A vertical continuous graphitization method based on heat absorption and release regulation

Abstract

The application discloses a vertical continuous graphitization method based on heat absorption and release regulation, and relates to the technical field of carbon material preparation. The application discloses a vertical continuous graphitization method based on heat absorption and release regulation, and relates to the technical field of carbon material preparation. The method comprises the following steps: starting to apply heat energy to the material, preheating and dehydrating the material; continuously applying heat energy to the material, driving the material temperature to rise, until the spontaneous temperature rising phenomenon of the material which is independent of external power is monitored in real time; reducing the external heat energy input to a preset value, so that the material continues to rise in temperature to a target peak temperature under the condition that the self-heat release reaction serves as a driving force; and stopping or reducing the external heat energy input, so that the material is cooled to a target discharge temperature at a controlled cooling rate. The application takes real-time temperature sensing as a judgment basis, actively identifies the time point when the material changes from the heat absorption stage to the heat release stage, and implements a differentiated power input and material running speed control strategy accordingly, so that the internal optimization utilization of energy in the graphitization process is realized, and the double goals of energy saving and consumption reduction and product quality improvement are achieved.

Description

Technical Field

[0001] This invention relates to the field of carbon material preparation technology, specifically a vertical continuous graphitization method based on endothermic and exothermic regulation. Background Technology

[0002] Artificial graphite materials are key materials in fields such as lithium-ion battery anodes, special metallurgy, and the nuclear industry. Their performance directly depends on the degree of graphitization, which is mainly achieved through high-temperature heat treatment (i.e., the graphitization process).

[0003] Calcined coke is the main raw material for the production of artificial graphite. Currently, the Atchison furnace and box furnace widely used in industry suffer from problems such as extremely high energy consumption, long production cycles, poor temperature uniformity, and severe environmental pollution. Vertical continuous graphitization furnaces, as an advanced type of equipment, have potential advantages such as high thermal efficiency, continuous production, and energy conservation and environmental protection; however, process control for processing calcined coke still faces challenges.

[0004] The deficiency in existing technologies lies in the fact that graphitization is generally considered a simple endothermic process, thus the focus is on how to efficiently provide heat from the outside. However, after in-depth research, the applicant discovered that calcined coke exhibits complex intrinsic thermal effects during graphitization: in a specific temperature range (approximately 1500℃-2200℃), processes such as carbon atom rearrangement and heteroatom removal are primarily endothermic reactions; while in higher temperature ranges (approximately 2200℃-2800℃), the rapid growth and merging of the carbon hexagonal network layer are accompanied by significant exothermic reactions. Existing technologies have failed to identify and utilize this intrinsic thermodynamic characteristic, leading to the following issues in vertical continuous graphitization furnaces: 1. Inappropriate energy configuration, local overheating or insufficient heating, affects product consistency.

[0005] 2. It is impossible to fully utilize the heat released by the reaction itself to reduce the total energy consumption.

[0006] 3. The temperature control curve does not match the evolution of the material's microstructure, affecting the final degree of graphitization.

