Summary:Utilizing convenient and flexible wireless temperature and thermal imaging technology to inspect blast furnace shells, the thermal imaging technique is employed to detect abnormal temperature areas. Once identified, point inspections are conducted on the concerned areas to prevent shell burn-through. Temperature data is collected and stored, and predictive analysis of the temperature sensing points is performed by reviewing historical trends, allowing for the implementation of appropriate measures. This ensures a favorable environment for the safe production of blast furnaces and prevents the occurrence of catastrophic incidents.
Keywords:Wireless Temperature Measurement; Furnace Shell; Wireless Probe; Local Area Network; Thermal Imaging
Introduction
In 2021, the Ironmaking Plant of Changgang Changzhi Iron & Steel Co., Ltd. (hereinafter referred to as Changgang) implemented the spirit of essentialized safety management of Changgang, with all levels fully promoting the implementation of essentialized safety management. Centered around the essentialized safety concept of "safety in absence, efficiency enhancement, and risk reduction, as well as isolation of hazards," the plant advanced essentialized safety transformations in high-risk areas and points prone to accidents, continuously improving them to effectively control risks on the job site. To achieve this, the plant's technical team conducted research and application of thermal imaging and wireless temperature measurement technology, yielding positive results.
1. Blast Furnace hearth and bottom defects and countermeasures
The "weak cooling zone" between adjacent cooling walls in the blast furnace hearth area is subject to "surface" monitoring, as the temperature difference in the cooling water represents thermal load. Typically, a burn-through in the hearth area occurs at a single point. Therefore, the weak cooling zone between the adjacent cooling walls in the hearth area is a monitored region. Evidence has shown that once a burn-through occurs in this weak cooling zone, the temperature difference in the water cannot provide timely early warnings. Thus, in addition to the "surface" monitoring of the temperature difference in the water between cooling walls, "point" monitoring through the furnace skin temperature monitoring system is also necessary to achieve the monitoring of the hearth's safe condition.
During the latter stages of the furnace operation, the temperature of the furnace hearth cannot be monitored solely by thermocouples: as the hearth erosion becomes severe, especially during the latter stages of the furnace operation, the internal lining temperature rises (above 800℃), affecting the temperature detection function of the thermocouples due to the high temperature. This results in a decrease in the stability and accuracy of temperature measurement, and there is a possibility of the temperature detection function failing. As the hearth erosion worsens continuously during the latter stages of the furnace operation, some thermocouples begin to fail, leading to the inability to monitor the hearth temperature. Therefore, a wireless temperature measurement device was introduced.
Status of Blast Furnace No. 2's Inspection
Utilizing thermocouples embedded in the inner lining of the hearth and bottom brick of the furnace, a total of 181 thermocouples are used to monitor the inner lining of the blast furnace, with 131 thermocouples in the hearth providing temperature data to create the "Hearth and Bottom Erosion Status Monitoring and Early Warning Software."
2) "Water Temperature Difference Heat Load Monitoring and Early Warning Software" utilizing 109 precision thermistors to provide data for 199 cold plates.
3) A thermal imaging system has been installed inside the furnace, allowing for the visibility of the shape of the furnace trough and material surface.
On this basis, Changgang independently developed a wireless hot blast furnace slag temperature online monitoring and early warning system, achieving safe monitoring of the hearth and the blast furnace body, thus preventing the occurrence of serious production accidents.
Features of the Online Monitoring and Early Warning System for the Skin Temperature of 3-Wire Blast Furnace Hearth
3.1 Online Solutions
Despite being a wireless transmission, due to the poor working conditions in the blast furnace production area, which include steam, water, high temperatures, gas, and dust, the construction of large equipment can interfere with signals. Therefore, we have adopted a combination of wireless and wired modes. Since the control room is far from the site, relying solely on wireless transmission over a long distance is unreliable. We have installed three wireless receivers on three pillars at different directions, which are a certain distance from the main body, in a better environment, suitable for cable routing. The nearby temperature probes are connected nearby.
The eight-port server utilizing ZLAN long steel has unified the signals from the three on-site wireless receivers to the power distribution room on the second floor, transmitting them via Ethernet to the duty room terminal. Just like a server, each receiver operates on a different frequency band, capable of simultaneously receiving 128 temperature probe signals, as shown in Figure 1.
