Secondary roasting charging and discharging process for graphitized product

Abstract

The graphitized product secondary roasting charging and discharging process comprises the following steps that S1, a high-purity graphite support or a multi-layer support structure is arranged in a hearth of a graphite furnace, and a graphite product is hoisted to the graphite support or the multi-layer support through a special clamp for charging; s2, sectional heating is adopted, the heating process is divided into a low-temperature section, a medium-temperature section and a high-temperature section, and the heating rate of each stage is controlled; s3, after roasting is completed, natural cooling is conducted, and after the temperature is reduced to the preset temperature, products are discharged out of the furnace; s4, the graphite product is clamped through a special clamp to be lifted out of the furnace, and in the step S1, the graphite product is vertically arranged on the graphite support and is arranged on the multi-layer support structure in a layered mode; when the secondary roasting charging and discharging process for the graphitized product is used, the stability and roasting uniformity of the product in a hearth can be guaranteed, segmented heating roasting is carried out in the furnace, graphite product cracking or performance reduction caused by temperature fluctuation can be avoided, the product quality is guaranteed, and the secondary roasting charging and discharging process for the graphitized product is suitable for application and popularization.

Description

Technical Field

[0001] The invention relates to the technical field of graphite roasting, in particular to a process for secondary roasting and loading a graphitized product. Background Art

[0002] Secondary roasting is a key process in graphite production, primarily used to improve the density, strength, and conductivity of graphite products. In recent years, the rapid development of new energy, electronics, aerospace, and other fields has led to an increasing demand for high-performance graphite materials, driving advancements in secondary roasting technology.

[0003] The invention patent with announcement number CN102173409B discloses a method for producing graphite carbon material, wherein the required components of the graphite carbon material are proportioned by weight, and 20-25 parts of melted pitch are added to every 99-101 parts of calcined petroleum coke dry material, which includes the following steps: (1) mixing the dry material with the binder, cooling the material, and forming it; (2) primary roasting; (3) primary impregnation; (4) secondary roasting; (5) secondary impregnation; (6) tertiary roasting; (7) graphitization process; the new graphite carbon material produced by this process has the characteristics of anti-oxidation, high temperature resistance, corrosion resistance, strong conductivity and good thermal shock resistance, and the product service life is more than three times that of ordinary graphite anodes.

[0004] Although the graphite products produced by the above process can improve the overall performance, during the secondary roasting process, the loading and unloading method of the graphite products cannot guarantee their own stability and roasting uniformity, and the internal roasting temperature cannot be segmented, which easily leads to quality problems such as product cracking, and the use effect is not ideal. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide a secondary baking and loading process for graphitized products that can ensure the stability and baking uniformity of the product in the furnace, and bake in stages in the furnace to avoid cracking or performance degradation of the graphite product due to temperature fluctuations, thereby ensuring product quality.

[0006] To achieve the above-mentioned purpose, the technical solution of the present invention is: a process for secondary roasting and loading graphitized products out of the furnace, comprising the following steps: S1: setting a high-purity graphite bracket or a multi-layer bracket structure in the furnace of the graphite furnace, and hoisting the graphite product onto the graphite bracket or the multi-layer bracket through a special clamp for loading into the furnace; S2: adopting a staged heating method, dividing the heating process into a low-temperature section, a medium-temperature section and a high-temperature section, and controlling the heating rate of each stage; S3: naturally cooling after roasting is completed, and taking the product out of the furnace after cooling to a predetermined temperature; S4: clamping the graphite product with a special clamp and lifting it out of the furnace.

[0007] Preferably, in step S1, the graphite product is vertically mounted on the graphite support and layered on the multi-layer support structure, and the surfaces of the graphite support and the multi-layer support structure are both coated with SiC material.

[0008] Preferably, the spacing between each layer of supports in the multi-layer support structure is 200-400 mm, the support beams are in a hollow mesh shape, and the opening rate is ≥40%.

[0009] Preferably, the special fixture for graphite is a fixture with self-locking claws. Before loading the furnace, the graphite product is fixed on a flexible pad woven with graphite limiters outside the furnace, and then the whole is pushed into the furnace after being fixed.

[0010] Preferably, the temperature of the low temperature section is 200-500°C, the temperature of the medium temperature section is 500-900°C, and the temperature of the high temperature section is 900-1300°C.

