Temperature uniformity improving type high-temperature electric heating furnace

Abstract

The invention relates to a temperature uniformity improving type high-temperature electric heating furnace, and belongs to the technical field of industrial heat treatment equipment. An airflow circulation and temperature equalization system is integrated in a shell of the electric furnace, and the electric furnace comprises an air inlet pipe, a pressure stabilizing cavity, flow equalization ceramics, an air distribution plate, an air distribution pipe, nozzles and temperature equalization ceramics. After entering through the gas inlet pipe, gas is subjected to pressure stabilization through the pressure stabilization cavity and homogenization through the flow equalizing ceramic, is distributed to the multiple paths of gas distribution pipes through the gas distribution plate, and finally forms uniform gas flow through the nozzles to be sprayed into the storage cavity. The temperature equalization ceramic is arranged between the storage cavity and the heater, and temperature equalization is promoted through the porous structure of the temperature equalization ceramic. The invention further provides a control method based on real-time temperature difference feedback, the air inlet flow is dynamically adjusted by monitoring the upper temperature and the lower temperature of the storage cavity, and intelligent temperature control is achieved. According to the design, through combination of multi-stage airflow distribution and active control, the furnace temperature uniformity is remarkably improved, and the device has the advantages of low flow resistance, low energy consumption, high adaptability, stable operation and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of industrial heat treatment equipment, specifically relating to a high-temperature electric heating furnace for processes such as material sintering and heat treatment, and particularly to an electric furnace structure and control method that improves the uniformity of temperature inside the furnace by optimizing airflow organization and introducing intelligent control. Background Technology

[0002] High-temperature electric furnaces, as core thermal equipment in modern industrial production, play an irreplaceable role in many key fields such as steel, non-ferrous metals, new energy material synthesis, ceramic sintering, and solid waste treatment. Their engineering significance lies not only in providing the necessary high-temperature environment for material heat treatment, smelting, synthesis, and sintering processes, but also in their performance directly determining the consistency of final product quality, the energy efficiency of the production process, and overall operating costs. With the increasing demands for product quality from industrial upgrading and the growing global pressure for energy conservation and emission reduction, the industry has placed extremely stringent requirements on the performance of high-temperature electric furnaces, especially the uniformity and control precision of their internal temperature field. However, in practical engineering applications, uneven temperature distribution within the furnace is a long-standing and challenging technical problem. This issue leads to differences in the thermal history experienced by different parts of the workpiece or material being processed, resulting in a series of chain reactions such as uneven product mechanical properties, decreased yield, and increased energy consumption, severely restricting the improvement of high-end manufacturing levels.

[0003] The reasons for poor temperature uniformity in high-temperature electric furnaces are multifaceted and complex. From the perspective of equipment structure, unreasonable furnace design, improper or damaged heating element layout, poor insulation leading to excessive local heat dissipation, inadequate furnace door sealing, and poor airflow organization can all directly disrupt the uniformity of the thermal field inside the furnace. From the perspective of the control system, errors in temperature measuring elements (such as the insertion depth and accuracy of thermocouples), imbalances in three-phase power distribution, and the inability of traditional control algorithms (such as conventional PID control) to fully adapt to the nonlinear changes in the thermophysical parameters of materials during heating are also important factors contributing to insufficient temperature control accuracy and increased temperature differences within the furnace.

[0004] To address the aforementioned engineering challenges, the industry has sought improvements through various technical solutions, including several patented technologies. One patent (CN113532120B) proposes setting up a zoned temperature equalization plate within the resistance furnace body, which embeds an air-supported support bag and a heat radiation plate assembly. This design aims to utilize airflow to cause deformation of the air bag, driving the heat-conducting components to conduct heat and radiate heat in contact with the material-shielded areas, thereby reducing uneven heating within the furnace. Another solution (CN102419101B) focuses on optimizing the arrangement of the heating elements themselves. By winding the heating alloy wire into a specific structure with dense pitch at both ends and sparse pitch in the middle (T+2T mode), and arranging it at non-equidistant intervals according to the furnace's heat requirements, the heat distribution better matches the actual process requirements, thereby improving furnace temperature uniformity. It is claimed that its uniformity at high temperatures can reach ±2.7℃ to ±3.15℃. The third approach (CN211346331U) focuses on the furnace structure, adopting a double-layer furnace box design. The heating pipes are wrapped around the outer wall of the inner furnace box and supplemented with heat-conducting rods that penetrate the inner cavity, attempting to create a relatively uniform "heat envelope" environment by improving the heat conduction path.

