Abstract
The fate of the nitrogen and sulfur present in seven caking coals during pyrolysis has been studied with a flow-type fixed-bed quartz reactor to examine the effects of these heteroatoms on coal fluidity. The Gieseler maximum fluidity (MF) appears around 450℃ with all coals. The MF values range from 1.1 to 4.1 log(ddpm) and depend strongly on the type of coal. The evolution of HCN, NH_3, H_2S and tar-S starts after 350℃, whereas char-N, organic-S and FeS_2 decrease beyond 350℃. FeS_2 can readily be transformed to FeS and H_2S at 350-650℃. The evolution amounts of gaseous N- and S-containing species depend on the kind of coal. The MF value tends to increase with increasing total amount of HCN, NH_3 or H_2S evolved up to 450℃. Although the addition of 1 wt% aliphatic-N, inorganic-N or S-containing compounds to coal decreases coal fluidity, but polycyclic aromatic compounds increase the fluidity.
