Grindability determination for wood chips and pellets
- Temmerman, M. (2013). Grindability determination for wood chips and pellets. Gembloux, Gembloux Agro BioTech - University of Liège,
|Grindability determination for wood chips and pellets
|Gembloux Agro BioTech - University of Liège
|The literature about energy requirements for product milling in mining industry shows the subject has been, and still is, considered by numerous authors. Several milling theories have been proposed for these industries, especially concerning ores milling. Biomass milling, prior to its use as biofuel, has been, by far, less studied. Nevertheless, few measurements 6 are available about energy needed for milling of particular biomass, in particular systems. But studies taking into account enough characteristic of the milled material (origin, moisture content, particle size distribution) are scarce. Moreover, the methods used to measure these properties are generally different. In consequence, nearly none biomass milling model has been proposed. Concerning wood densified product (pellets and briquettes) apparently no data are available yet. This study draws upon the milling theories developed for the ore processing industry (Von Rittinger, Kick and Bond theories which have been merged by Charles and Hukki) in order to define a method for characterizing wood chip and pellet energy consumption during milling. Thus it proposes parameters and measurement methods that have to be taken into account when milling modelling comes to an end for biomass or densified biomass. Energy consumption during wood milling depends on three main factors: the material moisture content, the particle size difference between the feed and the milled product, and the material itself. The latter may be characterized by a single grindability parameter based on an adaptation of Von Rittinger’s constant. A relation characterizing wood pellet energy consumption as a function of the particle size distribution of the pellet ingredients and the milled pellets is proposed as well. This is characteristic of each type of pellet for each moisture content value considered.