Energy consumption of bruquetting raw wooden material in biofuel production

Abstract

Fuel briquettes from wood raw materials are widely used in the economy, briquettes are an environmentally friendly source of energy. The technological process of their production includes several operations, the main of which are transport, drying, grinding and direct briquetting (pressing) of raw materials. Nowadays researchers are studying the production of fuel briquettes not only from sawdust, but also from tree bark, branches and roots. This raises the question of assessing the efficiency of wooden biofuel production, including energy consumption. Our article is devoted to the development of an approach to the theoretical assessment of energy costs at the stage of pressing prepared raw wood materials. The study bases on the analysis of the results obtained earlier in the field of mathematical modeling of the pressing of strengthening wooded materials. As a basis, a non-linear equation for pressing a wood material is used, taking into account the increase in the plasticity limit of the briquette material. The calculations in the article are performed using the methods of approximate solution of differential equations in the Maple computer mathematics system. The estimation of power consumption and power parameters of pressing coniferous wood sawdust is carried out. The results of the calculations showed that the energy costs caused by pressing the briquette material are almost linearly related to the density of the formed briquette. To obtain a briquette from softwood sawdust with a density of 1 t/m3, the working body of the press does work of approximately 40 kJ; to obtain a briquette of 1.2 t/m3 – approximately 55 kJ. According to a theoretical estimate, the force of the working body at the end of the pressing process reaches 700 kN (70 tf).