A vertical internal string graphitization furnace system

Abstract

This invention discloses a vertical internal series graphitization furnace system, including a rectifier transformer, a graphitization furnace, a cooling heat exchange tower, and an auxiliary system. The rectifier transformer, graphitization furnace, cooling heat exchange tower, and auxiliary system are all electrically connected to a control system. The graphitization furnace and rectifier transformer are electrically connected via a busbar, and the graphitization furnace and cooling heat exchange tower are connected via pipelines. The furnace structure designed in this invention is simple. Each graphitization furnace can be powered independently or multiple furnace chambers can be connected in series. The furnace operation requires no insulation material, making operation simple, energy-saving, and environmentally friendly. The integrated cooling tower enables automatic gas convection exchange, shortening the cooling time. The flue gas generated during power transmission is introduced into the exhaust gas treatment system for environmentally friendly emissions. The hot airflow during cooling can also be introduced into the pre-installed furnace for product preheating before power transmission, demonstrating significant energy-saving advantages in graphitization.

Description

Technical Field

[0001] This invention relates to the field of graphitization technology for carbon products, specifically a vertical internal series graphitization furnace system. Background Technology

[0002] A graphitization furnace is a thermal device that provides a high-temperature thermal field to transform amorphous carbon structures into graphite structures, thereby completing the graphitization process.

[0003] Common graphitization furnaces include Atchison graphitization furnaces, internal string graphitization furnaces, resistance heating graphitization furnaces, and induction heating graphitization furnaces. Compared to other furnace types, internal string graphitization furnaces have advantages such as short power supply cycle, high thermal efficiency, energy saving, uniform product quality, and the ability to process large-size products in batches. However, existing internal string graphitization furnaces require the use of insulating filling material, have complex loading and unloading operations, uneven contact between the product stringing surfaces, significant temperature differences between different parts of the furnace, long cooling times, and easy oxidation of the products. Therefore, those skilled in the art have provided a vertical internal string graphitization furnace system and its control technology to solve the problems mentioned in the background art. Summary of the Invention

[0004] The purpose of this invention is to provide a vertical internal graphitization furnace system to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A vertical internal series graphitization furnace system includes a rectifier transformer, a graphitization furnace, a cooling heat exchange tower, and an auxiliary system. The rectifier transformer, graphitization furnace, cooling heat exchange tower, and auxiliary system are respectively connected to the control system via electrical signals. The auxiliary system includes water, electricity, gas, exhaust gas treatment, energy, and auxiliary equipment. The graphitization furnace and the rectifier transformer are electrically connected via a busbar, and the graphitization furnace and the cooling heat exchange tower are connected via pipelines.

[0006] As a further aspect of the present invention, the control system adopts a PLC integrated control system.

[0007] As a further embodiment of the present invention: the graphitization furnace includes a furnace cover, a furnace body and a furnace bottom. The furnace cover, furnace body and furnace bottom are all steel double-layer jacketed structures. Cooling water is circulated inside the double-layer jacket. Graphite insulation felt is attached to the inner wall of the furnace chamber of the furnace cover and furnace body. Carbon black is insulated on the side of the furnace chamber of the furnace bottom and covered with graphite insulation felt. The furnace body and furnace bottom are connected and fixed by flanges. The furnace cover is a hoisting structure. When the furnace is being loaded, the furnace cover and furnace body are locked and sealed by locking buckles. The furnace as a whole has a vertical structure.

[0008] As a further embodiment of the present invention: the furnace cover has a through hole for a water-cooled jacket structure and is lined with a high-temperature resistant insulating ceramic ring for the upper electrode to pass through. An emergency exhaust port is provided in the center of the furnace cover. A hydraulic jacking device is installed on the furnace cover. The wires are arranged on the upper electrode and connected to the hydraulic jacking device. After the furnace is loaded, the upper electrode is pressed against the upper conductive wall.

