Energy-saving and heat-preserving type intermediate frequency steel shell furnace

Abstract

This utility model relates to an energy-saving and heat-insulating medium-frequency steel shell furnace, including a crucible. An induction coil is fitted around the bottom of the crucible, and a protective layer is fitted around the outside of the crucible. A multi-level insulation structure is provided between the protective layer and the crucible. The multi-level insulation structure includes, from the inside out, a layer of magnesia-chrome bricks, a layer of honeycomb insulation board, and a layer of silicon carbide fiber insulation. A hopper is located above the crucible, and a conveying pipe is located at the bottom of the hopper. The bottom end of the conveying pipe is located above the opening at the top of the crucible. A screw conveyor is located inside the conveying pipe. A support is located at the top of the crucible, and a combined drive assembly for driving the screw conveyor to rotate is located at the top of the support. This utility model ensures a stable high-temperature environment inside the crucible, reduces heat loss from the molten metal, lowers energy consumption, and extends smelting time; it improves energy utilization, enhances operational convenience and production efficiency, and has outstanding energy-saving advantages and economic value.

Description

Technical Field

[0001] This utility model relates to the field of medium-frequency steel shell furnace technology, and in particular to an energy-saving and heat-insulating medium-frequency steel shell furnace. Background Technology

[0002] A steel-shell furnace is a device used to melt metal ingots and scrap metals, adding necessary alloying components. Through processes such as slag removal and refining, these materials are smelted into the desired alloy. Medium-frequency steel-shell furnaces utilize induction coils to heat the metal in the crucible. However, due to the high thermal conductivity of the furnace-building materials, copper induction coils are prone to oxidation under heating conditions, especially when melting high-melting-point materials, severely impacting their lifespan.

[0003] For example, the existing technology CN210346290U achieves a certain degree of thermal insulation of the furnace body by setting up an induction coil thermal insulation layer, a thermal insulation layer, a thermal insulation filler layer, and a thermal insulation base. Furthermore, the use of a graphite crucible enhances its refractory performance. Its composite structure can withstand temperatures above 1600℃ and exhibits good thermal shock stability. However, this technology still has significant shortcomings: First, traditional insulation materials such as rock wool and ceramic fibers have high thermal conductivity, ranging from 0.04 to 0.08 W / (m·K), and are prone to pulverization under long-term high-temperature use, leading to a decrease in thermal insulation performance. Second, although the thermal insulation filler layer uses granular filling, the pore distribution is uneven, resulting in a significant thermal bridging effect. This causes the outer surface temperature of the furnace body to reach 80-100℃, with a heat loss rate exceeding 15%, failing to meet increasingly stringent energy-saving requirements. Moreover, the existing technology does not effectively integrate the material conveying and mixing system. Most equipment relies on manual feeding or simple mechanical feeding, resulting in low feeding accuracy and uneven mixing of alloy components. Manual feeding can easily lead to an imbalance in the distribution of metal materials, affecting smelting efficiency; traditional screw conveyors lack dynamic adjustment functions and cannot adjust the feeding speed in real time according to the furnace temperature, which can easily cause local overheating or insufficient melting. Utility Model Content

[0004] The purpose of this utility model is to address the shortcomings of existing technologies by proposing an energy-saving and heat-insulating medium-frequency steel shell furnace.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An energy-saving and heat-insulating medium-frequency steel shell furnace includes a crucible, an induction coil sleeved at the bottom of the crucible, a protective layer sleeved on the outside of the crucible, and a multi-level heat insulation structure between the protective layer and the crucible. The multi-level heat insulation structure includes a magnesia-chrome brick layer, a honeycomb insulation board layer, and a silicon carbide fiber insulation layer arranged from the inside out. A hopper is provided above the crucible, and a conveying pipe is provided at the bottom of the hopper. The bottom end of the conveying pipe is located above the opening at the top of the crucible. A screw conveyor is provided inside the conveying pipe. A support is provided at the top of the crucible, and a combined drive assembly for driving the screw conveyor to rotate is provided at the top of the support.

[0006] The above technical solution involves setting up a multi-level insulation structure between the protective layer and the crucible, consisting of a magnesium chrome brick layer, a honeycomb insulation board layer, and a silicon carbide fiber insulation layer. This creates a gradient insulation system that is "high temperature resistant, low thermal conductivity, and radiation reflection," significantly reducing furnace heat loss, increasing thermal efficiency to over 85%, reducing energy consumption, and maintaining a stable high-temperature environment inside the crucible.

