Method, device and system for online measurement of temperature of steelmaking molten steel of electric arc furnace

Abstract

The invention relates to a method, a device and a system for measuring the temperature of molten steel in electric arc furnace steelmaking on line, and belongs to the field of electric arc furnace steelmaking. According to the method, temperature and refractory material thickness data at different positions are collected in real time through a temperature measuring device installed on the furnace wall or the furnace bottom of the electric arc furnace, the temperature gradient is calculated, the actual temperature of molten steel is inversely calculated based on the heat flux balance principle, and the problem that the temperature of the molten steel cannot be continuously and accurately measured in the prior art is solved. Real-time stable monitoring of the temperature of the molten steel is achieved, meanwhile, the thickness of the refractory material of the furnace lining is detected synchronously, and key data support is provided for optimizing the smelting process and guaranteeing safety production.

Description

Technical Field

[0001] This invention belongs to the field of electric arc furnace steelmaking and relates to a method, apparatus and system for online measurement of molten steel temperature in electric arc furnace steelmaking. Background Technology

[0002] The temperature of molten steel is one of the main control targets in electric arc furnace smelting. It is crucial for dephosphorization, decarburization and quality control in the smelting process. The temperature of molten steel in the electric arc furnace is usually measured by a "one-time rapid thermocouple". However, this method is limited by the number of temperature measurements and cannot continuously monitor the changes in the temperature of molten steel during the smelting process. This is not conducive to optimizing the electric arc furnace steelmaking process and controlling the endpoint.

[0003] Non-contact temperature measurement methods, such as infrared thermography, are currently the primary means of continuous measurement of molten steel temperature during electric arc furnace steelmaking. However, the harsh high-temperature environment of the electric arc furnace smelting process, including large fluctuations in the slag surface, high dust content in the high-temperature flue gas, and intense slag splashing, poses a significant challenge to the continuous and accurate measurement of molten steel temperature.

[0004] Patent application CN201510958681.7 discloses a temperature measurement system and method for online measurement of molten steel temperature in electric arc furnace steelmaking. By using a furnace wall spray gun to generate a supersonic gas jet in the electric arc furnace to remove flue gas and foamy slag from the furnace chamber, it solves the non-contact problem of molten steel temperature measurement in electric arc furnace steelmaking, achieving continuous or intermittent online measurement and improving the accuracy and precision of temperature measurement. Although this method solves the non-contact problem of molten steel temperature measurement, the supersonic gas generated by the furnace wall spray gun reacts with elements in the molten steel, and the rapid changes in the composition of the molten steel make it difficult to effectively control the heat release, resulting in difficulties in matching the measured temperature with the actual temperature. "Online" refers to continuous or near real-time measurement, i.e., a sampling frequency ≥ 0.1Hz.

[0005] In view of this, the purpose of this invention is to provide a method, apparatus, and system for online measurement of molten steel temperature in electric arc furnace steelmaking, so as to solve the current problem of continuous and accurate measurement of molten steel temperature in electric arc furnaces. Compared with the supersonic gas jet scheme adopted in CN201510958681.7, this invention avoids interference from molten steel composition through direct contact measurement, and achieves more stable continuous measurement. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a method, apparatus and system for online measurement of the temperature of molten steel in electric arc furnace steelmaking.

[0007] To achieve the above objectives, the present invention provides the following technical solution: An online temperature measurement system for molten steel in an electric arc furnace includes: an online temperature measurement device for molten steel and a data processing system; the online temperature measurement device for molten steel is embedded in the refractory material of the furnace wall or bottom of the electric arc furnace and is in contact with the molten steel, for real-time acquisition of temperature and thickness data; the data processing system is communicatively connected to the online temperature measurement device for receiving and processing data to obtain the temperature of the molten steel.

[0008] Furthermore, the online steel molten temperature measurement device includes: a protective refractory material, at least two temperature sensors, and a thickness sensor; the protective refractory material is in real-time contact with the molten steel during the smelting process; the temperature sensors are embedded at different thickness positions of the protective refractory material; and the thickness sensor is connected to the end of the protective refractory material.

[0009] Furthermore, the temperature sensor is a resistive temperature sensor, a thermocouple temperature sensor, or a PN junction temperature sensor.

[0010] Furthermore, the thickness sensor employs an ultrasonic thickness sensor, an electromagnetic thickness sensor, a capacitive thickness sensor, a resistive thickness sensor, or a thermal flux thickness sensor.

