Reactivity study of two coal chars produced in a drop-tube furnace and a pulverized coal injection rig

The combustion behavior of coal depends upon not only the coal characteristics but also the combustion conditions. The current understanding about the combustion of coal char during the extreme conditions of pulverized coal injection into blast furnaces is incomplete. To increase the understanding, this research aims to compare the combustion performance of chars obtained from a drop-tube furnace (DTF) and a pulverized coal injection (PCI) rig, thereby giving an indication of the development of reactivity with the heating rate and combustion temperature. Two coals with similar volatile contents were selected, namely, VH, a vitrinite-rich coal, and VL, an inertinite-rich coal. Chars were prepared from these coals in either a DTF or a PCI rig. Different combustion performances of the two coals were observed in the two combustion test rigs. The high-vitrinite coal exhibited similar burnout in the two rigs, but the high-inertinite coal had significantly lower burnout in the DTF than in the PCI rig. Both the chars produced in the DTF had higher reactivity at temperatures over 750°C than the corresponding chars produced in the PCI rig. Coal maceral composition, char microstructure, and combustion conditions appear to contribute to this phenomenon, with the testing of additional coals being necessary to clarify influence