Utilization of Agricultural Residues and Their Mixtures for Energy Conversion and Creation of Empirical Model for Determination of Biofuel Pellet Characteristics

A total of three variants of pellets from field bean and potato waste mixtures were investigated and analyzed. Their physical, mechanical and chemical properties were examined, and the burning emissions of pellets were measured. An experimental study was performed to determine the dependence of density and compressive strength. An empirical linear regression model was developed, allowing calculation of the density and compressive strength dependence of pellets with 84–91% accuracy. The lower calorific value of the dry waste pellets was similar across all tested samples. The chemical properties of pellet ash were determined, and its suitability for use as a fertilizer was assessed. The pellet density ranged from 1269.24 kg m−3 (potato pellets) to 1369.89 kg m−3 (potato and bean MIX DC pellets). The moisture content of the pellets varied from 6.14% to 7.37%. The moisture content of the pellets increased with the proportion of potato waste meal in the mixture. The ash contains elements magnesium, iron, calcium, potassium, silicon, sodium and phosphorus. Potassium in potato pellet ash was found to have the highest concentration (60.42%), which has a direct effect on boiler slag. The share of potato waste in biofuels helps to remove soot from the chimney in the form of solid particles. It can therefore be stated that bean and potato waste can be used in the production of solid biofuels and that pellets produced with a 20% (1:4 ratio) potato waste fraction obtain the best properties.