[0009] As a further embodiment of the present invention: a lower air duct and an upper air duct are provided on one side of the furnace body. A lower butterfly valve is installed on the lower air duct. The inner wall of the lower air duct section between the lower butterfly valve and the furnace body is covered with graphite insulation felt. The lower butterfly valve is made of graphite. An air inlet pipe and an air outlet pipe are respectively provided at the upper and lower ends of the lower air duct. The lower air duct, the air inlet pipe, and the air outlet pipe are all water-cooled jacketed structures. An upper butterfly valve is installed on the upper air duct. The inner wall of the upper air duct section between the upper butterfly valve and the furnace body is covered with graphite insulation felt. The upper butterfly valve is made of graphite. An air outlet pipe is provided on the upper air duct. Both the upper air duct and the air outlet pipe are water-cooled jacketed structures.

[0010] As a further embodiment of the present invention: the other end of the furnace body is provided with three temperature measuring tubes, namely upper, middle and lower, the temperature measuring tubes having a water-cooled jacket structure, the inner wall being covered with graphite insulation felt, and the ends of the temperature measuring tubes being connected to an infrared thermometer.

[0011] As a further embodiment of the present invention: the bottom of the furnace bottom is provided with a support leg, the furnace bottom has a through hole of water-cooled jacket structure and is lined with a high-temperature resistant insulating ceramic ring for the lower electrode to pass through, the lower electrode is equipped with a lower conductive wall, and the top surface of the lower conductive wall is flush with the top surface of the insulation layer of the furnace bottom.

[0012] As a further embodiment of the present invention: the upper conductive walls are four disc-shaped graphite blocks, namely upper conductive wall one, upper conductive wall two, upper conductive wall three and upper conductive wall four, which correspond to upper electrode one, upper electrode two, upper electrode three and upper electrode four respectively. Upper electrode one and upper electrode three are connected by a wire array, and upper electrode two and upper electrode four are connected by a wire array. The middle section of the wire array is a flexible wire.

[0013] As a further embodiment of the present invention: the lower electrode is divided into lower electrode one and lower electrode two. The lower half of lower electrode one and lower electrode two are hollow water-cooled structures and are connected to the rectifier transformer through a busbar. The lower conductive wall is divided into three parts: lower conductive wall one, lower conductive wall two, and lower conductive wall three. Lower conductive wall one and lower conductive wall two are disc-shaped graphite blocks, and lower conductive wall three is a long strip disc-shaped graphite block. Lower conductive wall one and lower conductive wall two are respectively located on the lower electrode one and lower electrode two.

[0014] As a further embodiment of the present invention: two rows of carbon products are placed inside the furnace body, and the end face of each carbon product is leveled with conductive material, and the upper conductive wall is pressed on the carbon products.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The furnace structure designed in this invention is simple. Each graphitization furnace can be powered and operated independently, or multiple furnace chambers can be connected in series. The furnace does not require the filling of insulation material, making it simple to operate and energy-saving and environmentally friendly. It adopts inert gas protection for micro-positive pressure operation, completely isolating the furnace chamber from the risk of water and air ingress, thus possessing inherent safety. The matching cooling tower can realize automatic gas convection exchange to shorten the cooling time. The flue gas generated during the power supply process is introduced into the exhaust gas treatment system to achieve environmentally friendly emissions. The hot air flow during the cooling process can also be introduced into the installed furnace for product preheating before power supply, which has great energy-saving advantages in graphitization. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a vertical internal graphitization furnace system. Figure 2 This is a schematic diagram of the cross-sectional structure of the furnace chamber in a vertical internal graphitization furnace system. Figure 3 A schematic diagram of the lower electrode of the furnace chamber in a vertical internal graphitization furnace system, viewed from below. Figure 4 A top view schematic diagram of the conductive wall at the bottom of the furnace chamber in a vertical internal graphitization furnace system; Figure 5 A bottom view of the conductive wall on the furnace chamber in a vertical internal graphitization furnace system. Figure 6 This is a bottom-view schematic diagram of the upper electrode in a vertical internal graphitization furnace system.

