Effects of Biomass Particle Size on Slow Pyrolysis Kinetics and Fast Pyrolysis Product Distribution
- 270 Downloads
Thermochemical conversion of lignocellulosic biomass is a promising technique to produce biofuels and intermediates. The effects of important parameters such as biomass particle size, shape, composition, heating rate, and residence time on the kinetics of devolatilization and bio-oil composition need to be understood thoroughly in order to successfully scale up the process. Pyrolysis of mixed wood sawdust of eight different particle sizes (26.5–925 µm) is conducted at nine different heating rates (0.5–100 °C min−1) in a thermogravimetric analyzer, and at fast heating rates (~10,000 °C s−1) in analytical pyrolyzer coupled with gas chromatograph/mass spectrometer. The apparent activation energies (Eα) evaluated by isoconversional Friedman method in the very slow (0.5–3 °C min−1), slow (5–20 °C min−1) and medium heating rate regimes (50–100 °C min−1) were 153–203, 174–251 and 286–380 kJ mol−1, respectively. The yield of phenolics and linear hydrocarbons decreased, while the production of gases like CO and CO2 increased with particle size during fast pyrolysis. High yield of aromatics was obtained with medium sized particles (362.5, 512.5 μm). This study demonstrates that Eα decreases and increases with particle size in the very slow and slow heating regimes, respectively, which is attributed to the effect of particle shape that induces mass transfer limitations in the transport of volatiles, and intraparticle thermal gradients that induce tar decomposition reactions.
KeywordsBiomass Pyrolysis Particle size Kinetics Friedman method Py-GC/MS
The authors thank Department of Science and Technology (DST), India, for funding to procure thermogravimetric analyzer via FIST grant. R.V. thanks DST, India, for funding the Project via Grant No. SR/S3/CE/074/2012. The National Centre for Combustion Research and Development is sponsored by DST, India.
- 11.Onay, O., Kockar, O.M.: Slow, fast and flash pyrolysis of rapeseed. Renew. Energy. 28, 2417–2433 (2003)Google Scholar
- 14.ASTM E1131-08, Standard test method for compositional analysis by thermogravimetry. http://www.astm.org/Standards/E1131.htm (2014). Accessed Jan 2015
- 21.Pyroprobe® manual, C.D.S. Analytical Inc. U.S.A., http://files.instrument.com.cn/FilesCenter/20090428/2009428172842100691.pdf. Accessed on Nov 2016
- 23.Shulga, G., Betkers, T., Shakels, V., Neiberte, B., Verovkins, A., Brovkina, J., Belous, O., Ambrazaitene, A., Žukauskaite, A.: Effect of the modification of lignocellulosic materials with a lignin-polymer complex on their mulching properties. Bioresources 2, 572–582 (2007)Google Scholar
- 36.Gašparovič, L., Koreňová, Z., Jelemenskỳ, Ľ.: Kinetic study of wood chips decomposition by TGA. Chem. Pap 4, 174–181 (2010)Google Scholar
- 44.Ren, X., Gou, J., Wang, W., Li, Q., Chang, J., Li, B.: Optimization of bark fast pyrolysis for the production of phenol-rich bio-oil. Bioresources 8, 6481–6492 (2013)Google Scholar