; and the crucible is mounted on the kiln car, is configured to load a powder material, is adapted to movably connect to the positive-electrode rail and the negative-electrode rail, and can conduct electricity when the power supply energizes the positive-electrode rail and the negative-electrode rail, such that the powder material generates heat and heats up under the action of its own resistance. The present disclosure has a simple overall structure, high heating efficiency and low operating costs, and makes the properties of batches of powder materials uniform.

Description

Pre-carbonization system and method for graphite materials

[0001] Cross-reference to related applications

[0002] This disclosure claims priority and benefits to Chinese Patent Application No. 202411577731.2, filed on November 6, 2024, the entire contents of which are hereby incorporated by reference. Technical Field

[0003] This disclosure relates to the field of graphite precarbonization technology, and more particularly to a graphite precarbonization system and method. Background Technology

[0004] As the main electrode material for batteries, artificial graphite has core preparation processes including grinding, granulation, graphitization, and finished product processing. Among these processes, graphitization generates a large amount of volatiles, which can lead to poor material adhesion and venting. Therefore, pre-carbonization is usually required before graphitization to remove the volatiles contained in the precursor, reduce the pressure of the graphitization process, and improve production safety.

[0005] In related technologies, the equipment used for graphite precarbonization is mainly a tunnel kiln. By loading powdered materials containing petroleum coke into a graphite crucible, and then placing the graphite crucible on a kiln car to enter the tunnel kiln, the tunnel kiln is heated by electric heating or gas heating, thereby heating the powdered materials. This method of heating powdered materials by means of indirect heat conduction is not only inefficient and requires high furnace insulation, but also results in most of the heat being lost during the heat transfer process, thus leading to high energy consumption. In addition, the furnace occupies a large area, and the production capacity contributed per unit plant area is relatively small. Summary of the Invention

[0006] This disclosure aims to at least partially address one of the technical problems in the related art.

[0007] To address the aforementioned technical problems, this disclosure provides a graphite material pre-carbonization system and method.

[0008] The graphite pre-carbonization system disclosed in this embodiment includes: a kiln body, a positive electrode track, a negative electrode track, a kiln car, and a crucible. The kiln body has a tunnel cavity extending along a first direction and an oxygen-insulating gas inlet and an exhaust gas outlet communicating with the tunnel cavity. The tunnel cavity includes a connected heating zone and a cooling zone, which are arranged in a direction from the head to the tail of the kiln body. The heating zone is provided with the positive electrode track and the negative electrode track arranged at intervals along a second direction, which forms an angle with the first direction. Both the positive electrode track and the negative electrode track extend along the first direction and are connected to a power supply. The crucible is mounted on the kiln car and is adapted to move along the tunnel cavity. The crucible is used to load powder material and is adapted to be movably connected to the positive electrode track and the negative electrode track. The crucible is conductive when the power supply energizes the positive electrode track and the negative electrode track, so that the powder material heats up under its own resistance.

[0009] According to the graphite pre-carbonization system of this disclosure, a tunnel kiln structure for graphite pre-carbonization is constructed by cooperating with a kiln body, a positive electrode track, a negative electrode track, and a power supply. During the movement of the kiln car along the tunnel cavity, the crucible moves and connects with the positive and negative electrode tracks. Simultaneously, the power supply energizes the positive and negative electrode tracks, forming a closed loop between the power supply, the positive electrode track, the crucible, and the negative electrode track. This makes the crucible and the powder material loaded inside it conductive. At this time, the crucible and the powder material loaded inside it act as a resistor in the closed loop. Since the petroleum coke in the powder material is conductive and heats up quickly, the powder material can self-heat due to its resistance as the crucible moves with the kiln car in the heating zone. An oxygen-free gas (such as nitrogen) enters the tunnel cavity through an oxygen-free gas inlet to create an oxygen-free atmosphere. The exhaust gas (i.e., volatile matter generated during the heating of the powder material)... Fumes (such as asphalt fumes) are discharged from the exhaust outlet. Afterward, the kiln car drives out of the kiln body through the cooling zone, thus completing the pre-carbonization treatment of the powder material. In addition, the powder material directly heats up using its own resistance, resulting in low heat loss and allowing for a large single loading capacity in the crucible. Furthermore, the method of heating the crucible by moving it within the tunnel cavity with the kiln car allows multiple kiln cars to be accommodated simultaneously in the same tunnel cavity, enabling continuous production of graphite material pre-carbonization. This results in a large production capacity per unit area of ​​the pre-carbonization system and ensures the uniformity of the performance of the powder material in batches under consistent production conditions. At the same time, the positive and negative tracks can also provide auxiliary support to the crucible as the kiln car moves along the heating zone, ensuring the smooth movement of the kiln car. Therefore, compared with related technologies, this disclosure has a simple overall structure, high heating efficiency, low operating cost, and uniform performance of the powder material in batches.

[0010] In some embodiments, the heating zone includes a heating section and a heat preservation section connected to each other, the heat preservation section being closer to the cooling zone than the heating section, and the heating section having the positive electrode track and the negative electrode track;

[0011] Alternatively, each of the heating section and the heat preservation section is provided with the positive electrode track and the negative electrode track, the power supply input power to the positive electrode track and the negative electrode track of the heating section is P1, the power supply input power to the positive electrode track and the negative electrode track of the heat preservation section is P2, and P1 > P2.

[0012] Understandably, because petroleum coke in powder materials has slow thermal conductivity and slow heat dissipation, once graphite material is heated to the pre-carbonization temperature, it only needs to maintain the pre-carbonization temperature for the designed duration to achieve pre-carbonization. Dividing the heating zone into a heating section and a holding section allows the graphite material to be rapidly heated by the high-power electrical energy input in the heating section, while the smaller power electrical energy input in the holding section keeps the graphite material warm. This ensures the quality of the graphite material pre-carbonization process while further optimizing energy allocation, reducing production costs, and avoiding energy waste.

