Blast furnace is a black box, how to understand the various changes within the blast furnace well, one way is to reference the anatomy of the blast furnace, supplemented by a variety of theoretical calculations and practical experience to deduce the changes within the furnace; another way is to apply some visualisation technology to observe intuitively the condition of the blast furnace on-line.
The tuyere peephole is the most primitive and oldest device that can observe the changes inside the blast furnace visually. Blast furnace operator can observe the tuyere before the cyclone area of the combustion state, according to the degree of light and dark to determine the trend of the furnace temperature and the furnace cylinder circumferential work uniformity, to observe the working condition of the coal injection gun. Generally, large blast furnace relies on the camera to convert the working status into a video signal transmitted back to the main control room, in the monitor screen at the same time to display the image of the tuyere, the operator can simultaneously observe all the brightness of the coke movement and coal spraying conditions. And also through the image processing system, the computer processes and calculates the image to get the quantitative analysis data and change trend of the temperature condition of each tuyere and the condition of coal flow at the exit of the coal gun, which provides an important basis for the operator to judge the running trend of the furnace condition, and to guide the operation and adjustment of the blast furnace. The application of the camera reduces the operator’s work intensity, meanwhile the computer processing can be more accurate quantitative reflection of the working condition, more accurate research and judgement of the furnace condition trend.
The tuyere imager can help view the state in the lower part of the blast furnace, while the furnace imaging is realize the visualisation of the furnace in the upper part of the blast furnace. Initially, the furnace imaging using optical imaging technology, the defect is only when the furnace light source can see the furnace conditions, when the top temperature is low, the material of the furnace will be dark.
With the development of technology, the furnace infrared thermal imaging technology gradually improved and mature, and quickly replaced the furnace optical imaging and cross temperature measurement devices. Furnace infrared thermography is an uncooled focal plane detector developed to monitor the temperature field in the blast furnace, which can realise high-definition night vision of the charge surface and chute, and the distribution of airflow is clearly visible. It can real-time display high-definition video images of the material surface and chute, and the shape of the chute (part of it), liner wear, movement status, material discharging, and mechanical probe can be clearly seen; it can comprehensively monitor the temperature of the material surface and part of the chute, and can be set up with multiple temperature lines to real-time monitor the temperature of any point or multi-points; it can real-time monitor the maximum temperature, and the specified temperature range can be highlighted, etc., which can perfectly achieve the visualisation of the material surface of the blast furnace and the distribution of airflow.
Although the furnace imaging technology has realizes the visualization of the distribution of burden and gas flow in the furnace, the influence of different material surface shapes on the distribution of gas flow still cannot be quantitatively reflected, and the laser scanning system of the material surface in the blast furnace has been developed. Furnace material surface laser scanning system by projecting laser to the furnace material surface, and using the detection device to obtain the laser scanning image of the furnace, with special software processing, real-time material surface shape of the furnace curve and the material surface changes in real-time data. Through computer analysis and processing, it can get the accurate data of the curve of the shape of the material surface and the depth of the material line, the internal and external stacking angle of the material and the width of the burden platform, the position of the material eight points and the depth of the central funnel, etc. The operators of the blast furnace can make accurate adjustments to the operation system and the platform funnel through the change of the image and data information and the furnace condition in time to promote the reasonable distribution of the gas flow, which is conducive to the realization of the blast furnace’s stable working and energy saving.
In addition, the laser measurement technology of blast furnace charging, cylinder erosion early warning technology and furnace skin temperature measurement early warning technology, heat flow analysis technology, coal gun plugging measurement technology are also applied in some blast furnaces.