[0011] Preferably, the heating rate of the low temperature section is 13°C / min, the heating rate of the medium temperature section is 35°C / min, and the heating rate of the high temperature section is 2°C / min.

[0012] Preferably, a graphite tube heat exchanger is provided at the smoke exhaust port of the graphite furnace, a silicon carbide radiation plate is provided on the furnace top, the inner layer of the graphite furnace is provided with a high-purity graphite plate, the middle layer is provided with zirconia fiber felt, and the outer layer is provided with a steel water-cooled jacket.

[0013] Preferably, the cross section of the furnace of the graphite furnace is hexagonal, and guide cones are provided at the corners of the inner wall of the furnace.

[0014] The present invention discloses a process for secondary roasting and loading a graphite product out of a furnace, comprising the following steps: S1: arranging a high-purity graphite support or a multi-layer support structure in a furnace of a graphite furnace, and hoisting a graphite product onto the graphite support or the multi-layer support by a special clamp for loading the furnace; S2: adopting a segmented heating method, dividing the heating process into a low-temperature section, a medium-temperature section, and a high-temperature section, and controlling the heating rate of each stage; S3: naturally cooling after roasting, and unloading the product after the temperature drops to a predetermined temperature; S4: clamping the graphite product by a special clamp for hoisting and unloading the furnace, wherein in step S1, the graphite product is vertically loaded on the graphite support and layered loaded on the multi-layer support structure; compared with the prior art, the process for secondary roasting and loading a graphite product out of a furnace has the advantages of ensuring the stability and roasting uniformity of the product in the furnace during use, and the segmented heating and roasting in the furnace can avoid cracking or performance degradation of the graphite product due to temperature fluctuation, thereby ensuring the beneficial effect of product quality. DETAILED DESCRIPTION

[0015] Example 1: A process for secondary roasting and loading a graphitized product, comprising the following steps: S1: setting a high-purity graphite bracket or a multi-layer bracket structure in the furnace of a graphite furnace, and hoisting the graphite product onto the graphite bracket or the multi-layer bracket through a special clamp for loading into the furnace; S2: adopting a segmented heating method, dividing the heating process into a low-temperature section, a medium-temperature section and a high-temperature section, and controlling the heating rate of each stage; S3: naturally cooling after roasting is completed, and removing the product from the furnace after cooling to a predetermined temperature; S4: clamping the graphite product with a special clamp and hoisting it out of the furnace.

[0016] In step S1, the graphite product is placed on a high-purity graphite support for vertical installation, and on a multi-layer support structure for layered installation, to ensure the stability and uniformity of the graphite product in the furnace.

[0017] Specifically, in step S1, the graphite product is vertically mounted on the graphite support and layered on the multi-layer support structure. The surfaces of the graphite support and the multi-layer support structure are coated with SiC material to improve the high temperature resistance of the graphite support and the multi-layer support structure.

[0018] Vertical or layered loading can reduce the collision and deformation of products during the loading process, improve the product qualification rate, improve the uniformity of product heating, and enhance the overall performance.

[0019] In the solution of the present invention, the spacing between each layer of supports in the multi-layer support structure is 200-400 mm, the support beams are in a hollow mesh shape, and the opening rate is ≥40% to ensure uniform heat radiation.

[0020] In this embodiment, the logic of layered furnace charging is: Large-sized or high-density graphite blanks (such as electrode structures) are placed in the lower layer, and the strong convection zone at the bottom is used to accelerate the heating.

[0021] Medium-sized products are placed in the middle layer, and staggered stacking is adopted (spacing ≥ 500mm) to reduce the heat shielding effect.

[0022] Small or thin-walled graphite parts are placed on the upper layer to avoid deformation caused by direct hot air flow in the high-temperature section.

[0023] In this embodiment, the special graphite fixture is a fixture with self-locking claws. Before loading the furnace, the graphite product is fixed on a flexible pad woven with graphite limiters outside the furnace. After fixing, the whole is pushed into the furnace to reduce the loading time (<15 minutes / furnace). The flexible pad woven with graphite limiters is fixed on a graphite bracket or a multi-layer bracket structure.

[0024] The special fixture for graphite is a fixture with self-locking jaws, specifically a high-temperature resistant ceramic fixture (Al2O3 and ZrO2 composite material), which prevents the clamping force from damaging the graphite surface.

