Comminution energy and particulate properties of cutting and hammer-milled beech, oak, and spruce wood

Abstract

As a result of the development of innovative technologies for use of renewable materials, these materials are increasingly used for the production of precursors and basic chemicals for the chemical industry. The upstream process of comminution is a key element in the use of renewable raw materials, which impacts the consecutive disintegration of the materials, which means the separation of the three main components cellulose, hemicellulose and lignin as well as the handling. Energy efficiency of the comminution process is of utmost importance to make renewable resources more competitive with petrochemical products. The key parameters to increased energy efficiency are, besides the mill type and the mill operation parameters, the species of the renewable resource, in terms of moisture content and the mechanical properties. A better understanding of these interdependencies can help to improve the adjustment of particle size distribution and particle shape as well as the energy demand for the comminution process, which impacts the overall efficiency of the supply chain process, disintegration as well as the conversion. This work focuses on the comminution of lignocellulosic biomass in a cutting mill and a hammer mill and how the specific comminution energy and particulate properties are affected by the type of mill, the species of wood, the archived size reduction as well as the moisture content. Therefore two spices of hardwood, common beech (F. sylvatica L.) and oak (Q. robur L.), and one species of coniferous wood common, spruce (P. abies L.), where comminuted under variation of different process parameters. The specific comminution energies were determined and the comminution products were characterized by dynamic image analysis. This work describes the influence of the process parameters, internal classifying screen, type of stress and moisture content, on the comminution products and the specific comminution energy. From the results of the experiments, functions were determined which can describe the influence of the type of mill, the moisture content, the type of wood and the comminution ratio on the specific comminution energy.