[0007] Therefore, developing a new method that can accurately identify and control the intrinsic endothermic and exothermic reactions in the graphitization process is crucial for achieving high-quality, low-energy continuous graphitization production. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology in the improper energy configuration of graphitization, and to provide a vertical continuous graphitization method based on heat absorption and release regulation, so as to realize the internal optimization of energy utilization during the graphitization process and achieve the dual goals of energy saving and consumption reduction and product quality improvement.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A vertical continuous graphitization method based on endothermic and exothermic regulation utilizes a vertical continuous graphitization furnace to continuously graphitize calcined coke. The process steps of this method include: S1: The material is added from the top of the furnace. Under the combined action of the residual heat in the furnace and the external heating, the temperature gradually rises from room temperature to 800℃~1000℃. This mainly completes the removal of physically adsorbed moisture and some crystal water on the surface of the material, while also homogenizing the thermal state of the material to prepare for subsequent high-temperature forced heating. S2: The system continuously applies heat energy by heating the material itself through resistance (i.e., current is conducted through the material column), causing the material temperature to rise rapidly from about 1500°C to about 2200°C. In this range, the system continuously applies heat energy to the material at rated power, driving strong endothermic reactions such as carbon lattice rearrangement, transformation of disordered structure to ordered structure, and removal of heteroatoms. At the same time, the system activates real-time temperature monitoring to determine whether the material has entered the exothermic transformation zone. S3: When the system detects that the material spontaneously heats up without relying on external power increase under the condition of constant external power input, it determines that the material has entered the exothermic crystallization stage; the system responds immediately, adopts a ramp power reduction method to reduce the external heat energy input to the maintenance power, and simultaneously implements linkage adjustment of the material's travel speed based on the material's temperature rise rate dT / dt and / or temperature deviation ΔT, so that the material continues to heat up to the target peak temperature (2800℃±50℃) under the condition of its own exothermic reaction as the driving force, while preventing local overheating; S4: After the material reaches the peak temperature, it enters the homogenization and slow cooling section; the system stops or maintains the external heating input at a very low power, and controls the cooling rate by adjusting the material's travel speed, so that the material is slowly cooled to the target furnace temperature (150℃~250℃) within 1 to 3 hours and then discharged from the furnace, so as to ensure the integrity and stability of the product's microstructure and avoid thermal stress cracking.

[0010] Preferably, the determination of the spontaneous heating phenomenon adopts at least one of the following quantitative criteria: Criterion 1: Under the condition that the external energy input power remains unchanged, the measured temperature change rate dT / dt of the material is greater than or equal to the preset threshold α, and the duration of this state t is not less than the preset confirmation time t0; the value of α is in the range of 5℃ / min to 20℃ / min, and the value of t0 is in the range of 3s to 60s.

[0011] Criterion 2: The positive deviation ΔT of the measured temperature of the material from the theoretical expected temperature under the current power (or the extrapolated temperature under the previous stable state) is greater than or equal to the preset threshold β, and the duration is not less than t0; the value of β is in the range of 10℃~80℃, and t0 is the same as above.

[0012] Preferably, the starting trigger temperature for real-time temperature monitoring is set to 2000℃~2300℃. The system will not activate the exothermic conversion judgment logic when the temperature is below this trigger temperature in order to avoid misjudgment.

[0013] Preferably, the ramp power reduction method in S3 is as follows: after the spontaneous heating determination is established, the external power input decreases linearly at a constant slope of 10% to 20% of the rated power per minute until it reaches the maintenance power (generally 10% to 20% of the rated power) and remains stable; the speed linkage control strategy is as follows: when dT / dt increases and / or ΔT increases, the material travel speed is increased so that the material passes through the heat release peak area faster; when dT / dt decreases and / or ΔT decreases, the material travel speed is reduced to prolong the residence time of the material in the effective heat release zone; through the above bidirectional adjustment, the material temperature in the heat release section is maintained within a reasonable range of 2200℃ to 2800℃ and proceeds smoothly.

[0014] Preferably, before S1, a material pretreatment step is also included: the calcined coke raw material is strictly screened and graded according to the particle size range, and only materials with a particle size distribution range not exceeding ±30% of the median particle size are used in the same furnace to ensure the uniformity of resistance and heating consistency within the material column and to suppress local overheating or heating blind spots caused by particle size differences.

[0015] The basic principle of this invention is as follows: The transformation of carbon materials from an amorphous or disordered layered structure to an ideal graphite crystal structure is a thermally activated process in which the total free energy (G) of the system decreases monotonically, following the fundamental thermodynamic relationship: G = H − TS. Here, H is the enthalpy of the system, T is the thermodynamic temperature, and S is the entropy of the system. The driving force of the graphitization transformation originates from the lower free energy state of ordered graphite crystals. The transformation path involves a complex competition between enthalpy change (ΔH, i.e., thermal effect) and entropy change (ΔS, i.e., change in orderliness), which directly determines the direction and intensity of the thermal effect at different temperature stages.

