Optimization of a free-fall reactor for the production of fast pyrolysis bio-oil

Abstract

A central composite design of experiments was performed to optimize a free-fall reactor for the production of bio-oil from red oak biomass. The effects of four experimental variables including heater set-point temperature, biomass particle size, sweep gas flow rate and biomass feed rate were studied. Heater set-point temperature ranged from 450 to 650°C, average biomass particle size from 200 to 600μm, sweep gas flow rate from 1 to 5sL/min and biomass feed rate from 1 to 2kg/h. Optimal operating conditions yielding over 70wt.% bio-oil were identified at a heater set-point temperature of 575°C, while feeding red oak biomass sized less than 300μm at 2kg/h into the 0.021m diameter, 1.8m tall reactor. Sweep gas flow rate did not have significant effect on bio-oil yield over the range tested.