Investigation on Co-Combustion of Anthracite and Bituminite Based on Non-Isothermal Thermogravimetric Test

The cross-scale mechanism by which individual coal structures govern blended coal combustion behavior is systematically elucidated through non-isothermal thermogravimetric kinetic experiments integrated with Fourier-transform infrared spectroscopy analysis. Three anthracites and six bituminous coals were selected, with gradient-blending protocols designed based on a 20 wt % volatile matter threshold. Combustion kinetics were decoupled using the volume model, unreacted core model, and random pore model, complemented by scanning electron microscopy to characterize microstructural evolution. Results demonstrate that aliphatic side chains and oxygen-containing functional groups dominated the release of volatile between 250 to 450°C, with pyrolysis activation energy reduced by 56% as short-chain alkane proportions increase in blended fuels. In temperature range between, 450 and 700°C, kinetic continuity during fixed carbon oxidation is governed by synergistic interactions between aromatic condensation degrees and carbon structural order parameters, mediated through pore topology evolution and ash-layer diffusion limitations. Notably, in the DZX experimental group with a 1 : 1 blend ratio of anthracite X and bituminous Z, electron delocalization within aromatic condensation systems induced a leftward shift of combustion profiles, achieving a reduced burnout temperature of 680°C, thereby demonstrating structural complementarity of functional groups that transcends thresholds of traditional blending theories. By establishing a multiscale correlation framework integrating functional group-directed reorganization, pore topology evolution, and combustion kinetic response, this work delineates a quantitative structure-activity relationship between coal molecular units and macroscopic combustion performance, providing a molecular compatibility-driven theoretical foundation for optimizing industrial blended coal efficiency.