Combustion and mechanical properties of pellets from biomass and industrial waste

Experimental research findings are reported on the impact of industrial waste additives on the mechanical properties of pellets, their ignition and combustion. The compositions under study consisted of wood sawdust with coal slime/peat/a mixture of straw and rice husk. Composite pellets exhibited high moisture resistance and durability when subjected to vibration. The respective coefficients were 6–32 % higher than for sawdust without additives. The ignition characteristics of wood pellets tended to worsen when additional components were used in their composition. The ignition delay times increased by a factor of 3–4. In most cases, the use of additives increased the combustion duration of pellet fuels. The greatest environmental benefits in terms of carbon oxides were gained from mixtures of straw with rice husk and coal slime. СО2 and СО emissions decreased by 10–20 % and 10–54 %, respectively. A high nitrogen content in peat, coal slime and straw led to 5–94 % higher emissions of NOx for composite pellets. Using plant biomass and peat reduced the concentrations of sulfur oxides almost 3-fold. The results of multi-criteria analysis covering 13 energy, operational, economic and environmental components suggest that the difference in the relative efficiency indicator of wood pellets and compositions with industrial waste additives is 4.4–6.5 %.