Study on the combustion behavior of single coal particle using a thermal-imaging technique

Abstract

This study proposes a novel thermal-imaging detection technique that combines thermogravimetric analysis (TGA) with hyperspectral imaging to investigate the combustion behavior of single coal particles. The proposed technique enables the combustion reaction kinetics to be correlated with the observation of combustion regimes, as well as the combustion temperature and radiative parameters. The combustion behavior of two kinds of single coal particles, named Yinni (YN) and Datong (DT), is detected by the thermal-imaging technique. The results show that the single coal particles undergo a brief release of moisture/volatile, simultaneous combustion of volatile and char, and a relative long-term char oxidation during combustion. The combustion temperatures of the two single coal particles are approximately in the range of 750–1250 K, while the band-averaged emissivity values vary between 0.05 and 0.85. Furthermore, the simultaneous reaction rate, average temperature, and average emissivity of the two single coal particles during combustion are also obtained. It is found that the single coal particles follow a first-order reaction in the moisture/volatile release and char oxidation stages, and a complex reaction kinetics in the simultaneous combustion stage. The average temperature of the single coal particles is maintained at about 1000 K during the moisture/volatile release stage, but gradually increases during the simultaneous combustion and char oxidation stages. The average emissivity of the single coal particles keeps increasing in the release of moisture/volatile and simultaneous combustion stages, whereas remains basically unchanged in the long-term and slow char oxidation stage.