BURNOUT OF COALS - COMPARATIVE BENCH-SCALE EXPERIMENTS ON PULVERIZED FUEL AND FLUIDIZED-BED COMBUSTION

Coal characteristics which have an impact on unburnt fuel loss are not necessarily the same under different combustion conditions. A comparative study was undertaken to investigate which coal properties are relevant to coal lost as unburnt fuel in cases of pulverized fuel and fluidized bed combustion. From small scale experiments it was shown that rank is a principal factor for the degree of burnout in a once-through fluidized system, whereas ash and inertinite affect burnout in a high temperature drop tube furnace. Results from the latter are in qualitative agreement with literature data on ignition characteristics. Individual effects of inertinite and oxidized vitrinite have to be assessed by additional experiments.