[0017] In the diagram: 11. Rectifier transformer; 22. Graphitization furnace; 33. Cooling heat exchange tower; 1. Furnace cover; 2. Furnace body; 3. Furnace bottom; 4. Support leg; 5. Lower electrode; 6. Lower conductive wall; 7. Upper conductive wall; 8. Upper electrode; 9. Hydraulic jacking device; 10. Lower air duct; 101. Upper air duct; 12. Lower butterfly valve; 13. Upper butterfly valve; 14. Air inlet pipe; 15. Air outlet pipe; 16. Exhaust pipe; 17. Temperature measuring tube; 18. 19. Emergency exhaust port; 20. Conductor bar; 5.1. Lower electrode one; 5.2. Lower electrode two; 6.1. Lower conductive wall one; 6.2. Lower conductive wall two; 6.3. Lower conductive wall three; 7.1. Upper conductive wall one; 7.2. Upper conductive wall two; 7.3. Upper conductive wall three; 7.4. Upper conductive wall four; 8.1. Upper electrode one; 8.2. Upper electrode two; 8.3. Upper electrode three; 8.4. Upper electrode four. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figures 1-6 In this embodiment of the invention, a vertical internal series graphitization furnace system includes a rectifier transformer 11, a graphitization furnace 22, a cooling heat exchange tower 33, and an auxiliary system. The rectifier transformer 11, the graphitization furnace 22, the cooling heat exchange tower 33, and the auxiliary system are respectively connected to the control system via electrical signals. The control system centrally controls the system via electrical connections. The auxiliary system includes water, electricity, gas, exhaust gas treatment, energy, and auxiliary equipment. The graphitization furnace 22 and the rectifier transformer 11 are electrically connected via a busbar, and the graphitization furnace 22 and the cooling heat exchange tower 33 are connected via pipes. Multiple graphitization furnaces can be connected in series, allowing multiple furnaces to be powered simultaneously at one time.

[0020] Cooling heat exchange tower 33 is an air-cooled type, equipped with a safety valve and an air vent valve to measure and control the gas temperature, pressure and flow rate at the inlet and outlet.

[0021] The control system adopts a PLC integrated control system to realize automatic data acquisition, intelligent analysis and intelligent adjustment.

[0022] The graphitization furnace 22 includes a furnace cover 1, a furnace body 2, and a furnace bottom 3. The furnace cover 1, furnace body 2, and furnace bottom 3 are all steel double-layer jacketed structures. Cooling water is circulated inside the double-layer jacket. Graphite insulation felt is attached to the inner wall of the furnace chamber of the furnace cover 1 and furnace body 2. Carbon black is insulated on the side of the furnace chamber of the furnace bottom 3 and covered with graphite insulation felt. The furnace cover 1 and furnace bottom 3 are water-cooled jacketed structures, and the through holes are lined with high-temperature resistant insulating ceramic rings and sealing rings.

[0023] The furnace body 2 and the furnace bottom 3 are connected and fixed by flanges. The furnace cover 1 is a hoisting structure. When the furnace is loaded, the furnace cover 1 and the furnace body 2 are locked and sealed by locking buckles. The furnace as a whole has a vertical structure.

[0024] The furnace cover 1 has a through hole with a water-cooled jacket structure and is lined with a high-temperature resistant insulating ceramic ring for the upper electrode 8 to pass through. The center of the furnace cover 1 is provided with an emergency exhaust port 18, which is a water-cooled jacket structure and lined with a high-temperature resistant graphite felt. Pressure measurement and protection devices are provided, as well as automatic emergency exhaust and manual exhaust valves. A hydraulic jacking device 9 is installed on the furnace cover 1. The wire busbar 19 is connected to the hydraulic jacking device 9 together with the upper electrode 8. After the furnace is loaded, the upper electrode 8 is pressed against the upper conductive wall 7.

