Assessment of combustion characteristics of high ash Indian coal, petroleum coke and their blends for cement industry using TGA

This work investigates the combustion analysis of coal, petroleum coke and their blends. Coal and petroleum coke were characterized by proximate analysis, ultimate analysis, gross calorific value determination and ash analysis. Combustion performance of parent fuels and their blends were evaluated by thermogravimetric analysis followed by the analysis of different characteristics parameters, namely ignition temperature, peak temperature, burnout temperature and combustion efficiency. Results signify that petroleum coke has poor combustion characteristics compared to coal. After the rise in petroleum coke from 10 to 50 mass %, ignition temperature reduced from 413 to 385 °C, while insignificant variations occurred in peak temperature and burnout temperature. Such observations show natural reduction in ignition characteristics without significant modification in coal's burning profile. Combustion efficiency at 450 °C reduced from 46.18% to 34.77% as petroleum coke increased from 10 to 50 mass %, signifying decline in the combustion properties of coal. Kinetic analysis shows that petroleum coke has the maximum activation energy (182.11 kJ/mol) than coal (84.84 kJ/mol). Analysis of changes in enthalpy, Gibbs free energy and entropy inferred that individual combustion of both coal and petroleum coke is difficult, while blends have improved combustion characteristics than petroleum coke.