Influence of atmosphere (N2/CO2/H2O) on wood centimetre-scale particle devolatilisation at 800 °C

The influence of atmosphere (pure nitrogen, or nitrogen mixed with carbon dioxide and/or steam) on centimetre-scale wood particle devolatilisation was investigated. Experiments were performed in a home-designed analytical facility, which allows limitation of secondary extra-particle reactions. The product yields and compositions were determined. The organic gas species yields were dependent on the devolatilisation atmosphere, which could be due to intraparticular secondary reactions possibly catalysed by char, among which water gas-shift. The atmosphere had an influence on inorganic release, especially for the main elements K and Ca, and thereby on the char ash content. The inorganic elements remaining in char were shown to have a major catalytic influence on its reactivity for gasification with CO2, H2O or a mixture of both. These results show that in a pyro-gasification reactor, char gasification could be influenced by the atmosphere, not only because of differences of kinetics between steam and CO2 gasification, but also because of differences of reactivity linked to different inorganic contents.