Air-blast electric furnace device and smelting method

Abstract

The application provides a blast electric furnace device and a smelting method, which comprises a lower furnace body, an upper furnace body, a furnace cover and an electrode assembly. The lower furnace body is provided with a separation tank, a slag outlet and a metal liquid outlet. The upper furnace body is arranged on the lower furnace body and is provided with a longitudinally extending stacking space. The lower end of the stacking space is communicated with the separation tank. The furnace cover is installed on the lower furnace body or the upper furnace body and cooperates with the upper furnace body and the lower furnace body to form a smelting preheating space. The electrode assembly extends into the lower furnace body through the furnace cover. A hot air inlet is arranged at the lower part of the upper furnace body and is used for feeding hot air into the lower part of the stacking space to heat the materials accumulated in the stacking space. An air outlet is arranged at the upper part of the upper furnace body and is used for discharging the heat-exchanged flue gas. The stacking space simultaneously serves as a discharge channel for the electric arc smelting flue gas and the hot air to diffuse upward to the air outlet. In the material smelting process, the chemical energy of part of the hot air is used to replace the electric energy, the consumption of electricity is reduced, and the emission reduction and the economic benefit are improved.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a blast furnace device and smelting method. Background Technology

[0002] Under the low-carbon context, the steel industry faces enormous pressure to reduce carbon emissions. Furthermore, resource constraints pose even greater challenges to energy conservation and emission reduction in the steel sector. Currently, the typical carbon reduction technology path for the steel industry, avoiding blast furnaces, is: hydrogen-based (or gas-based) shaft furnace - reduced iron - electric arc furnace steelmaking process. However, this process is constrained by global refined iron ore resources and ore grade. The reduced iron produced by the shaft furnace generally has an iron content of only about 80%, which poses a significant challenge to the subsequent electric arc furnace steelmaking process, leading to a sharp increase in power consumption. The theoretical power consumption for smelting this type of reduced iron is as high as approximately 700 kWh / t, or even higher. How to smelt low-quality direct reduced iron in a low-cost, green, and low-carbon manner has become a major challenge.

[0003] To achieve low-cost, low-carbon smelting of low-quality direct reduced iron, reducing power consumption is the preferred approach.

[0004] 1) The average efficiency of converting fuel heat energy into electrical energy in China is currently around 40%. Considering the power transmission loss (90%) and the heat transfer efficiency of the electric furnace (generally 50%-70%), the energy transfer path through fuel calorific value - electrical energy - metal heat is 21.6% (metal heat / fuel calorific value * 100%). In other words, the total energy efficiency of the electric furnace process through current transfer is around 21.6%.

[0005] This data also shows that if a furnace has a chemical energy conversion efficiency of more than 30% to metal heat, the portion of electrical energy replaced by chemical energy will have energy-saving and emission-reduction effects.

[0006] 2) Considering that domestic electricity is mainly generated by coal-fired power plants, the electric furnace smelting of low-quality direct reduced iron with high gangue content not only results in high power consumption, but also leads to increased carbon emissions in the process. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a blast furnace device that uses part of the hot air chemical energy to replace electrical energy during the material smelting process, thereby reducing electricity consumption and lowering smelting costs.

[0008] To achieve the above and other related objectives, the technical solution of the present invention is as follows:

[0009] A blast furnace device, comprising:

[0010] The lower furnace body has a melting pool, and a slag outlet and a molten metal outlet are provided on the lower furnace body;

[0011] An upper furnace body is installed on top of a lower furnace body. The upper furnace body has a longitudinally extending material storage space for storing materials. The lower end of the material storage space is connected to the melting pool, and the materials can flow from the material storage space to the melting pool.

[0012] The furnace cover is installed on the lower or upper furnace body and together with the upper and lower furnace bodies, it forms a smelting preheating space.

[0013] The electrode assembly extends into the lower furnace body after passing through the furnace cover;

[0014] A hot air inlet is located at the lower part of the upper furnace body and is used to send hot air into the lower part of the stacking space to heat the materials piled up in the stacking space.

[0015] The air outlet is located at the top of the upper furnace body and is used to discharge the flue gas after heat exchange.

[0016] The material storage space also serves as a discharge channel for the electric arc melting fumes and hot air to diffuse upwards to the air outlet.

[0017] Optionally, the blast furnace device further includes a hot air generating device and a hot air ring pipe. The upper furnace body is provided with a plurality of hot air inlets at intervals along the circumference. Each hot air inlet is connected to the hot air ring pipe, and the hot air ring pipe is connected to the hot air generating device.

[0018] Optionally, the lower part of the upper furnace body is provided with a plurality of burners for injecting air into the furnace at circumferential intervals.

[0019] Optionally, the burner and the hot air inlet are located at the same height or at different heights; when the burner and the hot air inlet are located at the same height, the burner and the hot air inlet are alternately arranged along the circumference of the upper furnace body.

[0020] Optionally, the hot air inlet is a burner through which hot air is blown into the furnace.

[0021] Optionally, the furnace top of the upper furnace body is provided with a feeding device, the air outlet is located on the side or top of the upper part of the upper furnace body, and the air outlet is higher than the top of the material storage space.

[0022] Optionally, the lower end of the upper furnace body is a flared section, the inner wall of the flared section has a conical structure that is thinner at the top and thicker at the bottom, and the hot air inlet is located on the flared section.

[0023] Optionally, the upper furnace body is a cylindrical structure, or the upper part of the upper furnace body is a cylindrical structure and the lower part is a conical structure that is thinner at the top and thicker at the bottom; or the upper part of the upper furnace body is a cylindrical structure and the lower part is a constricted structure that first narrows and then expands.