[0025] A lower air duct 10 and an upper air duct 101 are provided on one side of the furnace body 2. A lower butterfly valve 12 is installed on the lower air duct 10. The inner wall of the lower air duct 10 section between the lower butterfly valve 12 and the furnace body 2 is covered with graphite insulation felt. The lower butterfly valve 12 is made of graphite. An air inlet pipe 14 and an exhaust pipe 16 are provided at the upper and lower ends of the lower air duct 10, respectively. The lower air duct 10, the air inlet pipe 14 and the exhaust pipe 16 are all water-cooled jacketed structures. Argon is preferred as the protective gas. The gas pressure and flow rate are controlled by valves and instruments. An upper butterfly valve 13 is installed on the upper air duct 101. The inner wall of the upper air duct 101 section between the upper butterfly valve 13 and the furnace body 2 is covered with graphite insulation felt. The upper butterfly valve 13 is made of graphite. An exhaust pipe 15 is provided on the upper air duct 101. Both the upper air duct 101 and the exhaust pipe 15 are water-cooled jacketed structures.

[0026] The other end of the furnace body 2 is equipped with three temperature measuring tubes 17, which are upper, middle and lower. The temperature measuring tubes 17 are water-cooled jacketed structures with graphite insulation felt attached to the inner wall. The ends of the temperature measuring tubes are connected to infrared thermometers. The inner walls of the temperature measuring tubes 17, lower air duct 10, upper air duct 101 and exhaust pipe 16 are covered with graphite insulation felt and are water-cooled jacketed structures. The lower butterfly valve 12 and the upper butterfly valve 13 are both made of graphite.

[0027] The bottom of the furnace bottom 3 is provided with a support leg 4. The furnace bottom 3 has a through hole for a water-cooled jacket structure and is lined with a high-temperature resistant insulating ceramic ring for the lower electrode 5 to pass through. The lower electrode 5 is equipped with a lower conductive wall 6, and the top surface of the lower conductive wall 6 is flush with the top surface of the insulation layer of the furnace bottom 3.

[0028] The upper conductive wall 7 consists of four disc-shaped graphite blocks: upper conductive wall 1 7.1, upper conductive wall 2 7.2, upper conductive wall 3 7.3, and upper conductive wall 4 7.4. These blocks correspond to the upper electrodes 8: upper electrode 1 8.1, upper electrode 2 8.2, upper electrode 3 8.3, and upper electrode 4 8.4, respectively. Upper electrodes 1 8.1 and 3 8.3 are connected by a wire strip 19, and upper electrodes 2 8.2 and 4 8.4 are also connected by a wire strip 19. The two ends of the wire strip 19 are made of rigid copper plates, and the middle section is made of flexible copper wire.

[0029] The lower electrode 5 is divided into lower electrode 1 5.1 and lower electrode 2 5.2. The lower half of lower electrode 1 5.1 and lower electrode 2 5.2 is a hollow water-cooled structure and is connected to the rectifier transformer 11 through a busbar. The lower conductive wall 6 is divided into three parts: lower conductive wall 1 6.1, lower conductive wall 2 6.2 and lower conductive wall 3 6.3. Lower conductive wall 1 6.1 and lower conductive wall 2 6.2 are disc-shaped graphite blocks, and lower conductive wall 3 6.3 is a long strip of disc-shaped graphite block. The lower electrodes 1 5.1 and lower electrode 2 5.2 are respectively located above lower conductive wall 1 6.1 and lower conductive wall 2 6.2.

[0030] Two rows of carbon products 20 are placed inside the furnace body 2. The end face of each carbon product 20 is leveled with conductive material, and the upper conductive wall 7 is pressed on the carbon product 20.

[0031] The working principle of this invention is as follows: In the empty furnace state, open the furnace cover 1, stack the carbon products 20 in sequence on the lower conductive wall 6 to form 4 carbon product columns, level the conductive material on the end face of each carbon product 20, adjust the height of each carbon product column to keep it consistent, and place the top of the conductive wall 7 on the upper surface. A gap is left between each carbon product column and each conductive wall 7 to complete the loading of carbon products into the furnace.

[0032] After the furnace is loaded, the furnace cover 1 is closed and locked in the furnace body 2. The hydraulic jacking device 9 applies a certain pressure to press the wire bar 19 tightly onto the upper electrode 8. The upper electrode 8 is pressed onto the upper conductive wall 7. The upper conductive wall 7 is pressed onto the carbon product 20. The carbon product 20 is pressed tightly in sequence.

