The thermal state and reduction conditions of ores in a lumpy zone have considerable effects on the shape of a cohesive zone and the thermal state in the lower part of a blast furnace. Therefore, a throat diameter probe and a shaft diameter probe were developed as new detection devices for surveying the state of the lumpy zone, and a mathematical model was also developed for estimating the state of the lumpy zone and the outside surface of a cohesive zone in a blast furnace.
The inductive model mentioned above was composed of five simultaneous ordinary differential equations concerning temperature and gas compositions, and these were solved numerically by making use of Runge-Kutta-Gill method. Simulations based on the model were carried out using actual operating data of Sakai No. 2 blast furnace, and it was confirmed that the accuracy of the model was fairly satisfactory in regard to the estimation of gas velocity and gas compositions. Furthermore, static characteristics of reduction reactions of ores by CO and H2 gas and temperature distributions in the lumpy zone were discussed on the basis of estimation results.
