Influence of Biomass Pellet Composition on Particulate Matter and Electrostatic Precipitator Efficiency

This study investigated the influence of fuel composition on particulate matter (PM) emissions and the efficiency of an electrostatic precipitator (ESP) during small-scale combustion. The research compared woody pellets (spruce, beech) with agro-pellets (straw, hay, sunflower). Elemental and X-ray fluorescence analyses showed that agro-pellets contained higher concentrations of ash-forming elements, including alkali metals, Cl, and Si, which led to the formation of fine fly ash and increased deposition on ESP walls. Combustion tests demonstrated that agro-pellets generated substantially higher PM concentrations in ESP-OFF conditions, with summary values of 672.4 mg·m^-3 for hay, 368.3 mg·m^-3 for straw, and 395.5 mg·m^-3 for sunflower. In contrast, woody pellets produced considerably lower emissions, measured at 76.3 mg·m^-3 for beech and 32.4 mg·m^-3 for spruce. The application of the ESP achieved high removal efficiencies across all fuels, ranging from 81% for hay to nearly 93% for spruce, with the most significant relative reductions observed in the fine PM fraction. Analyzed PM by X-ray fluorescence spectrometry after combustion of agro-pellets contained significantly higher concentrations of K, Cl, Na, and S, whereas PM after combustion of wood pellets exhibited comparatively lower levels of these elements. Other inorganic elements detected in the PM composition included Si, Ca, Mg, Mn, Fe, and P.