[0024] Optionally, the inner wall of the upper furnace body is provided with a baffle structure, and the baffle structure is positioned higher than the hot air inlet.

[0025] Optionally, the baffle structure is fixed to the upper furnace body, or the baffle structure includes a driving component and a baffle component, wherein the baffle component can be driven by the driving component to at least partially extend into or out of the material stacking space.

[0026] Optionally, the axis of the hot air inlet and / or burner is inclined and the blowing direction is downward.

[0027] Optionally, the furnace cover or upper furnace body is provided with nozzles for spraying carbon powder onto the preheated material.

[0028] Optionally, the blast furnace device further includes a circulation bypass, and the air outlet is connected to a dust removal pipe. The circulation bypass is connected between the hot air generator and the dust removal pipe, and is used to recover part of the flue gas flowing out of the air outlet to the hot air generator.

[0029] Optionally, the top of the upper furnace body is recessed downward to form a recessed portion, and the furnace cover is disposed in the recessed portion. The recessed portion and the side wall of the upper furnace body form an annular material storage space, which is located around the electrode assembly and the furnace cover.

[0030] Optionally, a sealing cover is provided on the upper furnace body above the furnace cover. The electrode assembly extends into the lower furnace body after passing through the sealing cover and the furnace cover. A sealing cavity is formed between the sealing cover and the furnace cover, and a sealing port is provided on the sealing cover for blowing air into the sealing cavity or drawing air from the sealing cavity.

[0031] Optionally, the furnace cover is installed on the lower furnace body, the furnace cover is arranged side by side with the upper furnace body, and the top of the furnace cover is lower than the top of the upper furnace body.

[0032] Optionally, the slag outlet is located on the side of the lower furnace body away from the material accumulation position.

[0033] Optionally, the lower furnace body is elongated, the furnace cover is located near the first end of the lower furnace body along its length, the upper furnace body is located near the second end of the lower furnace body along its length, and the slag outlet is located near the first end of the lower furnace body.

[0034] Optionally, the lower furnace body is provided with a pushing device for pushing materials toward the area where the electrode assembly is located.

[0035] The present invention also provides a smelting method using the aforementioned blast furnace device.

[0036] The lower furnace body maintains a portion of the molten pool, and materials are added to the upper furnace body. The materials accumulate from the lower furnace body upwards into the stacking space of the upper furnace body.

[0037] High-temperature hot air is blown into the lower part of the furnace body through the hot air inlet, and the hot air heats the material piled up in the stacking space.

[0038] In the lower furnace body, the electric arc melts the material that falls from the stacking space and is heated by hot air; the molten metal formed after the material melts sinks to the bottom of the lower furnace body, the slag layer floats on the molten metal, the molten metal is discharged from the molten metal outlet of the lower furnace body, and the slag is discharged from the slag outlet.

[0039] The flue gas generated during the electric arc smelting process of the electrode assembly and the hot air delivered by the hot air inlet diffuse upward through the gaps between the materials, preheating the materials in the stacking space and the downward-flowing materials, and then being discharged from the air outlet after heat exchange.

[0040] Optionally, during the smelting process, materials are continuously fed into the furnace body through a feeding device to form continuous smelting.

[0041] The present invention also provides a smelting method using the aforementioned blast furnace device.

[0042] The lower furnace body maintains a portion of the molten pool, and materials are added to the upper furnace body, where the materials accumulate in the material stacking space from the lower furnace body to the upper furnace body;

[0043] When the material accumulates to the first specified height, high-temperature hot air is blown into the lower part of the furnace body through the hot air vents to heat the material accumulated in the stacking space.

[0044] The electrode assembly is subjected to electric arc melting and the material is continuously fed. As the smelting material level drops, the feeding is stopped when the liquid level of the molten steel reaches the specified liquid level height or the material reaches the specified weight.

[0045] When the material height drops to the second specified height, the hot blast nozzle stops blowing without assistance, and the electrode assembly continues to perform electric arc melting until the remaining accumulated material is completely melted and the slag and molten metal are separated into layers; the molten metal is discharged from the molten metal outlet of the lower furnace body, and the molten slag is discharged from the slag outlet; wherein, the first specified height is higher than the second specified height;

[0046] After the slag and molten metal are removed, repeat the above steps.

[0047] Optionally, the flue gas generated during the electric arc smelting process of the electrode assembly and the hot air delivered by the hot air inlet diffuse upward through the gaps between the materials to preheat the materials in the stacking space and the downward-flowing materials, and are discharged from the air outlet after heat exchange.

[0048] As described above, the beneficial effects of the present invention are as follows: During smelting, the material is added to the upper furnace body and falls through the stacking space, gradually accumulating upwards from the melting pool below the stacking space until the accumulated material in the stacking space reaches a certain height below the air outlet. High-temperature hot air is injected from the hot air outlet to heat the material in the area from the hot air outlet to the top of the stacking space. The electrode assembly is smelted by electric arc in the melting pool. As the material accumulated below and around it gradually melts, the material in the stacking space falls naturally, and is also heated by the high-temperature hot air during the falling process. The hot air penetrates the material from the lower part of the upper furnace body and diffuses upwards, allowing the material to fully exchange heat as it descends. Since the stacking space also serves as part or all of the exhaust channel for flue gas, the smelting flue gas and hot air exchange heat with the material during the upward exhaust process. The reverse movement of material and hot air flow for heat conduction improves the heat utilization efficiency.