[0025] The temperature of the low-temperature section is 200-500°C, at which temperature the resin / asphalt volatilizes and falls off, and product bubbling can be avoided. The temperature of the medium-temperature section is 500-900°C, at which temperature the graphite product structure can shrink and initially graphitize. The temperature of the high-temperature section is 900-1300°C, at which temperature the crystal structure is ordered and the density can be improved. The heating rate of the low-temperature section is 13°C / min, and the escape rate of volatiles is strictly controlled to prevent cracking. The heating rate of the medium-temperature section is 35°C / min, and N2 protection is used to avoid oxidation weight loss. The heating rate of the high-temperature section is 2°C / min, ensuring isotropic shrinkage of the graphite. This avoids cracking or performance degradation of the graphite product due to temperature fluctuations, improves energy utilization and reduces energy consumption.

[0026] At the same time, this process can also be applied to graphite products of different specifications and uses.

[0027] Specifically, the high-temperature section uses a graphite heating element (direct resistance heating), and the heating rate is precisely controlled to keep the heating rate accuracy of the high-temperature section at ±1°C / min.

[0028] Furthermore, nitrogen protection is used during the heating stage to prevent graphite oxidation; a vacuum environment is used during the insulation stage to reduce the impact of impurities on graphite properties; insulation is carried out after cooling, and inert gas (such as argon) is used for insulation to prevent oxidation or deformation of the product during cooling; multiple protective shells are used to significantly improve the purity and performance of graphite products, reduce product defects caused by improper atmosphere, and are suitable for the production of high-precision, high-performance graphite products.

[0029] In addition, a graphite tube heat exchanger is provided at the smoke exhaust port of the graphite furnace, a silicon carbide radiation plate is provided on the furnace top, the inner layer of the graphite furnace is provided with a high-purity graphite plate, the middle layer is provided with zirconia fiber felt, and the outer layer is provided with a steel water-cooled jacket.

[0030] Specifically, a graphite tube heat exchanger (corrosion-resistant) is installed at the smoke exhaust port to preheat the combustion air to 300-400°C, with a recovery efficiency of >50%, to achieve flue gas waste heat recovery; a silicon carbide radiation plate is installed on the furnace top to reflect the radiation energy in the high-temperature area to the medium-temperature area to achieve radiation heat recovery.

[0031] Graphite furnace wall: The inner layer is high-purity graphite plate (anti-adhesion); the middle layer is zirconia fiber felt (thermal insulation); the outer layer is a stainless steel water-cooled jacket (temperature control). Airflow system: N2 is passed through the bottom (anti-oxidation) and forced convection is provided by an induced draft fan at the top, with a flow rate of 0.5-1.0 m / s.

[0032] In this embodiment, multiple layers of graphite sheets are arranged in the furnace, and the multiple layers of graphite sheets are staggered and stacked to achieve countercurrent heat exchange between flue gas and fresh gas, and have high temperature resistance; the heat energy of the graphite furnace is recovered by staggered stacking of the multiple layers of graphite sheets; in addition, since the sheets are graphite sheets, there are no metal parts inside, which can avoid corrosion caused by graphite dust.

[0033] Furthermore, the furnace is made of refractory materials to improve the furnace's high temperature resistance and heat conduction efficiency; Specifically, the refractory material is silica brick, the main component of which is silicon dioxide SiO2, with a content of ≥93%. It uses crystalline quartzite (silica) as the main raw material, along with a small amount of mineralizers (such as lime, iron and phosphorus) and binders (such as pulp waste liquid).

[0034] Mixing ratio: Silica particles (1-3mm): 50%; Silica fine powder (<0.5mm): 40%; Mineralizer (Ca+Fe2O3): 1%-(lime+iron phosphorus); Binder (such as lignin sulfonate): 1%.

[0035] Example 2: The refractory material is silica brick, the main component of which is silicon dioxide SiO2, with a content of ≥93%. Crystalline quartzite (silica) is the main raw material, along with a small amount of mineralizers (such as lime, iron and phosphorus) and binders (such as pulp waste liquid).

[0036] Ratio: silica particles (1-3mm): 55%; silica fine powder (<0.5mm): 45%; mineralizer (Ca+Fe2O3): 1.5% (lime+iron phosphorus); binder (such as lignin sulfonate): 2%.

[0037] Example 3: Silica particles (1-3 mm): 60%; silica fine powder (<0.5 mm): 50%; mineralizer (Ca+Fe2O3): 2% (lime+iron phosphorus); binder (such as pulp waste liquid): 3%.

