Simulation processes have been carried out to assess the mass and energy balances of the pyrolysis process in an auger reactor pilot plant. Forest woodchips were fed into the reactor with 6.2% of moisture content. Previous experiments showed that the highest bio-oil yield (59%) was achieved at 773 K and applying solid residence times longer than 2 minutes. These conditions were modelled using Aspen HYSYS simulation software and results showed that the process was not thermally autonomous. In order to scaling up the pilot plant and convert it into a mobile plant, a novel design was conceived to process 1500 kg/h of biomass (30% moisture content). It incorporates a drying unit and a char combustor. Simulation results showed that 12% of the char should be burnt to maintain positive the energy balance. The process is energy-independent when moisture content is lower than 20%. Further sensitivity analyses were performed studying different moisture contents, the efficiency of the drying stage and using air as carrier gas instead of nitrogen. This novel design will produce bio-oil as an energy vector with reduced transport costs since it will be able to process biomass from remote locations, which will contribute to sustainable forest management.

Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 1047-1051