Continuous roasting method and device for carbon blocks

Abstract

The invention provides a continuous roasting method and device for carbon blocks, and belongs to the field of carbon for aluminum. The method comprises the steps that under the protection of inert gas, according to a preset carbon block roasting process curve, carbon blocks to be roasted are continuously roasted, and continuous roasting sequentially comprises a preheating section, a heating section, a constant temperature section and a cooling section; in the preheating section, volatile substances generated in the heating process of the to-be-roasted carbon blocks are incinerated, and after released heat exchanges heat with inert gas, the inert gas returns to the preheating section, so that a closed-loop first internal circulation system is formed; in the heating section, the constant temperature section and the cooling section, inert gas enters from the tail end of the cooling section, advances in the direction opposite to the conveying direction of the carbon blocks, absorbs heat energy of all the sections along the way and is finally discharged from the starting end of the heating section, and the discharged inert gas is injected into the tail end of the cooling section again after being purified so as to form a closed-loop second inner circulation system. Therefore, the carbon emission in the roasting process is reduced while the homogeneity of the anode carbon block is improved.

Description

Technical Field

[0001] The present application relates to the technical field of carbon for aluminum, and in particular to a method and device for continuous roasting of carbon blocks. Background Art

[0002] Carbon anodes are the primary raw material for aluminum electrolysis, and their consumption is one of the main sources of direct carbon emissions in the industry. Roasting is a key step in carbon anode production, determining anode product quality, consumption indicators, and environmental impact.

[0003] The existing carbon anode roasting has long used open roasting furnaces as the main equipment, which has the disadvantages of short roasting furnace life, poor homogeneity of anode products, low thermal energy utilization, poor working environment, and low degree of automation, which seriously restricts the low-carbon, green and high-quality development of carbon for aluminum. From the perspective of heat income and expenditure in the carbon anode roasting process, the heat of heating carbon blocks accounts for about 15.68% of the total heat expenditure, the heat from the flue gas section accounts for about 27.66%, and the heat storage of the furnace body accounts for 33.5%, which accounts for a large proportion. When the open roasting furnace is operated, the heating position changes with the roasting curve, resulting in an unstable flue gas emission position and difficulty in utilizing the waste heat of the flue gas. This not only leads to the unnecessary loss of resources, but also has an adverse impact on the working environment of the furnace surface. At present, a lot of research work has been carried out at home and abroad on energy conservation and consumption reduction of carbon roasting furnaces. The energy consumption of anode production roasting has also steadily decreased, and the roasting natural gas consumption is 50 to 70m 3 / tc, and natural gas consumption during the roasting process produces CO2 emissions of approximately 108-150 kg / tc. However, due to the repeated heating and cooling thermal system, further reductions in energy consumption in open ring roasting furnaces are limited. Improving the homogeneity of anode carbon blocks while reducing carbon emissions during the roasting process is an urgent technical challenge. Summary of the Invention

[0004] The present application provides a method and apparatus for continuous roasting of carbon blocks to solve the following technical problem: how to improve the homogeneity of anode carbon blocks while reducing carbon emissions during the roasting process.

[0005] In a first aspect, an embodiment of the present application provides a method for continuous roasting of a carbon block, the method comprising:

[0006] Under the protection of inert gas, the carbon block to be roasted is continuously roasted according to the preset carbon block roasting process curve, and the continuous roasting includes a preheating section, a temperature rising section, a constant temperature section and a temperature falling section in sequence;

[0007] In the preheating section, volatile substances generated by the charcoal blocks to be roasted during the heating process are burned, and the released heat is heat-exchanged with the inert gas, and the inert gas returns to the preheating section to form a closed-loop first internal circulation system;

[0008] In the temperature rising section, the constant temperature section and the temperature falling section, the inert gas enters from the end of the temperature falling section, moves in the opposite direction of the carbon block conveying, absorbs heat energy from each section along the way, and is finally discharged from the starting end of the temperature rising section. After the discharged inert gas is purified, it is re-injected into the end of the temperature falling section to form a closed-loop second internal circulation system;

[0009] The temperature range of the first internal circulation system is room temperature to 550°C, and the temperature range of the second internal circulation system is 550°C to 1250°C.

[0010] Optionally, the purity of the inert gas is 99.9% to 99.99%.

[0011] Optionally, the temperature range of the preheating section is 300°C to 550°C, the temperature range of the heating section is 500°C to 1200°C, the temperature range of the constant temperature section is 1150°C to 1250°C, and the final temperature range of the cooling section is ≤250°C.

[0012] Optionally, the temperature of the waste heat released after the incineration treatment is 350°C to 550°C, and the temperature of the inert gas after the heat exchange is 300°C to 350°C.