[0005] Existing technologies mostly start from static physical structural modifications, such as introducing complex homogenizing internal components, optimizing the arrangement of heating elements, or improving the furnace body's insulation and heat conduction design. These methods can achieve results under certain operating conditions, but their adaptability may be limited. Many traditional improvement schemes fail to take furnace temperature uniformity as a real-time dynamic control target and lack closed-loop feedback control strategies based on real-time temperature field monitoring. For dynamically changing heat loads or complex process curves, their effect on maintaining uniformity may be weakened, and some complex structures may increase manufacturing and maintenance costs. Only by sensing the furnace's thermal field state in real time and dynamically adjusting the heating power and airflow organization can we achieve a leap from "static design" to "dynamic intelligent adaptation," thereby improving the temperature uniformity and energy efficiency of high-temperature electric furnaces in various complex application scenarios. Summary of the Invention

[0006] This invention aims to provide a high-temperature electric heating furnace with improved temperature uniformity, addressing the problems of uneven temperature distribution, poor adaptability, and lack of dynamic control capabilities in existing high-temperature furnaces. The core of this invention lies in the integration of a highly efficient airflow circulation and temperature equalization system. Through multi-stage airflow distribution and active temperature feedback control, it significantly improves the temperature uniformity of the storage cavity area.

[0007] The basic structure of this electric furnace includes a shell, an insulation layer, an electric heater, and a storage cavity. Its innovation lies in adding an airflow circulation and temperature equalization system to the traditional structure, consisting of an inlet pipe, a pressure stabilizing chamber, a flow equalization ceramic, a gas distribution plate, gas distribution pipes, nozzles, and a temperature equalization ceramic. Gas is introduced from the top inlet pipe, first stabilizing the pressure in the pressure stabilizing chamber, and then initially equalizing the airflow through the flow equalization ceramic (preferably honeycomb ceramic or foam ceramic). The equalized gas enters the gas distribution plate, where multiple gas distribution pipes distribute it to the nozzles, ultimately spraying it into the storage cavity as multiple uniform airflows. The temperature equalization ceramic (preferably open-pore foam ceramic) placed around the storage cavity further equalizes the temperature field within the cavity using its omnidirectionally interconnected pore structure and uniform flow resistance. Furthermore, this invention provides an intelligent control method that dynamically adjusts the airflow by real-time monitoring of the temperature difference between the upper and lower parts of the storage cavity, forming a closed-loop control to ensure excellent temperature uniformity under different operating conditions.

[0008] Compared with existing technologies, this invention combines static structural optimization with dynamic intelligent control. It not only improves airflow organization and heat field distribution through physical means, but also introduces an adaptive control mechanism, effectively overcoming the shortcomings of traditional electric furnaces in adapting to dynamic heat loads. It has significant advantages such as reasonable structure, good temperature uniformity, low energy consumption and reliable operation.

[0009] Its working principle is as follows: The working principle of this invention is based on the concept of combining forced convection with intelligent feedback control. The gas flow and heat exchange process is as follows: The working gas (which can be high-temperature gas introduced from the outside or circulating hot gas extracted from the bottom of the furnace) enters the top of the furnace body through the inlet pipe. The gas first undergoes pressure balancing in the pressure stabilizing chamber to eliminate the influence of pressure fluctuations on the subsequent flow field. Subsequently, the airflow passes downward through the flow-equalizing ceramic, whose porous structure divides the large airflow into numerous fine streams, achieving an initial uniform distribution of the airflow.

[0010] The gas, after being uniformly distributed, reaches the gas distribution plate and is then delivered to each nozzle through densely distributed gas distribution pipes. The nozzles employ a solid, porous structure to disperse the gas into fine, uniform multiple jets, which are vertically injected into the material storage cavity. These airflows directly act on the material area, powerfully stirring the atmosphere inside the furnace through convection heat transfer, breaking down temperature stratification, and enabling rapid and uniform heat transfer within the storage cavity.

