An on-line heat preservation method and system for preparing a steel ingot by an electroslag furnace

Abstract

This invention provides an online heat preservation method and system for steel ingot preparation in an electroslag furnace, relating to the field of electroslag furnace steel ingot preparation technology. The method includes acquiring real-time temperature data at different axial positions during the ingot unloading process; determining the temperature control mode and setting control parameters for a closed-loop control algorithm based on the unloading progress; calculating the required heating power for each axial position based on the deviation between the real-time temperature and the target temperature curve using a closed-loop control algorithm; and independently heating and compensating the corresponding axial position of the ingot within the heat preservation hood according to this power. This invention significantly improves temperature control accuracy through zoned closed-loop active compensation, reducing the axial temperature difference to within a few degrees, effectively suppressing microstructure segregation and crack defects, while simultaneously reducing energy consumption, achieving precise online heat preservation throughout the entire ingot unloading process.

Description

Technical Field

[0001] This invention relates to the field of electroslag furnace steel ingot preparation technology, and more specifically, to an online heat preservation method and system for electroslag furnace steel ingot preparation. Background Technology

[0002] In the process of preparing steel ingots in an electroslag furnace, the ingots are drawn from the crystallizer at a high temperature (typically 900-1100℃). If the cooling is too rapid or uneven after tapping, significant thermal stress will be generated inside the ingot, easily leading to quality defects such as surface cracks, internal segregation, and even fracture. Therefore, the steel ingots need to be heat-insulated after tapping to control their cooling rate and ensure the uniformity of the ingot's microstructure and the quality of the finished product. Currently, the heat insulation of electroslag furnace steel ingots after tapping mainly adopts passive insulation methods, such as installing insulation covers or insulation sleeves around the ingot. The physical isolation effect of the insulation materials slows down heat loss and reduces the cooling rate of the ingot.

[0003] However, the billet output speed of electroslag furnaces is slow (typically a few millimeters per minute), and the steel ingots remain in the insulation device for tens of hours. When using the passive insulation method described above, the insulation device cannot dynamically adjust according to the actual temperature changes of the steel ingot, resulting in large temperature fluctuations and difficulty in ensuring temperature control accuracy. Furthermore, the difference in residence time between the head (the first part of the billet to be ejected) and the tail (the last part of the billet to be ejected) within the insulation device is significant, leading to extremely uneven temperature distribution along the axial direction of the ingot, with temperature differences reaching tens or even hundreds of degrees Celsius. This uneven temperature distribution can cause quality defects such as segregation of the steel ingot structure, internal stress concentration, and cracks, severely affecting the yield and subsequent processing performance of the steel ingot. Summary of the Invention

[0004] This invention addresses the problems of low temperature control accuracy and significant axial temperature difference in existing electroslag furnace steel ingots after billet tapping, which easily leads to microstructure segregation and crack defects.

[0005] To address the aforementioned problems, this invention provides an online heat preservation method and system for preparing steel ingots in an electroslag furnace.

[0006] On one hand, the present invention provides an online heat preservation method for preparing steel ingots in an electroslag furnace, wherein the steel ingot is extracted from the electroslag furnace and passes through a heat preservation cover axially, the method comprising: Acquire real-time temperature data at different axial positions during the billet unloading process of steel ingots; The temperature control mode corresponding to the current stage is determined based on the billet production process, and the control parameters of the closed-loop control algorithm are set based on the temperature control mode. For each axial position, the required heating power is calculated using the closed-loop control algorithm with the control parameters set, based on the temperature deviation between the real-time temperature data and the preset target temperature curve. The steel ingot at the corresponding axial position inside the insulation cover is independently heated and compensated according to the heating power.

[0007] Optionally, determining the temperature control mode corresponding to the current stage based on the billet unloading process includes: The billet production process is divided into initial, middle and later stages; When the current stage is the initial stage, a low-power or no-heating temperature control mode is used; When the current stage is the intermediate stage, a dynamic compensation temperature control mode is adopted to adjust the heating power in real time according to the temperature deviation. When the current stage is the later stage, a high-precision closed-loop temperature control mode is adopted to reduce the axial temperature difference of the steel ingot.

[0008] Optionally, the closed-loop control algorithm is a variable parameter PID control algorithm, and its proportional, integral, and derivative coefficients are dynamically adjusted according to the current temperature deviation and the billet discharge process; when the temperature deviation exceeds a preset threshold, the integral term is temporarily removed.

[0009] Optionally, before calculating the required heating power, the method further includes: correcting the output of the closed-loop control algorithm based on at least one of the parameters of the thermal conductivity, specific heat capacity, and density of the steel ingot material.

[0010] Optionally, the real-time temperature data is acquired by a plurality of temperature sensing units arranged along the axial direction of the insulation cover; each temperature sensing unit includes at least two temperature measuring points symmetrically arranged on the same circumference of the insulation cover.

[0011] Optionally, a heating component is provided for each of the temperature sensing units; the heating component receives the heating power calculated for the axial position of the temperature sensing unit, and heats the steel ingot at the axial position with the heating power.

[0012] On the other hand, the present invention provides an online heat preservation system for preparing steel ingots in an electroslag furnace, comprising: A heat insulation cover is fitted over the outside of the steel ingot extracted from the electroslag furnace, and the heat insulation cover is coaxial with the steel ingot; Multiple temperature sensing units and multiple heating components are arranged along the axial direction of the heat insulation cover. Each heating component corresponds to one of the temperature sensing units and is used to heat the steel ingot at the axial position corresponding to the temperature sensing unit. A controller is electrically connected to each of the temperature sensing units and each of the heating components, and the controller is used to execute the above-described online heat preservation method.

[0013] Optionally, the heat insulation cover is divided into multiple temperature control sections along its axial direction. Each temperature control section is provided with a temperature sensing unit and a heating component at both ends of its axial direction. The heating power of the heating component is independently controlled by the controller according to the feedback signal of the temperature sensing unit at the corresponding position, forming multiple parallel local closed-loop control loops.