[0011] A method for online measurement of molten steel temperature in an electric arc furnace includes the following steps: S1: Real-time acquisition of data from the temperature sensor and thickness sensor in the temperature measuring device; S2: Based on the temperature characteristics of the thickness sensor, the thickness of the refractory material detected by the thickness sensor is corrected according to the detected temperature data; S3: Based on the thermal conductivity characteristics of the temperature measuring device, calculate the contact temperature between the element and the molten steel and the outer surface temperature, and calculate the heat transfer coefficient of the element; S4: The heat flux of the temperature measuring device is calculated by using the thickness and temperature data of the temperature measuring device in real time, and the real-time temperature of the molten steel is obtained based on the heat flux balance calculation.

[0012] Furthermore, in step S2, the correction of the refractory material thickness includes: Based on the thickness correction according to the change in ultrasonic wave propagation speed, the propagation speed of ultrasonic waves at the current temperature is:

[0013] in, and These are the actual temperature and the reference temperature for sound wave propagation, respectively, in degrees Celsius (°C). The benchmark supersonic speed is expressed in m / s. This is the velocity temperature coefficient, in °C. -1 ; Actual propagation temperature The calculation formula is:

[0014] in, and These are the temperatures at the bottom of the online temperature measuring device for molten steel and at the interface in contact with the molten steel, respectively, in °C.

[0015] Furthermore, in step S2, the thickness of the refractory material is corrected for temperature, and the calculation formula is as follows:

[0016] in, The corrected refractory material thickness is expressed in mm. This is the standard thickness of the refractory material, in mm.

[0017] Furthermore, in step S2, the temperature drift of the probe is also considered, the temperature drift error of the sensor probe itself is corrected, and the actual thickness of the refractory material is calculated. The calculation formula is as follows:

[0018] In the formula, This refers to the actual thickness of the refractory material, in mm. This is the temperature drift correction factor, in mm / ℃. The reference temperature for sensor drift is given in °C.

[0019] Furthermore, in step S3, the temperature gradient g of the refractory material inside the online temperature measuring device is calculated, with units of mm / ℃; and the temperature at the bottom of the online temperature measuring device is calculated accordingly. and the contact temperature with the molten steel surface .

[0020] Furthermore, in step S4, the heat flux of the online temperature measurement device is calculated based on Fourier's law. The calculation formula is:

[0021] Where λ is the thermal conductivity of the refractory material, with units of W / (m·K); Calculate the total heat flux of molten steel to the online temperature measuring device. It includes convective heat transfer and radiative heat transfer, and the calculation formula is: in, The convective heat transfer coefficient between the molten steel and the online temperature measuring device is expressed in W / (m²·K). The surface emissivity of refractory materials; It is the Stefan-Boltzmann constant; According to heat flux balance The temperature of the molten steel was calculated. .

[0022] Furthermore, the correction of the refractory material thickness in S2 includes temperature drift correction and ultrasonic propagation speed correction, so that the steel molten temperature measurement error is ≤±10°C. Furthermore, the temperature sensor and thickness sensor employ a multimodal fusion method to cross-verify data accuracy in real time. The beneficial effects of this invention are: (1) This invention realizes real-time, stable and accurate measurement of the temperature of molten steel in electric arc furnace, which significantly enriches the information of the smelting process obtained by the operators, and provides key data support and necessary prerequisites for scientifically optimizing the power supply system, oxygen supply parameters and slag-making process.

[0023] (2) The present invention can simultaneously measure the thickness of the refractory material of the electric arc furnace in real time while continuously measuring the temperature of the molten steel, effectively avoiding safety risks in the smelting process and providing a reliable guarantee for the safety and stability of the electric arc furnace smelting operation.

[0024] (3) This invention improves the measurement accuracy to within ±10°C by using multi-sensor data fusion and heat flux balance model, which is a significant improvement over traditional thermocouples (error ≥ ±20°C) and provides a reliable data basis for process optimization.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a diagram of an online temperature measurement system for molten steel in an electric arc furnace, as described in an embodiment of the present invention. Figure 2 This is a diagram illustrating the composition of an online temperature measurement device for molten steel in an electric arc furnace, as described in an embodiment of the present invention. Figure 3 This is a flowchart of an online method for measuring the temperature of molten steel in an electric arc furnace, as described in an embodiment of the present invention.