[0016] The first stage is a highly endothermic temperature range (approximately 1500℃~2200℃), during which carbon materials undergo the following key microscopic processes: First, the heteroatom bonds are completely broken. The remaining strong covalent bonds, such as C-H, C-O, C-N, and C-S, are then completely broken under thermal activation, releasing volatile gases such as H2, CO, CO2, H2S, and N2. The bond energies of these bonds are all in the range of 200–800 kJ / mol, and the bond-breaking process requires a large amount of energy to be absorbed from the outside.

[0017] Secondly, the highly disordered carbon layers in the calcined coke begin to overcome interlayer van der Waals forces and steric hindrance under thermal drive, undergoing local translation and rotation to achieve initial alignment of the carbon layers. During this process, the system evolves from a high-entropy disordered state to a low-entropy ordered state. According to thermodynamic principles, in order to maintain the continuous decrease in free energy, the system must use heat provided by the environment (i.e., external heating) to compensate for the increase in free energy caused by the decrease in entropy, which macroscopically manifests as a strong net endothermic reaction.

[0018] During this stage, the resistivity of the material begins to decrease significantly (from approximately 10). -3 Ω·m decreased to 10 -5 The interlayer spacing d002, measured by X-ray diffraction (XRD), decreases slowly from >0.340 nm (on the order of Ω·m), but the D peak representing disordered carbon in the Raman spectrum (around 1350 cm⁻¹) remains constant. -1 Relative G peak (approximately 1580 cm) -1 The intensity ratio (ID / IG) remains high, indicating that structural disorder still dominates. External high-energy input is an absolutely necessary condition for triggering and maintaining the graphitization process at this stage.

[0019] The second stage is the exothermic conversion and crystallization range (approximately 2200℃~2800℃). In this stage, after the carbon layer has completed initial ordering, the system enters the crystallization stage driven by enthalpy reduction (ΔH<0). First, the carbon hexagonal lattice layer grows rapidly. At the initially aligned edges of adjacent carbon hexagonal planes, numerous dangling bonds approach each other and spontaneously form new C-C σ-bond covalent networks. The lateral size and stacking height of the carbon domains increase dramatically. Many small domains merge through grain boundary elimination into a few large, highly intact graphite crystals. During this domain merging process, carbon atoms relax from high-energy grain boundary states or twisted bonding states to perfect sp... 2 In the lowest energy state within the plane of hybrid graphene, the C-C bond length and bond angle tend to ideal values, and the total enthalpy of the system is significantly reduced. The released energy, namely the latent heat of crystallization or grain boundary elimination energy, is dissipated to the surroundings in the form of heat. This mechanism is highly similar to the thermodynamic nature of the release of latent heat of solidification during the solidification of metal alloys or the release of heat by grain boundary elimination in the later stage of ceramic sintering.

[0020] This stage is a crucial basis for determining the implementation of this invention. Under quasi-adiabatic or adiabatic monitoring conditions, it can be observed that the internal temperature of the material continues to rise even when the external input power does not increase or even decreases, i.e., a "spontaneous heating" phenomenon. The heating rate dT / dt and the positive deviation ΔT between the measured temperature and the expected temperature both exceed preset thresholds. Simultaneously, XRD measurements of d... 002The wavelength rapidly approaches the ideal value of 0.3354 nm, the full width at half maximum (FWHM) of the G peak in the Raman spectrum narrows sharply, and the ID / IG ratio rapidly decreases to below 0.1, indicating that the graphite crystal structure is approaching perfection. The applicant's quantitative research shows that the material's own exothermic reaction contributes as much as 78%–82% to the total heat increase during this stage, while external electrical energy only needs to play a supplementary role of about 20%.