[0033] Connect all water, electricity, and gas pipelines, close all inlet and outlet ports of graphitization furnace 22 and cooling heat exchange tower 33, replace the gas with argon and maintain a certain pressure, and check the sealing of each part.

[0034] After setting the power supply curve, cooling curve, and other parameters in the control system, power supply and heating begin. During power supply, the current flows from the positive terminal of rectifier transformer 11 through the following terminals in sequence: lower electrode 5.1, lower conductive wall 6.1, carbon product 20 on lower conductive wall 6.1, upper conductive wall 7.1, upper electrode 8.1, left conductor bar 19, upper electrode 3 8.3, upper conductive wall 3 7.3, carbon product 20 on the left side of lower conductive wall 3 6.3, carbon product 20 on the right side of lower conductive wall 3 6.3, upper conductive wall 4 7.4, upper electrode 4 8.4, right conductor bar 19, upper electrode 2 8.2, upper conductive wall 2 7.2, carbon product 20 on lower conductive wall 2 6.2, lower conductive wall 2 6.2, lower electrode 2 5.2, and then returns to the negative terminal of rectifier transformer 11.

[0035] Argon gas is continuously introduced during the power supply process to maintain a certain pressure in the furnace. An infrared thermometer measures and controls the temperature inside the furnace. The carbon product 20 is continuously heated. The generated flue gas is discharged from the exhaust pipe 16 and introduced into the tail gas treatment system. When the furnace pressure is too high, the system alarms. The emergency exhaust port 18 is opened automatically or manually, and the graphitization furnace 22 is powered off and cooled down.

[0036] According to the cooling curve, the control system automatically adjusts the opening of the lower butterfly valve 12 on the lower air duct 10 and the upper butterfly valve 13 on the upper air duct 101, and measures the gas flow rate and temperature. The hot air flows into the cooling heat exchange tower 33 from the upper air duct 101, and after being cooled, it flows into the furnace from the lower air duct 10 to achieve circulating cooling.

[0037] After cooling is complete, argon gas supply is stopped, furnace cover 1 is opened, and the upper conductive wall and carbon products are unloaded sequentially, completing one furnace cycle. Each graphitization furnace 22 can be powered independently or multiple furnace chambers can be connected in series. The furnace does not require insulation material, making operation simple, energy-saving, and environmentally friendly. It adopts argon gas protection for micro-positive pressure operation, completely isolating the furnace chamber from the risk of water and gas ingress, thus possessing inherent safety. The matching cooling tower can realize automatic gas convection exchange to shorten the cooling time. The flue gas generated during the power supply process is introduced into the tail gas treatment system to achieve environmentally friendly emissions. The hot gas flow during the cooling process can also be introduced into the pre-loaded furnace for product preheating before power supply, which has great energy-saving advantages in graphitization.

