Study of biochar from pyrolysis and gasification of wood pellets in a nitrogen plasma reactor for design of biomass processes

The physio-chemical properties of biochar from nitrogen plasma reactor were investigated. The amount of biochar and its sieve particle size distribution decreased with increase in oxygen feed for gasification and increase in temperature for both biomass conversion processes. For gasification, the pore volume increased from 0.001 m(3)/g (raw) to 0.144 m(3)/g (biochar) at 700 degrees C and to 0.188 m(3)/g at 900 degrees C. The pore size of biochar (pyrolysis) increased from 21.948 angstrom at 400 degrees C to 34.626 angstrom at 1000 degrees C. For both processes, the biochar exhibited a more broken and non-parallel structure compared to that of the feed wood pellets. During plasma gasification, all the particles of size x < 300 mu m were entrained in product stream while those with particles x > 2 mm remained in the reactor chamber. The solid carbon element content in the biochar increased by 8% up to 93% when pyrolysis temperature was increased from 400 degrees C to 1000 degrees C. The carbon content decreased from 89% to 80% at 700 degrees C and from 93% to 86% at 900 degrees C when oxygen flowrate was increased from 0.15 kg/h to 0.6 kg/h. Agglomeration of elements K, Si, Mg, Al and Fe was observed as temperature increased for pyrolysis. The FTIR spectra revealed a new peak at 773 cm(-1) attributed to C-H bond related to olefin and aromatic structure in all biochar. These parameters are vital to understand practical process flow distributions and product separation mechanisms resulting from transportation of biochar within biomass systems to improve their design.