3.2 Hardware Aspects
1) Expanded temperature probe types; for the low-temperature range of 0～+80℃, utilize an adsorption installation method; for the high-temperature range of 80～+500℃, employ a transmitter adsorption combined with thermocouple threaded fixation to enhance the lifespan of the sensors.
2) Wireless temperature automatic monitoring involves installing a special contact furnace shell temperature online monitoring device (furnace shell temperature sensor) on the furnace shell, and then transmitting the temperature data of the monitoring points in real-time to the furnace shell temperature monitoring system of the computer system through a wireless communication network. The computer system continuously and in real-time monitors the temperature data changes at each measuring point, performs automatic calculations and analyses, and issues early warnings based on set thresholds. This guides the blast furnace operators to conduct targeted operations, enhancing the protective effect of the furnace and preventing incidents of furnace bottom burn-through.
3) The wireless communication furnace skin temperature sensor utilizes wireless digital communication, freeing itself from the constraints of cables. The measurement points can be placed arbitrarily (meanwhile, each measurement point is relatively independent; even if a specific measurement point fails, it will not affect the entire system's operation).
4) The furnace skin temperature sensor utilizes a magnetic suction installation method, making disassembly and assembly easy, with the process taking just 5 seconds to complete for one sensor.
5) In response to the possibility of demagnetization or vibration-induced detachment of the original adsorption-type sensor after installation, we have made technical improvements to the original sensor and applied for a utility model patent (ZL202022738420.3).
By monitoring the 2-3rd segments of the blast furnace hearth and the 7-9th segments of the炉腰炉身, the project's monitoring function is comprehensive and reliable, meeting the requirements for blast furnace shell process monitoring. The system features 1, 2, and 11-14 wireless frequency bands, each capable of installing 128 sensors. Currently, Station 1 uses 8 points, Station 2 uses 18 points, Stations 11 and 12 each use 30 points, Station 13 uses 8 points, and Station 14 uses 10 points. With a significant redundancy in monitoring points and wireless frequency bands, the project can be further expanded to other monitoring areas. By leveraging the characteristics of the monitoring points, the redundancy is applied to the temperature monitoring of the No. 9 hot blast stove shell and arch, enhancing the efficiency of the project.
Eight wireless, movable thermocouples for temperature measurement were installed in key areas such as the hot air main duct, hot air branch duct, furnace shell, and arch roof of the hot blast furnace, totaling 104 units.
3.3 Software Aspect
1) Accurate temperature monitoring, wireless transmission, and centralized display in the control room.
2) Developed an autonomous C# language-based data collection unit, which parses and converts the collected data, displays it in a formatted manner, and sends it back to the WINCC system platform. This maximizes the functionality of the WINCC work platform for operations and display purposes.
3) Leveraging Microsoft's free Text-to-Speech development package, Interop.SpeechLibSDK 5.1, we have independently developed a voice reading function for voice alarm settings, thereby enriching the alarm modes.
4) Achieved multi-point monitoring of the source with the blast furnace utilizing three receivers for unified reception, and implemented on-site split-screen looping display to avoid unnecessary costs from repeatedly adding receivers.
5) Achieve multi-point temperature monitoring with audible and visual alarms; independently store operational trends for easy review and root cause analysis.
6) Utilizing CAD 3D modeling technology, we have accurately reconstructed the internal structure of the furnace shell, precisely determining the installation locations. This ensures that each temperature sensing point corresponds to a specific structural element, with different colors used to denote various temperature points. By distinguishing between the display colors, it becomes easy to judge the temperature of the monitored areas, providing a clear and straightforward monitoring process.
7) Through real-time monitoring, we ensure blast furnace process requirements and safe production. The monitoring screen facilitates viewing and a warning system has been set up, such as: when the furnace tank temperature is below 50℃, it is in a safe operating state. A yellow warning is required between 50~55℃ temperatures, and staff on duty must inspect the site of the warning and investigate the cause. A red alert is issued and an alarm sounds when the temperature exceeds 55℃, at which point staff must take measures such as using water spray on the furnace body, reinforcing cooling with high-pressure water, controlling smelting intensity, and blocking风口 to ensure safety.
