Microwave Burden Sensor for Blast Furnaces

Abstract

Measurement of the kinematic movement of burden materials is important for the stable and efficient operation of the blast furnaces. Without devising several types of burden sensor, few of them are put to practical use because of limitation of the proposed principles which are insufficient for measuring burden materials having complexity of chemical and physical change during the deoxidation process in furnaces and bad surroundings in addition. A microwave sensor is newly developed, which is able to use at almost every part in a furnace. This sensor can get simultaneously signals relating to the descent velocity, the thickness of ore and coke layer and the particle size of burden by use of the reflecting and scattering X-band wave. Experimental results at laboratory showed that these variables can be measured by the microwave burden sensor within the accuracy of ± 10%.Various types of microwave sensor have been installed in the shaft, belly and boshof several furnaces. Even though a sensor installed in the level of about 1.5 m above a tuyere is surrounded by hot burden of about 1500°C, it indicates stable signal for more than half a year. Interesting signals such as stagnation of descending burden in the lower level of a furnace, disorder of burden size and mixing of ore and coke in the neighbour of a furnace shell could be detected.