Investigation of black poplar (Populus nigra L.) preparation and utilization for energy conversion

Abstract

The research investigations with a short rotation energy plant - black poplar (Populus Nigra L.) have been carried out at the Institute of Agricultural Engineering and Safety of Vytautas Magnus University. A chopper with a conical screw was selected for the energy plants chopping. This type of woody plant choppers is the most appropriate to use because these choppers cut plants by a conical screw with a sharpened outer edge and, therefore, can cut long enough and high quality chaff. The biometric characteristics of black poplar stems and thephysical-mechanical characteristics of the plant chaff were assessed: moisture content, bulk destiny, fall and natural crumble angles, chopped mass fractional composition, ash content and calorific value. The determined bulk destiny of the plant chaff varied from 112.3 to 218.5 kg·m-3DM (dry matter). Black poplar chopping quality, characterized by fractional composition, was also determined,. It was estimated that the largest part of fraction was concentrated on the sieves with a diameter of 8 and 16 mm holes - from 53.9 % to 71.8 %, and very small amount of dust was formed - from 0.04-0.09 %. The research results of the black poplar ash content and calorific value show that the ash content was relatively low and reached only 2.5 %. It shows that the chaff of black poplar burns relatively well and, in comparison with other sorts of energy plants, the determined lower calorific value of black poplar chaff dry mass is relatively high - 18.5 MJ·kg-1. The presented research results show that the usage of black poplar for biofuel is justified very well.