DYNAMIC BEHAVIOR OF SULFUR FORMS IN RAPID PYROLYSIS OF DENSITY-SEPARATED COALS

Non-caking bituminous coal was separated into three groups by sink-float in aqueous zinc chloride. These samples were rapidly pyrolysed in free fall at atmospheric pressure under nitrogen, at temperatures up to 1253 K and heating rates of 4000-6000 K s-1. The differences observed in the dynamic behaviour of sulfur forms, devolatilization and internal structure resulted from variation in maceral composition. The ultimate extent and release rate of volatile matter increased with decreasing density of sample. The experimental results indicate that rapid heating promoted the devolatilization reaction for the volatile precursors contained in the low-density group. Rapid pyrolysis also promoted the development of internal structure for the low-density group composed of exinite and vitrinite, but not for the high-density group enriched in inertinite. The organic sulfur content was reduced by 76, 67 and 34% within 0.4 s, in order of increasing density. The reactivity of organic sulfur is considerably affected by the change in sulfur forms with maceral group composition.