Cracking reactions of tar from pyrolysis of spruce wood

In order to investigate vapour phase cracking of tar from pyrolysis of spruce wood, experiments with small particles of spruce wood (0.5-1.0 mm) were carried out both in a thermogravimetric, analyser (TGA) and in a coupling of the TGA with a consecutive tubular reactor. In all experiments, the TGA was heated from 105 to 1050 degreesC at a heating rate of 5 K min(-1). The tubular reactor was operated at temperatures of 600, 700 and 800 degreesC at different residence times, these being achieved by providing the reactor with three independent heating zones. For the tubular reactor, a one-dimensional flow model was employed which took axial dispersion and the non-isothermal state into consideration. It was found that different types of tar are produced from pyrolysis of spruce wood. One of these types does not crack, for the other types, kinetic parameters for tar cracking and distribution coefficients for the formation of product gases were determined. (C) 2001 Elsevier Science Ltd. All rights reserved.