STABILIZATION OF FLOW OF PELLETS BASED ON COMPUTER-SIMULATION OF A METALLURGICAL REACTION IN A SHAFT FURNACE

Stabilizing the flow of ore pellets in a shaft furnance is important to maintenance of highly productive operation. Gas flow, gas pressure distribution, temperature distribution in gas and ores, distribution of gas component and degree of reduction of ore in a direct-reduction shaft furnance were computed, using a finite-element method. The calculated reduction degree of ore pellets was not uniform in spite of relatively uniform distributions of gas flow and temperature. From the knowledge that clustering cannot occur in a straining pellet layer, it was estimated that cluster formation usually takes place where a highly reduced region and a plug-flow region of pellets overlap. The simulation made it feasible to predict cluster formation. This analysis showed that separating the plug-flow region from the highly reduced region by controling the flow of pellets could realize stable operation of the shaft furnance without cluster formation.