Slow pyrolysis of wood particles: Characterization of volatiles by Laser-Induced Fluorescence

For a better understanding of the complex processes involved in slow pyrolysis of thermally thick wood particles it is essential to know the composition of the gaseous mixture leaving the pyrolyzing particle. In this work the volatiles in the pyrolysis product gas are characterized by means of in situ Laser-Induced Fluorescence. The results indicate that there are secondary heterogeneous cracking reactions of the primary and secondary tar species occurring in spherical beech wood particles with 25 mm diameter at conversions higher than approximately 0.6 and at heating rates of 0.3 K/s and 0.2 K/s. For pyrolysis of smaller beech wood particles of 0.5–1 mm size complete conversion was achieved without indications of secondary reactions at a heating rate of 0.3 K/s. In order to correctly model the composition of the gas mixture leaving a pyrolyzing wood particle, it may therefore be necessary to consider intra-particle heterogeneous cracking reactions.