[0021] The third stage is the structural relaxation and stability region (>2800℃). Above 2800℃, the main graphitization reaction tends to be completed, and the remaining processes mainly involve dislocation slip, lattice stress relaxation, and further volatilization of a small number of residual heteroatoms. The thermal effect is weak in this stage, and the process is controlled by diffusion kinetics. Excessive external heating input contributes little to further structural refinement and may instead cause carbon sublimation loss (sublimation point approximately 3642℃) or exacerbate high-temperature evaporative corrosion. Therefore, active heating should be stopped and controlled cooling should be initiated.

[0022] Compared with the prior art, the beneficial effects of the present invention are: 1. By actively identifying and fully utilizing the latent heat of crystallization released by the material itself, the external input power of this stage is reduced, ultimately reducing the overall energy consumption of the process.

[0023] 2. The segmented temperature control strategy ensures that the material undergoes heat treatment at each stage that is highly matched to the needs of its microstructure evolution, effectively avoiding thermal damage to carbon crystals caused by local overheating and incomplete graphitization caused by local underheating. Compared with the comparative process, the graphitization degree of the product obtained by this invention can stably reach 96%.

[0024] 3. By sensing the exothermic transformation in real time and responding quickly to reduce external power input, the system effectively avoids localized ultra-high temperatures caused by the superposition of exothermic reactions and external heating. This significantly reduces thermal shock damage to the high-temperature refractory lining, graphitized heating elements, and conductive system inside the furnace, extending the service life of the equipment and reducing equipment maintenance costs.

[0025] The technical solution of the present invention will be further described in detail below through embodiments. Attached Figure Description

[0026] Figure 1 A flowchart of the graphitization method provided by the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by those skilled in the art.

[0028] First, let's introduce the equipment, which mainly consists of the following components: Furnace body: A vertically arranged, enclosed graphitization reactor with a furnace height of 8 to 15 meters (11 meters is used in this embodiment). The cross-sectional area of ​​the furnace chamber is determined according to the designed production capacity.

[0029] Segmented heating system: The furnace body is divided into at least four independent and controllable temperature control functional sections in the height direction. Each section is equipped with an independent power input interface and adjustment unit, which supports independent setting and dynamic adjustment of the power of each section.

[0030] Transmission system: The continuous feeding mechanism driven by a variable frequency motor can steplessly adjust the downward speed of the material in the furnace within the range of 0.5m / h to 5m / h, i.e. the material travel speed.

[0031] Temperature sensing and monitoring system: Multiple thermocouples and / or high-temperature fiber optic temperature measuring instruments are installed in each functional section to realize real-time multi-point monitoring of the temperature field of the material column; the data acquisition frequency is not less than 1Hz, and it has the ability to calculate dT / dt (temperature change rate) and ΔT (temperature deviation) in real time.

[0032] Control Unit (PLC / DCS): Integrates the above-mentioned sensor data, executes the exothermic conversion judgment logic, and sends linkage control commands to the power regulation unit and the transmission system; supports users to set various judgment thresholds (α, β, t0) and process parameters such as power reduction slope.

[0033] like Figure 1 As shown, the specific content of this method includes: S1: In this stage, the material is located in the upper part of the furnace body, with a temperature range of room temperature to 800℃ (outlet temperature approximately 800℃ to 1000℃). It mainly utilizes the residual heat from conduction / radiation in the downstream high-temperature section, supplemented by a small amount of external heating, to remove surface moisture (physically adsorbed water) and crystal water from the material, and to homogenize the material temperature distribution. Material in this stage is continuously added from the top of the vertical feed pipe. The material distribution method should ensure a dense and uniform material column, avoiding bridging and voids.

