Investigation into the influence of varied plasma types and treatment durations on the combustion characteristics and kinetics of pulverised coal

Under the pressure of energy conservation and emission reduction, improving the combustion efficiency of pulverised coal is of great importance. This study employs multiple characterization techniques (e.g., SEM, BET, XPS), combined with VM, RPM, and URCM models, to systematically investigate the effects of different plasma types (Air, N2, O2) and treatment times (2 min, 5 min, 15 min, 30 min) on the physicochemical structure, combustion characteristics, and kinetics of pulverised coal. The plasma used in this study is a capacitively coupled non-thermal plasma (CCP), operating at a frequency of 13.56 MHz and a power of 500 W. The results show that short-term (5 min) treatment increases volatile matter and reduces calorific value. The Differential Thermal Analysis (DTA) curve of the treated coal is lower than that of raw coal, which is consistent with the calorific value test results. The specific surface area first increases and then decreases with increasing treatment duration under different atmospheres, while the pore size continues to expand. Both the combustibility index F and comprehensive combustion performance index S exhibit a trend of significant increase followed by decrease with prolonged treatment time. Oxygen plasma boosts combustion efficiency by 27.9 % and lowers activation energy by 18.937 kJ/mol (air: 17.952 kJ/mol; nitrogen: 10.135 kJ/mol), which enhances pulverised coal combustion efficiency. The VM and RPM models provide the best fit to the kinetic data. Raman and XPS analyses reveal that short-term plasma treatment disrupts C–C/C–H bonds, introduces oxygen-containing groups, and enhances aliphatic structures and active sites. This first-time time–gas perspective analysis offers novel approaches for enhancing coal utilisation efficiency.