[0007] Preferably, the combined drive assembly includes a motor located at the top of the support, a first bevel gear sleeved on the motor output shaft, a second bevel gear meshing at the lower end of the first bevel gear, a stirring rod coaxially inserted into the second bevel gear, the stirring rod being located inside the crucible, the stirring rod rotating through the top of the support, a spline rod coaxially slidably inserted into the bottom end of the screw conveyor, and magnetic couplers provided at the top end of the stirring rod and the bottom end of the spline rod.

[0008] Through the above technical solutions: the combined drive component achieves synchronous drive or independent control of the stirring rod and the screw conveyor through the linkage design of the motor, bevel gear and magnetic coupler. The magnetic coupler can disconnect / connect the transmission, and the material conveying and molten metal stirring are completed simultaneously during the smelting process, improving the uniformity of composition and simplifying the power system structure.

[0009] Preferably, the side wall of the feed pipe is provided with an electric push rod, the bottom end of the electric push rod is provided with an L-shaped support rod, the lower surface of the L-shaped support rod is embedded with a ball, and the ball slides and abuts against the lower surface of the magnetic coupler at the bottom end of the spline rod.

[0010] Through the above technical solutions, the electric push rod and L-shaped support rod, together with the ball bearing adjustment magnetic coupler air gap, can precisely control the start and stop of the screw conveyor and the transmission torque, realize the dynamic adjustment of material conveying, avoid overfeeding or feeding interruption, and improve operational flexibility.

[0011] Furthermore, the honeycomb insulation layer is made of 304 stainless steel, with a honeycomb aperture of 10mm and a thickness of 80mm, and the silicon carbide fiber insulation layer has a thickness of 50mm.

[0012] Through the above technical solutions: the honeycomb insulation panel layer uses the low thermal conductivity of the air layer to suppress heat conduction, and the silicon carbide fiber insulation layer strengthens the insulation through its porous structure. The combination of the two reduces the outer surface temperature of the furnace body by 30%-50% compared to the traditional design, further optimizing the insulation performance.

[0013] Furthermore, the protective layer has symmetrical bases at both ends, and each base has a hydraulic lifting assembly hinged to its top. The top of each hydraulic lifting assembly is hinged to the protective layer.

[0014] Through the above technical solutions, the hydraulic lifting component between the base and the protective layer can drive the furnace body to tilt and unload, realizing the rapid discharge of molten metal, while facilitating crucible replacement and equipment maintenance, improving operational safety and maintenance convenience.

[0015] Preferably, the silicon carbide fiber insulation layer comprises 60%-70% silicon carbide fiber, 20%-25% alumina powder, 10%-15% ceramic hollow microspheres and 3%-5% glass phase binder. The silicon carbide fiber and alumina powder form a porous structure with interwoven fibers and filled with ceramic hollow microspheres. The structure is obtained by compression molding and high-temperature sintering at 1200℃, with a porosity of 35%-45%.

[0016] Through the above technical solutions, the silicon carbide fiber insulation layer, through a specific ratio and a high-temperature sintering process of 1200℃, forms a porous structure with interwoven fibers, which has high fire resistance, low thermal conductivity and thermal shock resistance, extending the service life of the insulation layer and enhancing structural stability.

[0017] The beneficial effects of this utility model are as follows: 1. Through the gradient design of the multi-level insulation structure, a composite insulation system of "high temperature resistance barrier - air layer insulation - porous radiation reflection" is formed, which reduces the heat loss of the furnace body by more than 40%, increases the thermal efficiency to more than 85%, and controls the outer surface temperature to within 50℃. Compared with traditional medium frequency furnaces, it saves more than 30% energy. At the same time, it ensures the stability of the high temperature environment inside the crucible, reduces the heat loss of molten metal, reduces energy consumption, and extends the melting operation time. 2. The integrated design of the combined drive component and the hydraulic jacking system allows the screw conveyor and the stirring rod to be controlled synchronously or independently, such as stepless adjustment of the feeding speed and dynamic matching of the stirring intensity, ensuring uniform melting and mixing of the metal material; the hydraulic jacking component supports 95° tilt unloading of the furnace body and overall lifting for maintenance, and with the non-contact transmission of the magnetic coupler and the modular insulation layer structure, the crucible replacement time is shortened to less than 2 hours, significantly improving operational flexibility and equipment maintenance efficiency, and reducing the frequency of manual intervention and labor intensity.

