文摘
Pelletization of biomass for bioenergy purposes has established itself as an important step toward a reductionin the emissions of greenhouse gases. A novel pellet model describing the pressure forces in a press channelof a pellet mill has previously been published. The model gives a theoretical explanation of how the biomass-specific parameters, such as the friction coefficient and Poisson's ratio, influence the pelletizing pressure. Themodel showed that the pelletizing pressure increases exponentially as a function of the channel length. In thepresent paper, the pellet model is verified experimentally. When the back pressure needed to press pellets ofdifferent lengths out of the press channel is measured, it is shown that the pelletizing pressure does increaseexponentially as a function of the pellet length. Second, the back pressures of the hardwood beech are higherthan the corresponding pressures of the softwood pine for all tested pellet lengths. Least-squares fit of themodel to the data shows that the fitted parameters are in agreement with values from the literature. The procedurefor using a single pelleter unit as a means for simulating an industrial pelletizing process in a controllable wayis described.