[0034] S2, this stage is located in the upper middle part of the furnace, with a temperature range of 1500℃ to 2200℃. Current is passed through the material column, utilizing the material's own resistance to generate heat (i.e., direct resistance heating of the material column) to rapidly raise the material temperature from approximately 1500℃ to 2200℃. This stage should maintain a constant high power input (rated power) to ensure sufficient external energy to drive the strongly endothermic carbon lattice rearrangement and heteroatom removal reactions. When the temperature at each monitoring point inside the furnace reaches the range of 2000℃ to 2300℃, preferably 2200℃, the control system activates the real-time exothermic transition determination program. After activation, at least one of the following quantitative criteria will be used: Criterion 1: Under the condition that the external energy input power remains unchanged, the measured temperature change rate dT / dt of the material is greater than or equal to the preset threshold α, and the duration of this state t is not less than the preset confirmation time t0; the value of α is in the range of 5℃ / min to 20℃ / min, and the value of t0 is in the range of 3s to 60s.

[0035] Criterion 2: The positive deviation ΔT of the measured temperature of the material from the theoretical expected temperature under the current power (or the extrapolated temperature under the previous stable state) is greater than or equal to the preset threshold β, and the duration is not less than t0; the value of β is in the range of 10℃~80℃, and t0 is the same as above.

[0036] S3, this stage is located in the lower middle part of the furnace body, with a temperature range of 2200℃~2800℃. Once the exothermic transition judgment logic confirms that the material has entered the exothermic-dominant stage, the control system executes the following linked control actions: Power ramp reduction: The external input power decreases linearly at a constant slope of 10% to 20% of the rated power per minute until it drops to the sustaining power (approximately 10% to 20% of the rated power to compensate for necessary heat loss), after which the power remains stable.

[0037] Speed-linked regulation: Based on the real-time calculations of dT / dt and ΔT by the control system, the material's downward speed is dynamically adjusted according to the following rules: When dT / dt ≥ threshold α or ΔT ≥ threshold β (exothermic heat release is too intense), the material's downward speed is moderately increased to increase the amount of material in that temperature range per unit time, which is equivalent to increasing the heat absorption capacity, thereby suppressing overheating; when dT / dt < threshold α or ΔT < threshold β (exothermic heat release tends to be gradual), the material's downward speed is moderately reduced to prolong the material's residence time in the heat release zone, ensuring that heat release is fully completed. Through the above dynamic adjustment, the material temperature is controlled and steadily increased to its peak value within the range of 2200℃~2800℃.

[0038] S4, this stage is located in the lower part of the furnace body, with a temperature control range of 2800℃→150℃~250℃. In this stage, external active heating stops, and the material cools slowly at a controlled rate using its own sensible heat. By adjusting the material's downward flow speed in conjunction with an active cooling system (such as a water-cooled jacket or inert gas cooling circulation), the cooling rate is controlled within a reasonable range (generally not exceeding 100℃ / min), allowing the material to cool to 150℃~250℃, preferably 200℃, within approximately 1~3 hours. The material is then discharged from the bottom of the furnace to avoid excessively rapid cooling that could lead to thermal stress cracks.

[0039] To fully verify the technical effects of this invention, a systematic comparative experiment was conducted. All experiments used the same batch of petroleum-based calcined coke as raw material, with a pre-treated particle size of 5mm–15mm (particle size distribution not exceeding ±30% of the median particle size). Each experiment operated stably at a rated capacity of 100kg / h. After the operating conditions stabilized, samples were continuously taken for at least 24 hours. The sampled products were analyzed according to national standards for graphitization degree (X-ray diffraction), interlayer spacing d002, Raman ID / IG, and tap density. The cumulative electrical energy consumption was recorded to calculate the unit energy consumption (kWh / kg).

[0040] Comparative Example 1 A traditional Atchison furnace with a rated capacity of 500kVA is used. The calcined coke is mixed with quartz sand and loaded into the furnace. It is heated by electricity according to a standard heating curve, and the furnace core reaches a maximum temperature of 2800℃. After natural cooling to room temperature, the furnace is unloaded. The production cycle of a single furnace is approximately 240-300 hours (including heating, high-temperature holding and cooling), with a furnace loading of approximately 1.5t, which translates to a continuous equivalent capacity of approximately 100kg / h.

[0041] Test results: Total energy consumption 6.8~7.5kWh / kg, graphitization degree 88%~92%, d002=0.3365nm~0.3370nm, Raman ID / IG=0.25~0.35, large performance fluctuation within batches, graphitization degree of products in different positions in the furnace varies by more than 5%.

