Thermal characteristics, kinetics mechanism, and sulfur retention of waste tires and goat manure Co-combustion

Co-combustion is a promising approach to efficiently utilize energy while suppressing pollutant emissions, leveraging the complementary properties of different fuels. This study thoroughly investigates the (co-)combustion behavior of waste tires (WTs), goat manure (GM), and their blends. The results indicate that the incorporation of GM decreases both ignition and burnout temperatures, thereby improving the combustion characteristic index of the blends and enhancing overall combustion performance. Furthermore, the analysis reveals significant synergistic interactions between WTs and GM during co-combustion, particularly within the 300–700 °C temperature range. Kinetic analysis, using three model-free methods, consistently shows that activation energies (Eα) follow a pattern of initially increasing to a peak and then gradually decreasing across the conversion degree range of 0.05–0.95. Additionally, the flue gas analysis indicates that the GM addition can effectively suppress SO2 emission by 50–60 % during the co-combustion. The study further suggests that the sulfur retention is primarily linked to the formation of CaSO4, a compound with excellent thermal stability. Overall, these findings provide valuable insights into the practical application of co-combusting WTs and GM, offering a theoretical foundation for controlling pollutant emissions and enhancing energy utilization efficiency.