[0014] Optionally, the heating component is an induction heating coil, which is disposed between the inner wall of the insulation cover and the steel ingot and surrounds the outer side of the steel ingot; the insulation cover is a double-layer insulation cover, the temperature measuring point of the temperature sensing unit is embedded in the inner layer of the insulation cover, and its measuring end extends to the effective heating area corresponding to the heating component.

[0015] Optionally, each temperature control section is a split structure including a left half shell and a right half shell. The left half shell and the right half shell are respectively provided with an infrared thermometer and a semi-circular induction heating coil. The two infrared thermometers at the same end of the axial direction of each temperature control section form a set of temperature measuring points and constitute a temperature sensing unit. The two semi-circular induction heating coils form a circular induction heating coil and serve as the heating component. The upper end of the heat preservation cover is arranged opposite to the crystallizer outlet of the electroslag furnace.

[0016] The beneficial effects of this invention are: This invention discloses an online heat preservation method for steel ingots produced in an electroslag furnace. By acquiring real-time temperature data at different axial positions during the billet unloading process, it solves the problem of not being able to know the actual temperature changes of various parts of the steel ingot, providing a data foundation for subsequent precise control. The method dynamically determines the corresponding temperature control mode and sets the control parameters of the closed-loop control algorithm based on the billet unloading process (initial, middle, and late stages), enabling the heating strategy to match the heat dissipation characteristics and temperature difference evolution of the steel ingot at different stages, avoiding overcooling or overheating caused by a single control mode. For each axial position, the required heating power is independently calculated using the deviation between the real-time temperature and the target curve, employing a closed-loop control algorithm with pre-set parameters, achieving real-time and precise response to temperature deviations at various parts of the steel ingot. Finally, the steel ingot at the corresponding axial position within the heat preservation hood is independently heated and compensated according to the calculated heating power, forming a multi-zone, parallel local closed-loop temperature control loop. Therefore, the method of this invention realizes an online insulation method that transitions from passive insulation to active zoned closed-loop compensation, improving temperature control accuracy. The axial temperature difference between the head and tail of the steel ingot can be reduced to within a few degrees, effectively suppressing quality defects such as microstructure segregation, internal stress concentration, and cracks caused by uneven temperature. Simultaneously, since the heating power is applied only to the axial region requiring compensation, energy waste caused by overall heating or constant heating is avoided, resulting in reduced energy consumption as measured. In summary, the technical solution of this invention fundamentally solves the technical problems of low temperature control accuracy, large axial temperature difference, and easy cracking in the prior art, achieving positive effects such as improving steel ingot yield, ensuring microstructure uniformity, and reducing energy consumption.

[0017] The online heat preservation system for preparing steel ingots in an electroslag furnace according to the present invention has the same beneficial effects as the above-described online heat preservation method for preparing steel ingots in an electroslag furnace, and will not be repeated here. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of an online heat preservation method for preparing steel ingots in an electroslag furnace according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a heat insulation cover according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the opening structure of the heat insulation cover according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention; Wherein; 1-Insulation cover; 2-Temperature sensing unit; 3-Heating component; 400-Electronic device; 410-Memory; 420-Processor. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0020] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0021] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0022] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0023] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0024] To address the problems existing in the aforementioned related technologies, this embodiment provides a method and system for online heat preservation in the preparation of steel ingots using an electroslag furnace.

[0025] like Figure 1 As shown in the embodiment of the present invention, an online heat preservation method for preparing steel ingots in an electroslag furnace is provided. The steel ingot is extracted from the electroslag furnace and passes through the heat preservation cover 1 along the axial direction. The method includes: S1: Obtain real-time temperature data at different axial positions during the billet unloading process of the steel ingot.

[0026] Specifically, after the electroslag furnace billet unloading mechanism is started, the steel ingot is drawn downwards from the crystallizer at a speed of millimeters per minute, and immediately enters the insulation shroud 1 upon exiting the crystallizer. Since multiple temperature sensing units 2 are fixedly installed at different axial positions within the insulation shroud 1, each temperature sensing unit 2 can only detect the temperature of the axial region of the steel ingot corresponding to its installation position. As the steel ingot is slowly drawn out and moves downwards within the insulation shroud 1, different axial sections of the steel ingot sequentially pass through each temperature sensing unit 2. The controller (such as a PLC) reads the signals from all temperature sensing units 2 with a sampling period of 1 second. The temperature value of a temperature sensing unit 2 is only considered valid when there is a steel ingot at the corresponding position. For example, in the initial stage of billet unloading (0-2 hours), when the head of the steel ingot has just entered the insulation shroud 1, only 1-2 sets of temperature sensing units 2 detect the temperature; as unloading progresses, the number of effective measuring points gradually increases until all temperature sensing units 2 have valid signals after the entire length of the steel ingot has entered the insulation shroud 1.

[0027] S2: Determine the temperature control mode corresponding to the current stage based on the billet extrusion process, and set the control parameters of the closed-loop control algorithm based on the temperature control mode.

[0028] Specifically, the controller determines the stage of the billet forming process based on the ratio of the current billet length to the total ingot length. The billet forming process can be divided into three stages: initial stage (billet length less than 1 / 3 of the total length), middle stage (billet length between 1 / 3 and 2 / 3 of the total length), and later stage (billet length greater than 2 / 3 of the total length). Each stage corresponds to a different temperature control mode. In the initial stage, a low-power or no-heating temperature control mode is used. In the no-heating mode, passive insulation is used to slow down the heat dissipation of the ingot. In the low-power heating mode, active compensation is used to prevent the ingot temperature from dropping too quickly. In the middle stage, a dynamic compensation temperature control mode is used, adjusting the heating power in real time according to the temperature deviation. In the later stage, a high-precision closed-loop temperature control mode is used to reduce the axial temperature difference of the ingot. The controller sets the proportional coefficient K of the closed-loop control algorithm (e.g., a variable-parameter PID algorithm) according to the selected mode. p Integral coefficient K i Differential coefficient K d The initial values ​​are set as follows: For example, in the mid-stage and when the absolute value of the temperature deviation is ≤15℃, the proportional coefficient is set to 2.0, the integral coefficient to 0.5, and the derivative coefficient to 0.5; when the absolute value of the temperature deviation is >15℃, the proportional coefficient is set to 3.0, the integral coefficient to 0.8, and the derivative coefficient to 0.8. In the later stage, when the deviation is small, the proportional coefficient is set to 2.5, the integral coefficient to 1.0, and the derivative coefficient to 1.0 to achieve more precise temperature control.