[0042] Comparative Example 2 A vertical continuous graphitization furnace (11 meters high) of the same specifications as in the embodiments of this invention is used. The entire furnace body is continuously heated with a constant rated power, and the material descends at a fixed speed. No power reduction or speed linkage control is performed for the exothermic stage. The highest temperature inside the furnace is approximately 2700℃~2750℃ (limited by the upper limit of constant power heating, it is not possible to fully utilize the material's self-exothermic heat for further temperature increase).

[0043] Test results: Total energy consumption 5.2 kWh / kg, graphitization degree approximately 90%, d002=0.3368nm, Raman ID / IG=0.30, moderate performance fluctuation within batch, and due to occasional local overheating events in the high-temperature zone, there is a problem of faster furnace lining wear.

[0044] Comparative Example 3 The same vertical continuous graphitization furnace is used, and the furnace body is simply divided into three areas: preheating section, high temperature heating section and cooling section. The power of each section is fixed, but there is no distinction between heat absorption and heat release stages. The power in the high temperature heating section (1500℃~2800℃) is kept constant, and there is no heat release sensing and control function.

[0045] Test results: Total energy consumption 4.8 kWh / kg, graphitization degree approximately 92%, d002=0.3362nm, Raman ID / IG=0.22. Product uniformity is improved compared to Comparative Example 2, but there is still a risk of power waste and local overheating during the exothermic phase.

[0046] Example 1 The invention employs a four-stage heat absorption and release control process. The equipment is a vertical continuous graphitization furnace, 11 meters high, with a rated power of 450kW (the rated power of each stage can be adjusted independently).

[0047] Process control parameter settings: Section S1 is located at the top of the furnace body, 0-1.5m above the furnace body. The target outlet temperature is 900℃-1000℃. It mainly utilizes waste heat and has an external power of about 80kW, accounting for about 18% of the rated power.

[0048] Section S2 is located in the upper part of the furnace body, 1.5m to 4m: target temperature 1500℃→2200℃, external power fully on (approximately 300kW, accounting for approximately 68% of rated power), maintaining high power density heating at rated power. The exothermic transition monitoring trigger temperature is set to 2200℃.

[0049] Section S3 is located 4m to 8m in the middle of the furnace body. The heating rate threshold α = 10℃ / min, the temperature positive deviation threshold β = 30℃, and the confirmation duration t0 = 10s. The response is triggered when either of the two criteria is met. After the spontaneous heating is detected, the power decreases linearly at a slope of 15% of the rated power / min, and finally stabilizes at a maintenance power of about 50kW (about 11% of the rated power). The material downward speed is based on 1.5m / h. When dT / dt > 15℃ / min or ΔT > 50℃, the speed increases to 2.0 to 2.5m / h; when dT / dt < 5℃ / min or ΔT < 10℃, the speed decreases to 1.0m / h.

[0050] S4 is located 8m to 11m below the furnace body: active heating is stopped, and the material is slowly cooled down over about 2 hours by adjusting the material's downward speed, with the furnace exit temperature controlled at 200℃.

[0051] Test results: Total energy consumption was 3.7 kWh / kg (approximately 23% lower than Comparative Example 3 and approximately 46% lower than Comparative Example 1); graphitization degree was 96%, d002 = 0.3358 nm, Raman ID / IG = 0.08; tap density was 0.96 g / cm³. 3The graphitization degree within each batch fluctuated by less than 1%, resulting in optimal product consistency. In the exothermic management section (2200℃→2800℃), the measured heat release from the material itself contributed approximately 80% of the heating heat, while external electrical energy accounted for only about 20%, fully verifying the effective capture and utilization of reaction heat by this invention. Compared with the traditional constant power method, the local peak temperature in the high-temperature zone decreased by approximately 150℃, and the furnace lining life is expected to be extended by more than 20%.