[0013] In some embodiments, the pre-carbonization system further includes a first insulating track, of which there are two, one of which is connected between the positive electrode track of the heating section and the positive electrode track of the heat preservation section, and the other of which is connected between the negative electrode track of the heating section and the negative electrode track of the heat preservation section, and the crucible is adapted to be movably connected to the first insulating track.

[0014] It is understandable that by using a first insulating track to connect the conductive tracks (i.e., the positive and negative tracks) between the heating section and the insulation section, the conductive tracks controlled by voltages of different power in the heating section and the insulation section can be isolated to ensure the reliable operation of the entire pre-carbonization system.

[0015] In some embodiments, the oxygen-insulating gas inlet is located at the tail end of the kiln body, and the exhaust gas outlet is located at the head end of the kiln body.

[0016] It is understandable that placing the oxygen-insulating gas inlet at the tail end of the kiln and the exhaust gas outlet at the head end of the kiln can both cool the kiln cars, crucibles, and powder materials entering the cooling zone with the oxygen-insulating gas, and also allow the oxygen-insulating gas flowing from the cooling zone to the heating zone to quickly discharge the exhaust gas (i.e., volatile matter, asphalt fumes, etc.) generated during the heating process of the powder materials from the exhaust gas outlet, so as to prevent the problem of powder materials caking due to exhaust gas retention.

[0017] In some embodiments, the pre-carbonization system further includes a combustion furnace and a hot air inlet. The combustion furnace is located on the outer periphery of the kiln body and has an air inlet and an air outlet. The air inlet of the combustion furnace is connected to the exhaust gas outlet, and the air outlet of the combustion furnace is connected to the hot air inlet. The hot air inlet is located on the kiln body and is connected to at least one of the heating section and the heat preservation section.

[0018] It is understandable that a large amount of combustible gas is released after the powder material is carbonized. The combustible gas is recycled and burned in the combustion furnace. The heat generated is then recycled to the heating section or heat preservation section in the tunnel cavity through the hot air inlet, which realizes the full utilization of energy and reduces the pressure of exhaust gas treatment.

[0019] In some embodiments, the hot air inlet is located at the end of the cooling zone adjacent to the insulation section, so that the high-temperature hot air introduced through the hot air inlet can flow sequentially through the insulation section and the heating section.

[0020] Understandably, in order to maximize energy utilization, the hot air inlet is located near the insulation section in the cold air zone. With the help of nitrogen flow, the high-temperature hot air introduced by the hot air inlet can pass through the insulation section and the heating section, thereby assisting the heating zone in achieving pre-carbonization of powder materials, reducing the demand for electricity, and thus reducing the processing cost of graphite materials.

[0021] In some embodiments, an exhaust fan is also connected between the air inlet of the combustion furnace and the exhaust outlet, the exhaust fan being used to draw out the exhaust gas from the tunnel cavity.

[0022] In some embodiments, a blower is also connected between the gas outlet of the combustion furnace and the hot air inlet. The blower is used to send the high-temperature hot air in the combustion furnace into the tunnel cavity to heat the tunnel cavity.

[0023] Understandably, the design of the aforementioned exhaust fan and blower can further improve the smoothness of airflow in the entire pre-carbonization system, thereby ensuring the pre-carbonization efficiency of graphite materials.

[0024] In some embodiments, the pre-carbonization system further includes a second insulating track located in the cooling zone and adapted to be movably connected to the crucible, the second insulating track extending along the first direction;

[0025] There are two second insulating tracks. One of the second insulating tracks is connected to the end of the positive track of the insulation section away from the end of the heating section, and the other second insulating track is connected to the end of the negative track of the insulation section away from the end of the heating section.

[0026] Understandably, as the kiln car travels along the cooling zone, the second insulated track can continue to provide auxiliary support for the crucible, ensuring the kiln car moves smoothly and further optimizing the overall performance of the pre-carbonization system.

[0027] In some embodiments, the pre-carbonization system further includes a feeding zone and a feeding zone, both located on the outer periphery of the kiln body. The feeding zone is used to unload the pre-carbonized powder material in the crucible, and the feeding zone is used to load the powder material into the crucible.

[0028] In some embodiments, the feeding zone and the loading zone are arranged in a direction from the tail of the kiln body toward the head.

[0029] In some embodiments, the precarbonization system further includes a travel track, the kiln car being movably connected to the travel track, the travel track including a first track and a second track connected together, the first track being located within the tunnel cavity and extending along the first direction, the second track being located on the outer periphery of the kiln body, and at least a portion of the second track passing sequentially through the feeding area and the loading area.

[0030] In some embodiments, the kiln car includes a chassis and wheels, the crucible is mounted on the chassis, and the wheels are pivotally mounted on the chassis and adapted to travel along the kiln body;

[0031] The chassis is an insulating board, or the chassis is provided with an insulating coating, so as to insulate the kiln car from the crucible, avoid unnecessary waste of electrical energy, and at the same time ensure the operational safety of the pre-carbonization system.

[0032] In some embodiments, the pre-carbonization system further includes a partition connected to the chassis, the partition being two in number and spaced apart along the first direction, the partition defining a limiting cavity for accommodating the crucible.

[0033] In some embodiments, the partition is a high-temperature resistant thermal insulation partition, which may be one of a mullite partition and an aluminum silicate partition;

[0034] Alternatively, the partition may be provided with a high-temperature resistant insulation coating, which may be either a mullite layer or an aluminum silicate layer.

[0035] Another embodiment of the graphite material pre-carbonization method of this disclosure, based on the graphite material pre-carbonization system described in any of the above embodiments, the pre-carbonization method includes the following steps:

[0036] Preparation: Slidingly connect the crucible to both the positive and negative electrode tracks, and introduce oxygen-insulating gas into the tunnel cavity through the oxygen-insulating gas inlet. The crucible is installed on the kiln car and loaded with powder material.

[0037] Pre-carbonization involves the kiln car moving along the tunnel cavity, with the positive and negative tracks energized by a power supply. The crucible becomes conductive, causing the powder material to heat up due to its own resistance. The generated exhaust gas is discharged from the exhaust gas outlet until the kiln car leaves the kiln body, completing the pre-carbonization of the powder material.