[0049] In the material smelting process, some of the hot air chemical energy is used to replace electrical energy, reducing electricity consumption and thus achieving emission reduction and improved economic efficiency. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of a long blast furnace device in one embodiment;

[0051] Figure 2 for Figure 1 Top view;

[0052] Figure 3 This is a schematic diagram of the structure of a long blast furnace device in another embodiment;

[0053] Figure 4 for Figure 3 A top view (excluding the hot air generator and dust removal pipe);

[0054] Figure 5 This is a schematic diagram of the structure of a long blast furnace device in another embodiment;

[0055] Figure 6 for Figure 5 Top view (excluding hot air generator, dust removal pipe, and circulation bypass);

[0056] Figure 7 A schematic diagram of a long blast furnace device employing two sets of three electrodes;

[0057] Figure 8 for Figure 7 Top view (excluding hot air generator, dust removal pipe, and circulation bypass);

[0058] Figure 9 for Figure 7 A magnified view of a portion of the text;

[0059] Figure 10This is a schematic diagram of a movable baffle structure used in one embodiment;

[0060] Figure 11 This is a schematic diagram of a circular blast furnace device using a single electrode in one embodiment.

[0061] Figure 12 This is a schematic diagram of a circular blast furnace device using DC dual electrodes in one embodiment.

[0062] Figure 13 This is a schematic diagram of a circular blast furnace device using AC three electrodes in one embodiment.

[0063] Figure 14 for Figure 13 A top-down view;

[0064] Figure 15 A schematic diagram of the surface heat conduction model of a traditional electric furnace burner (pure oxygen or oxygen-enriched combustion);

[0065] Figure 16 This is a schematic diagram of the hot air heat transfer model of the present invention.

[0066] Part number explanation:

[0067] 1-Electrode assembly 1, 2-Furnace cover, 3-Upper furnace body, 31-Straight cylindrical section; 32-First conical section; 33-Second conical section; 4-Hot air ring pipe 4, 5-Hot air inlet, 6-Slag outlet, 7-Lower furnace body, 8-Molten metal outlet, 9-Feeding device, 10-Dust removal pipe, 11-Circulation bypass, 12-Hot air generator, 13-Drive device, 14-Material, 15-Slag liquid, 16-Molten metal, 17-Nozzle, 18-Pushing device, 19-Blocking structure, 19a-Blocking component, 19b-Drive component, 19c-Swing arm, 20-Air outlet; 21-Recessed part; 22-Sealing cover; 23-Sealing cavity; 24-Stacking space. Detailed Implementation

[0068] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0069] Example

[0070] Research has shown that in addition to adopting a series of technical measures (such as scrap preheating and electric furnace design optimization), reducing electric furnace power consumption can also be achieved by implementing energy grading in electric furnace smelting to improve energy utilization efficiency.

[0071] Using cold scrap steel / reduced iron as raw material as an example:

[0072] Scrap steel / reduced iron raw material 40℃

[0073] Tapping temperature of molten steel: 1460~1640℃

[0074] The flame temperature of a natural gas burner is 2000℃ (even higher temperatures can be achieved with pure oxygen / oxygen-enriched gas).

[0075] Arc temperature 4000~8000℃

[0076] The data above shows that, due to the temperature difference between the heat source and the heated medium, the theoretical efficiency of chemical burners heating cold scrap steel / reduced iron is relatively high (over 50-80%); however, the theoretical efficiency of chemical burners heating the surface heat of molten steel is very low (less than 20%), as demonstrated by the surface heat conduction model of traditional electric furnace burners (pure oxygen or oxygen-enriched combustion). Figure 15 As shown, the theoretical thermal efficiency of electric arc heating is very high for both scrap steel and molten steel, but it is limited by the low energy conversion efficiency of electricity production.

[0077] The concept of energy tiered transfer in electric arc furnace production is to use chemical energy to preheat scrap steel / reduced iron raw materials in a lower temperature range (100-1200℃, depending on the equipment structure) to avoid the problem of low power generation energy efficiency (40%), while using electric energy for heating and smelting in a higher temperature range (800-1640℃).

[0078] For chemical energy heat transfer modes, the heat transfer efficiency can vary greatly depending on the design. The following theoretically achievable blower heat transfer model has a hot air gas-solid contact heat transfer efficiency that, without considering heat dissipation, can reach (1200-300) / 1200*100% = 75% (related to material temperature, hot air / flue gas temperature, material heating time, stacking space size, stacking space height, etc.), which is much higher than the total efficiency of electric heating 21%, and also higher than the thermal efficiency of surface heat conduction of traditional electric furnace burners (after the electric furnace forms a flat melting pool, the thermal efficiency is less than 20%).

[0079] The high-temperature hot air forced draft mode does not require a very high temperature for the hot air (compared to the burner of a traditional electric furnace: natural gas + pure oxygen), which provides a wide range of choices for fuel and heat source. The hot air heat transfer model of this invention is as follows: Figure 16 As shown.

[0080] Therefore, combining blast heating with an electric furnace is an important technical approach to improve the overall thermal efficiency of the electric furnace. This requires sufficient space and height for material stacking, and the formation of a counter-current heat transfer mechanism between the material and the hot airflow. Based on this, the present invention provides a blast electric furnace device and smelting method. It can be used to melt low-quality direct reduced iron, smelt mixed feedstocks of direct reduced iron / scrap steel (crushed material), or melt certain metal ores.

[0081] like Figures 1 to 14As shown in the example, a blast furnace device includes a lower furnace body 7, an upper furnace body 3, a furnace cover 2, an electrode assembly 1, etc.

[0082] The lower furnace body 7 has a melting pool for separating the molten material 14 and the slag liquid 15. The lower furnace body 7 is provided with a slag outlet 6 and a molten metal outlet 8, wherein the height of the slag outlet 6 is higher than the height of the molten metal outlet 8. The material 14 can be direct reduced iron (e.g., sponge iron produced by a vertical furnace), or the material 14 includes direct reduced iron and scrap steel, or the material 14 is an alloy ore.