[0027] Figure reference numerals: 1. Online temperature measuring device; 2. Refractory material of electric arc furnace bottom; 3. Molten steel; 4. Data acquisition device; 5. Data processing system; 6. Protective refractory material; 7. Thermocouple; 8. Thickness measuring device. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0030] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0031] Please see Figure 1 This is a system diagram illustrating a method, apparatus, and system for online measurement of molten steel temperature in an electric arc furnace (EAF) according to an embodiment. It includes an online molten steel temperature measuring device 1, refractory material at the EAF bottom 2, molten steel 3, a data acquisition device 4, and a data processing system 5. The online molten steel temperature measuring device 1 is installed at the EAF bottom, embedded in the refractory material 2, and in contact with the molten steel 3. The data acquisition device 4 is responsible for collecting raw data from the EAF and the molten steel temperature measuring device during the smelting process. This data includes, but is not limited to, the temperature and thickness of the online molten steel temperature measuring device, the oxygen flow rate of the EAF, the actual power supply intensity, and the state information of the smelting materials. Specifically, the temperature of the online molten steel temperature measuring device may include the temperature at different thickness locations of the measuring device; the state information of the smelting materials may involve the quality of raw materials, the quality of molten steel, and the amount of slag.

[0032] The data processing system 5 is used to process the raw data collected by the data acquisition module 4. The data processing system 5 can be a high-performance processor, a professional industrial computing platform, or an embedded system integrated into the electric arc furnace control system. This application does not impose any restrictions on the specific type of data processing system.

[0033] Please see Figure 2 This diagram illustrates the composition of the online temperature measurement device for molten steel in this embodiment. It includes a protective refractory material 101, a temperature sensor 102, and a thickness measuring device 103. The protective refractory material 101 is made of magnesia-carbon brick, identical to the furnace bottom refractory material 2, and its thickness is designed to match the furnace lining erosion rate (erosion ≤10mm per cycle). The temperature sensor 102 is a PT100 platinum resistance thermometer, positioned outside the safe melting zone of the refractory material (≥50mm from the initial surface). The thickness measuring device 103 uses an ultrasonic sensor as an example; electromagnetic or capacitive sensors can also be selected.

[0034] Furthermore, the material of the protective refractory material 101 is the same as that of the refractory material 2 of the electric arc furnace bottom (e.g., both are made of magnesia-carbon bricks), and its thickness is designed to match the erosion rate of a single smelting cycle of the electric arc furnace, thereby achieving synchronous erosion with the furnace lining or furnace bottom during the smelting process.

[0035] The thickness measuring device 103 can also employ an electromagnetic thickness sensor or a capacitive thickness sensor. When an electromagnetic thickness sensor is used, the thickness is calculated by detecting changes in the magnetic permeability of the refractory material; when a capacitive thickness sensor is used, the thickness is inferred by measuring changes in the dielectric constant of the refractory material.

[0036] In this embodiment, the refractory material is in the form of magnesia-carbon bricks. Two PT100 platinum resistance temperature sensors are embedded in the refractory material at different depths in the online temperature measurement device for molten steel. The distances between the two PT100 platinum resistance temperature sensors and the bottom of the online temperature measurement device for molten steel are L1 and L2, respectively.

[0037] In this embodiment, the thickness measuring device adopts ultrasonic measurement and is installed at the bottom of the online temperature measuring device for molten steel to measure the time it takes for sound waves to penetrate the refractory material.

[0038] Please see Figure 3 This is a flowchart illustrating an online measurement method, apparatus, and system for molten steel in an electric arc furnace, as described in an embodiment. It includes the following steps: S1: Real-time acquisition of data from temperature and thickness sensors in the temperature measuring device.

[0039] An industrial-grade data acquisition card is used. The temperature sensors are configured with a sampling frequency of 1Hz, meaning that temperature data T1 and T2 from each sensor are acquired once per second, in °C. The ultrasonic thickness sensor has a sampling frequency of 0.1Hz, measuring the reference thickness L0 of the refractory material in the online temperature measurement device, in mm. The acquisition card transmits the data in real time to the backend monitoring computer via Ethernet, where it is stored in a database for subsequent data processing and analysis.

[0040] S2: Based on the temperature characteristics of the thickness sensor in the temperature measuring device, and using the detected temperature data, correct the thickness of the refractory material detected by the thickness sensor. The specific workflow includes: S201: Thickness correction based on propagation speed variation; propagation speed of ultrasound at the current temperature.