[0013] In a second aspect, the present application provides a continuous roasting device for carbon blocks, wherein the device is adapted to the method described in any one of the embodiments of the first aspect, and the device comprises:

[0014] The kiln body is divided into a preheating section, a temperature rising section, a constant temperature section and a temperature falling section in sequence along the conveying direction of the carbon blocks, and is used to continuously perform a roasting process on the carbon blocks to be roasted in the preheating section, the temperature rising section, the constant temperature section and the temperature falling section;

[0015] The electric heating component is provided in the preheating section, the temperature rising section and the constant temperature section, and is used to heat the carbon block to be roasted according to a preset carbon block roasting process curve;

[0016] A circulating water cooling component is provided in the temperature-lowering section and is used to indirectly cool the heated carbon blocks to be roasted;

[0017] The carrying component is used to horizontally transport the carbon blocks through the preheating section, the temperature rising section, the constant temperature section and the temperature falling section in sequence;

[0018] a first internal circulation system covering the preheating section, the first internal circulation system including a gas heat exchanger and a flue gas incinerator, for incinerating volatile substances generated by the charcoal blocks to be roasted during the heating process, and after heat exchange between the released heat and the inert gas, the inert gas returns to the preheating section;

[0019] The second internal circulation system covers the temperature rising section, the constant temperature section and the temperature falling section. In the second internal circulation system, the inert gas enters from the end of the temperature falling section, moves in the opposite direction of the carbon block conveying, absorbs the heat energy of each section along the way, and is finally discharged from the starting end of the temperature rising section. The discharged inert gas is purified and then injected into the end of the temperature falling section again.

[0020] Optionally, the circulating water cooling component includes a water-cooled heat exchange pipe embedded in the top of the furnace cavity and a manual valve for adjusting the flow rate.

[0021] Optionally, the first internal circulation system is provided with a side bottom air inlet point, and the side bottom air inlet point is distributed in the refractory heat storage layer of each section of the furnace body in the preheating section, for dispersed multi-point air intake.

[0022] Optionally, the second internal circulation system is provided with a tail air inlet point, and the tail air inlet point is distributed in each section of the furnace body in the cooling section.

[0023] Optionally, the electric heating component is a silicon carbon rod or an electric heating component. The number and arrangement density of the electric heating components are configured according to temperature gradient requirements, and no fuel such as natural gas, coal gas or heavy oil is used throughout the process.

[0024] Optionally, segmented fire walls are provided between the preheating section, the temperature rising section, the constant temperature section and the temperature falling section, and the segmented fire walls are made of silicon carbide.

[0025] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0026] The embodiment of the present application provides a method for continuous roasting of carbon blocks. The present application effectively solves a number of technical problems in the process of roasting carbon blocks by constructing two closed-loop internal circulation systems. First, in response to the problems of severe heat loss and low thermal energy utilization efficiency in traditional roasting, the present application incinerates the volatile substances generated by the carbon blocks in the preheating section, utilizes the heat released and forms a first internal circulation system through inert gas heat exchange, making full use of the heat; in the heating, constant temperature and cooling sections, the inert gas countercurrently absorbs the heat energy of each section to form a second internal circulation system, maximally recovering the heat energy of the high-temperature section for preheating the carbon blocks in the low-temperature section, significantly improving the thermal energy utilization efficiency. Secondly, if the volatile substances generated by the roasting of carbon blocks are not handled properly, they will pollute the environment and waste energy. The present application incinerates the volatile substances in the preheating section, and the heat released is used to preheat the carbon blocks, forming a closed-loop first internal circulation system, which not only avoids the direct emission of volatile substances, but also realizes energy recycling and effectively treats volatile substances. Furthermore, the roasting of carbon blocks requires precise temperature control, which is difficult to achieve with traditional methods. The present application divides the roasting process into four stages: preheating, heating, constant temperature, and cooling, and constructs two closed-loop internal circulation systems. The temperature range of the first internal circulation system is room temperature to 550°C, and the temperature range of the second internal circulation system is 550°C to 1250°C, to achieve precise segmented temperature control, ensure temperature stability in each stage, and improve roasting quality. In addition, traditional roasting will produce a large amount of pollutants. In the second internal circulation system of the present application, the exhausted inert gas is purified and then re-injected into the system to effectively remove pollutants and reduce environmental pollution; at the same time, volatile substances are incinerated and their heat is utilized to avoid direct emissions and reduce pollution risks. Finally, the traditional roasting method has low production efficiency and is difficult to meet the needs of large-scale production. The present application adopts a continuous roasting method to achieve continuous production of carbon blocks; the two closed-loop internal circulation systems reduce heat loss, shorten roasting time, and further improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 A schematic flow chart of a continuous roasting method for carbon blocks provided in an embodiment of the present application;

[0030] Figure 2 A first structural schematic diagram of a continuous roasting device for carbon blocks provided in an embodiment of the present application;

[0031] Figure 3 A second structural schematic diagram of a continuous roasting device for carbon blocks provided in an embodiment of the present application;

[0032] Reference numerals:

[0033] 1- kiln body, 11- preheating section, 12- heating section, 13- constant temperature section, 14- cooling section, 15- roasting kiln head loading chamber, 16- roasting kiln tail discharge chamber, 2- electric heating component, 3- circulating water cooling component, 4- carrying component, 5- first internal circulation system, 51- gas heat exchanger, 52- flue gas incinerator, 53- side bottom air inlet point, 6- second internal circulation system, 61- tail air inlet point, 7- inert gas conveying component;

[0034] S1-metal shell, S2-fiber blanket (board), S3-lightweight mullite insulation brick, S4-high-quality mullite insulation brick, S5-electric heating component, S6-high-aluminum material, S7-baked carbon block, S8-carbon plate, S9-hyperbolic sealing groove, S10-kiln car, S11-kiln foundation. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments disclosed in this application, any other embodiments that can be derived by those skilled in the art without creative work are deemed to fall within the scope of protection of this application.