[0038] The technical advantages of the graphite precarbonization method according to the embodiments of this disclosure are the same as those of the graphite precarbonization system described above, and will not be repeated here.

[0039] In some embodiments, after the pre-carbonization operation, the method further includes:

[0040] Unloading: Unload the pre-carbonized powder material from the crucible in the unloading area;

[0041] Loading: Reloading the powder material into the crucible in the feeding area.

[0042] In some embodiments, at least one kiln car is accommodated in the tunnel cavity, and when the previous kiln car is in the tunnel cavity, a set time interval is set to allow the next kiln car to enter the tunnel cavity. Attached Figure Description

[0043] Figure 1 is a schematic diagram of the structure of a graphite precarbonization system according to an embodiment of the present disclosure (the kiln car and crucible are not shown in the figure).

[0044] Figure 2 is a schematic diagram of the connection structure between the kiln body, kiln car and crucible in the graphite material precarbonization system of an embodiment of this disclosure.

[0045] Figure 3 is a schematic diagram of the connection structure between the kiln car, crucible and negative electrode track in the graphite material precarbonization system of an embodiment of this disclosure.

[0046] Figure 4 is a schematic flowchart of a graphite precarbonization method according to an embodiment of the present disclosure.

[0047] Figure 5 is a schematic flowchart of a graphite material precarbonization method according to another embodiment of this disclosure.

[0048] Attached reference numerals: 1. Kiln body; 11. Tunnel cavity; 111. Heating zone; 1111. Heating section; 1112. Insulation section; 112. Cooling zone; 12. Insulating gas inlet; 13. Tail gas outlet; 2. Positive track; 3. Negative track; 4. Kiln car; 41. Chassis; 42. Wheels; 5. Crucible; 6. First insulated track; 7. Combustion furnace; 8. Hot air inlet; 9. Second insulated track; 91. Third insulated track; 92. Feeding area; 93. Feeding area; 94. Traveling track. Detailed Implementation

[0049] Embodiments of this disclosure are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting it.

[0050] In related technologies, the equipment used for graphite precarbonization is mainly a tunnel kiln. By loading powdered materials containing petroleum coke into a graphite crucible, and then placing the graphite crucible on a kiln car to enter the tunnel kiln, the tunnel kiln is heated by electric heating or gas heating, thereby heating the powdered materials. This method of heating powdered materials by means of indirect heat conduction is not only inefficient and requires high furnace insulation, but also results in most of the heat being lost during the heat transfer process, thus leading to high energy consumption. In addition, the furnace occupies a large area, and the production capacity contributed per unit plant area is relatively small.

[0051] Based on the above-mentioned technical problems, this disclosure provides a graphite pre-carbonization system, which aims to reduce heat loss during the heat transfer process when heating powder materials to at least a certain extent, so as to achieve efficient heating of powder materials and effectively reduce energy consumption and operating costs.

[0052] Referring to Figures 1 to 3, an embodiment of the graphite material pre-carbonization system of this disclosure includes a kiln body 1, a positive electrode track 2, a negative electrode track 3, a kiln car 4, and a crucible 5. The kiln body 1 has a tunnel cavity 11 extending along a first direction and an oxygen-insulating gas inlet 12 and a tail gas outlet 13 communicating with the tunnel cavity 11. The tunnel cavity 11 includes a heating zone 111 and a cooling zone 112 communicating with each other. The heating zone 111 and the cooling zone 112 are arranged in a direction from the head to the tail of the kiln body 1. The heating zone 111 is provided with a direction along the first direction. Positive and negative tracks 2 and 3 are arranged at intervals in two directions, with the second direction forming an angle with the first direction. Both positive and negative tracks 2 and 3 extend along the first direction and are connected to the power supply. A crucible 5 is installed on the kiln car 4 and is adapted to move along the tunnel cavity 11. The crucible 5 is used to load powder materials and is adapted to be movably connected to the positive and negative tracks 2 and 3. The crucible 5 can conduct electricity when the power supply energizes the positive and negative tracks 2 and 3, so that the powder materials can heat up under their own resistance.

[0053] The graphite pre-carbonization system disclosed herein comprises a kiln body 1, a positive electrode track 2, a negative electrode track 3, and a power supply, forming a tunnel kiln structure for graphite pre-carbonization. As the kiln car 4 moves along the tunnel cavity 11, the crucible 5 moves and connects with the positive electrode track 2 and the negative electrode track 3. Simultaneously, the power supply energizes the positive electrode track 2 and the negative electrode track 3, forming a closed circuit between the power supply, the positive electrode track 2, the crucible 5, and the negative electrode track 3. This makes the crucible 5 and the powder material it contains conductive. At this time, the crucible 5 and the powder material it contains act as a resistor in the closed circuit. Since the petroleum coke in the powder material is conductive and heats up quickly, the powder material can self-heat due to its resistance as the crucible 5 moves with the kiln car 4 in the heating zone 111. An oxygen-free gas (such as nitrogen) enters the tunnel cavity 11 through the oxygen-free gas inlet 12 to create an oxygen-free atmosphere. The exhaust gas (i.e., the volatile matter produced during the heating of the powder material)... Fumes (such as asphalt fumes) are discharged from the exhaust outlet 13. Afterwards, the kiln car 4 drives out of the kiln body 1 through the cooling zone 112, thus completing the pre-carbonization treatment of the powder material. In addition, the powder material directly heats up by utilizing its own resistance, resulting in low heat loss. This allows for a larger single-filling capacity in the crucible 5. Furthermore, the method of moving and heating the crucible 5 within the tunnel cavity 11 along with the kiln car 4 also enables multiple kiln cars 4 to be accommodated simultaneously within the same tunnel cavity 11, achieving continuous production of graphite material pre-carbonization. This results in a large production capacity per unit area of ​​the pre-carbonization system. Under the same production conditions for the same batch of powder material, the uniformity of the powder material performance is ensured. At the same time, the positive electrode track 2 and the negative electrode track 3 can also provide auxiliary support for the crucible 5 when the kiln car 4 moves along the heating zone 111, ensuring the smooth movement of the kiln car 4. Therefore, compared with related technologies, the present disclosure has a simple overall structure, high heating efficiency, low operating cost, and uniform performance of batch powder materials.