[0083] The upper furnace body 3 is installed on the lower furnace body 7 and located above the lower furnace body 7. The upper furnace body 3 is provided with a longitudinally extending stacking space 24. The stacking space 24 has a certain longitudinal height. The lower end of the stacking space 24 is connected to the melting pool. The stacking space 24 is used to store material 14. The material 14 can fall from the stacking space 24 to the melting pool. When material 14 is added to the upper furnace body 3, the material 14 can fall under its own gravity and accumulate from bottom to top in the melting pool below the stacking space 24 and in the stacking space 24.

[0084] The cross-sectional shape of the material stacking space 24 of the upper furnace body 3 can be circular, rectangular, or polygonal.

[0085] The furnace cover 2 is installed on the lower furnace body 7 or the upper furnace body 3. The furnace cover 2, the upper furnace body 3, and the lower furnace body 7 together form a smelting preheating space. The furnace cover 2 has an electrode hole. The electrode assembly 1 passes through the electrode hole of the furnace cover 2 and extends into the melting pool of the lower furnace body 7. There is a seal between the electrode assembly 1 and the electrode hole.

[0086] The lower part of the upper furnace body 3 is provided with a hot air inlet 5. High-temperature hot air can be introduced into the lower part of the upper furnace body 3 through the hot air inlet 5 to preheat the material 14 piled in the material storage space 24. This includes heating the material 14 directly sprayed by the hot air, as well as heating the material 14 in the space above the hot air inlet 5 during the upward diffusion of the hot air.

[0087] An air outlet 20 is provided at the upper part of the upper furnace body 3 for discharging smelting flue gas in the smelting preheating space. The stacking space 24 also serves as an upward discharge channel for the smelting flue gas and hot air generated during the melting of the electrode assembly 1. The upper end of the discharge channel is connected to the air outlet 20. During the upward process of the smelting flue gas and hot air, they also exchange heat with the downward material 14, thereby further heating the downward material 14 and the material 14 in the stacking space 24. During the electric arc melting process, the material 14 in the melting pool gradually melts, and the material 14 in the stacking space 24 gradually falls (i.e., the material 14 descends).

[0088] In the above-described apparatus, during smelting, material 14 is added to the upper furnace body 3. Material 14 falls through the stacking space 24 and gradually accumulates upward from the melting pool below the stacking space 24 until material 14 is also accumulated in the stacking space 24 (the height of the accumulation can be set as needed). High-temperature hot air is injected from the hot blast port 5 to heat the material 14 accumulated in the stacking space, that is, the material in the area from the hot blast port to the top of the stack. The electrode assembly 1 performs electric arc melting in the melting pool. As the material 14 accumulated below gradually melts, the material 14 in the stacking space 24 falls naturally. During the falling process, it is also heated by the high-temperature hot air. The hot air penetrates the material 14 from the lower part of the upper furnace body 3 and diffuses upward, allowing the material 14 to fully exchange heat as it descends. Since the stacking space 24 serves as the exhaust channel for flue gas, the smelting flue gas also exchanges heat with the material 14 during the upward exhaust process, improving the heat utilization efficiency.

[0089] In this embodiment, during the smelting process of material 14, some of the electrical energy is replaced by hot air chemical energy, reducing electricity consumption and thus achieving emission reduction and improved economic efficiency. The temperature of the hot air is above 700°C, typically between 1000°C and 1500°C.

[0090] The hot air generating device 12 can be a combustion device, such as a hot air furnace, which uses chemical fuels such as natural gas, coal (pulverized), and heavy oil to generate high-temperature flue gas, or even under oxygen-rich / pure oxygen conditions.

[0091] The hot air source can also be the flue gas produced by the hot air generator 12 and the flue gas produced by the electric furnace itself.

[0092] In some embodiments, to improve heating efficiency and heating uniformity, a plurality of hot air inlets 5 are arranged circumferentially at intervals on the lower part of the upper furnace body 3. The hot air inlets 5 can be circular or circumferentially flat. A hot air ring pipe 4 surrounds the outer side of the lower part of the upper furnace body 3. Each hot air inlet 5 is connected to the hot air ring pipe 4. The air inlet of the hot air ring pipe 4 is connected to the hot air generating device 12.

[0093] In some embodiments, a burner is arranged inside the hot air inlet 5 or the hot air inlet 5 is replaced with a burner, and the material 14 is heated by combustion through the burner.

[0094] In other embodiments, the lower part of the upper furnace body 3 is provided with both hot air inlets 5 and burners. Multiple burners are arranged around the circumference of the upper furnace body 3, which means that the heating method can be combined with hot air blowing and burner combustion.

[0095] Specifically, the burner and the hot air inlet 5 are located at the same height or at different heights. When the burner and the hot air inlet 5 are located at the same height, the burner and the hot air inlet 5 can be arranged alternately along the circumference of the upper furnace body 3, or they can be arranged according to requirements.

[0096] In some embodiments, a feeding device 9 is provided on the top of the upper furnace body 3, and the air outlet 20 is located on the side or top of the upper part of the upper furnace body 3, and the air outlet 20 is higher than the top of the stacking space 24. The top feeding and side air outlet method is adopted, which is convenient for layout. The air outlet 20 is higher than the top of the stacking space 24, so that all materials 14 can be heat exchanged and the materials 14 are prevented from escaping from the air outlet 20.