[0052] Table 1 shows the comprehensive performance comparison data of each process route: Table 1: Comparison of Overall Performance of Various Process Routes

[0053] The energy consumption and heat source contribution analysis of each functional segment in Example 1 is shown in Table 2: Table 2: Energy Consumption and Heat Balance Analysis of Each Functional Section in Example 1

[0054] In the exothermic management section (2200℃→2800℃), the total heat required for the material's temperature rise (Qtotal) is determined by calculating the material's specific heat capacity and temperature rise, while the external input electrical energy (Qelec) is obtained by integrating the power meter. Based on this, the material's own exothermic contribution is calculated: This data demonstrates that above 2200℃, the graphitization reaction process is primarily driven by the material's own exothermic response, with external electrical energy input playing only a supplementary role of approximately 20%. This invention, by actively identifying and efficiently utilizing this inherent thermodynamic characteristic, reduces the external power input to the exothermic management section by approximately 83% (from 300 kW to 50 kW), which is the direct technical reason for achieving a total energy consumption reduction of approximately 23%. Simultaneously, due to the high degree of matching between energy supply and the material's intrinsic thermodynamic requirements, overheating damage is avoided, resulting in a higher degree of graphitization (96%) and optimal product uniformity (batch-to-batch variation <1%).

[0055] The complete and multi-dimensional comparative experimental data strongly demonstrate the technological advancement and substantial innovation of this invention, which is based on the intrinsic thermodynamic mechanism of the graphitization process and implements a segmented differentiated temperature control strategy.

[0056] Finally, it should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents; that is, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A vertical continuous graphitization method based on heat absorption and release regulation, characterized in that, Includes the following steps: S1: Begin applying heat energy to the material to preheat and dehydrate it; S2: Continuously apply heat energy to the material to drive the material temperature to rise until the material shows a spontaneous heating phenomenon that does not depend on external power. S3: Reduce the external heat input to a preset value, so that the material can continue to heat up to the target peak temperature under the condition of its own exothermic reaction; S4: Stop or reduce external heat input to cool the material to the target furnace exit temperature at a controlled cooling rate.

2. The method according to claim 1, characterized in that, In step S2, the spontaneous heating phenomenon of the material independent of external power increase is determined by at least one of the following temperature criteria: Under the condition that the external energy input remains constant, the rate of change of material temperature dT / dt is greater than or equal to a preset threshold. The temperature deviation ΔT between the measured temperature of the material and the set temperature is greater than or equal to the preset threshold.

3. The method according to claim 2, characterized in that, The preset threshold for dT / dt is 5–20 °C / min, and / or the preset threshold for ΔT is 10–80 °C.

4. The method according to claim 2 or 3, characterized in that, When making the determination, the duration for which dT / dt is greater than or equal to a preset threshold and / or the duration for which ΔT is greater than or equal to a preset threshold is not less than 3s to 60s.

5. The method according to claim 4, characterized in that, The starting temperature for real-time monitoring is 2000–2300℃.

6. The method according to claim 2, characterized in that, The S3 adopts a ramp-down power reduction method, where the external energy input decreases at a rate of 10% to 20% of the rated power per minute until the maintenance power is reached.

7. The method according to claim 6, characterized in that, Specifically, S3 is a speed linkage control based on dT / dt and / or ΔT: when dT / dt increases and / or ΔT increases, the material travel speed is increased; when dT / dt decreases and / or ΔT decreases, the material travel speed is decreased.

8. The method according to claim 1, characterized in that, In S3, the cooling rate is specifically controlled by adjusting the material travel speed so that the material is discharged from the furnace after the temperature drops to the target discharge temperature within 1 to 3 hours.

9. The method according to claim 8, characterized in that, The target furnace exit temperature is 150–250℃.

10. The method according to claim 1, characterized in that, It also includes a material pretreatment step, in which the calcined coke raw material is graded according to the particle size range before S1, and only materials with a particle size distribution range not exceeding ±30% are used in the same furnace.

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