[0054] Specifically, the first direction can be the front-to-back direction shown in the figure. The kiln body 1 can extend along the first direction. The head of the kiln body 1 corresponds to the front end of the kiln body 1 in the figure, and the tail end of the kiln body 1 corresponds to the rear end of the kiln body 1 in the figure. The tunnel cavity 11 is a tunnel-like space that runs through the kiln body 1. The power supply can be a copper busbar, and the positive electrode rail 2 and the negative electrode rail 3 can be connected to the copper busbar. Both the positive electrode rail 2 and the negative electrode rail 3 can be made of high-temperature resistant conductive materials, such as graphite, silicon carbide, etc. The heating zone 111 is located at the front end of the cooling zone 112 in the figure. The second direction can be the left-to-right direction shown in the figure. The oxygen-free gas (such as nitrogen) introduced into the oxygen-free gas inlet 12 must maintain an oxygen-free atmosphere in the tunnel cavity 11, that is, the oxygen concentration in the tunnel cavity 11 is less than 1000 ppm. The crucible 5 is not limited to a cubic or cuboid structure. The crucible 5 can be slidably connected to the positive electrode rail 2 through the positive electrode tab, and slidably connected to the negative electrode rail 3 through the negative electrode tab. The specifications of crucible 5 are affected by the inner diameter of tunnel cavity 11. For example, when the side length of a conventional tunnel cavity is 1.5m, the side length of crucible 5 can be 40cm, 50cm, 60cm, 80cm, 100cm, etc. The larger the crucible 5, the more powder material can be heated in a single batch, and the greater the production capacity. However, increasing the length of electrically heated powder material will increase the resistance, and a large amount of heat energy will accumulate near the electrode tab (positive electrode tab or negative electrode tab), causing local overheating and affecting the heating effect on the powder material.

[0055] Furthermore, in this disclosure, the tab is equivalent to a wire, while the powder material is the resistor. The size of the tab is determined based on the total amount of powder material and the total resistance. The higher the resistance, the wider the tab, similar to how the higher the power of an electrical appliance, the thicker the wire. The current carrying capacity of graphite electrodes is generally 10–12 A / cm. 2 Based on calculations, if the powder material filling crucible 5 is 80cm × 80cm × 60cm (with a filling height of 60cm), and the current is approximately 1000A, the required electrode area is 100cm². 2 The lower limit of the tab size is (80cm × 1.25cm). Since the contact with the conductive track needs to be considered, it should not be too small. It is recommended that the tab size be 80cm × 10cm.

[0056] Optionally, the nitrogen flow rate can be 200 Nm³. 3 / h, 400Nm 3 / h, 600Nm 3 / h, 800Nm 3 / h etc., of which the nitrogen gas flow rate is generally determined based on the inner diameter and temperature of the tunnel cavity 11 and the gas flow rate. Under unobstructed conditions, the gas flow rate needs to be 5-8m / s.

[0057] Optionally, the width of the positive electrode tab can be 5cm, 10cm, 15cm, 20cm, etc.

[0058] Referring to Figure 1, in some embodiments, the heating zone 111 includes a heating section 1111 and a heat preservation section 1112 connected to each other. The heat preservation section 1112 is closer to the cooling zone 112 than the heating section 1111. The heating section 1111 is provided with a positive electrode track 2 and a negative electrode track 3. In this case, the heat preservation section 1112 may not be limited to using the heat preservation method in the prior art to keep the powder material in the crucible 5 warm.

[0059] Alternatively, each of the heating section 1111 and the heat preservation section 1112 is provided with a positive rail 2 and a negative rail 3. The power supply input power to the positive rail 2 and negative rail 3 of the heating section 1111 is P1, and the power supply input power to the positive rail 2 and negative rail 3 of the heat preservation section 1112 is P2, where P1 > P2.

[0060] Understandably, because petroleum coke in powder materials has slow thermal conductivity and slow heat dissipation, once the graphite material is heated to the pre-carbonization temperature, it only needs to maintain the pre-carbonization temperature for the designed duration to achieve pre-carbonization. Dividing the heating zone 111 into a heating section 1111 and a heat preservation section 1112 allows the graphite material to be rapidly heated by the high-power electrical energy input into the heating section 1111, while the lower-power electrical energy input into the heat preservation section 1112 keeps the graphite material warm. This ensures the quality of the graphite material pre-carbonization process while further optimizing energy allocation, reducing production costs, and avoiding energy waste.

[0061] Specifically, both the heating section 1111 and the heat preservation section 1112 can be connected to a power supply via a transformer to facilitate control and adjustment of different input power to the heating section 1111 and the heat preservation section 1112. The heating section 1111, the heat preservation section 1112, and the cooling zone 112 can be arranged sequentially from front to back and connected to each other.

[0062] It should be noted that the specific length of the heating section 1111 can be designed according to the weight of the powder material loaded in the crucible 5, the heat transfer capacity, the heat transfer performance of the petroleum coke, the traveling speed of the kiln car 4, and the heating time. If the heating rate is fast, the length of the heating section 1111 can be shortened. The specific length of the holding section 1112 is generally determined by the traveling speed of the kiln car 4 and the holding time. Typically, the length of the heating section 1111 can be smaller, while the length of the holding section 1112 can be a middle value. For example, the length of the heating section 1111 can be 5m, 10m, 15m, etc., the length of the holding section 1112 can be 10m, 15m, 20m, etc., and the length of the cooling zone 112 can be 15m, 20m, 25m, etc. The input power of the heating section 1111 can be 600KW, 700KW, 800KW, 900KW, etc.

