Measurement and modeling on local ash layer induced combustion temperature heterogeneity of single coal/biomass particle

The in-situ measurement experiments of single coal/biomass particle combustion were conducted on a high-resolution micro-infrared online visualization system, with heterogenetic temperature distribution modification and modeling. Morphology and combustion characteristics of coal and biomass single particles were comparatively analyzed, and the evolution pattern and surface temperature were obtained. Results showed that coal particles performed two-stage shrinking processes and progressive temperature distribution, while the biomass particles showed a one-stage shrinking process and random temperature distribution during combustion. The instantaneous heat release capacity of biomass is comparable to that of coal. Biomass particles had lower combustion temperature on the surface than coal particles, with a difference of 33 °C. For coal particles, the calculated carbon core temperature was significantly higher than the measurements (>200 °C) and decreased with increasing temperature and decreasing ash layer thickness. This model facilitated the quantitative assessment of heat transfer retardation effects induced by ash layer formation.