[0038] Example 4: The refractory material can also be high-alumina bricks, whose main component is Al2O3. According to the content of Al2O3, it can be divided into three grades: specifically, first-level high-alumina bricks: Al2O3 content ≥75%; second-level high-alumina bricks: Al2O3 content 60-75%; third-level high-alumina bricks: Al2O3 content 48-60%.

[0039] Taking the first-grade high-alumina brick as an example, its proportion is: high-alumina bauxite clinker (Al2O3 ≥ 85%): 80%, combined clay (Al2O3 30%-40%): 15%, additives (such as silicon powder): 1% (to improve sintering properties); it can improve the high temperature resistance and heat conduction efficiency of the furnace.

[0040] Example 5: The proportion of first-grade high-alumina bricks is as follows: high-alumina bauxite clinker (Al2O3 ≥ 85%): 83%, combined clay (Al2O3 30%-40%): 17%, additives (such as silicon powder): 2% (to improve sintering properties); it can improve the high-temperature resistance and heat conduction efficiency of the furnace.

[0041] Example 6: The proportion of first-grade high-alumina bricks is as follows: high-alumina bauxite clinker (Al2O3 ≥ 85%): 85%, combined clay (Al2O3 30%-40%): 20%, additives (such as silicon powder): 3% (to improve sintering properties); it can improve the high-temperature resistance and heat conduction efficiency of the furnace.

[0042] Based on the above embodiment, the cross-section of the furnace of the graphite furnace is hexagonal, which is more conducive to stacking graphite products than a circular furnace. Guide cones are provided at the corners of the inner wall of the furnace to avoid airflow dead corners.

[0043] In addition, an adjustable downward pressure valve is installed on the top of the furnace to control the pressure fluctuation during volatile removal and maintain the internal pressure at ±5Pa.

[0044] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A process for secondary roasting and loading graphitized products out of a furnace, characterized in that: The process includes the following steps: S1: setting a high-purity graphite support or a multi-layer support structure in the furnace of the graphite furnace, and hoisting the graphite product onto the graphite support or the multi-layer support through a special clamp for loading into the furnace; S2: adopting a segmented heating method, dividing the heating process into a low-temperature section, a medium-temperature section and a high-temperature section, and controlling the heating rate of each stage; S3: cooling naturally after the roasting is completed, and taking the product out of the furnace after cooling to a predetermined temperature; S4: clamping the graphite product with a special clamp and hoisting it out of the furnace.

2. The process for secondary roasting and discharging graphitized products according to claim 1, characterized in that: In the step S1, the graphite product is mounted vertically on the graphite support and in layers on the multi-layer support structure, and the surfaces of the graphite support and the multi-layer support structure are both coated with SiC material.

3. The process for secondary roasting and discharging graphitized products according to claim 2, characterized in that: In the multi-layer support structure, the spacing between each layer of supports is 200-400mm, the support beams are in a hollow mesh shape, and the opening rate is ≥40%.

4. The process for secondary roasting and discharging graphitized products according to any one of claims 1 to 3, characterized in that: The special fixture for graphite is a fixture with self-locking claws. Before loading the furnace, the graphite product is fixed on a flexible pad woven with graphite limiters outside the furnace. After fixing, the whole thing is pushed into the furnace.

5. The process for secondary roasting and loading graphitized products according to claim 1, characterized in that: The temperature of the low temperature section is 200-500°C, the temperature of the medium temperature section is 500-900°C, and the temperature of the high temperature section is 900-1300°C.

6. The process for secondary roasting and loading graphitized products according to claim 5, characterized in that: The heating rate of the low temperature section is 13°C / min, the heating rate of the medium temperature section is 35°C / min, and the heating rate of the high temperature section is 2°C / min.

7. The process for secondary roasting and loading graphitized products according to claim 1, characterized in that: The graphite furnace is provided with a graphite tube heat exchanger at the smoke exhaust port, a silicon carbide radiation plate is provided on the furnace top, the inner layer of the graphite furnace is provided with a high-purity graphite plate, the middle layer is provided with a zirconia fiber felt, and the outer layer is provided with a steel water cooling jacket.

8. The process for secondary roasting and loading graphitized products according to claim 7, characterized in that: The cross section of the furnace of the graphite furnace is hexagonal, and guide cones are provided at the corners of the inner wall of the furnace.