Investigation of efficiency of pellet burning methods in a full scale rotary dryer

Today, interest in pellet fuels obtained from forest wastes and different biomass has increased due to the decrease in fossil fuels and problems in energy supply, and countries taking some measures to reduce carbon emission values. Pellets obtained from different raw materials have different calorific values, different ash ratios, and different mechanical properties. Pellet, which is an increasingly environmentally friendly fuel, is preferred both in industrial applications and domestic use. While the use of pellets to generate energy can be in the form of combustion pyrolysis and gasification, the most common use is direct combustion. Since the calorific value of the pellet is lower than fossil fuels, this study was conducted to investigate the efficient burning system of the pellet. When we classify the combustion of pellets in terms of connection to the boiler, it is seen that it can be fed from the bottom, the top, and horizontally. Bottom-fed systems are stokers, while top- and horizontally fed systems are burners. In the study, it is aimed to reveal the amount of savings that can be made compared to the stoker system in case of burning pellets with a fully automated burner. In the study, it was investigated which of the pellet combustion systems, with burner or stoker, provides more efficient combustion. The study was carried out by connecting stoker and burner to the boiler section of drying ovens in a pellet production facility. The study was carried out in two exactly identical rotary dryers for wood chips, keeping the raw material inlet and outlet moisture rates exactly the same. In one furnace, the pellet was burned by feeding from the bottom with a stoker, while in the second furnace, the pellet was fed by feeding from the top burner. At the end of the study, 10% less pellets were burned in the combustion made with the top feeding with the burner. It has been observed that 10% savings can be achieved in pellet consumption with combustion systems made with burners. The study was carried out with pellets with a lower calorific value of 4100 kcal/kg obtained from oak and pine wood residues. Stoker and burner are mounted on the boiler parts of two rotary dryers, respectively. At the end of the study, it was observed that 10% less pellets were burned in the drying process with the burner system, and pellet consumption could be reduced with the top-fed burner system.