[0029] S3: For each axial position, the required heating power is calculated using a closed-loop control algorithm with set control parameters based on the temperature deviation between the real-time temperature data and the preset target temperature curve. Specifically, for each axial position i with a valid temperature signal, the controller first calculates the temperature deviation. T 2i The target temperature at this location at the current time is obtained by looking up a table based on a preset target temperature curve. (T) 1i This is the real-time temperature acquired in step 1. Then, the controller calls the variable-parameter PID algorithm with parameters set in step 2, and calculates the heating power output value according to the following discretization formula. For the i-th axial position in the k-th sampling period, the heating power output value U is calculated by the following formula: Among them, K p K i K d This coefficient is dynamically determined based on the current temperature deviation *e* and the billet exit stage, where Δt is the sampling period (which can be 1 second). To prevent integral saturation, when the absolute value of the temperature deviation exceeds a preset threshold (e.g., 15°C), the controller temporarily adjusts the integral coefficient K. i Set it to 0, and restore it after the deviation shrinks to within the threshold.

[0030] For example, during the middle stage of billet production, the real-time temperature at a certain axial position is 775℃, the target temperature is 790℃, and the deviation is +15℃. In this case, the mid-stage large deviation parameter (K) is used. p =3.0, K i =0.8, K d =0.8), the calculated U≈45%, meaning that 45% of the rated power needs to be output to compensate for the heat. If the real-time temperature at another axial position during the same period is 820℃, the target temperature is 810℃, and the deviation is -10℃, then the calculated output power may be 0 or an extremely low value.

[0031] S4: Perform independent heating compensation on the steel ingots at the corresponding axial positions inside the insulation cover 1 according to the heating power.

[0032] Specifically, the controller will calculate the heating power value U at each axial position in step 3. iThe signals are converted into corresponding control signals and output to the heating component 3, such as an induction heating coil, corresponding to the axial position. Each heating coil operates independently, generating an alternating electromagnetic field according to the received power value to electromagnetically induction heat the corresponding area of ​​the steel ingot. Since each induction heating coil and its corresponding temperature sensing unit 2 are one-to-one in the axial position, multiple parallel local closed-loop control loops are formed. For example, when a certain axial position requires 45% heating power, its corresponding induction coil heats at this power; while at another axial position, due to a higher temperature and a calculated power of 0, the corresponding induction coil does not heat. Each area does not interfere with the others, achieving independent heating compensation in each zone. At the same time, the insulation material on the inner wall of the insulation cover 1 reduces heat loss to the environment, forming a synergistic effect with active heating. The above steps S1 to S4 are repeated with a period of 1 second until the steel ingot completely leaves the insulation cover 1, thereby maintaining a uniform and controllable steel ingot temperature throughout the billet unloading process.

[0033] It should be noted that the above embodiment effectively solves the defects of passive heat preservation methods in the background technology, such as low temperature control accuracy, large axial temperature difference, and easy cracking, by acquiring temperature data at different axial positions during the billet unloading process in real time, dynamically adjusting the temperature control mode and closed-loop control algorithm parameters according to the billet unloading process, and independently calculating the heating power for each axial position and implementing zonal compensation. Specifically, in this embodiment, after the steel ingot is extracted from the electroslag furnace, it passes through the heat preservation cover 1 along the axial direction. Multiple temperature sensing units 2 set along the axial direction of the heat preservation cover 1 are used to collect temperature data of each part in real time, avoiding the blind spot of not being able to know the actual temperature change of the steel ingot in the traditional method. The corresponding temperature control mode is determined according to the billet unloading process (for example, dividing the billet unloading into different stages such as the initial, middle, and late stages), and the control parameters of the closed-loop control algorithm are set based on the mode, so that the heating strategy can be dynamically adjusted according to the residence time of the steel ingot in the heat preservation cover 1. In the early stages of billet extrusion, a low-power or no-heating mode is used to prevent the ingot surface from cooling down too quickly. In the middle stages, a dynamic compensation mode is used to adjust the heating power in real time according to the temperature deviation. In the later stages, a high-precision closed-loop mode is used to reduce the axial residual temperature difference. Based on this, for each axial position, the required heating power is independently calculated using a closed-loop control algorithm with pre-set parameters, based on the temperature deviation between the real-time temperature and the preset target temperature curve. The corresponding axial position of the ingot within the insulation cover 1 is then independently heated and compensated according to this power. Since the heating compensation for each axial position depends only on the temperature deviation of that position, it can accurately eliminate the large temperature difference caused by the significant difference in residence time between the head and tail of the ingot within the insulation cover 1, reducing the axial temperature difference to within a few degrees. This suppresses quality defects such as microstructure segregation, internal stress concentration, and cracks, improving the yield and subsequent processing performance of the ingot. Simultaneously, because the heating power is calculated on demand based on the actual temperature deviation, it avoids the energy waste that passive insulation cannot actively compensate for and constant heating may cause, resulting in a significant reduction in energy consumption in actual measurements. In summary, this embodiment, with active zone closed-loop compensation as its core, achieves online precise temperature control throughout the entire process of electroslag furnace ingot billet production, resulting in positive technical effects such as improving ingot quality and reducing energy consumption.

[0034] In one embodiment of the present invention, determining the temperature control mode corresponding to the current stage based on the billet extrusion process includes: dividing the billet extrusion process into an initial stage, a middle stage, and a later stage; when the current stage is the initial stage, adopting a low-power or no-heating temperature control mode; when the current stage is the middle stage, adopting a dynamic compensation temperature control mode, adjusting the heating power in real time according to the temperature deviation; and when the current stage is the later stage, adopting a high-precision closed-loop temperature control mode to reduce the axial temperature difference of the steel ingot.

