Abstract
AbstractThe 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.
Highlights
Radiation, and especially particle radiation, is the dominating heat transfer mechanism in pulverized fuel combustion systems [1]
The results show that the iron content directly influences the emissivity of char during combustion
Radiative properties of hydrothermal carbonization (HTC) chars, especially when being doped with single ash compounds, have not been reported, yet. This step is undertaken here, employing the sole technique, which is known to measure the emissivity of HTC chars doped with SiO2 and Fe2O3 to compare the influence of these important coal ash constituents on the emissivity of burning particles
Summary
Especially particle radiation, is the dominating heat transfer mechanism in pulverized fuel combustion systems [1]. Several influences on the emissivity were investigated by Graeser and Schiemann [12,13,14,15] and Graeser et al [16]: They found decreasing emissivity with increasing burnout [12, 13] and increasing particle temperature and an influence of the reaction atmosphere [14] and the fuel rank [15] on the emissivity They observed a general correlation between untreated and leached coal chars, where the latter had lower emissivity, which was attributed to their lower mineral content [16]. This step is undertaken here, employing the sole technique, which is known to measure the emissivity of HTC chars doped with SiO2 and Fe2O3 to compare the influence of these important coal ash constituents on the emissivity of burning particles
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