Visualization of the soot formation process in the volatile flame of single coal particle using 10-kHz PAHs-PLIF, LII and LIS

Abstract

Soot formation process during coal combustion is one of a key phenomenon to achieve a high-performance furnace. This is because the thermal radiation of soot influences the temperature distribution and the heat transfer process in the furnaces. In this study, polycyclic aromatic hydrocarbons (PAHs) and soot were visualized by a 10 kHz planar laser induced fluorescence (PLIF), laser induced incandescence (LII) and laser induced scattering (LIS) to investigate the soot formation processes in the volatile flame of single pulverized coal particle combustion. In addition, the magnified high-speed imaging was conducted to capture the combustion behavior of the single coal particle. Pulverized coal particles entered high temperature region formed by hydrogen/air diffusion flame in the counterflow. Results showed that five typical combustion behaviors were observed by magnified high-speed imaging. This paper succeeded in visualizing the process from the release of volatile matter to soot formation of single pulverized coal particles with high-speed PAHs-PLIF, LII and LIS measurements. The results showed that the size of PAHs and soot areas was similar, but the duration of PAHs was longer than soot. Also, the PAHs signal was locally high, suggesting that PAHs were directly released from pulverized coal.