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A vertical internal series graphitization furnace system, comprising a rectifier transformer (11), a graphitization furnace (22), a cooling heat exchange tower (33), and an auxiliary system, characterized in that, The rectifier transformer (11), graphitization furnace (22), cooling heat exchange tower (33) and auxiliary system are respectively connected to the control system via electrical signals. The auxiliary system includes a water supply device, a power supply device, a gas supply device, a tail gas treatment device, an energy supply device and auxiliary devices. The graphitization furnace (22) and the rectifier transformer (11) are electrically connected via a busbar, and the graphitization furnace (22) and the cooling heat exchange tower (33) are connected via a pipeline. The graphitization furnace (22) includes a furnace cover (1), a furnace body (2) and a furnace bottom (3). The furnace cover (1) has a through hole for a water-cooled jacket structure and is provided with a high-temperature resistant insulating ceramic ring for the upper electrode (8) to pass through. An emergency exhaust port (18) is provided in the center of the furnace cover (1). A hydraulic jacking device (9) is installed on the furnace cover (1). The wire bar (19) is set on the upper electrode (8) and is connected to the hydraulic jacking device (9) together with the upper electrode (8). After the furnace is loaded, the upper electrode (8) is pressed on the upper conductive wall (7). The furnace body (2) has a lower air duct (10) and an upper air duct (101) on one side, respectively. A lower butterfly valve (12) is installed on the lower air duct (10). Graphite insulation felt is applied to the inner wall of the section of the lower air duct (10) between the lower butterfly valve (12) and the furnace body (2). The lower butterfly valve (12) is made of graphite. An air inlet pipe (14) and an exhaust pipe (16) are respectively provided at the upper and lower ends of the lower air duct (10). The air inlet pipe (14) and the exhaust pipe (16) are both water-cooled jacketed structures. An upper butterfly valve (13) is installed on the upper air pipe (101). Graphite insulation felt is attached to the inner wall of the upper air pipe (101) section between the upper butterfly valve (13) and the furnace body (2). The upper butterfly valve (13) is made of graphite. An exhaust pipe (15) is provided on the upper air pipe (101). The upper air pipe (101) and the exhaust pipe (15) are both water-cooled jacketed structures. The bottom of the furnace bottom (3) is provided with a support leg (4). The furnace bottom (3) has a through hole of a water-cooled jacket structure. A high-temperature resistant insulating ceramic ring is provided in the through hole for the lower electrode (5) to pass through. A lower conductive wall (6) is installed on the lower electrode (5). The top surface of the lower conductive wall (6) is flush with the top surface of the insulation layer of the furnace bottom (3). The upper conductive wall (7) consists of four disc-shaped graphite blocks: upper conductive wall one (7.1), upper conductive wall two (7.2), upper conductive wall three (7.3), and upper conductive wall four (7.4), which correspond to upper electrode one (8.1), upper electrode two (8.2), upper electrode three (8.3), and upper electrode four (8.4) of the upper electrode (8), respectively. Upper electrode one (8.1) and upper electrode three (8.3) are connected by a wire strip (19), and upper electrode two (8.2) and upper electrode four (8.4) are connected by a wire strip (19). The middle section of the wire strip (19) is a flexible wire.

2. The vertical internal series graphitization furnace system according to claim 1, characterized in that, The control system adopts a PLC integrated control system.

3. The vertical internal series graphitization furnace system according to claim 1, characterized in that, The furnace cover (1), furnace body (2) and furnace bottom (3) are all steel double-layer jacketed structures. Cooling water is circulated inside the double-layer jacket. The furnace cover (1) and furnace body (2) are covered with graphite insulation felt on the inner wall of the furnace chamber, and the furnace bottom (3) is covered with insulating carbon black on the side of the furnace chamber and covered with graphite insulation felt. The furnace body (2) and furnace bottom (3) are fixed by flange connection. The furnace cover (1) is a hoisting structure. When the furnace is running, the furnace cover (1) and furnace body (2) are locked and sealed by locking buckles. The furnace as a whole has a vertical structure.

4. A vertical internal series graphitization furnace system according to claim 1, characterized in that, The other end of the furnace body (2) is provided with three temperature measuring tubes (17) at the top, middle and bottom. The temperature measuring tube (17) is a water-cooled jacket structure with graphite insulation felt attached to the inner wall. The end of the temperature measuring tube is connected to an infrared thermometer.

5. A vertical internal series graphitization furnace system according to claim 1, characterized in that, The lower electrode (5) is divided into lower electrode one (5.1) and lower electrode two (5.2). The lower half of lower electrode one (5.1) and lower electrode two (5.2) is a hollow water-cooled structure and is connected to the rectifier transformer (11) through a busbar. The lower conductive wall (6) is divided into three parts: lower conductive wall one (6.1), lower conductive wall two (6.2) and lower conductive wall three (6.3). Lower conductive wall one (6.1) and lower conductive wall two (6.2) are disc-shaped graphite blocks, and lower conductive wall three (6.3) is a long strip disc-shaped graphite block. Lower electrode one (5.1) and lower electrode two (5.2) are respectively located above lower conductive wall one (6.1) and lower conductive wall two (6.2).

6. A vertical internal series graphitization furnace system according to claim 1, characterized in that, Two rows of carbon products (20) are placed inside the furnace body (2). A conductive material for contact leveling is provided between the end faces of each carbon product (20). The upper conductive wall (7) presses on the carbon product (20).

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