[0035] Specifically, the controller determines the current stage based on the ratio of the current billet length to the total ingot length. For example, when the billet length is less than 1 / 3 of the total length, it is considered the initial stage. In this stage, the ingot head enters the insulation shroud 1, and the temperature is still close to the crystallizer outlet temperature. Applying a large heating power at this time may lead to local overheating. Therefore, a low power (e.g., 10%~20% of the rated power) or no heating mode is adopted, mainly relying on the insulation material of the inner layer of the insulation shroud 1 to passively slow down heat dissipation and prevent the ingot surface from cooling down rapidly due to excessive temperature difference with the environment. When the billet length is between 1 / 3 and 2 / 3 of the total length, it is considered the intermediate stage. At this time, the ingot head has been in the insulation shroud 1 for a longer period of time, and the temperature begins to drop significantly, while the tail has just entered the insulation shroud 1, and the temperature is still high, and the axial temperature difference gradually increases. The controller dynamically adjusts the heating power based on the temperature deviation between the actual temperature and the target temperature at each axial position: the larger the deviation, the higher the heating power; the smaller the deviation, the lower the heating power. For example, if the measured temperature at a certain axial position is 775℃ while the target temperature is 790℃, with a deviation of +15℃, then 45% of the rated power will be output for compensation; if the measured temperature at another position is 820℃ while the target temperature is 810℃, with a deviation of -10℃, then the output power will be 0. When the length of the billet that has been unloaded is greater than 2 / 3 of the total length, it is considered to be in the later stage. At this time, the head of the steel ingot will leave the insulation cover 1, and the tail has been inside the cover for a considerable period of time. Although the axial temperature difference has decreased, fine adjustment is still required. The controller adopts a high-precision closed-loop control mode. For example, the proportional coefficient is lowered to prevent overshoot, the integral coefficient is appropriately increased to eliminate steady-state error, and the derivative coefficient is used to suppress fluctuations, thereby gradually stabilizing the temperature at each axial position within a small range of the target value, ultimately reducing the temperature difference between the head and tail of the steel ingot to within a few degrees. Through the above-mentioned phased differentiated control, this embodiment can maintain the uniformity and stability of the steel ingot temperature with the most suitable control intensity throughout the entire billet unloading process, which lasts for more than ten hours.

[0036] It should be noted that the above embodiments effectively solve the problems of low temperature control accuracy, large axial temperature difference, and crack defects caused by the inability to dynamically adjust passive heat preservation by dividing the billet unloading process into three stages: initial, middle, and late stages, and adopting differentiated temperature control modes for each stage. Specifically, in the initial stage, a low-power or no-heating mode is used to avoid the rapid cooling of the steel ingot due to excessive temperature difference with the environment when it just exits the crystallizer, thus preventing the formation of surface cracks. In the middle stage, a dynamic compensation mode is adopted, adjusting the heating power according to the real-time temperature deviation, so that the temperature at each axial position can be compensated in a timely manner, avoiding the large temperature fluctuations caused by the inability to actively adjust in the traditional method, and improving the temperature control accuracy to within ±5℃. In the late stage, a high-precision closed-loop mode is adopted to further reduce the residual temperature difference between the head and tail of the steel ingot, reducing the axial temperature difference to within a few degrees, thereby suppressing the microstructure segregation and internal stress concentration caused by uneven temperature. At the same time, since the control modes of each stage are deeply coupled with the billet unloading process, heating energy is applied only as needed in the time and area where compensation is required, avoiding unnecessary energy waste. In summary, this embodiment, with segmented differentiated active control as its core, overcomes the inherent defects of passive heat preservation methods at their root, and achieves online precise heat preservation throughout the entire process of electroslag furnace steel ingot production, resulting in positive technical effects such as improving steel ingot quality and reducing energy consumption.

[0037] In one embodiment of the present invention, the closed-loop control algorithm is a variable parameter PID control algorithm, and its proportional, integral, and derivative coefficients are dynamically adjusted according to the current temperature deviation and billet extrusion process; when the temperature deviation exceeds a preset threshold, the integral term is temporarily removed.

[0038] Specifically, to prevent overshoot and oscillation caused by integral saturation, the controller monitors the absolute value of the temperature deviation in real time. When the absolute value of the temperature deviation exceeds a preset threshold (e.g., 15°C), the integral coefficient K is immediately adjusted. i Setting the integral term to zero temporarily removes the integral term, allowing only the proportional and differential terms to function. Once the absolute value of the temperature deviation falls back below the threshold, the integral coefficient is restored, reintroducing the integral action to eliminate steady-state error. For example, if a sudden disturbance at a certain axial position during the billet production stage causes the measured temperature to drop sharply to 760℃ (target 790℃, deviation +30℃), and the integral term continues to accumulate at this point, it will lead to excessive output power and subsequent severe overshoot. In this embodiment, the controller detects a deviation exceeding 15℃ and automatically adjusts K... i Setting the value to 0, the output power is calculated solely from the proportional and derivative terms, thus suppressing integral saturation. When the temperature rises back to within 15°C of the absolute value of the temperature deviation, the integral term is restored to ensure that the final temperature is precisely stabilized near the target value. Through the mechanism combining variable parameters and integral separation, the closed-loop control algorithm in this embodiment can respond quickly when the deviation is large and avoid overshoot when the deviation is small, thereby improving the temperature control quality during the ingot tapping and holding process in an electroslag furnace.