[0018] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of an energy-saving and heat-insulating medium-frequency steel shell furnace proposed in this utility model; Figure 2 This is a side view of the structure of an energy-saving and heat-insulating medium-frequency steel shell furnace proposed in this utility model. Figure 3 This is a schematic diagram of a multi-layer insulation structure for an energy-saving and heat-insulating medium-frequency steel shell furnace proposed in this utility model. Figure 4 This utility model proposes an energy-saving and heat-insulating medium-frequency steel shell furnace. Figure 2 A magnified schematic diagram of the local structure at point A.

[0020] In the diagram: 1. Protective layer; 2. Crucible; 3. Induction coil; 4. Magnesia-chrome brick layer; 5. Honeycomb insulation board layer; 6. Silicon carbide fiber insulation layer; 7. Support; 8. Stirring rod; 9. Motor; 10. First bevel gear; 11. Second bevel gear; 12. Magnetic coupler; 13. Spline rod; 14. Screw conveyor; 15. Hopper; 16. Feed pipe; 17. Hydraulic lifting assembly; 18. Electric push rod; 19. L-shaped support rod; 20. Ball bearing; 21. Base. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0022] Example 1, referring to Figures 1 to 4 An energy-saving and heat-insulating medium-frequency steel shell furnace includes a crucible 2, an induction coil 3 fitted at the bottom of the crucible 2, a protective layer 1 fitted on the outside of the crucible 2, and a multi-level heat insulation structure between the protective layer 1 and the crucible 2. The multi-level heat insulation structure includes a magnesium chrome brick layer 4, a honeycomb insulation board layer 5, and a silicon carbide fiber insulation layer 6 arranged from the inside to the outside. A hopper 15 is provided above the crucible 2, and a conveying pipe 16 is provided at the bottom of the hopper 15. The bottom end of the conveying pipe 16 is located above the opening at the top of the crucible 2. A screw conveyor 14 is provided inside the conveying pipe 16. A support 7 is provided at the top of the crucible 2, and a combined drive assembly for driving the screw conveyor 14 to rotate is provided at the top of the support 7.

[0023] In this embodiment, the combined drive assembly includes a motor 9 mounted on the top of the support 7. A first bevel gear 10 is sleeved on the output shaft of the motor 9. A second bevel gear 11 meshes with the lower end of the first bevel gear 10. A stirring rod 8 is coaxially inserted into the second bevel gear 11. The stirring rod 8 is located inside the crucible 2 and rotates through the top of the support 7. A spline rod 13 is coaxially slidably inserted into the bottom end of the screw conveyor 14. Magnetic couplers 12 are provided at the top of the stirring rod 8 and the bottom of the spline rod 13. An electric push rod 18 is provided on the side wall of the feed pipe 16. An L-shaped support rod 19 is provided at the bottom end of the electric push rod 18. A ball bearing 20 is embedded in the lower surface of the L-shaped support rod 19. The ball bearing 20 slides against the lower surface of the magnetic coupler 12 at the bottom end of the spline rod 13. Next, the honeycomb insulation layer 5 is made of 304 stainless steel with a honeycomb pore diameter of 10mm and a thickness of 80mm. The silicon carbide fiber insulation layer 6 has a thickness of 50mm. The protective layer 1 has symmetrical bases 21 at both ends. The top of each base 21 is hinged with a hydraulic lifting component 17. The top of each hydraulic lifting component 17 is hinged to the protective layer 1. The silicon carbide fiber insulation layer 6 contains 60%-70% silicon carbide fiber, 20%-25% alumina powder, 10%-15% ceramic hollow microspheres and 3%-5% glass phase binder. The silicon carbide fiber and alumina powder form a porous structure with interwoven fibers and filled with ceramic hollow microspheres. It is made by molding and sintering at 1200℃, with a porosity of 35%-45%.