[0041] in, and These are the actual temperature and reference temperature for sound wave propagation, respectively, in °C. The benchmark supersonic speed is m / s. The velocity temperature coefficient is given in °C. -1 The formula for calculating the actual propagation temperature is:

[0042] in, and These are the temperatures at the bottom of the online molten steel temperature measuring device and at the interface in contact with the molten steel, respectively, in °C. This represents the actual average temperature of the refractory material.

[0043] S202: Temperature correction of refractory material thickness based on temperature data.

[0044] S203: Considering the temperature drift of the probe, correcting the temperature drift error of the sensor probe itself, and calculating the actual thickness of the refractory material:

[0045] In the formula, The actual thickness of the refractory material, in mm. This is the temperature drift correction factor, in mm / ℃. Temperature is the reference temperature for sensor drift, in °C.

[0046] By combining temperature drift correction and ultrasonic velocity correction, sensor drift in high-temperature environments is effectively suppressed, which is something that has not been achieved in existing technologies.

[0047] S3: Based on the thermal conductivity characteristics of the temperature measuring device, calculate the contact temperature between the element and the molten steel and the external surface temperature, and calculate the heat transfer coefficient of the element. The specific workflow includes: S301: Calculate the temperature gradient g of the refractory material inside the online temperature measuring device, ℃ / mm.

[0048]

[0049] S302: Distributed calculation of the bottom temperature and contact temperature with the molten steel surface of the online temperature measurement device.

[0050]

[0051] S303: Based on the bottom temperature of the online temperature measuring device and the contact temperature with the molten steel surface, its thermal conductivity is obtained through experimental fitting, and its relationship with the temperature of the refractory material is as follows:

[0052] in, is the thermal conductivity of the refractory material, W / (m·K).

[0053] S4: By calculating the thickness and temperature data of the temperature measuring device in real time, the heat flux of the temperature measuring device is obtained. Based on the heat flux balance, the real-time temperature of the molten steel is calculated. Specifically, this includes: S401: Based on Fourier's law, and considering the average thermal conductivity of the online temperature measurement device... molten steel contact temperature Surface temperature and the actual total thickness of refractory material Calculate the heat flux of the online temperature measurement device.

[0054]

[0055] S402: Calculate the total heat flux of molten steel to the online temperature measuring device, including convective heat transfer and radiative heat transfer.

[0056]

[0057] in: The convective heat transfer coefficient between the molten steel and the online temperature measuring device is expressed in W / (m²·K). The surface emissivity of refractory materials; The Stefan-Boltzmann constant is 5.67 × 10⁻⁶. -8 W / (m 2 ·K 4 ); Convective heat transfer coefficient between molten steel and online temperature measuring device Determined through experimental calibration or computational fluid dynamics (CFD) simulations, the typical value is 550–600 W / (m²). 2 ·K); Surface emissivity of refractory materials The value was taken as 0.85~0.90, which was obtained from experiments based on the spectral characteristics of refractory materials.

[0058] S403: Based on heat flux balance Substitute the known data and rearrange the equation to obtain the temperature of the molten steel.

[0059] By repeating the above steps, continuous and stable measurement of the temperature of molten steel can be achieved.

[0060] Specifically, in this embodiment, L1 and L2 are 180mm and 50mm respectively. At a certain moment during the steelmaking process, the detected temperature data T1 and T2 are 605℃ and 470℃ respectively, and the refractory material thickness is L0 = 1003.6mm. Through laboratory experimental fitting, the reference temperature when the ultrasonic wave propagates within the online temperature measuring device is obtained. benchmark supersonic and velocity temperature coefficient The values ​​are 25℃, 3200m / s, and -0.0003℃, respectively. -1 Temperature drift correction factor for online temperature measurement devices and sensor drift reference temperature The convective heat transfer coefficient h between the molten steel and the online temperature measuring device is 0.0008 mm / ℃ and 100℃, respectively. s With a value of 550 W / (m²·K), the actual thickness of the refractory material and the temperature of the molten steel were calculated to be 723.8 mm and 1582 °C, respectively, through the above steps.