[0011] In this process, the homogenizing ceramic plays a crucial role. Its internal three-dimensional network of open holes provides numerous meandering paths for the airflow, forcing thorough mixing of the gas and efficiently radiating and conducting heat to the material surface, ultimately forming a stable high-temperature homogenous zone within the chamber. Simultaneously, the control system continuously operates: temperature data is collected in real time by temperature sensors (such as thermocouples) located at the top and bottom of the chamber, calculating the temperature difference ΔT. When ΔT exceeds a preset threshold, the system automatically increases the airflow rate to enhance convective stirring and reduce the temperature difference; when the temperature difference returns to within the allowable range, the flow rate is maintained or reduced to conserve energy. This dynamic control mechanism ensures that the electric furnace maintains optimal temperature uniformity throughout long-term operation. Attached Figure Description

[0012] Figure 1 This is a top view of an embodiment of the present invention.

[0013] Figure 2 yes Figure 1 The diagram shows the structure of the air distribution plate in the embodiment shown.

[0014] Figure 3 yes Figure 1 A cross-sectional view of the structure of the embodiment shown.

[0015] Figure 4 This is a flowchart of the control method of the present invention.

[0016] In the diagram: 1. Shell; 2. Inlet pipe; 3. Flow equalization ceramic; 4. Pressure stabilizing chamber; 5. Insulation layer; 6. Air distribution plate; 7. Air distribution pipe; 8. Nozzle; 9. Heater; 10. Temperature equalization ceramic; 11. Storage chamber. Detailed Implementation

[0017] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 , Figure 2 and Figure 3 As shown in the figure, in this embodiment of a high-temperature electric heating furnace with improved temperature uniformity, the shell 1 is provided with, from top to bottom, an air inlet pipe 2, a pressure stabilizing chamber 4, a flow equalizing ceramic 3, a gas distribution plate 6, a gas distribution pipe 7, a nozzle 8, a heater 9, a temperature equalizing ceramic 10, and a storage cavity 11. The electric heater 9 is evenly arranged around the storage cavity 11, and a heat insulation layer 5 is filled between the electric heater 9 and the shell 1 to reduce heat loss.

[0018] In this embodiment, the flow equalization ceramic 3 is a high-porosity foam ceramic block, whose function is to disperse the airflow and make it flow downwards evenly. The gas distribution plate 6 is horizontally fixed in the furnace body, and the number of gas distribution pipes 7, which is 8 times the number of air inlet pipes 2, is arranged on it in an array. Each gas distribution pipe 7 is connected to a nozzle 8 at its lower end. The nozzle 8 is a solid cylinder with multiple tiny injection holes drilled on its side and bottom, which can evenly disperse and spray the gas. The temperature equalization ceramic 10 is placed around the storage cavity 11. It is made of open-pore foam ceramic, and its pore structure is interconnected in all directions, ensuring that the resistance in all directions is uniform when the airflow passes through, thereby effectively equalizing the temperature.

[0019] The gas flow is as follows: a high-pressure gas pump pumps high-temperature gas into the inlet pipe 2. After the gas pressure is stabilized in the pressure stabilizing chamber 4, it flows downward through the flow equalization ceramic 3 for uniform flow. Then, it is distributed to each gas distribution pipe 7 through the gas distribution plate 6, and finally, a uniform jet is formed by the nozzle 8 and blown onto the material in the storage chamber 11. The control process is as follows: Figure 4 As shown, thermocouples are installed at the top and bottom of the storage cavity 11 to monitor the temperatures T1 and T2 in real time. After calculating the temperature difference ΔT, the control system uses a PID algorithm to dynamically adjust the power of the air pump, thereby precisely controlling the air intake flow rate and stabilizing the temperature difference within the storage cavity 11 within ±3℃. This invention has a compact structure and significant temperature uniformity, making it particularly suitable for high-end material preparation fields where extremely high uniformity of heat treatment temperature is required.

