Effect of moisture content and particle size on beech biomass agglomeration

The utilisation of biomass agglomerates is an attractive option for heat and power production to reduce greenhouse gas emissions. Agglomeration of biomass, such as tableting, can increase bulk density, improve storability, reduce transportation costs and increase the quality of products. The purpose of this study is to analyse the effects of moisture content and particle size on beech biomass agglomerates and also to identify the optimal conditions of the process for producing tablets with high density. Beech biomass was compressed in a load cell by a hydraulic piston press with 25 mm diameter. Effects of the independent variables, including moisture content (4.71 wt.% to 19.55 wt.% with particle size < 1 mm, and 4.74 wt.% to 19.45 wt.% with particle size < 2 mm) were investigated. Results showed that at the same pressure, increasing moisture content resulted in lower density of the tablet, tablets made from raw material with the smaller particle size have lower strength than tablets made from material with the larger particle size, and a new compression equation can be introduced, which contains moisture content as parameter.