[0039] It should be noted that this embodiment employs a variable-parameter PID control algorithm, dynamically adjusting the proportional, integral, and derivative coefficients based on the current temperature deviation and billet extrusion progress. Simultaneously, when the temperature deviation exceeds a preset threshold, the integral term is temporarily removed to prevent integral saturation. This improves the temperature control accuracy and stability during the billet extrusion and holding process of electroslag furnace steel ingots, effectively solving the problems of passive holding methods, such as lack of dynamic adjustment, low temperature control accuracy, and susceptibility to overshoot. Specifically, due to the large range of temperature deviation variations at different stages (initial, middle, and late stages) and different axial positions during billet extrusion, a fixed-coefficient PID controller struggles to balance response speed and steady-state accuracy: large deviations may result in slow response, while small deviations are prone to overshoot. In this embodiment, the proportional, integral, and derivative coefficients are adjusted in real-time based on the current temperature deviation and billet extrusion progress. When the deviation is large, the proportional coefficient is increased for rapid compensation; when the deviation is small, the proportional coefficient is decreased, and the integral action is appropriately enhanced to eliminate steady-state error, thereby controlling the steel ingot temperature fluctuation within ±5℃. Meanwhile, when the absolute value of the temperature deviation exceeds the preset threshold, the integral term is temporarily cut off to avoid output saturation and subsequent severe overshoot caused by excessive accumulation of the integral term when the deviation remains large. The integral action is resumed after the deviation falls back within the threshold, ensuring the stability of the control. This mechanism is particularly suitable for the conditions where the billet output speed of the electroslag furnace is slow and the steel ingot stays in the insulation hood 1 for tens of hours. It can effectively suppress the oscillations that may be caused by long-term adjustment and prevent the steel ingot from generating new thermal stress or structural defects due to temperature overshoot. In summary, the control algorithm combining variable parameter PID and integral separation in this embodiment solves the technical problems of low temperature control accuracy, large temperature fluctuation and easy overshoot in the background technology from the control strategy level with an active, adaptive and nonlinear adjustment method, further improving the temperature uniformity of steel ingots and the quality of finished products.

[0040] In one embodiment of the present invention, before calculating the required heating power, the method further includes: correcting the output of the closed-loop control algorithm based on at least one of the parameters of thermal conductivity, specific heat capacity, and density of the steel ingot material.

[0041] Specifically, before executing the closed-loop control algorithm to calculate the heating power, the controller first retrieves the thermal properties of the current steel ingot material, such as thermal conductivity λ, specific heat capacity c, and density ρ, from the built-in material database. For example, using 45 steel as a reference, its thermal conductivity λ0, specific heat capacity c0, and density ρ0 are used to calculate the material correction factor. Then, the proportionality coefficient K determined in step S2 based on the billet extrusion process and temperature deviation is... p K i K dThe corrected control parameters are obtained by multiplying each parameter by the correction factor. Finally, these corrected parameters are substituted into the PID formula to calculate the heating power. For example, when smelting 304 stainless steel, the calculated value of f is approximately 3.44. If the original proportional gain is 2.0, the corrected value is 6.88, thus increasing the heating power accordingly to compensate for the increased heat required by stainless steel due to its poor thermal conductivity and large heat capacity. When smelting aluminum alloys with even higher thermal conductivity, the correction factor is less than 1, and the heating power automatically decreases to avoid overheating. Through this material-adaptive correction, this embodiment can seamlessly adapt to different steel grades and even different types of metal materials without changing the control algorithm structure. It eliminates the need for repeated manual parameter tuning by operators, significantly improving process adaptability and control accuracy.

[0042] It should be noted that this embodiment improves the adaptability to the differences in thermal properties of different steel grades by correcting the output of the closed-loop control algorithm based on at least one of the parameters of the steel ingot material, namely thermal conductivity, specific heat capacity, and density, before calculating the heating power. This effectively overcomes the shortcomings of passive heat preservation methods, such as the inability to dynamically adjust according to material characteristics and poor process adaptability. Specifically, different steel grades (e.g., H13 mold steel, 304 stainless steel, 45 steel, etc.) have significant differences in thermal conductivity, specific heat capacity, and density. Materials with low thermal conductivity transfer heat slowly and require higher heating power to achieve the same temperature compensation effect; materials with high specific heat capacity and density require more heat to raise the unit temperature. In this embodiment, the controller uses the thermal property parameters of a reference steel grade (e.g., 45 steel) as a benchmark to calculate the correction coefficient f for the current steel grade, and then multiplies the proportional, integral, and derivative coefficients in the variable parameter PID algorithm by this correction coefficient, thereby enabling the heating power to automatically adapt to the actual heat demand of different steel grades. For example, for stainless steel with low thermal conductivity and high heat capacity, the correction factor f is greater than 1, and the heating power is increased accordingly, avoiding low temperatures due to insufficient heating. For aluminum alloys with high thermal conductivity and low heat capacity, the correction factor f is less than 1, and the heating power is automatically reduced to prevent overheating. This mechanism allows this embodiment to directly switch between producing different steel grades without repeated manual adjustment of control parameters, significantly improving production efficiency and process flexibility. Simultaneously, because the heating power is precisely matched to the actual material requirements, energy waste or temperature control inaccuracies caused by parameter mismatch are avoided, further improving the temperature uniformity of the steel ingot and suppressing the risk of microstructure segregation and cracking caused by improper heating. In summary, this embodiment, with adaptive correction of material properties as its core method, fundamentally solves the technical problems of passive heat preservation methods being unable to adapt to different steel grades and having poor temperature control consistency, achieving beneficial effects such as improving process versatility and ensuring the stability of steel ingot quality.

[0043] In one embodiment of the present invention, real-time temperature data is collected by a plurality of temperature sensing units 2 arranged along the axial direction of the heat insulation cover 1; each temperature sensing unit 2 includes at least two temperature measuring points symmetrically arranged on the same circumference of the heat insulation cover 1.

[0044] Specifically, six temperature sensing units 2 are arranged along the axial direction of the insulation cover 1. Each temperature sensing unit 2 includes two infrared thermometers, which are symmetrically arranged at 180° on the same circumference of the insulation cover 1, meaning there are two symmetrical temperature measuring points at each axial position. When the steel ingot passes through the insulation cover 1, each temperature measuring point collects the surface temperature of the steel ingot at its corresponding position. The controller takes the arithmetic mean of the temperature values ​​collected by the two symmetrical temperature measuring points at the same axial position as the real-time temperature data for that axial position, thereby reducing measurement errors caused by slight eccentricity or uneven local heat dissipation that may exist in the steel ingot in the crystallizer. At the same time, the controller monitors the temperature difference between the two temperature measuring points at the same axial position in real time. When the temperature difference exceeds the preset alarm value, the controller issues an alarm signal, prompting the operator to check the alignment of the crystallizer or whether there is slag accumulation on the inner wall of the insulation cover 1, to avoid long-term eccentricity leading to uneven circumferential structure of the steel ingot. By using the above-mentioned paired symmetrical temperature measurement points and average value processing method, this embodiment can obtain a more accurate and reliable temperature feedback signal, providing high-quality input data for subsequent closed-loop control, thereby improving temperature control accuracy and system robustness.

