Abstract
Bench scale pulverized coal combustor with oxygen has been designed. Experiment is conducted in a down-fired, cylindrical and vertical furnace. An Indonesian sub-bituminous coal is used for combustion experiment. In burner design, the strong swirl burner could not realize flame stabilization, because coal particles with carrier flow were cut off the flow passage into the furnace by untidiness flow. On the other hand, weak swirl burner experiment was able to obtain good mixing flow pattern and flame stabilization. High combustion efficiency at 99.7 % has been achieved, and it depends on the oxygen ratio and primary and secondary oxygen flow ratio (Rf). The NOx concentration is raged from 1650 to 1800 ppm on the complete combustion region, and conversion ratio of fuel nitrogen to NOx (CRNOx) is increased significantly as the oxygen ratio increased. Decrease in weight fractions of Na, Mg, K and Ca that have lower boiling points in ash is confirmed, since the very high temperature flame vaporized these matters.
