Effect of Humidified Blast on Blast Furnace Operation from the Viewpoint of Softening and Melting Process of Ore Burdens

Abstract

Oil-less operation of the blast furnace has been carried out on the background of the recent oil market soar-up. During the early period of oil-less operation, the furnace encountered a temporary instability resulting from the increase in slips, but currently the stabilized operation has been maintained mainly due to the application of the humidified blast.
In order to clarify the effect of hydrogen upon the blast furnace operation from the viewpoint of softening and melting process of ore burdens, softening under-load tests have been carried out under simulated blast furnace conditions.
H₂ addition improves the softening resistivity of burdens and shifts the beginning temperature of pressure drop to the higher temperature side by virtue of the reduction enhancement effect of H₂ at high temperature. This results in the cohesive zone with narrowed width. Possible influence of the cohesive zone width on in-furnace permeability has been examined by using a simulation model for estimating the infurnace pressure distribution. The calculation in the case of non-humidified blast indicates the increase in pressure gradient in the region of cohesive zone. The humidified blast decreases the possibility of slip occurrence and helps the stable operation.