Claims

1. A high-temperature electric heating furnace with improved temperature uniformity, comprising a shell (1), an insulation layer (5), an electric heater (9), and a storage cavity (11), wherein the insulation layer (5), the electric heater (9), and the storage cavity (11) are all located inside the shell (1); the electric heater (9) is evenly distributed around the storage cavity (11), and the insulation layer (5) is disposed between the electric heater (9) and the shell (1); the insulation layer (5) is in close contact with the inner wall of the shell (1), characterized in that, The electric furnace also integrates an airflow circulation and temperature equalization system, which includes: an air inlet pipe (2), a flow equalization ceramic (3), a pressure stabilizing chamber (4), a gas distribution plate (6), a gas distribution pipe (7), a nozzle (8), and a temperature equalization ceramic (10); the air inlet pipe (2) is located at the top of the shell (1) and is used to introduce gas; the pressure stabilizing chamber (4) is located below the air inlet pipe (2) and is used to stabilize the air inlet pressure; the flow equalization ceramic (3) is located below the pressure stabilizing chamber (4) and is used to equalize the airflow; the gas distribution plate (6) is located below the flow equalization ceramic (3), and the gas distribution plate (6) is provided with multiple gas distribution pipes (7), each gas distribution pipe (7) being connected to a nozzle ( 8) The nozzle (8) faces the storage cavity (11). A heat insulation layer (5) is provided between the gas distribution plate (6) and the electric heater (9). The heat insulation layer (5) is closely attached to the lower surface of the gas distribution plate (6). The gas distribution pipe (7) is embedded in the heat insulation layer (5). The temperature equalization ceramic (10) is provided between the storage cavity (11) and the heater (9) to equalize the temperature in the storage cavity (11). The gas enters through the air inlet pipe (2) and then passes through the pressure stabilizing chamber (4) to stabilize the pressure, the flow equalization ceramic (3) to equalize the flow, the gas distribution plate (6) to distribute the gas, the gas distribution pipe (7) and the nozzle (8) to spray out, so as to improve the temperature uniformity of the storage cavity (11) area.

2. The high-temperature electric heating furnace with improved temperature uniformity according to claim 1, characterized in that, The flow equalization ceramic (3) is a honeycomb ceramic or a foam ceramic.

3. The high-temperature electric heating furnace with improved temperature uniformity according to claim 1, characterized in that, The uniform temperature ceramic (10) is an open-cell foam ceramic, which has a pore structure that is interconnected in all directions and has uniform resistance in all directions when airflow passes through it.

4. A high-temperature electric heating furnace for improving temperature uniformity according to claim 1, characterized in that, The nozzle (8) is a solid structure with multiple spray holes on its sidewalls and / or ends.

5. A high-temperature electric heating furnace with improved temperature uniformity according to claim 1, characterized in that, The number of air distribution pipes (7) is 5 to 10 times the number of air intake pipes (2).

6. A high-temperature electric heating furnace with improved temperature uniformity according to claim 1, characterized in that, The air source connection method of the air intake pipe (2) is any one of the following: Method 1: Connect to an external high-temperature gas source via a high-pressure air pump to input high-temperature gas into the furnace; Method 2: A high-pressure air pump is connected to the hot gas accumulation area at the bottom of the furnace body to extract the hot gas in the furnace and pump it back into the air inlet pipe (2) to achieve gas circulation.

7. A control method for an electric furnace based on any one of claims 1-6 to improve the temperature uniformity of a high-temperature electric heating furnace, characterized in that, Includes the following steps: Step S1: Real-time detection of the first temperature value T1 at the bottom and the second temperature value T2 at the top of the storage cavity (11); Step S2: Calculate the temperature difference ΔT = |T1 - T2|; Step S3: Compare the temperature difference ΔT with a preset temperature threshold ΔT0; Step S4: Based on the comparison results, adjust the gas flow rate to the intake pipe (2): - When ΔT > ΔT0, increase the gas flow rate to enhance gas circulation and reduce the temperature difference; - When ΔT ≤ ΔT0, maintain or reduce the current gas flow rate.

8. The control method according to claim 7, characterized in that, In step S4, the adjustment range of the gas flow rate is directly proportional to the temperature difference ΔT or has a PID (proportional-integral-derivative) relationship.

9. The control method according to claim 7, characterized in that, The temperature of the bottom and top of the storage cavity (11) is detected by thermocouples or infrared temperature sensors inserted inside it.

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