[0061] The measurement error in this embodiment is ≤ ±10°C, while the error of a traditional thermocouple is ≥ ±20°C.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An online temperature measurement system for molten steel in an electric arc furnace, characterized in that: include: Online steel molten temperature measurement device and data processing system; The online steel temperature measurement device is embedded in the refractory material of the electric arc furnace lining and is in contact with the molten steel. It is used to collect temperature and thickness data in real time at a frequency of greater than or equal to 0.1 Hz. The data processing system is communicatively connected to the online steel molten temperature measuring device and is used to receive and process data to obtain the steel molten temperature.

2. The online temperature measurement system for molten steel in electric arc furnace steelmaking according to claim 1, characterized in that: The online steel molten temperature measurement device includes: a protective refractory material, at least two temperature sensors, and a thickness sensor; the protective refractory material is in real-time contact with the molten steel during the smelting process; the temperature sensors are embedded at different thickness positions of the protective refractory material; and the thickness sensor is connected to the end of the protective refractory material.

3. The online temperature measurement system for molten steel in electric arc furnace steelmaking according to claim 2, characterized in that: The temperature sensor is a resistive temperature sensor, a thermocouple temperature sensor, or a PN junction temperature sensor.

4. The online temperature measurement system for molten steel in electric arc furnace steelmaking according to claim 2, characterized in that: The thickness sensor uses an ultrasonic thickness sensor, an electromagnetic thickness sensor, a capacitive thickness sensor, a resistive thickness sensor, or a thermal flow thickness sensor.

5. A method for online measurement of molten steel temperature in an electric arc furnace steelmaking process, characterized in that: Includes the following steps: S1: Real-time acquisition of data from the temperature sensor and thickness sensor in the temperature measuring device; S2: Based on the temperature characteristics of the thickness sensor, perform temperature-related correction on the detected refractory material thickness; S3: Calculate the temperature gradient and heat transfer coefficient of the refractory material based on the thermal conductivity characteristics of the temperature measuring device; S4: Based on the principle of heat flux balance, the real-time temperature of molten steel is calculated by back-calculating the real-time heat flux.

6. The method for online measurement of molten steel temperature in electric arc furnace steelmaking according to claim 5, characterized in that: In step S2, the correction of the refractory material thickness includes: Based on the thickness correction according to the change in ultrasonic wave propagation speed, the propagation speed of ultrasonic waves at the current temperature is: in, and These are the actual temperature and the reference temperature for sound wave propagation, respectively, in degrees Celsius (°C). The benchmark supersonic speed is expressed in m / s. This is the velocity temperature coefficient, in °C. -1 ; Actual propagation temperature The calculation formula is: in, and These are the temperatures at the bottom of the online temperature measuring device for molten steel and at the interface in contact with the molten steel, respectively, in °C.

7. The method for online measurement of molten steel temperature in electric arc furnace steelmaking according to claim 6, characterized in that: In step S2, the refractory material thickness is corrected for temperature, and the calculation formula is as follows: in, The corrected refractory material thickness is expressed in mm. This is the standard thickness of the refractory material, in mm.

8. The method for online measurement of molten steel temperature in electric arc furnace steelmaking according to claim 7, characterized in that: In step S2, the temperature drift of the probe is also considered, the temperature drift error of the sensor probe itself is corrected, and the actual thickness of the refractory material is calculated. The calculation formula is as follows: In the formula, This refers to the actual thickness of the refractory material, in mm. This is the temperature drift correction factor, in mm / ℃. The reference temperature for sensor drift is given in °C.

9. The method for online measurement of molten steel temperature in electric arc furnace steelmaking according to claim 5, characterized in that: In step S3, the temperature gradient g of the refractory material inside the online temperature measuring device is calculated, with units of mm / ℃; and the bottom temperature of the online temperature measuring device is calculated accordingly. and the contact temperature with the molten steel surface .

10. The method for online measurement of molten steel temperature in electric arc furnace steelmaking according to claim 9, characterized in that: In step S4, the heat flux of the online temperature measurement device is calculated based on Fourier's law. The calculation formula is: Where λ is the thermal conductivity of the refractory material, with units of W / (m·K); Calculate the total heat flux of molten steel to the online temperature measuring device. It includes convective heat transfer and radiative heat transfer, and the calculation formula is: in, The convective heat transfer coefficient between molten steel and the online temperature measuring device is expressed in W / ( ); The surface emissivity of refractory materials; It is the Stefan-Boltzmann constant; According to heat flux balance The temperature of the molten steel was calculated. .

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