[0036] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0037] This application aims to address a series of challenges in the existing technology: the difficulty in significantly reducing natural gas consumption, the energy waste caused by the repeated heating and cooling system, the uneven temperature distribution (temperature differences of up to 50°C) caused by improper flue wall material box design, air leakage caused by flue creep deformation, and damage caused by frequent loading and unloading of material boxes. These issues collectively affect the stability of roasting quality. In addition, the heating position constantly changes according to the roasting curve, resulting in unstable flue gas emission positions, which poses a huge challenge to centralized flue gas recovery, treatment, and waste heat utilization.

[0038] Compared with existing open roasting furnace technology, the innovative technical effect of this application forms a relatively stable preheating section, heating section, constant temperature section, and cooling section in the roasting furnace, allowing the carbon blocks to move horizontally through the entire heat treatment process of preheating, heating, high temperature, and cooling, realizing the upgrade of roasting process system and equipment. On the one hand, it can solve the problems of repeated heating and cooling in the open ring roasting furnace, such as heat storage and heat dissipation in the furnace body and heat loss in the flue gas section, facilitating the centralized recovery, treatment, and utilization of flue gas; on the other hand, it can improve the homogeneity of the anode, reduce carbon emissions during the roasting process, reduce labor intensity, and realize the upgrading of the carbon industry.

[0039] Figure 1 A schematic flow chart of a continuous roasting method for carbon blocks provided in an embodiment of the present application.

[0040] like Figure 1 As shown, the present application provides a continuous roasting method for carbon blocks, the method comprising:

[0041] S1. Under the protection of inert gas, the carbon block to be roasted is continuously subjected to a roasting process having a preheating section, a temperature rising section, a constant temperature section and a temperature falling section according to a preset carbon block roasting process curve;

[0042] Continuous, standardized baking of carbon blocks is achieved through segmented temperature control, replacing the traditional intermittent process. The carbon blocks are sequentially preheated, heated, maintained, and cooled by a carrier, eliminating the energy waste associated with repeated heating and cooling cycles in traditional processes. Gases such as N2 are used to isolate oxygen and prevent oxidation of the carbon blocks (e.g., high-temperature oxidation of prebaked anodes).

[0043] In some embodiments, the purity of the inert gas is 99.9% to 99.99%.

[0044] During the roasting process, an inert gas such as N2 is used to create a protective atmosphere in the furnace to protect the carbon blocks from oxidation. For example, the purity of the inert gas can be 99.9%, 99.91%, 99.92%, 99.93%, 99.95%, 99.97%, or 99.99%.

[0045] In some embodiments, the temperature range of the preheating zone is 300°C to 550°C, the temperature range of the heating zone is 500°C to 1200°C, the temperature range of the constant temperature zone is 1150°C to 1250°C, and the final temperature range of the cooling zone is ≤250°C.

[0046] Controlling the temperature of the preheating section between 300°C and 550°C will help the carbon blocks to precipitate asphalt volatiles (such as tar, benzene series, etc.), thus laying a good foundation for the subsequent high-temperature roasting process. The temperature of the heating section is limited to 500°C ~ 1200°C, and the temperature can be increased to the constant temperature section temperature in a gradient to ensure uniform transformation of the internal structure of the carbon block and avoid thermal stress cracking. The temperature of the constant temperature section is limited to 1150°C ~ 1250°C, which can achieve high-temperature curing of the carbon block (such as graphitization) and ensure the homogeneity and mechanical strength of the anode. The final temperature of the cooling section is limited to ≤250°C to avoid safety risks caused by high temperature when the carbon blocks are out of the furnace, which is convenient for subsequent transportation and storage. Exemplarily, the temperature range of the preheating section can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, etc., the temperature range of the heating section can be 500°C, 700°C, 900°C, 1000°C, 1200°C, etc., the temperature range of the constant temperature section can be 1150°C, 1170°C, 1190°C, 1200°C, 1220°C, 1240°C, 1250°C, etc., and the final temperature range of the cooling section can be 250°C, 230°C, 200°C, 180°C, 150°C, etc.

[0047] In some embodiments, the temperature of the incineration waste heat released after the incineration treatment is 350°C to 550°C, and the temperature of the inert gas after the heat exchange is 300°C to 350°C.

[0048] The temperature of the incineration waste heat is 350℃~550℃. The heat released by the incineration of volatiles can be used to preheat the inert gas, recover the waste heat, and reduce energy waste. The temperature of the inert gas after heat exchange is limited to 300℃~350℃, which can provide preheated inert gas for the preheating section and reduce the energy consumption of electric heating. For example, the temperature of the incineration waste heat released after incineration treatment can be 350℃, 380℃, 400℃, 450℃, 500℃, 550℃, etc., and the temperature of the inert gas after heat exchange can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, etc.