8) The system features operational screens for furnace shell trends, hot blast stove trends, etc., which facilitate monitoring. It offers real-time recording of historical data, capable of storing three months' worth of temperature change data, making it easier to trace historical operational trends, conduct root cause analysis, identify issues, and develop effective blast furnace operation and maintenance strategies.
Ankorri Online Temperature Monitoring System Solution
4.1 Overview
The electrical contact online temperature measurement device is suitable for monitoring the temperature of equipment such as cable joints, circuit breaker contacts, knife switches, high-voltage cable middle heads, dry transformers, and low-voltage high-current devices within high and low-voltage switchgear cabinets. It prevents potential safety hazards caused by overheating due to oxidation, loosening, dust, and other factors during operation, enhancing equipment safety. It provides timely, continuous, and accurate reflection of the equipment's operating status, reducing the incidence of equipment accidents.
The Acrel-2000T Wireless Temperature Measurement Monitoring System communicates directly with equipment at the bay level via RS485 bus or Ethernet. The system design adheres to international standards such as Modbus-RTU and Modbus-TCP, significantly enhancing security, reliability, and openness. It features remote signaling, measurement, control, tuning, setting, event alarms, curves, bar graphs, reports, and user management. The system can monitor the operational status of wireless temperature measurement system equipment, achieve rapid alarm response, and prevent severe faults from occurring.
4.2 Application Locations
Temperature monitoring suitable for power equipment in various industrial sectors such as ubiquitous power Internet of Things, steel mills, chemical plants, cement factories, data centers, hospitals, airports, power plants, coal mines, and transformer substations.
4.3 System Structure
Temperature Online Monitoring System Structure Diagram
4.4 System Features
The Acrel-2000T temperature monitoring system is installed in the duty monitoring room, enabling remote surveillance of the operating temperatures of all switchgear within the system. The system boasts the following main functions:
1) Temperature Display: Shows the real-time values of each temperature sensing point within the power distribution system, and allows for remote data viewing via computer WEB or mobile APP.
2) Temperature Trend Curves: View the temperature trend curve for each temperature measurement point.
3) Operation Reports: Query and print temperature data for each temperature measurement point.
4) Real-time Alerts: The system can issue alerts for abnormal temperatures at each temperature sensing point. It features real-time voice alarm capabilities, enabling voice alerts for all events. Alert methods include pop-up windows and voice alarms, as well as SMS/APP push notifications to promptly remind on-duty personnel.
5) Historical Event Inquiry: Stores and manages records of events such as temperature limits, facilitating users in tracing historical system events and alarms, and conducting inquiries, statistics, and accident analysis.
Effects Achieved Post-5 Implementation
Following the implementation of the project at the ironmaking plant's No. 9 blast furnace, operators can promptly understand the wall temperatures and their trends in the dangerous areas of the blast furnace, enabling timely adoption of effective furnace protection measures to prevent safety accidents. Drawing upon the project's establishment of an "online monitoring and early warning system for furnace shell temperatures" in the blast furnace is undoubtedly an effective approach.
The project has expanded the participation of professionals through a local area network, enabling the study of measures to eliminate faults in their nascent stages. After detecting high-temperature areas with a portable thermal imaging device, it's convenient and timely to reposition the wireless temperature sensors for monitoring.
You can view the historical trends of temperature data at any time, predict environmental conditions, and plan ahead accordingly.
6 Conclusion
The complexity of the existing issues and the difficulty in resolving them may lead to severe production and safety accidents. The presence of these issues also hinders the organized and efficient operation of blast furnaces. How can we, through proactive control and utilizing advanced technical means and measures, identify the root causes of problems in advance? We should apply advanced industrial technology to address these issues with a "minimally invasive" approach. Treat the resolution of these root causes as a focal point, prevent the escalation of issues into a larger "disease area," leverage the principle of benchmarking to achieve more with less, reduce the maintenance costs of the blast furnace, create a conducive environment for efficient smelting, generate economic benefits, and lay a solid foundation for the continuous advancement of safety production and environmental protection efforts.
Reference
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