[0097] The air outlet 20 can be connected to the dust collection pipe 10 to guide the flue gas into the dust collection device for subsequent dust removal. Alternatively, the air outlet 20 can be connected to a flue gas recovery and recycling circulation pipeline. In this example, the blast furnace device also includes a circulation bypass 11. The air outlet 20 is connected to the dust collection pipe 10, and the circulation bypass 11 is connected between the hot air generator 12 and the dust collection pipe 10. This bypass is used to recover a portion of the flue gas flowing out of the air outlet 20 back to the hot air generator 12. A drive device 13 can also be installed to guide the circulating flue gas, such as a high-temperature fan or a jet pump.

[0098] In some embodiments, the upper furnace body 3 has a cylindrical structure (not shown in the figure). To prevent the material 14 from scouring, clogging, or blocking the hot air vent 5, a baffle structure 19 is provided on the inner wall of the upper furnace body 3. The baffle structure 19 is positioned higher than the hot air vent 5. For example, the baffle structure 19 can be located above the hot air vent 5. The baffle structure 19 can be arranged in a ring along the inner wall of the upper furnace body 3 or only above the corresponding hot air vent 5. Utilizing the stacking characteristics of solid particulate materials, a local cavity is formed in the area of ​​the hot air vent 5 to prevent the hot air vent 5 from being blocked.

[0099] In some embodiments, the baffle structure 19 and the cylindrical upper furnace body 3 can also be combined to form a constricted structure with a wider bottom and a narrower top, but this will leave a passage for the material 14 to descend and will not close the upper furnace body 3.

[0100] In some embodiments, the baffle structure 19 can also be designed as a fixed structure, fixed to the inner wall of the upper furnace body 3, or it can be configured as a movable structure. For example Figure 10 As shown, the baffle structure 19 includes a driving component 19b and a baffle component 19a. The baffle component 19a can be driven by the driving component 19b to extend into or out of the material storage space 24. It is configured as a movable structure, which can move the baffle structure 19 when needed to prevent the material 14 from caking on the baffle component 19a and to facilitate the downward movement of the material 14 within the upper furnace body 3. For example, during the movement of the baffle component 19a, the material 14 on the baffle component 19a can be scraped off by the furnace wall.

[0101] For example, the retaining component 19a can be hydraulically extended or retracted to partially extend into or retract from the stacking space 24; or as... Figure 11As shown, it is configured as a swing structure. The driving component (not shown) can drive the material blocking component 19a to swing in and out through the swing arm 19c, so as to partially extend into or out of the material stacking space 24. The swing direction is to swing back and forth along the direction from inside the furnace to outside the furnace.

[0102] In some embodiments, the movement trajectory of the stop member 19a is a straight line, for example... Figure 10 As shown, in some other embodiments, the movement trajectory of the stop component 19b can be an arc, such as... Figure 11 and Figure 13 As shown.

[0103] like Figure 1 and Figure 3 As shown, in some embodiments, the upper part of the upper furnace body 3 is cylindrical or other shapes, and the lower end of the upper furnace body 3 is a flared section. The diameter of the inner wall of the flared section is larger at the bottom and smaller at the top, forming a conical structure. The hot air vent 5 is located on the flared section. In this embodiment, the natural angle of the material 14 is utilized to prevent the hot air vent 5 from being blocked. The baffle structure 19 may not be provided. Of course, to further prevent the hot air vent 5 from being washed away, blocked, or blocked by the material 14, a baffle structure 19 may also be provided above the hot air vent 5.

[0104] like Figure 5 , Figure 7 , Figure 9 As shown, in some embodiments, the upper part of the upper furnace body 3 is cylindrical or has a variable diameter, while the lower part is a constricted structure that first narrows and then expands (from top to bottom). For example... Figure 9 As shown, it includes a straight section 31, a first conical section 32, and a second conical section 33. The diameter of the first conical section 32 gradually decreases from top to bottom, while the diameter of the second conical section 33 gradually increases from top to bottom. The hot air inlet 5 is arranged on the second conical section 33. The constricted position of the first conical section 32 can be used for guidance to prevent the material 14 from impacting or clogging the nozzle or burner arranged at the hot air inlet 5. Of course, a baffle structure 19 can also be set at the same time.

[0105] In some embodiments, the axis of the hot air inlet 5 and / or the burner is inclined, and the blowing direction is downward. This prevents the hot air inlet 5 from being blocked and increases the accumulation range of flue gas penetrating the material 14, thereby improving the heat exchange efficiency between the material 14 and the hot air.

[0106] In some embodiments, a nozzle 17 for injecting carbon powder into the preheated material is provided in the lower region of the accumulated material to create a reducing atmosphere and increase iron production. The nozzle 17 is located on the furnace cover or in the lower part of the upper furnace body.

[0107] The electric furnace can be a DC electric furnace, with one electrode and a corresponding bottom electrode, such as... Figure 11 As shown. The electric furnace can use an AC circuit or a DC furnace; electrode assembly 1 uses three electrodes and three-phase AC power, as shown. Figure 14As shown. Alternatively, two electrodes can be used, with direct current, as shown. Figure 13 As shown. Or a DC current consisting of three bottom electrodes and three electrodes; for example, using six electrodes, such as... Figure 1 and Figure 2 As shown, it can be two sets of three-phase AC; as Figure 3 and Figure 4 As shown, it can also be three sets of DC.

[0108] like Figures 10 to 13 As shown, in some embodiments, the center of the furnace top of the upper furnace body 3 is recessed downwards to form a recessed portion 21 (recessed area). The furnace cover 2 is disposed in the recessed portion 21, and the recessed portion 21 and the side wall of the upper furnace body 3 enclose a material stacking space 24. This material stacking space 24 is a ring around the circumference of the upper furnace body 3, forming an annular space. The electrode assembly 1 extends from the furnace cover 2 into the melting pool, and the material stacking space 24 is located around the electrode assembly 1 and the furnace cover 2. The concave structure can reduce the length of the electrode in the electric furnace to prevent the electrode assembly 1 from being corroded and broken by the smelting environment. The furnace cover 2 and the upper furnace body 3 constitute the annular material stacking space 24 and the exhaust channel for the flue gas to diffuse and penetrate upwards through the gaps in the material 14. This structure can use a single electrode, a double electrode, or a triple electrode.

