Abstract
The present paper describes the results of the THF-solubles accumulation phenomenon in chars. The chars obtained from two Japanese bituminous coals, Akabira and Miike coals, were pyrolyzed in a TG and a free fall reactor under a nitrogen stream at atmospheric pressure. The maximum temperature range and heating rates, respectively, were 300-600°C and 3 or 100°C /min in the TG, and were 363-682°C, up to 1.0 × 105°C /min calculated in the free fall reactor. The properties of chars produced by each apparatus were analyzed and compared at the same conversion by THF extraction, H/C ratio and FT-IR. For each coal, rapid pyrolysis (100 and 105°C /min heating rates) allowed the THF-solubles fraction (thought of as heavy primary products) to accumulate in the char as heating rate increased. The maximum yields of THF-solubles in chars also appeared at low conversions, 0.15-0.2 for Akabira coal and 0.08-0.13 for Miike coal. Variations in H/C and Har/Hal ratios were small in this region of low conversion. From these results, we can say that heavy primary products still remain in char particles without secondary reaction.
