Triple-Gaussian distributed activation energy model for the thermal degradation of coal and coal chars under a CO2 atmosphere

Coal and coal char thermal degradation in a CO2 atmosphere is particularly important to understand and model as a rate-determining step in the gasification process. The work presented here aims to provide a global kinetic model that accurately represents the thermal degradation of Sanxing (SX) coal and coal char under a CO2 atmosphere and to determine the kinetic parameters of the thermal degradation. In the work presented, a novel approach has been used that involves a triple-Gaussian DAEM that simultaneously considers the primary pyrolysis, secondary pyrolysis, and the process of newly generated char gasified by CO2. The result of the model shows accurate reproduction of the thermal degradation behavior of SX coal and chars and provides significant information about the relative occurrence of the three steps. For SX coal and Char500, the residual error of the triple-Gaussian DAEM is approximately 0.35 to 0.22 times that of the double Gaussian DAEM. For Char850, the ratio is lower, approximately 0.12 times that of the double Gaussian DAEM. This indicates that the triple-Gaussian DAEM is more suitable for describing the thermal degradation of chars acquired at high temperatures (500-850 degrees C) under a CO2 atmosphere.