[0063] Referring to Figure 1, in some embodiments, the pre-carbonization system further includes a first insulating track 6. There are two first insulating tracks 6, one of which is connected between the positive electrode track 2 of the heating section 1111 and the positive electrode track 2 of the heat preservation section 1112, and the other is connected between the negative electrode track 3 of the heating section 1111 and the negative electrode track 3 of the heat preservation section 1112. The crucible 5 is adapted to be movably connected to the first insulating track 6.

[0064] It is understandable that by using the first insulating track 6 to connect the conductive tracks (i.e., the positive track 2 and the negative track 3) between the heating section 1111 and the heat preservation section 1112, the conductive tracks of the heating section 1111 and the heat preservation section 1112, which are controlled by voltages of different power, can be isolated to ensure the reliable operation of the entire pre-carbonization system.

[0065] Referring to Figure 1, in some embodiments, the oxygen-insulating gas inlet 12 is located at the tail end of the kiln body 1, and the exhaust gas outlet 13 is located at the head end of the kiln body 1.

[0066] It is understandable that the oxygen-insulating gas inlet 12 is located at the tail end of the kiln body 1, while the exhaust gas outlet 13 is located at the head end of the kiln body 1. This allows the oxygen-insulating gas to cool the kiln car 4, crucible 5, and powder materials entering the cooling zone 112. It also allows the oxygen-insulating gas flowing from the cooling zone 112 to the heating zone 111 to be quickly discharged from the exhaust gas outlet 13, which generates exhaust gas (i.e., volatile matter, asphalt fumes, etc.) during the heating process of the powder materials. This prevents the exhaust gas from accumulating and causing the powder materials to clump together.

[0067] Referring to Figure 1, in some embodiments, the pre-carbonization system further includes a combustion furnace 7 and a hot air inlet 8. The combustion furnace 7 is located on the outer periphery of the kiln body 1 and has an air inlet and an air outlet. The air inlet of the combustion furnace 7 is connected to the exhaust gas outlet 13, and the air outlet of the combustion furnace 7 is connected to the hot air inlet 8. The hot air inlet 8 is located on the kiln body 1 and is connected to at least one of the heating section 1111 and the heat preservation section 1112.

[0068] It is understandable that a large amount of combustible gas will be released after the powder material is carbonized. The combustible gas is recycled to the combustion furnace 7 for incineration, and the heat generated is then recycled to the heating section 1111 or the heat preservation section 1112 in the tunnel cavity 11 through the hot air inlet 8, which realizes the full utilization of energy and reduces the pressure of exhaust gas treatment.

[0069] Specifically, the combustion furnace 7 has a combustion chamber and a first burner and a second burner connected to the combustion chamber. The first burner is connected to the exhaust gas outlet 13 through an air inlet, and the second burner is connected to a natural gas source so that the exhaust gas and natural gas can burn in the combustion chamber to generate high-temperature hot gas.

[0070] Referring to Figure 1, in some embodiments, the hot air inlet 8 is located at the end of the cooling zone 112 adjacent to the insulation section 1112, that is, the hot air inlet 8 is located at the front end of the cooling zone 112, so that the high-temperature hot air introduced by the hot air inlet 8 can flow through the insulation section 1112 and the heating section 1111 in sequence.

[0071] Understandably, in order to maximize energy utilization, the hot air inlet 8 is positioned near the insulation section 1112 in the cold air zone. With the help of nitrogen flow, the high-temperature hot air introduced by the hot air inlet 8 can penetrate through the insulation section 1112 and the heating section 1111, thereby assisting the heating zone 111 in achieving pre-carbonization of powder materials, reducing power demand, and thus reducing the processing cost of graphite materials.

[0072] In some embodiments, an exhaust fan (not shown in the figure) is also connected between the air inlet of the combustion furnace 7 and the exhaust outlet 13. The exhaust fan is used to draw out the exhaust gas in the tunnel cavity 11.

[0073] In some embodiments, a blower (not shown in the figure) is also connected between the gas outlet of the combustion furnace 7 and the hot air inlet 8. The blower is used to send the high-temperature hot air in the combustion furnace 7 into the tunnel cavity 11 to heat the tunnel cavity 11.

[0074] Understandably, the design of the aforementioned exhaust fan and blower can further improve the smoothness of airflow in the entire pre-carbonization system, thereby ensuring the pre-carbonization efficiency of graphite materials.

[0075] Referring to Figure 1, in some embodiments, the pre-carbonization system further includes a second insulating track 9 located in the cooling zone 112 and adapted to be movably connected to the crucible 5, the second insulating track 9 extending along a first direction.

[0076] Furthermore, there are two second insulating tracks 9. One second insulating track 9 is connected to the end of the positive track 2 of the heat preservation section 1112 away from the end of the heating section 1111, and the other second insulating track 9 is connected to the end of the negative track 3 of the heat preservation section 1112 away from the end of the heating section 1111.

[0077] Understandably, as the kiln car 4 travels along the cooling zone 112, the second insulated track 9 can continue to provide auxiliary support for the crucible 5 to ensure the smooth movement of the kiln car 4 and further optimize the overall performance of the pre-carbonization system.

[0078] Specifically, the positive electrode track 2, negative electrode track 3, first insulating track 6, and second insulating track 9 can all have the same structure, which is beneficial for the smooth movement of the crucible 5 with the kiln car 4 within the tunnel cavity 11. In addition, since the kiln body 1 inlet does not need to be heated and cannot be heated (because petroleum coke is easily burned or oxidized when heated in air, which will affect the pre-carbonization quality of the graphite material), in order to ensure that the crucible 5 can be aligned with the conductive track in the heating zone 111, a third insulating track 91 can be installed at the kiln body 1 inlet. The third insulating track 91 extends along the first direction and its tail end is connected to the conductive track in the heating section. The specific structure of the third insulating track 91 is also the same as the aforementioned track structure, in order to reduce production difficulty and ensure the smooth movement of the crucible 5.

