Influence of the Mineral Content on the Emissivity of Hydrothermal Char

Abstract

The influence of minerals on solid fuel conversion is an important topic and has so far been addressed focusing mainly on the catalytic effects. Here, the impact of iron oxide on the emissivity of burning char particles was investigated. Synthetic, hydrothermally carbonized char was doped with SiO2 or with a mixture of SiO2 and Fe2O3. The sample was then exposed to an oxy-fuel atmosphere in a laboratory reactor. An established pyrometer/infrared (IR) spectrometer setup was used to measure the size, temperature, and IR radiation of single burning particles. Based on these measurements, the spectral and total emissivity in the near-IR (1.25–2.25 μm) and the total emissivity in the mid-IR region (2.4–5.5 μm) were calculated. The results show that the iron content directly influences the emissivity of char during combustion.