[0049] In some embodiments, the carbon blocks to be roasted include, but are not limited to, pre-baked anodes and graphite cathodes that discharge pitch volatiles after heating and undergo oxidation reactions when in contact with air during the high-temperature process.

[0050] In some embodiments, the temperature deviation of the furnace atmosphere is within ±10°C.

[0051] S2. In the preheating section, volatile substances generated by the charcoal blocks to be roasted during the heating process are burned, and the released heat is heat-exchanged with the inert gas, and the inert gas is returned to the preheating section to form a closed-loop first internal circulation system;

[0052] The inert atmosphere in the preheating section forms the first internal circulation system. During the preheating phase, the carbon blocks release a large amount of volatiles. These inert gases are then incinerated in an external incineration system and discharged. During this discharge process, heat exchange with the gases preheats the inert gases in this section, achieving flue gas purification and waste heat utilization within the first internal circulation system. Advanced waste heat recovery technology not only purifies volatiles but also effectively recovers waste heat, thus resolving the issues of unstable flue gas emission locations and difficulty in utilizing waste heat in traditional processes.

[0053] S3, in the temperature rising section, the constant temperature section and the temperature falling section, the inert gas enters from the end of the temperature falling section, moves in the opposite direction of the carbon block conveying, absorbs heat energy from each section along the way, and is finally discharged from the starting end of the temperature rising section. The discharged inert gas is purified and then re-injected into the end of the temperature falling section to form a closed-loop second internal circulation system;

[0054] The inert gas in the heating, constant, and cooling sections forms a second internal circulation system. The inert gas flows into the kiln from the rear end, in the opposite direction of the carbon block conveying path, and is discharged from the front end of the heating section. During this process, it fully absorbs the waste heat from the heating and constant sections. The discharged high-temperature inert gas is purified and then reinjected into the system, reducing gas loss and fresh gas consumption, and achieving the second internal circulation of the inert gas. This improves inert gas utilization, reduces energy consumption, and reduces carbon emissions.

[0055] The temperature range of the first internal circulation system is room temperature to 550°C, and the temperature range of the second internal circulation system is 550°C to 1250°C.

[0056] Figure 2 A first structural schematic diagram of a continuous roasting device for carbon blocks provided in an embodiment of the present application; Figure 3 This is a second structural schematic diagram of a continuous roasting device for carbon blocks provided in an embodiment of the present application.

[0057] like Figure 2 and Figure 3 As shown, the present application provides a continuous roasting device for carbon blocks, which is adapted to the method described in any one of the embodiments of the first aspect, and comprises:

[0058] The kiln body 1 is divided into a preheating section 11, a temperature rising section 12, a constant temperature section 13 and a temperature falling section 14 in sequence along the conveying direction of the carbon blocks, and is used to continuously perform a roasting process on the carbon blocks to be roasted in the preheating section 11, the temperature rising section 12, the constant temperature section 13 and the temperature falling section 14;

[0059] The electric heating component 2 is provided in the preheating section 11, the temperature rising section 12 and the constant temperature section 13, and is used to heat the carbon blocks to be roasted according to a preset carbon block roasting process curve;

[0060] The circulating water cooling component 3 is provided in the cooling section 14 and is used to indirectly cool the heated carbon blocks to be roasted;

[0061] The carrying component 4 is used to horizontally transport the carbon blocks through the preheating section 11, the temperature rising section 12, the constant temperature section 13 and the temperature falling section 14 in sequence;

[0062] A first internal circulation system 5, which covers the preheating section 11 and includes a gas heat exchanger 51 and a flue gas incinerator 52, for incinerating volatile matter generated by the charcoal blocks to be roasted, and the released incineration waste heat is exchanged with the inert gas and then returned to the preheating section 11;

[0063] The second internal circulation system 6 covers the temperature rising section 12, the constant temperature section 13 and the temperature falling section 14. In the second internal circulation system 6, the inert gas enters from the end of the temperature falling section 14, flows in the opposite direction of the carbon block conveying and absorbs the heat energy of each section, and is discharged from the starting end of the temperature rising section 12. The discharged inert gas is re-injected into the end of the temperature falling section 14 after purification.

[0064] In some embodiments, the circulating water cooling component 3 includes a water-cooled heat exchange pipe embedded in the top of the furnace cavity and a manual valve for adjusting the flow rate.

[0065] The charcoal blocks are cooled indirectly by circulating water, using water-cooled heat exchange pipes embedded in the top of the furnace chamber, through which cooling water is passed for forced heat exchange. Manual valves are installed at the inlet and outlet of each branch to adjust the cooling water flow, thereby precisely controlling the cooling rate and ensuring that the charcoal block temperature remains below 250°C.

[0066] In some embodiments, the first internal circulation zone 5 is provided with a side bottom air inlet point 53, and the side bottom air inlet point 53 is distributed in the refractory heat storage layer of each section of the furnace body in the preheating zone 11 for dispersed multi-point air intake.

[0067] In some embodiments, the second internal circulation system 6 is provided with a tail air inlet point 61 , and the tail air inlet point 61 is distributed in each furnace section of the temperature-lowering section 14 .

