Production and quality analysis of biofuel pellets from Canadian forest and agricultural biomass
Priyabrata Pradhan, Omex Mohan, Vinoj Kurian, Amit Kumar
Abstract
Three different Canadian biomass feedstocks, namely hardwood, softwood, and wheat straw, were used to produce fuel pellets without the addition of binders. Pilot experiments were carried out in a semi-industrial flat die pellet mill (8.5 kW) to examine the effects of feedstock type, moisture level (at 10 and 15 %), and die configuration (4 levels) on pellet production. Die configuration significantly influences pellet quality and performance parameters like temperature, current, power consumption, throughput capacity, and material loss. In this study, it was found that a 10 % moisture content in the feed and a die length-to-diameter ( l/d ) ratio of 2.58 are optimal for softwood pelletization. A feed moisture content of 15 % was found to be the optimum for hardwood (with an l/d of 2.08) and wheat straw (with an l/d of 2.92). Under optimum conditions, softwood pellets showed bulk density and durability values of 679 kg m −3 and 97.7 %, respectively, similar to pellets from wheat straw (97.5 %, 694 kg m −3 ) and hardwood (96 %, 624 kg m −3 ). Scanning electron microscopic images show a close agglomeration of biomass particles in high-quality pellets. This study found the total energy consumption for wheat straw pelletization to be 13 % of the energy content of wheat straw pellets. Finally, the combustion characteristics results indicated that the pellets produced are suitable for use as solid biofuels. • Studied moisture content and die configuration effects on Canadian biomass pelleting. • Standard quality fuel pellets were produced at pilot scale without adding binders. • Top-quality pellets had 97.7 % durability and a bulk density of 679 kg/m³. • Long-run tests on wheat straw pelletizing required 13 % of pellet's total energy content.