[0024] The working principle of this embodiment: Medium frequency induction heating mechanism The induction coil 3 at the bottom of crucible 2 is connected to a medium-frequency power supply, converting the mains frequency AC power into a 100-10000Hz medium-frequency current. The alternating current generates a strong magnetic field within the induction coil. The magnetic lines of force penetrate the metal material inside the crucible, inducing eddy currents within the metal and achieving rapid heating using the Joule heating effect. The skin effect of medium-frequency heating preferentially heats the metal surface, and combined with the mechanical stirring of the stirring rod 8, it significantly improves temperature uniformity.

[0025] Multi-level thermal insulation structure Magnesium chrome brick layer 4: As the inner layer, it directly contacts the high-temperature crucible. It is made of high-temperature resistant and corrosion-resistant magnesium chrome bricks to withstand the thermal shock of molten metal and initially block heat transfer.

[0026] The honeycomb insulation panel layer 5 is made of 304 stainless steel with a honeycomb structure, 10mm in diameter and 80mm in thickness, forming an air insulation layer that utilizes the low thermal conductivity of air to reduce heat loss through conduction. The staggered arrangement of the honeycomb cells further suppresses the thermal bridging effect, reducing the thermal conductivity to 0.02-0.04 W / (m·K).

[0027] Silicon carbide fiber insulation layer 6: Composed of 60%-70% silicon carbide fiber, 20%-25% alumina powder, and ceramic hollow microspheres, it is sintered at 1200℃ to form a porous structure with a porosity of 35%-45%. The high melting point and low thermal conductivity of silicon carbide fiber, combined with the radiation reflection effect of ceramic hollow microspheres, effectively blocks heat from being conducted to the outside.

[0028] The three-layer structure works synergistically to reduce the outer surface temperature of the furnace body by 30%-50% compared to traditional designs, and increase the thermal efficiency to over 85%.

[0029] Motor 9 drives both stirring rod 8 and screw conveyor 14 through the meshing of first bevel gear 10 and second bevel gear 11. The specific path is as follows: The motor output shaft → first bevel gear 10 → second bevel gear 11 → stirring rod 8 rotates.

[0030] The motor synchronously drives the second bevel gear 11, which is connected to the spline rod 13 through the magnetic coupler 12, thereby driving the screw conveyor 14 to rotate.

[0031] The air gap adjustment of the magnetic coupler is crucial: when the electric actuator 18 retracts, the L-shaped support rod 19 drives the ball bearing 20 to press down on the spline rod 13, increasing the air gap of the magnetic coupler 12 and stopping the screw conveyor from driving; conversely, when the electric actuator extends, the air gap decreases, and the screw conveyor resumes operation. This design allows for independent control of the stirring and conveying functions, for example, retaining only stirring in the later stages of smelting to promote homogenization of the composition.

[0032] The screw conveyor 14 is connected to the magnetic coupler 12 via a splined rod 13 and can slide axially. When the electric actuator 18 adjusts the position of the splined rod, the height of the screw conveyor's inlet changes accordingly, thereby controlling the material's falling speed. Furthermore, the splined rod's sealed design prevents high-temperature dust from entering the transmission mechanism, ensuring long-term reliable operation.

[0033] The hydraulic lifting assembly 17 is hinged to the base 21 and is driven by a hydraulic cylinder to rotate the protective layer 1 around the hinge point. The specific process is as follows: The hydraulic pump station provides pressurized oil, which drives the piston rod of the hydraulic cylinder to extend, causing the furnace body to tilt around the bottom hinge axis.

[0034] Displacement sensors monitor the tilt angle in real time, and the PLC control system ensures that the hydraulic cylinders on both sides move synchronously with an accuracy of ±1.0mm.

[0035] The tilting angle can be adjusted according to the material discharge requirements, up to a maximum of 95°, which facilitates the rapid discharge of molten metal.

[0036] The hydraulic lifting system allows the furnace body to be fully lifted, facilitating the replacement of crucibles or the maintenance of induction coils.

[0037] The non-contact transmission of magnetic couplers avoids the wear of traditional mechanical couplings and reduces maintenance frequency.

[0038] Collaborative Workflow Preparation before smelting: Start motor 9 and drive screw conveyor 14 through magnetic coupler 12 to send metal material in hopper 15 into crucible 2 through conveying pipe 16.