[0079] Referring to Figure 1, in some embodiments, the pre-carbonization system further includes a feeding zone 92 and a feeding zone 93. Both the feeding zone 92 and the feeding zone 93 are located on the outer periphery of the kiln body 1. Taking the figure as an example, the feeding zone 92 and the feeding zone 93 are located at the right end of the kiln body 1. The feeding zone 92 is used to unload the pre-carbonized powder material in the crucible 5, and the feeding zone 93 is used to load the powder material into the crucible 5.

[0080] Specifically, the specific structure and working principle of the unloading area 92 and the loading area 93 can be described using existing technologies in this field, and will not be elaborated here.

[0081] Referring to Figure 1, in some embodiments, the feeding zone 92 and the loading zone 93 are arranged in a direction from the tail to the head of the kiln body 1, that is, the feeding zone 92 is located at the rear end of the loading zone 93.

[0082] It is understandable that by adopting the above-mentioned arrangement of the unloading area 92 and the loading area 93, the unloading can be completed in the unloading area 92 and the loading can continue in the loading area 93 after the kiln car 4 leaves the rear of the kiln body 1. This ensures the continuity of the graphite pre-carbonization operation and makes the entire pre-carbonization system compact, scientific and reasonable.

[0083] Referring to Figures 1 and 2, in some embodiments, the precarbonization system further includes a travel track 94, to which the kiln car 4 is movably connected. The travel track 94 includes a first track and a second track connected together. The first track is located inside the tunnel cavity 11 and extends along a first direction. The second track is located on the outer periphery of the kiln body 1, and at least a portion of the second track passes through the feeding area 92 and the loading area 93 in sequence.

[0084] Understandably, the laying of the first and second tracks enables the kiln car 4 to continuously operate between the kiln body 1, the feeding zone 92, and the loading zone 93, further improving the automation performance and production efficiency of the pre-carbonization system.

[0085] Referring to Figures 2 and 3, in some embodiments, the kiln car 4 includes a chassis 41 and wheels 42. The crucible 5 is mounted on the chassis 41, and the wheels 42 are pivotally mounted on the chassis 41 and adapted to travel along the kiln body 1. That is, the wheels 42 can be rolledly connected to the travel track 94. The chassis 41 is an insulating plate, or the chassis 41 is provided with an insulating coating to make the kiln car 4 and the crucible 5 insulated from each other, avoiding unnecessary energy waste, and ensuring the operational safety of the pre-carbonization system.

[0086] Referring to Figure 2, in some embodiments, the pre-carbonization system also includes a partition (not shown in the figure), which is connected to the chassis 41. There are two partitions arranged at intervals along a first direction, that is, the partitions are arranged in the front and rear direction of the kiln car 4. A limiting cavity for accommodating the crucible 5 is defined between the two partitions.

[0087] Furthermore, the partition is a high-temperature resistant insulation partition, which can be either a mullite partition or an aluminum silicate partition.

[0088] Alternatively, the partition may be equipped with a high-temperature resistant insulation coating, which may be either a mullite layer or an aluminum silicate layer.

[0089] It is understandable that the partition confines the crucible 5 within the limiting cavity. Since the partition has high temperature resistance and heat preservation properties, it can keep the crucible 5 warm, further ensuring energy utilization.

[0090] Referring to Figure 2, in some embodiments, the crucible 5 has a receiving cavity with a top opening for loading powder material, wherein the loading height of the powder material is lower than the top of the receiving cavity.

[0091] In some embodiments, the height difference between the loading height of the powder material and the height of the top of the accommodating cavity is not less than 20 cm.

[0092] It should be noted that if the powder material completely fills the cavity, the powder material at the top is easily blown off by the nitrogen flow, resulting in loss. Therefore, the loading height of the powder material should be lower than the top of the cavity, and the height difference between the two should not be less than 20cm.

[0093] Referring to Figure 4, this disclosure proposes a method for pre-carbonizing graphite materials. Based on the graphite material pre-carbonization system of any of the above embodiments, the pre-carbonization method includes the following steps:

[0094] Step S1, Preparation: The crucible 5 is slidably connected to both the positive electrode track 2 and the negative electrode track 3. Insulation gas is introduced into the tunnel cavity 11 through the insulation gas inlet 12. The crucible 5 is installed on the kiln car 4 and loaded with powder material.

[0095] Step S2, pre-carbonization, involves the kiln car 4 moving along the tunnel cavity 11 and the power supply energizing the positive track 2 and the negative track 3. The crucible 5 becomes conductive, causing the powder material to heat up under its own resistance. The generated exhaust gas is discharged from the exhaust gas outlet 13 until the kiln car 4 leaves the kiln body 1, completing the pre-carbonization of the powder material.

[0096] The technical advantages of the graphite precarbonization method according to the embodiments of this disclosure are the same as those of the graphite precarbonization system described above, and will not be repeated here.

[0097] Referring to Figure 5, in some embodiments, after the pre-carbonization operation, the pre-carbonization method further includes:

[0098] Step S3, unloading: unload the pre-carbonized powder material in crucible 5 in the unloading area 92;

[0099] Step S4, loading: reload the powder material into the crucible 5 in the feeding area 93.

[0100] Therefore, in some embodiments of this disclosure, the graphite pre-carbonization method includes steps S1 and S2; in other embodiments, the graphite pre-carbonization method includes steps S1, S2, S3, and S4. Thus, the graphite pre-carbonization method of this disclosure can be either of the two methods described above.

[0101] Referring to Figures 4 and 5, in some embodiments, the tunnel cavity 11 accommodates at least one kiln car 4, and when the previous kiln car 4 is in the tunnel cavity 11, a set time interval is set to allow the next kiln car 4 to enter the tunnel cavity 11, so as to realize continuous production of graphite material pre-carbonization operation.

[0102] Specifically, this disclosure can generally accommodate 15-20 crucibles 5 to simultaneously carry out the pre-carbonization of graphite materials, which greatly reduces investment costs, improves production efficiency, and ensures the consistency of pre-carbonization performance of batch graphite materials.

