engleski

Optimization of energy wood chips quality by proper raw material manipulation

Forest fuel is by nature a very diverse source of energy. Most of its properties are given and limit the possibility of upgrading the fuel in the forest production process. Because of that, the ones that can be manipulated during the transformation from raw material source (tree biomass) to useful and easy to handle forest fuel form (wood chips) are of great importance. This research was conducted in order to determine the impact of raw material preparation by different harvesting systems on the quality of produced wood chips in respect to particle size distribution and ash content. The research material was procured in a spruce plantation thinning operation. It consisted of pulp wood and whole trees harvested with partially mechanized harvesting systems (chain- saw and skidder) and of pulp wood, stem wood and tops harvested with mechanized harvesting systems (harvester and forwarder). The roadside chipping of the unseasoned raw material was done by a drum chipper. Sampling of produced wood chips was done on a total of 21 chipping cycles (truck loads) and laboratory analyses were performed in accordance with the HRN EN standards for Solid biofuels. Results of laboratory analyses were statistically processed. Analysis of variance on the quality parameters of different raw material types was performed and correlation between the quality parameters was tested. The median value of particle size distribution showed statistically significant difference in between the raw material groups. A negative correlation was found between the median value of particle size distribution and the ash content. Results of this research indicate a possibility to manipulate the natural ash content of the forest fuel (a given value that varies mainly with the tree part used as raw material) and the polluting ash content (a consequence of (miss)handling in the procurement chain) to minimize the fuel quality deterioration. Results obtained in this research can be regarded as an indicator of necessity to expand the research-based knowledge to various stand and operational conditions, as a crucial tool of the forest fuels quality control in order to produce the forest fuel of the best possible quality even from the lower quality raw material and more important to avoid that from the high-quality raw materials a forest fuel of poor quality is produced.

particle size distribution; ash content

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