[0045] In one embodiment of the present invention, a heating component 3 is provided for each temperature sensing unit 2; the heating component 3 receives the heating power calculated for the axial position of the temperature sensing unit 2, and heats the steel ingot at the axial position with the heating power.

[0046] Specifically, each temperature sensing unit 2 arranged along the axial direction of the insulation cover 1 corresponds to an independent heating component 3 (e.g., a ring-shaped induction heating coil). After calculating the heating power for a certain axial position, the controller converts the power value into a corresponding control signal and outputs it to the heating component 3 corresponding to the temperature sensing unit 2 at that position. After receiving the control signal, the heating component 3 performs electromagnetic induction heating on the corresponding axial position of the steel ingot according to the calculated heating power. For example, if the temperature deviation calculation at a certain axial position in the middle section requires 45% of the rated power, the controller sends the control signal corresponding to 45% power to the induction heating coil corresponding to that position sensor. The induction heating coil then generates an alternating electromagnetic field with this power to heat and compensate for that section of the steel ingot. Since each heating component 3 only responds to the power command of its corresponding temperature sensing unit 2, and each heating component 3 is independent of each other, independent heating of multiple axial positions is achieved. This one-to-one correspondence ensures the locality of the control loop. Each temperature sensing unit 2 in the closed loop only reports the temperature at its corresponding location. The controller calculates the power at that location based solely on this feedback, and the heating component 3 applies heat only to that location. The loops do not interfere with each other. Therefore, even if there are significant temperature differences at different axial positions of the steel ingot, precise compensation can be performed simultaneously and independently, effectively reducing axial temperature differences and suppressing microstructure segregation and crack defects. Furthermore, since the heating power is applied only to the axial region requiring compensation, energy waste caused by overall heating is avoided, further improving energy efficiency.

[0047] On the other hand, the present invention provides an online heat preservation system for steel ingot preparation in an electroslag furnace, including a heat preservation cover 1, a plurality of temperature sensing units 2 and a plurality of heating components 3 arranged along the axial direction of the heat preservation cover 1, and a controller. The heat preservation cover 1 is used to cover the outside of the steel ingot extracted from the electroslag furnace, and the heat preservation cover 1 is coaxial with the steel ingot. The heating components 3 correspond one-to-one with the temperature sensing units 2 and are used to heat the steel ingot at the axial position corresponding to the temperature sensing unit 2. The controller is electrically connected to each group of temperature sensing units 2 and each heating component 3 respectively, and the controller is used to execute the above-described online heat preservation method for steel ingot preparation in an electroslag furnace.

[0048] Specifically, the insulation cover 1 has a cylindrical structure, and its upper end is sealed and connected to the billet outlet of the electroslag furnace crystallizer. Along the axial direction of the insulation cover 1, multiple temperature sensing units 2 (e.g., six, each containing two infrared thermometers arranged symmetrically at 180°) and multiple induction heating coils are uniformly fixed and installed on the inner wall of the insulation cover 1. Each induction heating coil corresponds axially to one of the temperature sensing units 2. Each induction heating coil surrounds the outside of the steel ingot and is located at the same axial height as its corresponding temperature sensing unit 2. The controller uses a programmable logic controller (PLC), whose analog input ports are connected to the signal output terminals of each group of temperature sensing units 2, and whose analog output ports or PWM output ports are connected to the power drive module of each induction heating coil. The controller internally stores a database of thermophysical parameters for different steel grades, preset target temperature curves, and a piecewise variable parameter PID control algorithm program. When the electroslag furnace begins billet tapping, the controller collects signals from each temperature sensing unit 2 in real time. Based on a pre-set sampling period (e.g., 1 second) and the billet tapping process, it dynamically executes steps S1 to S4 in the above method embodiment, generating the heating power control signal required for each axial position and outputting it to the corresponding induction heating coil. This achieves online, zoned, independent closed-loop temperature control of the entire length of the steel ingot. The inner layer material of the insulation cover 1 is an insulation material (e.g., ceramic fiber blanket), which passively reduces heat loss and works synergistically with active heating. This system has a compact structure, high control precision, and is applicable to the billet tapping insulation process of various steel grades and ingot types in electroslag furnaces.

[0049] like Figure 2 and Figure 3 As shown, in one embodiment of the present invention, the heat insulation cover 1 is divided into multiple temperature control sections along its axial direction. Each temperature control section is provided with the temperature sensing unit 2 and the heating component 3 at both ends of its axial direction. The heating power of the heating component 3 is independently controlled by the controller according to the feedback signal of the temperature sensing unit 2 at the corresponding position, forming multiple parallel local closed-loop control loops.

[0050] Specifically, the insulation cover 1 is evenly divided into three temperature control sections along the axial direction. Within each temperature control section, a temperature sensing unit 2 and an independent heating component 3 are installed at its upper and lower ends, respectively. The upper temperature sensing unit 2 corresponds axially to the upper heating component 3, and the lower temperature sensing unit 2 corresponds axially to the lower heating component 3. The controller receives the real-time temperature signal collected by each temperature sensing unit 2, calculates the required heating power for the corresponding location, and sends a power control signal to the heating component 3 corresponding to that temperature sensing unit 2. The power control loop of each heating component 3 is independent, forming multiple parallel local closed-loop control loops. For example, when the upper temperature sensing unit 2 of a certain temperature control section detects that the ingot temperature at that location is lower than the target value, the controller only increases the power of the upper heating component 3 corresponding to that temperature sensing unit 2, without affecting the lower heating component 3 of the same temperature control section or the heating components 3 of other temperature control sections.

