Raceway behaviors in blast furnace with pulverized coal injection

Abstract

The blast furnace raceway shows different characteristics with PCR (pulverized coal injection rate). It was found in this study that with the increase of PCR the raceway depth decreases, and the size of birds nest and sometimes with liquid holdup, increases. Oxygen enrichment with co-axial lances was known to be very effective on the extension of raceway depth and size reduction of birds nest. It was also found that there are various factors which affect the coke properties at tuyere level of the blast furnace. Coke traveling time was calculated to be extended with PCR and it had a close relationship with the coke size in bosh. Coke mean size decreased with the increase of coke traveling time, that is, with the increase of PCR. Both DI (the strength of coke in cold) and CSR (the strength of coke after reaction) were also decreased with PCR. RAFT (Raceway Adiabatic Flame Temperature) had a tendency to be decreased with the increase of PCR, which is obtained by the estimation of coke temperature via XRD analysis. From the analysis of alkali contents in coke sampled along the radius of the blast furnace, it was understood that no difference in alkali contents betweenmore » fine and lump coke represents that coke fines generated from upper burden might appear at tuyere level.« less