Model study of the effects of coal properties and blast conditions on pulverized coal combustion

Abstract

High coal burnout within the raceway is important for the operation of a blast furnace. It is usually achieved by adjusting some operational parameters in practice. In this work, a three-dimensional model we developed recently is used to investigate the effects of some key operational parameters on coal burnout. The results confirm that notable improvements in final burnout can be achieved for coals with more fine particles and high volatile matter, and by higher oxygen enrichment. The use of high blast temperature can increase coal burnout, but the further increase in blast temperature over 1 200°C has little effect on final burnout. The effects of these parameters on other combustion characteristics are also analysed, in terms of volatile content, temperature field and gas species distribution, aiming to understand the underlying mechanisms behind these improvements. It is demonstrated that local oxygen supply is very important for high burnout in addition to coal properties. In addition, it is necessary to consider the raceway region when investigating the effects of these variables on coal burnout. This study helps identify appropriate and cheaper coals and optimise operating conditions to maximize the benefits of pulverized coal injection. © 2009 ISIJ.