[0103] The working process of this graphite pre-carbonization system will now be explained in detail, based on its specific structure:

[0104] 1) Move the kiln car 4 along the second track to the feeding area 93 and stop. Fill the crucible 5 with powder material through the pneumatic device of the feeding area 93 so that the filling height of the powder material is less than 20cm from the top of the accommodating cavity and scrape the powder material level.

[0105] 2) The kiln car 4 moves along the second track to the entrance of the kiln body 1, so that the traveling wheel 42 is aligned with the first track, and the positive and negative electrodes of the crucible 5 are respectively aligned with a third insulating track 91.

[0106] 3) Natural gas is introduced into the combustion furnace 7 for pre-burning. High-temperature hot air is introduced into the tunnel cavity 11 through the hot air inlet 8 so that the heating zone 111 is heated to 800°C for furnace baking. This prevents excessive temperature loss of powder materials during initial operation and avoids abnormal situations where the processing indicators are not up to standard. At the same time, the oxygen-insulating gas inlet 12 is opened to continuously introduce nitrogen into the tunnel cavity 11 from the cooling zone 112 at the designed speed.

[0107] 4) After the furnace drying is completed, the transformers of heating section 1111 and heat preservation section 1112 are switched on and energized.

[0108] 5) The kiln car 4 is driven by hydraulic pressure to enter the tunnel cavity 11 at a set running speed throughout the entire process. After the first kiln car 4 enters, the next kiln car 4 is sent in at set intervals. The heating section 1111 can accommodate up to 3 kiln cars 4 entering at the same time. The heat preservation section 1112 adjusts the input power in real time according to the operating conditions.

[0109] 6) Based on the increase in volatile matter content at tail gas outlet 13, gradually reduce the amount of natural gas supplied to combustion furnace 7.

[0110] Based on the following dimensions: heating section 1111 is 5m long, heat preservation section 1112 is 20m long, cooling zone 112 is 30m long, crucible 5 has dimensions of 80cm×80cm×80cm, the total amount of powder material is approximately 200KG, and the nitrogen flow rate at the aeration gas inlet 12 is 800Nm. 3 Taking a kiln car 4 traveling at a speed of 10 m / h and with a set interval of 10 min per car as an example, the volatile matter detection of the pre-carbonization system was tested by changing the power supply of the heating section 1111 and the heat preservation section 1112. Specifically, in Example 1, the power supply of the heating section 1111 was 700 kW and the power supply of the heat preservation section 1112 was 400 kW; in Example 2, the power supply of the heating section 1111 was 700 kW and the power supply of the heat preservation section 1112 was 200 kW; and in Example 3, the power supply of the heating section 1111 was 500 kW and the power supply of the heat preservation section 1112 was 200 kW. The volatile matter detection results for different batches are shown in Table 1 below.

[0111] Table 1. Detection results of volatile matter in different batches

[0112] As shown in Table 1, batch A01, which is the first batch during furnace startup, experienced unstable atmosphere after the furnace drying process, resulting in higher volatile matter levels compared to a stable state. However, it can be observed that in Example 1, the volatile matter levels remained below 1%. In Examples 2 and 3, the volatile matter levels were higher due to reduced heat preservation and heating power. As the kiln 1 operated, the volatile matter levels across different batches stabilized, indicating that the heat preservation section 1112 and heating section 1111 of the kiln 1 were approaching a steady state. The table shows that Examples 1 and 2, during stable operation, consistently achieved a volatile matter level <1% after pre-carbonization. This suggests that when the power supply to the heating section 1111 is 700KW, the power supply to the heat preservation section 1112 can be reduced. This is because the heating of the atmosphere in the heat preservation section 1112 and heating section 1111 by the combustion furnace 7 reduces heat dissipation from the crucible 5, requiring only lower power for heat preservation of the powder material. Comparing Examples 2 and 3, while keeping the power supply of the insulation section 1112 constant at 200KW, the power supply of the heating section 1111 was reduced. The volatile matter content of the pre-carbonized powder material could not meet the process requirements. It is speculated that the reduced power supply of the heating section 1111 prevented the powder material from reaching the target temperature, resulting in a slow rate of volatile matter release. Under a constant insulation time, the target could not be met. This result also indicates that the length of the insulation section 1112 has basically reached the minimum critical value and cannot be further shortened.

[0113] In addition, samples were taken from different positions of the material layer in crucible 5 of batch A09 in Example 2 to test whether there was any inhomogeneity inside crucible 5 during the direct heating process. The results are shown in Table 2 below. The analysis of the results shows that the performance of each layer and position remained basically uniform after processing, indicating that the direct heating method of this disclosure will not cause uneven processing of materials in different areas of crucible 5.

[0114] Table 2. Volatile matter detection results at different locations in different material layers.

[0115] Based on the feeding process calculations, Examples 1 to 3 had a running time of 4 hours and a total processing capacity of 5 tons. The energy consumption statistics for each example are shown in Table 3. Example 2 had lower energy consumption and met the process requirement of <1% volatile matter after calcination. The average energy consumption per ton of material processed in Example 2 was 728 kWh / ton. Compared to a traditional electrically heated tunnel kiln, the direct electric heating method consumes approximately 30% of the electricity, significantly reducing processing costs.

[0116] It should be added that, as the pre-carbonization process stabilizes, the volatile matter of the powder material can gradually fully meet the requirements of the combustion furnace 7, and the natural gas consumption gradually decreases. At the same time, due to the heat supply of the combustion furnace 7, the average power of the insulation section 1112 shows a continuous downward trend, indicating that the tunnel kiln scheme disclosed in this paper can further optimize energy consumption during operation.

[0117] Table 3 Energy Consumption Statistics for Each Implementation Example

[0118] Therefore, compared with related technologies, this disclosure has the following advantages:

[0119] 1) Compared with traditional tunnel kiln for petroleum coke precarbonization, the actual power consumption of this disclosure is reduced by 70%, which improves energy utilization efficiency and greatly reduces the processing cost of graphite anode.