[0051] It should be noted that in this embodiment, the insulation cover 1 is divided into segments along the axial direction, with temperature sensing units 2 and heating components 3 independently installed at both ends of each segment. The controller independently controls the power of the corresponding heating components 3 based on feedback from each temperature sensing unit 2, forming multiple parallel local closed-loop control loops. This allows for precise and independent compensation for the actual temperature difference at different axial positions of the steel ingot, effectively reducing the axial temperature difference, suppressing microstructure segregation and crack defects, and simultaneously reducing energy consumption through on-demand heating. This achieves online precise temperature control throughout the entire process of electroslag furnace steel ingot billet production. Through this method of independent control at both ends of the axial direction and parallel operation of each temperature control segment, this embodiment achieves precise and independent adjustment of the temperature distribution along the entire length of the steel ingot, effectively suppressing the axial temperature difference.

[0052] In one embodiment of the present invention, the heating component 3 is an annular induction heating coil, which is disposed between the inner wall of the heat insulation cover 1 and the steel ingot and surrounds the outer side of the steel ingot; the heat insulation cover 1 is a double-layer heat insulation cover, the temperature measuring point 2 of the temperature sensing unit is embedded in the inner layer of the heat insulation cover 1, and its measuring end extends to the effective heating area of ​​the corresponding heating component 3.

[0053] Specifically, each heating component 3 employs a ring-shaped induction heating coil, which is arranged coaxially with the steel ingot in the gap between the inner wall of the insulation cover 1 and the outer surface of the steel ingot. The coil can be fixed to the inner shell of the insulation cover 1 by an insulating bracket, with its inner side maintaining a predetermined distance (e.g., 20~50mm) from the outer surface of the steel ingot to ensure electromagnetic induction efficiency while avoiding contact. The insulation cover 1 has a double-layer structure, with the inner layer being insulation material (such as ceramic fiber blocks or high-alumina needle-punched fiber blankets). Each temperature sensing unit 2 employs an armored infrared thermometer, embedded in the insulation material of the inner layer of the insulation cover 1, with its measuring end extending from the insulation material into the effective heating area of ​​the corresponding ring-shaped induction heating coil. The effective heating area refers to the axial range within which the induction coil can generate a significant electromagnetic field and effectively heat the steel ingot when energized. By placing the temperature measuring end in this area and close to the surface of the steel ingot (e.g., 1-5 mm away from the surface of the steel ingot), the temperature measured by the temperature sensing unit 2 can accurately reflect the temperature rise of the steel ingot under the action of the corresponding heating component 3, thereby providing accurate feedback signals for closed-loop control and improving the system's response speed and control accuracy.

[0054] It should be noted that in this embodiment, by encircling the outside of the steel ingot with the induction heating coil and extending the temperature measuring end of the temperature sensing unit 2 into the effective heating area of ​​the corresponding coil, the temperatures measured by the two measuring points of the temperature sensing unit 2 can accurately reflect the temperature rise of the steel ingot under the action of the heating component 3, thereby improving the accuracy and real-time performance of the temperature feedback signal. This structural design effectively shortens the lag time between heating and detection, avoids control delays caused by the temperature measuring point being far from the heating area, and thus improves the response speed and control accuracy of the closed-loop control system. It provides a reliable data basis for precise zoned temperature control, and helps to further reduce the axial and circumferential temperature difference of the steel ingot and suppress quality defects.

[0055] In one embodiment of the present invention, each temperature control section is a split structure, including a left half shell and a right half shell. An infrared thermometer and a semi-circular induction heating coil are respectively provided on the left half shell and the right half shell. Two infrared thermometers at the same end of the axial direction of each temperature control section form a set of temperature measuring points and serve as temperature sensing units 2. Two semi-circular induction heating coils form a circular induction heating coil and serve as heating components 3. The upper end of the heat insulation cover 1 is used to connect with the crystallizer outlet of the electroslag furnace.

[0056] Specifically, each temperature control section adopts a split structure, divided into a left half-shell and a right half-shell in the circumferential direction, and the two half-shells can be opened and closed relative to each other. On the inner wall of the left half-shell, an infrared thermometer and a semi-circular induction heating coil are respectively installed at both ends (upper and lower) of the axial direction of the temperature control section; similarly, on the inner wall of the right half-shell, an infrared thermometer and a semi-circular induction heating coil are also installed at both ends of the same axial direction. When the left and right half-shells are closed, the two infrared thermometers at the same end (such as the upper end) of the same axial direction of the temperature control section form a set of temperature measuring points, that is, form a temperature sensing unit 2; at the same time, the two semi-circular induction heating coils at this end are closed to form a complete ring induction heating coil, that is, form a heating component 3, which surrounds the outside of the steel ingot. Each semi-circular coil itself constitutes an independent electromagnetic induction circuit, which can independently heat the half of the steel ingot it covers, and the circumferential uniform heating is achieved after the left and right half-shells are closed. The upper end of the insulation cover 1 is positioned opposite to the billet outlet of the electroslag furnace crystallizer, ensuring that the steel ingot immediately enters the insulation cover 1 after being extracted from the crystallizer, reducing exposure time. Through the above-mentioned split structure and the symmetrical arrangement of infrared thermometers and semi-circular coils on the left and right halves of the shell, this embodiment achieves refined independent temperature control with axial segmentation and circumferential segmentation, which can eliminate axial temperature difference and compensate for circumferential temperature difference caused by steel ingot eccentricity or uneven local heat dissipation.

[0057] Both the left and right halves of the shell are fitted with drive mechanisms (electric push rods or cylinders). The fixed end of the drive mechanism is mounted on the equipment frame, while the movable end is hinged to the outer wall of the half-shell. When steel ingots need to be installed or the equipment needs maintenance, the drive mechanism drives the left and right halves to separate to open the insulation cover 1, facilitating the entry or removal of the steel ingot. During normal billet discharge and insulation, the drive mechanism pushes the left and right halves to move relative to each other, causing the two halves to align at the center plane, forming a complete cylindrical temperature control section. A sealing strip can be installed at the mating surface to ensure the insulation effect. When a temperature control section needs maintenance or replacement, the drive mechanism of that section can be opened separately without affecting the operation of other sections, improving the maintainability of the system. At the same time, the split structure also facilitates the pre-opening of the insulation cover 1 before the steel ingot is discharged, and then closing it after the head of the steel ingot enters the designated position, thereby reducing the uncontrolled exposure time of the initial section of the steel ingot.

