Combustion characteristics and kinetic analysis of pulverized coal and semicoke

To explore the combustion performance of blended fuels after adding semicoke, the combustion processes of coal, semieoke, and their mixture were studied by thermogravimetric analysis (TGA) and the combustion characteristic parameters were obtained. Due to the different mechanisms in different temperature ranges of combustion reaction, the kinetics of the combustion process was analyzed by the sectioning method, and the shrinking core models of interracial chemical reaction and internal diffusion were used to model the process at the earlier stage and the later stage to obtain the kinetic parameters, respectively. The results show that with increasing semicoke content in blended fuels, the ignition index and the combustion characteristic index decrease, and the combustion activation energy of blended fuels increases from 76.79 kJ·mol^-1 to 92.75 kJ·mol^-1 at the earlier stage and from 102.62 kJ·mol^-1 to 107.94 kJ·mol^-1 at the later stage. It is demonstrated that the combustion performance of blended fuel deteriorates with the increasing semicoke content. By comparing the combustion characteristic parameters and kinetic parameters of blended fuels with different semicoke contents, the mass fraction of semicoke should be controlled below 15%.