JUN-ICHIRO YAGI

Abstract:

Charcoal is an attractive material in blast furnace operation due to its high possibility of CO2 emission mitigation. This paper describes exergy analysis of practical operation data of ironmaking blast furnaces and dynamic simulation of the blast furnaces by using a multi-dimensional CFD model. Exergy analysis provides a comparison of energy consumption and CO2 emission between practical operations of the ironmaking blast furnaces with respective coal and charcoal charging. As a result, charcoal charging can decrease CO2 emission due to global carbon circulation with plantation of eucalyptus. But lump charcoal has not enough strength for the operation of large blast furnaces thus at present lump charcoal is charged only in small size blast furnaces. Injection of pulverized charcoal through tuyeres is another promising technology which can be applied to large blast furnaces. Dynamic simulation has been conducted by using the CFD model of blast furnace process on the practical operations of a large blast furnace with a respective injection of pulverized coal and charcoal at the rate of 200kg/thm. Simulation results showed good agreement with practical operation data. Afterwards, mixed injection of pulverized coal ad charcoal was simulated providing slightly higher productivity in the case of the injection rate of 100kg(PC)/thm+100kg(PCH)/thm than the case of 200kg(either PC or PCH)/thm. Higher combustion rate of the pulverized charcoal than the pulverized coal contributed this results. The dynamic simulation clarifies also the changes of in-furnace phenomena which is effective information for controlling the operation. Keywords: Charcoal, Blast furnace, Exergy, Mathematical model,