Impact of Torrefaction on Flash Pyrolysis Products of Biomass and Comparison to Fossil Fuels

摘要

A substitution of fossil fuels with alternative biofuels combined with carbon capture and storage technology can be used for the reduction of CO_2 emissions from pulverized fuel furnaces. Pretreating raw biomass via torrefaction improves its properties concerning energy density, grindability and storage. Furthermore, the torrefaction process influences the composition and amount of released devolatilization products under flame conditions. In this study, the effect of torrefaction of beech wood on flash pyrolysis products is investigated. Rhenish lignite and Colombian bituminous coal are chosen as reference fossil fuels. Flame equivalent conditions are approximated with a small scale fluidized reactor located inside an electrically heated furnace. Temperature is varied from 873 K to 1473 K while atmosphere is kept constant at 100 vol.-% N_2. Experiments show, that torrefaction has a significant impact on pyrolysis products and which behave under reaction conditions quite similar to Rhenish lignite. Furthermore, a relation between yields of hydrocarbons, temperature and fuel is derived.