This study presents the Raman spectroscopy analysis of the carbon structure on the surface of pulverized coal char particles sampled at different positions in a pilot-scale blowpipe. To evaluate the degree of char oxidation, we compared the experimental data of the samples before and after mild oxidation. The results showed that the surface crystallinity of large char particles before mild oxidation increased, irrespective of the sampling position in the radial direction. This suggested that large particles were exposed to higher temperatures than small particles in the blowpipe. Moreover, the surface crystallinity of the small char particles before and after mild oxidation was almost the same. This indicated that the small particles had already been oxidized in the blowpipe. On the other hand, the surface crystallinity of the large char particles changed drastically after mild oxidation. This was because large particles passed through an oxygen-lean region and the char oxidation of these particles did not progress as much as in the small particles. These results were consistent with those obtained from previous studies. Therefore, Raman spectroscopy is useful for tracking the reaction behavior of coal char particles in a blowpipe.
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