[0068] In some embodiments, the electric heating component 2 is a silicon carbon rod or an electric heating component 2. The number and arrangement density of the electric heating components 2 are configured according to the temperature gradient requirements, and no natural gas, coal gas or heavy oil fuel is used throughout the process.

[0069] In some embodiments, segmented fire walls are provided between the preheating section 11 , the temperature rising section 12 , the constant temperature section 13 , and the temperature falling section 14 , and the segmented fire walls are made of silicon carbide.

[0070] The furnace refractory materials and structures are subdivided according to the temperature range. Different roasting zones are equipped with segmented fire walls to separate the temperature and control the temperature of each zone.

[0071] Therefore, this application systematically overcomes the core difficulties of traditional roasting technology by relying on the innovative design of process segments, efficient use of gas circulation, optimization of heating methods, and improvement of equipment structure, and demonstrates the following significant advantages:

[0072] 1. Energy consumption and cost optimization

[0073] (1) Dual internal circulation heat recovery system: The first internal circulation system (preheating section) recovers 350-550°C waste heat by incinerating volatiles, and preheats the inert gas to 300-350°C through a heat exchanger, reducing the power consumption in the preheating stage by about 30%. The inert gas in the second internal circulation system (high temperature section) flows in reverse to absorb 550-1250°C waste heat, with a recycling rate exceeding 90%, reducing fresh gas consumption and heat loss. Electric heating (silicon carbon rods / electric heating components) is used throughout the process to avoid natural gas / heavy oil consumption, reduce energy costs by more than 40%, and adapt to renewable electricity to further reduce carbon emissions.

[0074] (2) Continuous production achieves energy saving: By replacing the traditional intermittent "repeated heating and cooling" process, the heat storage and heat dissipation losses of the furnace body are effectively eliminated, reducing the unit energy consumption by more than 50%.

[0075] 2. Improvement of roasting quality

[0076] (1) Precise temperature control and uniformity: Four independent temperature control stages (preheating 300-550°C, heating 500-1200°C, constant temperature 1150-1250°C, cooling ≤250°C) ensure a temperature deviation of ≤±10°C in the furnace, solving the 50°C temperature difference problem of traditional fire channels. This allows for a more uniform transformation of the internal structure of the carbon blocks. Horizontal continuous transportation prevents mechanical damage caused by repeated loading and unloading of the material bin, reducing the roasting scrap rate from 5% in traditional processes to less than 1%.

[0077] (2) Anti-oxidation protection: High-purity inert gas (such as nitrogen N2) with a purity of 99.9% to 99.99% is used to effectively isolate oxygen and significantly inhibit the oxidation reaction of carbon materials such as pre-baked anodes in high-temperature environments, thereby reducing the oxidation loss rate by 60% and significantly improving the homogeneity of the anode.

[0078] 3. Environmental Protection and Sustainability

[0079] (1) In terms of centralized flue gas treatment, the first internal circulation system achieves a pollutant removal rate of over 95% by centrally incinerating volatile organic compounds (such as tar and benzene series), ensuring that flue gas emissions meet the country's strict environmental protection standards. The second internal circulation system reduces carbon emission intensity by over 70% by reducing inert gas emissions, effectively supporting the achievement of national carbon emission reduction targets.

[0080] (2) No waste gas and fuel pollution: Abandon natural gas / coal gasification, eliminate SO2, NO x Emissions of combustion waste gas are reduced to achieve "zero carbon roasting", which is in line with the green manufacturing policy.

[0081] 4. Production Efficiency and Automation

[0082] (1) Continuous assembly line operation: The carrier components push the carbon blocks through four sections continuously, shortening the production cycle and increasing production capacity. The entire process is automatically controlled (temperature, gas flow, cooling water regulation), reducing manual intervention, labor intensity, and operating errors close to zero.

[0083] (2) Long-life equipment structure: Partitioned fire walls (made of silicon carbide) isolate the high-temperature section, reducing creep deformation and air leakage in the fire channel wall, extending the equipment life from 5 years in traditional processes to over 10 years. Embedded water-cooled heat exchange tubes for non-contact cooling avoid the problem of "material box damage and leakage" in traditional processes, reducing maintenance frequency.

[0084] 5. Process flexibility and applicability

[0085] (1) Compatible with multiple varieties: Applicable to various carbon blocks such as pre-baked anodes and graphite cathodes. By adjusting the density of electric heating elements and gas circulation parameters, the roasting curves of different products can be quickly switched.

[0086] (2) Comprehensive utilization of waste heat: The 300-350°C heat recovered by the first internal circulation system can be reused (such as preheating raw materials or heating the factory area), and the comprehensive energy efficiency is increased to more than 90%.

[0087] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0088] The continuous roasting method of a carbon block provided in an embodiment of the present application may specifically include the following steps:

[0089] 1. Metal Shell Masonry. The entire kiln is designed as a frame structure. The metal frame columns are carefully selected from high-quality profiles and welded using precision craftsmanship. The kiln columns are securely installed on embedded parts or foundations. The kiln sleepers adopt an integrated base design, and the rails are laid on top of it, forming a convenient, detachable, semi-assembled structure. Steel plates are laid on both sides of the base to effectively support the refractory materials on the side.