[0109] The sides and bottom of the recessed part 21 are both furnace covers, or the sides of the recessed part 21 are part of the upper furnace body 3, and the bottom of the recessed part 21 is a furnace cover.

[0110] like Figure 12 As shown, in some embodiments, a sealing cover 22 is provided on the upper furnace body 3 above the furnace cover 2, that is, the sealing cover 22 is provided at the opening of the recess 21. The electrode assembly 1 extends into the lower furnace body 7 after passing through the sealing cover 22 and the furnace cover 2. The electrode assembly 1 is sealed with the sealing cover 22 and the furnace cover 2 respectively. A sealing cavity 23 is formed between the sealing cover 22 and the furnace cover 2, and the sealing cover 22 is provided with a sealing port for blowing air into the sealing cavity 23 or drawing air from the sealing cavity 23. This improves the airtightness of the electrode holes on the furnace cover 2, improves the production environment, prevents smelting flue gas from entering the external environment, and reduces pollution.

[0111] In this embodiment, the upper furnace body 3 and the lower furnace body 7 can be corresponding circular, rectangular or other polygonal structures.

[0112] In some embodiments, the furnace cover 2 is mounted on the lower furnace body 7, and the furnace cover 2 and the upper furnace body 3 are arranged side by side on the lower furnace body 7, with the top of the furnace cover 2 being lower than the top of the upper furnace body 3. The length direction of the lower furnace body 7 is formed along the side-by-side direction of the furnace cover 2 and the upper furnace body 3.

[0113] In this example, the slag outlet 6 is located on the lower furnace body 7 on the side away from the material 14 accumulation position, that is, on the side away from the upper furnace body 3 and close to the furnace cover 2. This is to reduce the amount of iron carried away by the slag liquid 15 during slag discharge.

[0114] Specifically, such as Figures 1 to 9 As shown, the lower furnace body 7 is elongated and can be a long strip. From a top view, it can be a rectangle connected to a circle, or two circles connected together. The corresponding upper furnace body 3 can be a circle or a polygon. The furnace cover 2 is close to the first end of the lower furnace body 7 along the length direction, and the upper furnace body 3 is close to the second end of the lower furnace body 7 along the length direction. The slag outlet 6 is close to the first end of the lower furnace body 7.

[0115] Typically, to clean the molten pool in the lower furnace body 7 for equipment maintenance, a drain port (not shown in the figure) can be installed at an appropriate location at the bottom.

[0116] In some embodiments, a pushing device 18 is provided on the lower furnace body 7 to push the material 14 toward the area where the electrode assembly 1 is located, thereby improving the smelting efficiency. The pushing device 18 can be hydraulic or mechanical, such as a hydraulic cylinder + water-cooled guide pusher structure.

[0117] In this embodiment, whether it is a long electric furnace or a circular electric furnace, its furnace cover, upper furnace body, and lower furnace body all form a single chamber. The flue gas within the entire chamber can rise to preheat the material and then be discharged from the air outlet.

[0118] This blast furnace is suitable for smelting both low-quality and high-quality direct reduced iron (DRI). The materials can be DRI, scrap steel, a mixture of scrap steel and DRI, or metallic ore.

[0119] This embodiment also discloses a smelting method, which uses the aforementioned blast furnace device, for example, a long electric furnace device;

[0120] The lower furnace body 7 maintains a portion of the molten pool (i.e., leaves a portion of molten metal 16), and adds material 14 to the upper furnace body 3. The material 14 falls from the stacking space 24 of the upper furnace body 3 into the molten pool and gradually accumulates from bottom to top, that is, it gradually accumulates from the molten pool below the stacking space 24 / lower furnace body 7 until the stacking space 24 of the upper furnace body 3 contains material 14, which can be accumulated to a specified height and adjusted as needed.

[0121] High-temperature hot air is blown into the lower part of the furnace body 3 through the hot air inlet 5. The hot air heats the material 14 piled in the material storage space 24, including the material 14 directly blown by hot air and the material 14 heated by hot air diffusion upward.

[0122] In the lower furnace body 7, the electric arc melts the material 14 that falls by gravity and is heated by hot air; the molten metal 16 formed after the material 14 melts sinks to the bottom of the lower furnace body 7, and the slag liquid 15 floats on the molten metal 16. The molten metal 16 is discharged from the higher molten metal 16 outlet 8 of the lower furnace body 7, and the slag liquid 15 is discharged from the lower slag outlet 6.

[0123] Furthermore, the flue gas generated during the electric arc smelting process of electrode assembly 1, the hot air supplied by hot air inlet 5, and the flue gas generated by burner / nozzle (when burner or nozzle is installed) rise upwards. The flue gas and hot air (i.e., the hot air in the smelting preheating space) diffuse upwards through the gaps between the materials 14, preheating the materials 14 in the stacking space 24 and the downward-moving materials 14, thus fully utilizing the waste heat of the smelting flue gas. The flue gas and hot air after heat exchange are discharged from air outlet 20 for dust removal or recycling, etc.

[0124] When the electric arc has not started melting, during the accumulation of material 14, there will be a mixture of material 14 and molten metal 16 at the bottom of the melting pool; when the melting reaches a small amount of material 14, the bottom is molten metal 16, and the slag liquid 15 layer and material 14 float on top.

