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Project background
Baosteel Steelmaking Plant has always relied on the visual observation and empirical judgment of operators to judge the refractory of ladle lining, lacking effective and accurate judgment methods.
The current ladle age management mode, for the purpose of ladle use safety, adopts the mode of cycle management as the main and dynamic management as the auxiliary, that is, the ladle age of overhaul cycle ≤ 150 times, and the ladle age of minor overhaul cycle ≤ 25 times. Although the residual thickness of refractory material is also specified (the working layer brick of ladle wall ≥ 60mm), due to the inability to accurately judge, the post measurement is only carried out during ladle overhaul, which may lead to the waste of refractory materials caused by the early offline of ladle.
There are potential safety hazards and waste of refractory materials in the judgment method of ladle lining and ladle age management mode.
Infrared application
1.Imported infrared thermal imager
The infrared thermal imager is independently installed on the mechanical support next to the tilt table. During the operation of the ladle infrared monitoring system, only the on-site operators need to input the ladle number and ladle posture, which does not affect the normal production process.
2.Necessity of ladle transformation
If the ladle lining is damaged and not repaired in time, it will lead to the production accident of steel leakage and the accident of staff injury. If the ladle lining damage can be detected in time and the real-time alarm can remind the staff to repair, it will improve the safety of production and avoid the damage to personnel and equipment caused by the accident and the human and material resources consumption caused by the emergency repair.
Damage to the ladle lining will change the thermal conductivity of the ladle, resulting in changes in the temperature field on the surface of the ladle. Online infrared thermal imaging can provide real-time infrared imaging of the ladle surface, monitor the temperature field of the ladle surface in real time, and store the temperature field data of the ladle surface.
After storing the data for a period of time, analyze and infer the alarm threshold of the temperature field on the surface of the ladle and set it as the alarm value. After setting the alarm threshold, the data of the ladle surface temperature field is analyzed in real time. When the ladle surface temperature field reaches the alarm condition, the real-time alarm reminds the staff to overhaul the ladle to avoid safety accidents.
By analyzing the temperature field data of the ladle surface, on the premise of ensuring the safe production of the ladle, appropriately extend the service life of the ladle, reduce the waste of refractory materials and reduce the production cost.
Case analysis
1.Scheme details
The whole system consists of hardware system and software system. Their composition and functions are detailed below.
Hardware design: the hardware equipment is installed on site and in the control room. The scene mainly includes infrared thermal imager and operation console, and the control room has analysis host and audible and visual alarm.
2.Hardware design
When the ladle reaches the 3# tilting table for slag dumping, it is in the process of slag dumping. When the on-site staff observed that the ladle was in the following three postures, the on-site staff pressed the infrared photo button to take infrared photos of the ladle.
- The ladle falls to the tilting table at 0 ° and the front of the ladle faces the infrared thermal imager when it falls stably;
- The ladle rotates 90 °, and the bottom of the ladle faces the infrared thermal imager;
- The ladle rotates 180 °, and the back of the ladle faces the infrared thermal imager. The infrared photos are transmitted to the analysis host in the control room through the network. The analysis host stores the infrared photos and stores the data of the ladle surface temperature field according to the ladle number, ladle block number and time; The audible and visual alarm is connected to the analysis host and sends an alarm signal to remind the staff to overhaul the ladle.
3.Software design
The analysis software completes the data storage of ladle surface temperature field, analyzes the data of ladle surface temperature field, realizes the alarm function, and reminds the staff to overhaul the ladle.
1) Data storage
2) Analysis alarm function
3) Establish the corresponding model of ladle shell temperature and lining residual thickness
1) Data storage
The infrared photos of the ladle are transmitted to the analysis host in the control room through the network. The analysis software stores the data of the ladle surface temperature field in the form of Excel and infrared pictures according to the ladle number, ladle block number and time. The statistical data include the highest temperature value, the lowest temperature value and the average temperature value, and can analyze the temperature change of the iron shell in combination with the steel grade produced in the ladle information management system, process path and turnover time.
A group of files lasting one year shall be established for each ladle overhaul cycle, and the historical records can be played back, and the data of ladle surface temperature field can be called out in time for analysis.
2) Analysis alarm function
The initial value of the alarm threshold is as follows: 460 ℃ of the slag feeding line; 440 ℃ in the middle of the cladding wall; Lower slag line 410 ℃; 550 ℃ at the water inlet at the bottom of the package; Breathable brick 480 ℃; The prefabricated part at the bottom of the package is 460 ℃. According to the statistical data of ladle surface temperature field, analyze and correct the alarm threshold of ladle surface temperature field and set it as the alarm threshold.
After setting the alarm threshold, the infrared image is transmitted to the analysis computer in the control room for real-time analysis. If the temperature field on the surface of the ladle reaches the alarm condition, the alarm window pops up on the software interface of the analysis host, and the audible and visual alarm connected to the analysis host sends out the alarm reminder signal. After the operator in the control room operates the software interface of the analysis host, the alarm pop-up window and the alarm reminder of the audible and visual alarm are removed, The operator arranges the maintenance work according to the alarm reminder.
3) Establish the corresponding model of ladle shell temperature and lining residual thickness
Combined with the different thermal conductivity and original thickness of different refractory materials in different parts of the ladle, the temperature measurement data record of the ladle iron shell, and the residual thickness data of the working layer measured during the ladle maintenance, through a period of data accumulation, establish the data range of the iron shell temperature corresponding to the different residual thickness of the ladle working layer, judge the residual thickness of the refractory material of the ladle lining through the measured temperature, and gradually change the use times of LF The mode of managing the number of cycles according to the cycle realizes the dynamic management according to the residual thickness, improves the number of ladle uses, and reduces the consumption of refractory materials.
Installation method
The infrared thermal imager is installed on the mechanical structure support next to the tilt table (the specific installation method needs to be negotiated again). There is a nitrogen gas source near the installation of the infrared thermal imager. The nitrogen gas source is connected to the air inlet of the lens protection assembly with a gas pipe after being treated by the pressure reduction filter assembly. The electrical connection shall be laid in cable trench and bridge according to the wiring specification of continuous casting workshop, and the cable from infrared thermal imager to cable trench shall be laid in pipe.
Conclusion
Through the research of Baosteel ladle temperature field on-line monitoring and management system technology, the safety of ladle use can be improved, the smooth flow of steelmaking logistics can be guaranteed, the production cost can be reduced, and the steelmaking production efficiency can be improved; Reduce the waste of refractory materials and save production costs.
Therefore, on-line monitoring of ladle temperature field is necessary, and the transformation scheme is technically feasible.