[0039] The hydraulic lifting assembly 17 resets the furnace body to a horizontal position, and the electric push rod 18 is turned off to stop the screw conveyor from feeding material.

[0040] Melting process: The medium frequency power supply is started, the induction coil 3 heats the metal material to a molten state, and the stirring rod 8 rotates synchronously to promote homogenization.

[0041] The multi-layer insulation structure effectively reduces heat loss, increasing the furnace's thermal efficiency to over 85%.

[0042] After smelting is completed, the hydraulic lifting assembly 17 drives the furnace body to tilt, and the molten metal flows out through the crucible opening.

[0043] During the tilting process, the stirring rod 8 rotates continuously at a low speed to prevent the molten metal from solidifying and clogging the discharge port.

[0044] After the equipment is shut down, the furnace body can be lifted using the hydraulic system to replace the crucible or check the condition of the insulation layer.

[0045] In summary, this utility model integrates medium-frequency induction heating, multi-level heat preservation, intelligent transmission control, and a hydraulic tilting furnace system to achieve a highly efficient, energy-saving, and flexible metal smelting process, which is suitable for high-temperature smelting needs in casting, metallurgy, and other fields.

[0046] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An energy-saving and heat-insulating intermediate frequency steel shell furnace, comprising a crucible (2), the lower part of the crucible (2) is sleeved with an induction coil (3), and the outer side of the crucible (2) is sleeved with a protective layer (1), characterized in that, A multi-level insulation structure is provided between the protective layer (1) and the crucible (2). The multi-level insulation structure includes a magnesium chrome brick layer (4), a honeycomb insulation board layer (5), and a silicon carbide fiber insulation layer (6) arranged from the inside to the outside. A hopper (15) is provided above the crucible (2). A conveying pipe (16) is provided at the bottom of the hopper (15). The bottom end of the conveying pipe (16) is located above the opening at the top of the crucible (2). A screw conveyor (14) is provided inside the conveying pipe (16). A support (7) is provided at the top of the crucible (2). A combined drive assembly for driving the screw conveyor (14) to rotate is provided at the top of the support (7).

2. The energy-saving and heat-preserving intermediate frequency steel shell furnace according to claim 1, characterized in that, The combined drive assembly includes a motor (9) located on the top of the support (7). The output shaft of the motor (9) is fitted with a first bevel gear (10). The lower end of the first bevel gear (10) meshes with a second bevel gear (11). The second bevel gear (11) is coaxially inserted with a stirring rod (8). The stirring rod (8) is located inside the crucible (2). The stirring rod (8) rotates through the top of the support (7). The bottom end of the screw conveyor (14) is coaxially slidably fitted with a spline rod (13). The top end of the stirring rod (8) and the bottom end of the spline rod (13) are both provided with magnetic couplers (12).

3. The energy-saving and heat-preserving medium-frequency steel shell furnace according to claim 2, characterized in that, The side wall of the feed pipe (16) is provided with an electric push rod (18), and the bottom end of the electric push rod (18) is provided with an L-shaped support rod (19). The lower surface of the L-shaped support rod (19) is embedded with a ball (20), and the ball (20) slides against the lower surface of the magnetic coupler (12) at the bottom end of the spline rod (13).

4. The energy-saving and heat-preserving medium-frequency steel shell furnace according to claim 3, characterized in that, The honeycomb insulation layer (5) is made of 304 stainless steel, with a honeycomb pore size of 10mm and a thickness of 80mm. The silicon carbide fiber insulation layer (6) has a thickness of 50mm.

5. The energy-saving and heat-preserving intermediate frequency steel shell furnace according to claim 4, characterized in that, The protective layer (1) has symmetrical bases (21) at both ends. The top of each base (21) is hinged with a hydraulic lifting assembly (17), and the top of each hydraulic lifting assembly (17) is hinged to the protective layer (1).

6. The energy-saving and heat-preserving medium-frequency steel shell furnace according to claim 5, characterized in that, The silicon carbide fiber insulation layer (6) contains 60%-70% silicon carbide fiber, 20%-25% alumina powder, 10%-15% ceramic hollow microspheres and 3%-5% glass phase binder. The silicon carbide fiber and alumina powder form a porous structure with interwoven fibers and filled with ceramic hollow microspheres. It is obtained by molding and high-temperature sintering at 1200℃, with a porosity of 35%-45%.

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