Comparison of gasification and pyrolysis of thermal pre-treated wood board waste

The second step of a two-step process of thermo-chemical conversion of wood board waste is discussed in this paper. GC-TCD and FTIR analyses of the gas product enable to compare the two proposed way: pyrolysis and gasification of the pre-treated and virgin wood board sample between 800 and 1000 degrees C. The effect of the first step of the process (low-temperature pyrolysis which aims to remove nitrogen initially present in wood board waste) has shown to be really efficient as the production of ammonia observed during the second step decreases by a factor 6-8 jointly to a slight decrease of the energy recovery. The first step also prevents the production of hydrogen cyanide and is therefore essential. Concerning pre-treated samples, the best results have been obtained at 1000 degrees C with samples pre-treated at 250 degrees C. The way of gasification has been shown to be more efficient in term of energy recovery but leads to a production of ammonia larger than in the case of the pyrolysis way. The conversion of the pyrolysis residual char into an activated char must be considered since it presents a potential economic interest. (C) 2008 Elsevier B.V. All rights reserved.