[0058] like Figure 4 As shown, an electronic device 400 provided in this embodiment of the invention includes a memory 410 and a processor 420 coupled to the memory 410; the memory 410 is configured to store a computer program; the processor 420 is configured to perform the following operations when the computer program is executed: Acquire real-time temperature data at different axial positions during the billet unloading process of steel ingots; The temperature control mode corresponding to the current stage is determined based on the billet production process, and the control parameters of the closed-loop control algorithm are set based on the temperature control mode. For each axial position, the required heating power is calculated using the closed-loop control algorithm with set control parameters, based on the temperature deviation between the real-time temperature data and the preset target temperature curve. The steel ingots at the corresponding axial positions inside the insulation cover 1 are independently heated and compensated according to the heating power.

[0059] This invention provides a non-volatile computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor performs the following operations: Acquire real-time temperature data at different axial positions during the billet unloading process of steel ingots; The temperature control mode corresponding to the current stage is determined based on the billet production process, and the control parameters of the closed-loop control algorithm are set based on the temperature control mode. For each axial position, the required heating power is calculated using the closed-loop control algorithm with set control parameters, based on the temperature deviation between the real-time temperature data and the preset target temperature curve. The steel ingots at the corresponding axial positions inside the insulation cover 1 are independently heated and compensated according to the heating power.

[0060] The following description refers to an electronic device 400 that can serve as a server or client of the present invention, which is an example of a hardware device that can be applied to various aspects of the present invention. Electronic device 400 is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic device 400 can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0061] Electronic device 400 includes a computing unit that can perform various appropriate actions and processes based on a computer program stored in read-only memory (ROM) or a computer program loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The computing unit, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0062] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.

[0063] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for online heat preservation in electroslag furnace for preparing steel ingots, characterized in that, The steel ingot is drawn from the electroslag furnace and passes axially through the heat insulation cover (1), the method comprising: Acquire real-time temperature data at different axial positions during the billet unloading process of steel ingots; The temperature control mode corresponding to the current stage is determined based on the billet production process, and the control parameters of the closed-loop control algorithm are set based on the temperature control mode. For each axial position, the required heating power is calculated using the closed-loop control algorithm with the control parameters set, based on the temperature deviation between the real-time temperature data and the preset target temperature curve. The steel ingot at the corresponding axial position inside the heat insulation cover (1) is independently heated and compensated according to the heating power.

2. The online heat preservation method according to claim 1, characterized in that, The method of determining the temperature control mode corresponding to the current stage based on the billet unloading process includes: The billet production process is divided into initial, middle and later stages; When the current stage is the initial stage, a low-power or no-heating temperature control mode is used; When the current stage is the intermediate stage, a dynamic compensation temperature control mode is adopted to adjust the heating power in real time according to the temperature deviation. When the current stage is the later stage, a high-precision closed-loop temperature control mode is adopted to reduce the axial temperature difference of the steel ingot.

3. The online heat preservation method according to claim 2, characterized in that, The closed-loop control algorithm is a variable parameter PID control algorithm, and its proportional, integral, and derivative coefficients are dynamically adjusted according to the current temperature deviation and the billet extrusion process; when the temperature deviation exceeds a preset threshold, the integral term is temporarily removed.

4. The online heat preservation method according to claim 1, characterized in that, Before calculating the required heating power, the method further includes: correcting the output of the closed-loop control algorithm based on at least one of the parameters of the thermal conductivity, specific heat capacity, and density of the steel ingot material.

5. The online heat preservation method according to claim 1, characterized in that, The real-time temperature data is collected by multiple temperature sensing units (2) arranged along the axial direction of the heat insulation cover (1); each temperature sensing unit (2) includes at least two temperature measuring points symmetrically arranged on the same circumference of the heat insulation cover (1).

6. The online heat preservation method according to claim 5, characterized in that, Each of the temperature sensing units (2) is provided with a heating component (3); the heating component (3) receives the heating power calculated for the axial position of the temperature sensing unit (2) and heats the steel ingot at the axial position with the heating power.

7. An online heat preservation system for preparing steel ingots in an electroslag furnace, characterized in that, include: A heat insulation cover (1) is fitted over the outside of the steel ingot extracted from the electroslag furnace, and the heat insulation cover (1) is coaxial with the steel ingot; Multiple temperature sensing units (2) and multiple heating components (3) are arranged along the axial direction of the heat insulation cover (1). The heating components (3) correspond one-to-one with the temperature sensing units (2) and are used to heat the steel ingot at the axial position corresponding to the temperature sensing unit (2). A controller is electrically connected to each of the temperature sensing units (2) and each of the heating components (3), and the controller is used to perform the online heat preservation method for preparing steel ingots in an electroslag furnace according to any one of claims 1 to 6.

8. The system according to claim 7, characterized in that, The heat insulation cover (1) is divided into multiple temperature control sections along its axial direction. Each temperature control section is provided with a temperature sensing unit (2) and a heating component (3) at both ends of its axial direction. The heating power of the heating component (3) is independently controlled by the controller according to the feedback signal of the temperature sensing unit (2) at the corresponding position, forming multiple parallel local closed-loop control loops.

9. The system according to claim 8, characterized in that, The heating component (3) is a ring-shaped induction heating coil, which is located between the inner wall of the heat insulation cover (1) and the steel ingot and surrounds the outer side of the steel ingot; the heat insulation cover (1) is a double-layer heat insulation cover, and the temperature measuring point of the temperature sensing unit (2) is embedded in the inner layer of the heat insulation cover (1), and its measuring end extends to the effective heating area corresponding to the heating component (3).

10. The system according to claim 9, characterized in that, Each of the temperature control sections is a split structure, including a left half shell and a right half shell. The left half shell and the right half shell are respectively provided with an infrared thermometer and a semi-circular induction heating coil. The two infrared thermometers at the same end of the axial direction of each temperature control section form a set of temperature measuring points and serve as the temperature sensing unit (2). The two semi-circular induction heating coils form a ring induction heating coil and serve as the heating component (3). The upper end of the heat preservation cover (1) is set opposite to the crystallizer outlet of the electroslag furnace.

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