The rotary kiln in the iron and steel plant is an important device for calcining pallets in the ironmaking process. It comprises the kiln body, transmission device, supporting roller, runner, other supporting devices, kiln head and kiln tail sealing device, kiln head cover, and combustion device. The rotary kiln body is the part that is heated. The inner lining of the rotary kiln is refractory, and a steel plate is on the surface. During normal operation, the internal temperature is over 1200°C, and the burning zone temperature is 1300 to 1400°C. The key lies in the effective means of temperature measurement and temperature trend analysis of the inner wall and outer wall of the rotary kiln.
Pain Points in Rotary Kiln Temperature Monitoring
Due to the heating of the burning zone, the inner wall close to the rotary kiln head has the highest temperature in the rotary kiln. With the increasing time of rotary kiln operations, the inner lining will become thinner and even fall off due to the constant high temperature and friction of clinkers. Consequently, the pipe wall temperature changes drastically, and the temperature in the rotary kiln becomes unevenly distributed, hampering stable and reliable operations of rotary kilns.
An overly high temperature will cause over-calcination, while a low temperature will cause under-calcination. Neither will produce ideal calcination results. Traditional manual routine inspection can hardly discover exceptional areas, unable to impose effective safety controls for rotary kilns.
Advantages of Thermal Cameras
- Professional temperature measurement tools help freely select monitored areas and automatically obtain the highest temperature point for regular inspection. Thermal image comparison helps discover the damage in the kiln lining and notifies staff or links automation devices for control.
- The settings of temperature threshold, duration, and sampling interval are available to achieve data collection. Thermal cameras are used to measure the temperature field of the outer wall. Then, analysis is conducted for the linear relationship between the outer wall temperature and corrosion in the inner lining refractory, and the obtained relationship serves as the reference for making maintenance plans.
- Thermal cameras feature flexible and convenient operations. Preliminary constructions, such as fixed platform installation and cable layout, are no longer needed, and the device maintenance cost is relatively low.
- It provides a secondary development SDK to support users for secondary development, empowering them to form unique advantages.
Main Applications of Thermal Cameras in Rotary Kiln Temperature Monitoring
1. Temperature Monitoring of the Rotary Kiln Outer Wall
The rotary kiln is large and keeps rotating, causing difficulties in the manual inspection. Besides, single-point temperature measurement will cause detection omission, and faults cannot be promptly eliminated. Thermal cameras enable all-weather temperature monitoring, temperature trend analysis, and alarm prompts for the rotary kiln outer wall to replace manual inspection. The thermal cameras effectively transmit images and temperature data to the control room in real time to prevent, handle, and trigger alarms for problems in advance.
2. Temperature Monitoring of the Rotary Kiln Inner Wall
The rotary kiln head sprays fuel into the kiln. The exhaust gas generated through combustion goes to the material and then is let out from the rotary kiln discharge head. The temperature gradually decreases from the rotary kiln head to the rotary kiln discharge head. The temperature at the quenching position of the rotary kiln head can reach 1400°C, but the temperature at the rotary kiln discharge head is only 500 to 800°C. Thermal cameras can monitor the operation status and temperature fields of the combustion in the rotary kiln in real time for real-time visual display of temperature and historical temperature queries.
Recommended Thermal Camera Products by Raythink
- Adjustable -20°C~+150°C and 0°C~+550°C measurement levels
- ±2°C or ±2% measurement accuracy
- Multiple lenses are available, and electric focusing
- PoE power supply and easy wire routing; Support GB28181 and ONVIF protocols
- Control PTZ via the RS-485 interface
- Implement the online real-time monitoring of multiple devices and data collection when equipped with professional PC software
- Windows & Linux-based SDKs are available to support secondary development by users
System Software
With the Raythink VIS-Patrol PC Client industrial temperature measurement and monitoring system, multiple devices can be networked to connect to the software platform for image displaying. A maximum of 64 real-time images can be displayed for video preview, and palette selection, temperature measurement tool configuration, and alarm configuration are supported. The temperature data curve and report are automatically generated to effectively monitor the whole process in the rotary kiln.
How to Take an Infrared Thermal Image of Premium Quality?
Please refer to the following suggestions for using a thermal camera to take a premium-quality thermal image of the rotary kiln:
- Select thermal cameras with high thermal sensitivity for scenarios with a small regional temperature difference in the rotary kiln. Select products or levels of proper measurement ranges according to the temperature and scenes of the inner and outer walls of the rotary kiln.
- The temperature is high in the operating environment of the devices in the rotary, and explosion-proof shells are needed to protect the lens. The water jacket can be installed, or part of the temperature in the rotary can be exported.
- Use automatic measurement first, and then enable the temperature width stretch function. Manually set the temperature width to the minimum and include the previously measured temperature range to enrich the image details.