Effects of the operating parameters on the production of bio-oil in the fast pyrolysis of Japanese larch

This study examined the kinetics of the pyrolysis of Japanese larch using thermogravimetric analysis (TGA), and fast pyrolysis with a bubbling fluidized bed reactor and a two-staged char removal system under various reaction conditions. The effects of the reaction conditions on the chemical and physical characteristics of bio-oil were also examined. Japanese larch was decomposed at temperatures ranging from 250 to 380 °C. The apparent activation energies ranged from 220 and 1009 kJ mol−1 when the pyrolytic conversion increased from 5 to 95%. The optimal reaction temperature for the production of bio-oil was 450 °C. The bio-oil yield decreased with decreasing feed size due to overheating. The bio-oil yields increased gradually with increasing flow rate and feeding rate but these increases were not significant. The use of the product gas as the fluidizing medium was effective for the production of bio-oil, giving the highest bio-oil yield of 64 wt%, but the introduction of oxygen had a slightly negative effect on the bio-oil yield. In addition, high-quality bio-oil, which contains <0.005 wt% solid, no ash, and low concentrations of alkali and alkaline earth metals, could be produced using the two-staged char removal system. With the exception of the reaction temperature and partial oxidation, the other pyrolysis conditions did not significantly affect the chemical and physical characteristics of bio-oil.