Abstract
In the present study, we attempted to reduce tar emitted during pyrolysis of coal by utilizing char-volatiles interaction (CVI) phenomena in a circulating fluidized bed (CFB) reactor. The CFB reactor is consisted of bubbling-bed pyrolyzer and combustor made of quartz, therefore, behavior of solids can be directly observed. Coal was fed in the pyrolyzer at the temperature range from 550 to 900℃ and then pyrolyzed to from volatiles including gas and tar. Product gas from the pyrolyzer was analyzed by GC, and light/heavy tar was collected by traps and then analyzed. Resultant char was circulated to the combustor at 850℃ to be partially combusted. Un-burnt char particles were circulated to the pyrolyzer. That is, char is recycled to the pyrolyzer. In other words, CVI would be enhanced by the char recycling. The product gases, especially, H_2 and CO were increased by the char recycling. On the other hand, light tar such as benzene, naphthalene etc. was decreased, and heavy tar was also decreased by the char recycling.