[0120] 2) The tunnel kiln structure of the direct heating method has been tested and found that the material inside crucible 5 is heated relatively evenly, the process parameters of the material in different areas are uniform, and the performance of the product processed in a single batch is evenly distributed.

[0121] 3) The direct heating method tunnel kiln structure makes full use of the combustibility of volatiles, and the heat energy is fully utilized after combustion in the combustion furnace 7, while reducing the pressure of tail gas treatment.

[0122] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 this disclosure and simplifying the description, and are not intended to 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 this disclosure.

[0123] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0124] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0125] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0126] In this disclosure, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0127] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A graphite material pre-carbonization system, comprising: The kiln body (1) has a tunnel cavity (11) extending along a first direction and an oxygen-insulating gas inlet (12) and a tail gas outlet (13) communicating with the tunnel cavity (11). The tunnel cavity (11) includes a heating zone (111) and a cooling zone (112) communicating with each other. The heating zone (111) and the cooling zone (112) are arranged in a direction from the head to the tail of the kiln body (1). Positive electrode track (2) and negative electrode track (3), the heating zone (111) is provided with the positive electrode track (2) and the negative electrode track (3) arranged at intervals along a second direction, the second direction is at an angle to the first direction, the positive electrode track (2) and the negative electrode track (3) both extend along the first direction and are connected to the power supply; as well as A kiln car (4) and a crucible (5), wherein the crucible (5) is mounted on the kiln car (4) and is adapted to travel along the tunnel cavity (11), the crucible (5) is used to load powder material and is adapted to be movably connected to the positive electrode track (2) and the negative electrode track (3), and the crucible (5) is conductive when the power supply energizes the positive electrode track (2) and the negative electrode track (3) so that the powder material heats up under its own resistance.

2. The graphite material pre-carbonization system according to claim 1, wherein, The heating zone (111) includes a heating section (1111) and a heat preservation section (1112) that are connected to each other. The heat preservation section (1112) is closer to the cooling zone (112) than the heating section (1111). The heating section (1111) is provided with the positive electrode track (2) and the negative electrode track (3). Alternatively, each of the heating section (1111) and the heat preservation section (1112) may be provided with the positive electrode track (2) and the negative electrode track (3), the power supply input power to the positive electrode track (2) and the negative electrode track (3) of the heating section (1111) is P1, and the power supply input power to the positive electrode track (2) and the negative electrode track (3) of the heat preservation section (1112) is P2, where P1 > P2.

3. The graphite material pre-carbonization system according to claim 2, wherein, It also includes a first insulating track (6), of which there are two. One of the first insulating tracks (6) is connected between the positive track (2) of the heating section (1111) and the positive track (2) of the heat preservation section (1112), and the other first insulating track (6) is connected between the negative track (3) of the heating section (1111) and the negative track (3) of the heat preservation section (1112). The crucible (5) is adapted to be movably connected to the first insulating track (6).

4. The graphite material pre-carbonization system according to any one of claims 1-3, wherein, The oxygen-insulating gas inlet (12) is located at the tail end of the kiln body (1), and the exhaust gas outlet (13) is located at the head end of the kiln body (1).

5. The graphite material pre-carbonization system according to any one of claims 2-4, wherein, It also includes a combustion furnace (7) and a hot air inlet (8). The combustion furnace (7) is located on the outer periphery of the kiln body (1) and has an air inlet and an air outlet. The air inlet of the combustion furnace (7) is connected to the exhaust gas outlet (13), and the air outlet of the combustion furnace (7) is connected to the hot air inlet (8). The hot air inlet (8) is located on the kiln body (1) and is connected to at least one of the heating section (1111) and the heat preservation section (1112). And / or, the hot air inlet (8) is located at the end of the cooling zone (112) adjacent to the heat preservation section (1112) so that the high-temperature hot air introduced by the hot air inlet (8) can flow through the heat preservation section (1112) and the heating section (1111) in sequence.

6. The graphite material pre-carbonization system according to claim 5, wherein, A blower is also connected between the air inlet of the combustion furnace (7) and the exhaust outlet (13), and the blower is used to draw out the exhaust gas in the tunnel cavity (11).

7. The graphite material pre-carbonization system according to claim 5 or 6, wherein, A blower is also connected between the air outlet of the combustion furnace (7) and the hot air inlet (8). The blower is used to send the high-temperature hot air in the combustion furnace (7) into the tunnel cavity (11) to heat the tunnel cavity (11).

8. The graphite material pre-carbonization system according to any one of claims 2-7, wherein, It also includes a second insulating track (9) located in the cooling zone (112) and adapted to be movably connected to the crucible (5), the second insulating track (9) extending along the first direction; There are two second insulating tracks (9). One of the second insulating tracks (9) is connected to the positive track (2) of the heat preservation section (1112) away from the end of the heating section (1111). The other second insulating track (9) is connected to the negative track (3) of the heat preservation section (1112) away from the end of the heating section (1111).

9. A method for pre-carbonizing graphite materials, based on the graphite material pre-carbonization system as described in any one of claims 1-8, wherein, Includes the following steps: Prepare by sliding the crucible (5) to both the positive electrode track (2) and the negative electrode track (3), and introducing oxygen gas into the tunnel cavity (11) through the oxygen gas inlet (12). The crucible (5) is installed on the kiln car (4) and loaded with powder material. Pre-carbonization is performed by having the kiln car (4) move along the tunnel cavity (11) and powering the positive track (2) and the negative track (3) with a power supply. The crucible (5) becomes conductive and the powder material heats up under its own resistance. The generated exhaust gas is discharged from the exhaust gas outlet (13) until the kiln car (4) leaves the kiln body (1), thus completing the pre-carbonization of the powder material.

10. The method for pre-carbonizing graphite materials according to claim 9, wherein, The tunnel cavity (11) can accommodate at least one kiln car (4), and when the previous kiln car (4) is in the tunnel cavity (11), the next kiln car (4) enters the tunnel cavity (11) at intervals of a set time.

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