Detailed mapping of the mass and energy balance of a continuous biomass torrefaction plant

Biomass torrefaction was tested on pilot scale (50 kg h(-1) throughput) for 3 types of wood: spruce, ash and willow at torrefaction temperatures of 250 degrees C-265 degrees C. Quantitative analysis of process streams was accomplished by utilising on- and off-line analytical methods. The data obtained from the pilot tests could be very well translated into large-scale operations. A theoretical overall thermal efficiency of 88-89% was calculated for a large-scale heat-integrated torrefaction process that uses wet woody feedstock containing a mass fraction of 45% moisture. These results show that a pilot plant is most suitable not only for exploration of (new) feedstocks but also for generating experimental data that provide valuable information for the design of full-scale plants. The detailed mapping of the mass and energy balances presented in this work can be used further as input for process optimisation, evaluation of commercial viability and techno-economic analyses which can further help in up-scaling and commercialisation of the torrefaction technology. (C) 2016 Elsevier Ltd. All rights reserved.