[0090] 2. Internal refractory masonry: Heavy and light refractory materials such as mullite, high alumina, and clay are used for masonry, and a hyperbolic seal structure is used to prevent cross-fire; drainage, exhaust, and air inlets are reserved at the top, sides, and bottom of the kiln.

[0091] 3. The silicon carbon rod is energized to heat the preheating section, the heating section and the holding section. According to the specific requirements of the process curve, the appropriate temperature is set for each section, and the maximum temperature is determined to be 1200℃.

[0092] 4. Nitrogen with a purity of up to 99.95% is introduced into the kiln body through a nitrogen generator. After passing through the preset air inlet points in the heating and cooling sections and preheating the refractory materials, it is dispersed into multiple points to supply gas to the furnace.

[0093] 5. Start the waste gas collection pipe and incinerator, and at the same time turn on the stirring fan at the front end of the preheating section, so that the cold air in the kiln is preheated by the heat exchanger of the high-temperature pipe at the outlet of the incinerator and then enters the furnace again, while the waste gas is treated and discharged in compliance with the standards.

[0094] 6. Start the circulating water cooling system on the top of the kiln, and then adjust the circulating water volume according to the process requirements of the cooling rate.

[0095] 7. Arrange the charcoal blocks to be roasted on the step kiln car. Place a carbon plate as a pad under the charcoal blocks to be roasted. Set a support of about 65mm high between the carbon plate and the kiln car table.

[0096] 8. Use manual or automatic control to send the kiln cart loaded with carbon blocks into the kiln in turn. According to the set roasting process curve, complete the whole production process of preheating, heating, constant temperature and cooling to below 250℃ before taking the carbon blocks out of the kiln.

[0097] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings.

[0098] Example 1

[0099] The present invention relates to a method for baking carbon blocks, and relates to an innovation of the method. Using N2 protection to prevent oxidation and using electric heating, carbon blocks with a size of 850×700×700mm (length×width×height) are placed on a carbon plate in a layer and row. The volume density of the carbon blocks is 1.65g / cm 3The volatile matter content is 7%, the weight is 680kg, the distance between the carbon plate and the kiln car table is set to about 65mm high support, and it is evenly pushed into the 40.5m roasting kiln, using a 166.5h roasting curve. During the roasting process, 99.95% purity, pressure of 0.3MPa, and flow rate of 500Nm 3 / h of N2; cooling water pressure is 0.3Mpa, cooling water temperature is 30℃, flow rate is 70m 3 / h.

[0100] The first inert gas internal circulation system: the temperature curve of the heating is 19 hours, the preheating temperature reaches 320℃; and then through the fire wall of this section, the temperature is continued to rise for 27 hours, and the temperature is raised to 520℃. The flue gas containing volatile gases is discharged and incinerated by electric heating to meet the emission standards. The flue gas treatment capacity is about 1000m 3 / h, the flue gas temperature is 700℃, part of the heat is recovered by the stirring fan in the preheating section and re-introduced into the furnace to perform forced convection preheating on the carbon blocks.

[0101] Continue to heat up, the second inert gas internal circulation system: the temperature curve of heating is 70 hours, and the temperature rises to 1150℃; the temperature curve of constant temperature section is 13 hours, and the constant temperature is 1150℃, during which the highest temperature of carbon block reaches 1080℃; the temperature curve of cooling section is 37.5 hours, and it is taken out of the furnace after cooling to about 230℃.

[0102] The carbon block calcined at 1080℃ weighs 646kg and has a bulk density of 1.57g / cm 3 The volatile matter content is 0.7%, the outer surface is free of oxidation and cracks, and the resistivity is 58μΩ.m, which meets the requirements of the secondary coke standard for key indicators such as volatile matter content not exceeding 1.50%, crushing strength not less than 76%, and wear resistance not exceeding 9.0%.

[0103] Example 2

[0104] The present invention relates to a method for baking carbon blocks, and relates to an innovation of the method. Using N2 protection to prevent oxidation and using electric heating, carbon blocks with a size of 300×300×300mm (length×width×height) are placed on a carbon plate in two layers and two rows. The volume density of the carbon blocks is 1.67g / cm 3 The volatile matter content is 6%, the weight is 450kg, the distance between the lower carbon plate and the kiln car table is set to about 60mm high support, and the two layers of carbon blocks are separated by carbon plates with a spacing of 50mm. They are evenly pushed into the 40.5m roasting kiln, using a 120h roasting curve. During the roasting process, 99.9% purity, pressure of 0.3MPa, and flow rate of 400Nm 3 / h of N2; cooling water pressure is 0.3Mpa. Cooling water temperature is 30℃, flow rate is 60m 3 / h.

[0105] The first inert gas internal circulation system: The temperature curve is first set to heat up to 330℃ in 10 hours, then pass through the fire wall, and continue to heat up to 510℃ for 22 hours. The flue gas containing volatile gases is burned by electric heating and then meets the emission standards. The flue gas treatment capacity is about 800m 3 / h, the flue gas temperature is 700℃, and the stirring fan in the preheating section recovers part of the heat and re-introduces it into the furnace to achieve forced convection preheating of the carbon blocks.

