Renewable resources have been gaining increasing importance for energy generation in recent years. Lignocellulosic biomass, as an alternative to limited crude oil, can be utilized to produce these chemicals. The upstream process of comminution is a key element in the use of renewable raw materials. However, comminution is a highly energy consumptive process, making it necessary to assess the benefits of fine comminution in terms of reducing energy consumption by an adequate characterization of the products. The key factors to increased energy efficiency are, besides the mill type and the mill operation factors, the species of the renewable resource, in terms of water content and the mechanical properties which are the dominant factors in biomass size reduction. A better understanding of these interdependencies can help to improve the adjustment of particle size distribution and particle shape. As well as the total specific surface area and the energy demand for the comminution process, which impacts the overall efficiency of the supply chain process, disintegration, and the conversion. This work, therefore, focuses on the comminution of woody biomass in a cutting mill. It reports the effects of the influencing parameter of the biomass on the comminution process, the energy consumption, and the physical properties of the products regarding their particle size. Furthermore, selected experiments have been carried out on a swing hammer mill to compare the influence of the type of stressing.

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Comminution of Woody Renewable ResourcesA key element in the use of renewable raw materials is besides disintegration the upstream process of comminution. Based on an optimized fine comminution, not only the yield of the disintegration process can be increased, but also the energy requirement for comminution can be significantly reduced. In this work, the comminution of the woody renewable resources common spruce and common beech in a cutting mill was studied. For comparison experiments were carried out on a hammer mill. The influence of water content and nature of the raw material on the specific comminution energy and products was examined.

An essential element for sustainable use of renewable resources is an efficient comminution process for which the relation between energy input and size reduction is of great importance. Fine comminution of beech, oak, and spruce wood chips in cutting and hammer mills at different moisture content levels is investigated. The influence of the different process parameters as well as the size reduction performed by the hammer and cutting mill on the specific comminution energy is reported and the particulate properties of the comminution products are reported. Considering the energy requirements, functional relations were derived from the experimental results, which describe the relation between comminution energy and size reduction.