Co-combustion Characteristics and Kinetic Analysis of Sediment From Dianchi Lake

ObjectivesUrban rivers and lakes often serve as carriers of sewage, with a large amount of sediment enriched with nitrogen and heavy metal elements. The combustion disposal method is clean, efficient, economical, and environmentally friendly. Studying the combustion kinetics of the sediment is crucial for its disposal and utilization.MethodsThe thermogravimetric analysis method is employed to compare and analyze the single combustion characteristics of the sediment in Dianchi Lake. In order to provide a reference for practical engineering applications, the sediment is co-combusted with coal at mixing ratios of 10%, 20%, and 30%. Using KAS, FWO, and Coats methods, 11 commonly used kinetic mechanism functions and solid-state reaction mechanism functions are selected to fit the activation energy and mechanism functions of each reaction stage.ResultsThe combustion of sediment is divided into four stages. Compared with sludge and coal slurry, it has a lower ignition temperature, making it easier to burn, but a higher burnout temperature, indicating differences in the overall combustion characteristics. When sediment is burned at different heating rates, lower heating rates are more conducive to combustion. Co-combusting sediment with coal shows a synergistic effect, and their interaction has a positive impact on the combustion characteristics. As the mixing ratio increases, the ignition performance improves. However, when the mixing ratio reaches 30%, the combustibility index significantly decreases, indicating that excessive mixing ratio is detrimental to improving the combustion performance of the fuel. The final fitting shows that the reaction mechanisms in the second and third stages of the combustion process are consistent, while the fourth stage is different.ConclusionsSediment can be used as a fuel, burning of sediment and coal can improve the ignition performance of coal and conducive to the stable combustion of coal, but the mixing ratio should not exceed 30%. The research results provide a reference for practical engineering applications.