[0106] Continue to heat up, and the second inert gas internal circulation system: the temperature curve of the heating section is 38 hours, and the heating temperature reaches 1100℃; the temperature curve of the constant temperature section is 24 hours, and the constant temperature is 1100℃, during which the highest temperature of the carbon block reaches 1060℃; the temperature curve of the cooling section is 26 hours, and the temperature is cooled to about 210℃ before being taken out of the furnace.

[0107] After calcination at 1060°C, the carbon block weighs 427 kg and has a bulk density of 1.59 g / cm 3 The volatile matter content is 0.6%, the outer surface of the carbon block is free of oxidation and cracks, and the resistivity is 55μΩ.m, meeting the requirements of the industry standard first-class product.

[0108] Example 3

[0109] The present invention relates to a method for baking carbon blocks, and is an innovation in the method. Using nitrogen (N2) for protection to effectively prevent oxidation reactions, and at the same time, using electric heating, carbon blocks with dimensions of 1700×700×680mm (length×width×height) are neatly arranged in one layer and one column on a carbon plate. The volume density of the carbon blocks is 1.64g / cm 3 The volatile matter content is 8%, the weight is 1200kg, and a stable support of about 70mm is set between the lower carbon plate and the kiln car table. It is evenly pushed into the 80 (or more than 80) meter roasting kiln and a roasting curve of 201.8h is used. During the roasting process, 99.99% purity, 0.3MPa pressure, and 650Nm flow rate are introduced. 3 / h of N2; cooling water pressure is 0.3Mpa, cooling water temperature is 30℃, flow rate is 100m 3 / h.

[0110] The first inert gas internal circulation system: the temperature curve of the heating is 21.3 hours, the preheating temperature reaches 350℃, and passes through the fire wall of this section, and continues to heat up for 30 hours, and the temperature reaches 550℃. The flue gas containing volatile gases is burned by electric heating and then meets the emission standards. The flue gas treatment capacity is about 1300m 3 / h, the flue gas temperature is 800℃, part of the heat is recovered by the stirring fan in the preheating section and re-introduced into the furnace to perform forced convection preheating on the carbon blocks.

[0111] Continue to heat up, the second inert gas internal circulation system: the temperature curve of the heating section is 90 hours, the heating temperature reaches 1200℃; the temperature curve of the constant temperature section is 13 hours, the constant temperature is 1200℃, during which the highest temperature of the carbon block reaches 1100℃; the temperature curve of the cooling section is 47.5 hours, and it is taken out of the furnace after cooling to about 240℃.

[0112] After calcination at 1100℃, the carbon block weighs 1140kg and has a bulk density of 1.56g / cm 3 The volatile matter content is 0.7%, the outer surface of the carbon block is free of oxidation and cracks, and the resistivity is 54μΩ·m, which meets the requirements of the first-class product in the YS / T285-2022 "Prebaked Anodes for Aluminum Electrolysis" standard.

[0113] Example 4

[0114] The present invention relates to a method for baking carbon blocks, and relates to an innovation of the method. Using N2 protection to prevent oxidation and electric heating, carbon blocks with a size of 1550×650×620mm (length×width×height) are placed on a carbon plate in a 1-layer 2-row arrangement. The volume density of the carbon blocks is 1.66g / cm 3 The volatile matter content is 7.5%, the weight is 1060kg, the distance between the lower carbon plate and the kiln car table is set to about 60mm high support, the two layers of carbon blocks are separated by carbon plates with a spacing of 60mm, and are evenly pushed into the 80 (or more than 80) meter roasting kiln, using a 240h roasting curve. During the roasting process, 99.99% purity, pressure of 0.3MPa, and flow rate of 750Nm 3 / h of N2; cooling water pressure is 0.3Mpa, cooling water temperature is 30℃, flow rate is 150m 3 / h.

[0115] The first inert gas internal circulation system: the temperature curve of the heating is 24 hours, the preheating temperature is 340℃, and it passes through the fire wall of this section, and continues to heat up for 33 hours, and the temperature is raised to 540℃. The flue gas containing volatile gases is burned by electric heating and then meets the emission standards. The flue gas treatment capacity is about 2100m 3 / h, the flue gas temperature is 750℃, part of the heat is recovered by the stirring fan in the preheating section and re-introduced into the furnace to perform forced convection preheating on the carbon blocks.

[0116] Continue to heat up, the second inert gas internal circulation system: the temperature curve of the heating section is 100.5 hours, the heating temperature reaches 1200℃; the temperature curve of the constant temperature section is 30 hours, the constant temperature is 1200℃, during which the highest temperature of the carbon block reaches 1090℃; the temperature curve of the cooling section is 52.5 hours, and the carbon block is taken out of the furnace after cooling to about 220℃.

[0117] After calcination at 1090°C, the carbon block weighs 1007 kg and has a bulk density of 1.58 g / cm 3 The volatile matter content is 0.75%, the outer surface is free of oxidation and cracks, and the resistivity is 56μΩ.m, which meets the technical requirements of the industry standard first-class product.