[0125] In the above method, continuous smelting can be achieved by continuously feeding materials into the furnace body 3 through the feeding device 9, continuously blowing hot air, and continuously melting the electrode assembly 1.

[0126] After entering through the hot air inlet, the hot air should penetrate the gaps between the materials and preheat the entire material piled up in the upper part of the stacking space, that is, at least preheat the piled material above the position of the hot air inlet. The stacking space 24 forms a channel for material accumulation, material downward movement, and flue gas and hot air dispersion upward movement.

[0127] This embodiment also discloses an intermittent feeding smelting method, employing the aforementioned blast furnace device, such as a long or circular blast furnace device, as described above. Figure 5 , Figure 9 The structure shown is as follows;

[0128] Specifically, the lower furnace body 7 maintains a portion of the molten pool (i.e., leaves a portion of molten metal 16), and adds material 14 to the upper furnace body 3. The material 14 is gradually piled up from the lower furnace body 7 to the stacking space 24; that is, it is gradually piled up from the molten pool below the stacking space 24 until the stacking space 24 of the upper furnace body 3 contains material 14, which can be piled up to a specified height and adjusted as needed.

[0129] When the material 14 accumulates to the first specified height, feeding is stopped, and high-temperature hot air is blown into the lower part of the furnace body 3 through the hot air vent 5 to heat the material 14 accumulated in the stacking space 24.

[0130] Electrode assembly 1 performs electric arc melting, where the electric arc melts the material 14 that falls by gravity and is heated by hot air. As the material 14 near the melting pool melts, the material 14 in the upper part moves downward under gravity, and the hot air continues to heat the downward material 14. The material is also continuously fed. As the smelting material level drops, the feeding stops when the molten steel reaches a specified level or the material reaches a specified weight. For example, the feeding stops when the material 14 reaches the weight of a single smelting.

[0131] As the electric arc melting proceeds, when the height of the material 14 drops to the second designated height, the hot blast outlet 5 stops blowing, and the electrode assembly 1 continues to be energized for electric arc melting until the remaining accumulated material 14 is completely melted and the slag liquid 15 and molten metal 16 are separated into layers. The molten metal 16 is discharged from the molten metal outlet 8 of the lower furnace body 7, and the slag liquid 15 is discharged from the slag outlet 6. The slag discharge and molten metal 16 discharge operations are completed, and a single smelting is completed. The above operations are repeated to form intermittent feeding smelting.

[0132] The first specified height is higher than the second specified height. The first specified height can be the height of the top of the material storage space 24 or a height close to its top. The second specified height can be a height lower than the position of the hot air inlet 5, or slightly higher than the position of the hot air inlet 5, or exactly level with the position of the hot air inlet 5. That is, when the material 14 falls to this height, the heating efficiency of the hot air is not high and it is not economical, so the hot air can be stopped. This example is only for illustration, and the specific conditions can be set according to the smelting requirements.

[0133] During the smelting process, the flue gas generated by the electric arc smelting of electrode assembly 1, the flue gas generated by the burner / nozzle (when a burner or nozzle is installed), and the blown-in hot air (or hot air after heat exchange with the material 14) rise upwards, together preheating the stacking space 24 and the downward-flowing material 14. The flue gas and hot air diffuse upwards, passing through the gaps between the materials 14, and form contact heat conduction heating with the downward-flowing material 14. The flue gas and hot air after heat exchange are discharged from the air outlet 20 for dust removal or recycling, etc.

[0134] In this blast furnace, the oxidation-reduction characteristics of the hot air need to be adjusted according to different raw material properties. For example, if material 14 is mainly porous and flammable direct reduced iron, which is sensitive to the oxygen content in the flue gas, then a reducing gas (low oxygen content, containing reducing components such as CO, C, and H2) can be selected for the blast hot air. Coke or coal can be mixed or layered as needed during batching. For other metal ores and scrap steel that are not sensitive to oxygen, direct heating with natural gas can be used. Generally, mixing coke, coal, and other solid combustibles into the batching of material 14 can increase the proportion of chemical energy in the furnace and improve its reducing properties.

[0135] Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A forced-air electric furnace device, characterized in that, include: The lower furnace body has a melting pool, and a slag outlet and a molten metal outlet are provided on the lower furnace body; An upper furnace body is disposed on top of a lower furnace body. The upper furnace body contains a longitudinally extending material storage space for storing materials. The lower end of the material storage space connects to the melting pool, allowing the materials to flow downwards from the material storage space to the melting pool. The inner wall of the upper furnace body is provided with a baffle structure, positioned higher than the hot air inlet. The baffle structure is fixed to the upper furnace body. Alternatively, the baffle structure includes a driving component and a baffle component, the baffle component being driven by the driving component to at least partially extend into or retract from the material storage space. The furnace cover is installed on the lower or upper furnace body and together with the upper and lower furnace bodies, it forms a smelting preheating space. The electrode assembly extends into the lower furnace body after passing through the furnace cover; A hot air inlet is located at the lower part of the upper furnace body and is used to send hot air into the lower part of the stacking space to heat the materials piled up in the stacking space. The air outlet is located at the top of the upper furnace body and is used to discharge the flue gas after heat exchange. The material storage space also serves as a discharge channel for the electric arc melting fumes and hot air to diffuse upwards to the air outlet.

2. The blast furnace device according to claim 1, characterized in that: The blast furnace device also includes a hot air generating device and a hot air ring pipe. The upper furnace body has a plurality of hot air inlets arranged at intervals along the circumference. Each hot air inlet is connected to the hot air ring pipe, and the hot air ring pipe is connected to the hot air generating device.

3. The blast furnace device according to claim 2, characterized in that: The lower part of the upper furnace body is provided with multiple burners arranged circumferentially for injecting air into the furnace.

