Importance of Temperature, Moisture Content, and Species for the Conversion Process of Wood Residues Into Fuel Pellets


  • Niels Peter K. Nielsen
  • Douglas J. Gardner
  • Torben Poulsen
  • Claus Felby


Wood pellets, pelletizing, biofuel, compression, friction, viscosity, adhesion, extractives, densification, sawdust


In wood pellet production, knowledge is needed about the raw material properties that affect the energy requirements for pelletizing and pellet quality. This study presents novel methods for this purpose, including analyses of influence of the raw material properties on the energy requirements in the sequence of subprocesses (compression, flow, and friction components) that constitute the pelletizing process, and the strength of the pellets. The methods were used to analyze the importance of pelletizing temperature and MC and the differences between sawdust of European beech (Fagus sylvática L) and Scots pine (Pinus sylvestris L). Results showed that increasing temperature and MC decreased the energy requirements for all components of the pelletizing process and that beech required more energy than pine in all components. Beech produced the stronger pellets; increasing temperature resulted in stronger pellets, whereas increasing MC caused weaker pellets. Also, a method to quantify the energy requirements for the combined pelletizing process is presented. The methods can be used to analyze the allocation of the energy requirements of pelletizing in the die and can be useful tools for analyzing the pelletizing properties of wood and other biomass residues.


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Research Contributions