[0118] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0119] In an embodiment of the present application, the carbon blocks to be roasted are placed in a continuous roasting kiln and continuously transported by an automatic stepping trolley. During the heating process, electric heating is adopted in combination with inert gas (such as N2) protection to ensure that the carbon blocks are evenly heated and avoid oxidation. During the cooling process, indirect cooling is performed by circulating water to effectively control the cooling rate of the carbon blocks. This method accurately constructs a preheating section, a heating section, a constant temperature section and a cooling section inside the roasting furnace to ensure that the carbon blocks go through the preheating, heating, high-temperature treatment and cooling stages in sequence during horizontal movement, thereby achieving a comprehensive upgrade of the roasting process and equipment.

[0120] In the embodiment of the present application, the problems of heat storage, heat dissipation and heat loss of flue gas in the traditional open ring roasting furnace caused by repeated heating and cooling are solved, which facilitates the centralized recovery, treatment and utilization of flue gas.

[0121] In the examples of this application, the homogeneity of the anode is significantly improved, the energy consumption and labor intensity of roasting are reduced, and the upgrading of the carbon industry is promoted. The method is efficient, energy-saving, and environmentally friendly and is suitable for large-scale industrial production.

[0122] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A continuous roasting method for carbon blocks, comprising: Under the protection of inert gas, the carbon block to be roasted is continuously roasted according to the preset carbon block roasting process curve, and the continuous roasting includes a preheating section, a temperature rising section, a constant temperature section and a temperature falling section in sequence; In the preheating section, volatile substances generated by the charcoal blocks to be roasted during the heating process are burned, and the released heat is heat-exchanged with the inert gas, and the inert gas returns to the preheating section to form a closed-loop first internal circulation system; In the temperature rising section, the constant temperature section and the temperature falling section, the inert gas enters from the end of the temperature falling section, moves in the opposite direction of the carbon block conveying, absorbs heat energy from each section along the way, and is finally discharged from the starting end of the temperature rising section. After the discharged inert gas is purified, it is re-injected into the end of the temperature falling section to form a closed-loop second internal circulation system; The temperature range of the first internal circulation system is room temperature to 550°C, and the temperature range of the second internal circulation system is 550°C to 1250°C.

2. The method according to claim 1, characterized in that The purity of the inert gas is 99.9% to 99.99%.

3. The method according to claim 1, characterized in that The temperature range of the preheating section is 300°C to 550°C, the temperature range of the heating section is 500°C to 1200°C, the temperature range of the constant temperature section is 1150°C to 1250°C, and the final temperature range of the cooling section is ≤250°C.

4. The method according to claim 1, wherein The temperature of the incineration waste heat released after the incineration treatment is 350°C to 550°C, and the temperature of the inert gas after the heat exchange is 300°C to 350°C.

5. A continuous roasting device for carbon blocks, adapted for the method according to any one of claims 1 to 4, comprising: The kiln body is divided into a preheating section, a temperature rising section, a constant temperature section and a temperature falling section in sequence along the conveying direction of the carbon blocks, and is used to continuously perform a roasting process on the carbon blocks to be roasted in the preheating section, the temperature rising section, the constant temperature section and the temperature falling section; The electric heating component is provided in the preheating section, the temperature rising section and the constant temperature section, and is used to heat the carbon block to be roasted according to a preset carbon block roasting process curve; A circulating water cooling component is provided in the temperature-lowering section and is used to indirectly cool the heated carbon blocks to be roasted; The carrying component is used to horizontally transport the carbon blocks through the preheating section, the temperature rising section, the constant temperature section and the temperature falling section in sequence; a first internal circulation system covering the preheating section, comprising a gas heat exchanger and a flue gas incinerator, wherein the first internal circulation system is used to incinerate volatile substances generated by the charcoal blocks to be roasted during the heating process, and the released heat is heat-exchanged with the inert gas, and the inert gas is returned to the preheating section; The second internal circulation system covers the temperature rising section, the constant temperature section and the temperature falling section; in the second internal circulation system, the inert gas enters from the end of the temperature falling section, moves in the opposite direction of the carbon block conveying, absorbs the heat energy of each section along the way, and is finally discharged from the starting end of the temperature rising section. The discharged inert gas is purified and then injected into the end of the temperature falling section again.

6. The device according to claim 5, characterized in that The circulating water cooling component includes a water-cooling heat exchange pipe embedded in the top of the furnace cavity and a manual valve for regulating flow.

7. The device according to claim 5, characterized in that The first internal circulation system is provided with a side bottom air inlet point, and the side bottom air inlet point is distributed in the refractory heat storage layer of each section of the furnace body in the preheating section, and is used for dispersed multi-point air intake.

8. The device according to claim 5, characterized in that The second internal circulation system is provided with a tail air inlet point, and the tail air inlet point is distributed in each section of the furnace body in the cooling section.

9. The device according to claim 5, characterized in that The electric heating components are silicon carbon rods or electric heating components. The number and arrangement density of the electric heating components are configured according to temperature gradient requirements, and no natural gas, coal gas or heavy oil fuel is used throughout the process.

10. The device according to claim 5, characterized in that Segmented fire walls are provided between the preheating section, the temperature rising section, the constant temperature section and the temperature falling section, and the material of the segmented fire walls is silicon carbide.

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