4. The blast furnace device according to claim 3, characterized in that: The burner and the hot air inlet are located at the same height or at different heights; when the burner and the hot air inlet are located at the same height, the burner and the hot air inlet are alternately arranged along the circumference of the upper furnace body.

5. The blast furnace device according to claim 1, characterized in that: The hot air inlet is a burner that blows hot air into the furnace.

6. The blast furnace device according to claim 2, characterized in that: The furnace top of the upper furnace body is equipped with a feeding device, and the air outlet is located on the side or top of the upper part of the upper furnace body, and the air outlet is higher than the top of the material storage space.

7. The blast furnace device according to claim 1, characterized in that: The lower end of the upper furnace body is a flared section, and the inner wall of the flared section has a conical structure that is thinner at the top and thicker at the bottom. The hot air inlet is located on the flared section.

8. The blast furnace device according to claim 1, characterized in that: The upper furnace body has a cylindrical structure, or the upper part of the upper furnace body is a cylindrical shape and the lower part is a conical structure that is thinner at the top and thicker at the bottom; or the upper part of the upper furnace body is a cylindrical shape and the lower part is a constricted structure that first narrows and then expands.

9. The blast furnace device according to claim 3, characterized in that: The axis of the hot air inlet and / or burner is inclined, and the blowing direction is downward.

10. The blast furnace apparatus according to claim 1, characterized in that: The furnace cover or upper furnace body is equipped with nozzles for spraying carbon powder onto the preheated material.

11. The blast furnace apparatus according to claim 1, characterized in that: The blast furnace device also includes a circulation bypass, and the air outlet is connected to a dust removal pipe. The circulation bypass is connected between the hot air generator and the dust removal pipe, and is used to recover part of the flue gas flowing out of the air outlet to the hot air generator.

12. The blast furnace apparatus according to any one of claims 1-11, characterized in that: The furnace top of the upper furnace body is recessed downward to form a recessed part, and the furnace cover is disposed in the recessed part. The recessed part and the side wall of the upper furnace body form an annular material storage space, which is located around the electrode assembly and the furnace cover.

13. The blast furnace apparatus according to claim 12, characterized in that: A sealing cover is provided on the upper furnace body above the furnace cover. The electrode assembly extends into the lower furnace body after passing through the sealing cover and the furnace cover. A sealing cavity is formed between the sealing cover and the furnace cover, and a sealing port is provided on the sealing cover for blowing air into the sealing cavity or drawing air out of the sealing cavity.

14. The blast furnace apparatus according to any one of claims 1-11, characterized in that: The furnace cover is installed on the lower furnace body, and the furnace cover is arranged side by side with the upper furnace body, with the top of the furnace cover being lower than the top of the upper furnace body.

15. The blast furnace apparatus according to claim 14, characterized in that: The slag outlet is located on the side of the lower furnace body away from the material accumulation area.

16. The blast furnace apparatus according to claim 14, characterized in that: The lower furnace body is elongated, the furnace cover is located near the first end of the lower furnace body along its length, and the upper furnace body is located near the second end of the lower furnace body along its length; the slag outlet is located near the first end of the lower furnace body.

17. The blast furnace apparatus according to claim 14, characterized in that: The lower furnace body is equipped with a material pushing device for pushing materials toward the area where the electrode assembly is located.

18. A smelting method, employing the blast furnace apparatus according to any one of claims 1-17, characterized in that: The lower furnace body maintains a portion of the molten pool, and materials are added to the upper furnace body. The materials accumulate from the lower furnace body upwards into the stacking space of the upper furnace body. High-temperature hot air is blown into the lower part of the furnace body through the hot air inlet, and the hot air heats the material piled up in the stacking space. In the lower furnace body, the electric arc melts the material that falls from the stacking space and is heated by hot air; the molten metal formed after the material melts sinks to the bottom of the lower furnace body, the slag layer floats on the molten metal, the molten metal is discharged from the molten metal outlet of the lower furnace body, and the slag is discharged from the slag outlet. The flue gas generated during the electric arc smelting process of the electrode assembly and the hot air delivered by the hot air inlet diffuse upward through the gaps between the materials, preheating the materials in the stacking space and the downward-flowing materials, and then being discharged from the air outlet after heat exchange.

19. The smelting method according to claim 18, characterized in that: During the smelting process, materials are continuously fed into the furnace body through a feeding device to form continuous smelting.

20. A smelting method, employing the blast furnace apparatus according to any one of claims 1-17, characterized in that: The lower furnace body maintains a portion of the molten pool, and materials are added to the upper furnace body, where the materials accumulate in the material stacking space from the lower furnace body to the upper furnace body; When the material accumulates to the first specified height, high-temperature hot air is blown into the lower part of the furnace body through the hot air vents to heat the material accumulated in the stacking space. The electrode assembly is subjected to electric arc melting and the material is continuously fed. As the smelting material level drops, the feeding is stopped when the liquid level of the molten steel reaches the specified liquid level height or the material reaches the specified weight. When the material height drops to the second specified height, the hot blast nozzle stops blowing, and the electrode assembly continues to perform electric arc melting until the remaining accumulated material is completely melted and the slag and molten metal are separated into layers; the molten metal is discharged from the molten metal outlet of the lower furnace body, and the molten slag is discharged from the slag outlet; wherein, the first specified height is higher than the second specified height; After the slag and molten metal are removed, repeat the above steps.

21. The smelting method according to claim 20, characterized in that: The flue gas generated during the electric arc smelting process of the electrode assembly and the hot air delivered by the hot air inlet diffuse upward through the gaps between the materials, preheating the materials in the stacking space and the downward-flowing materials, and then being discharged from the air outlet after heat exchange.

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