Update for Combustion Properties of Wood Components

The combustion properties of various biomass and wood materials from various references and from our laboratory were reanalysed. The net heat of combustion for cellulosic materials was found to be 13.23 kJ/g times the ratio of stoichiometric oxygen mass to fuel mass, ro, regardless of the material composition. Bomb calorimeter data for original, charred and volatilized material components provide gross heating values, while elemental analysis of the materials for carbon, hydrogen, oxygen and ash provide direct evaluation for ro. We corrected these data as provided in various references by converting gross heating values to lower heating values and converting elemental compositions, char fractions and ro to a moisture-free and ash-free basis. Some existing formulae were found to disagree with data from vegetation, charred wood with high ash content, and with volatiles from cellulose treated with the fire retardant NaOH. We also established various functional correlations of ro with elemental compositions, or volatization fractions of untreated and treated materials, or material fractions for cellulose, lignin and extractives, or volatile fractions for tar, combustible gases and inert gases in pure nitrogen carrier gas. An interesting predictive result provides nearly constant heat of combustion while the volatile tar fraction is decreasing and combustible and inert gas fractions are increasing with time during the charring of Douglas-fir wood. Published in 2002 by John Wiley & Sons, Ltd.