Gray Correlation Analysis of CO Generation Pattern during Process of Low-temperature Spontaneous combustion of Jurassic Coal

ABSTRACT

Spontaneous combustion of coal is a phenomenon that exists in all coal mining countries. The characteristics of CO production during the spontaneous combustion of coal are the focus of attention of researchers. A novel programmed oxidation heating simulation system with a small-sample size was developed to study the combustion characteristics. The device was used to study the characteristics of CO generation during low-temperature coal oxidation under different conditions (three coal ranks, six particle sizes, four air volumes, and four oxygen concentrations). The microscopic characteristics of the coal structure were tested through Fourier-transform infrared spectroscopy (FTIR), and three types of active functional groups were observed. Ten factors affecting gas production in the low-temperature oxidation stage were analyzed by gray correlation. This study found that moisture in coal had the greatest effect on CO generation, followed by O-containing functional groups. Aliphatic hydrocarbons had the least correlation with CO generation. Further, the CO concentration increased exponentially during the heating process in low-temperature oxidation. In the low-temperature stage, carboxyl, carbonyl, and side-chain C–O bonds of the benzene ring were the main sources of CO generation.

KEYWORDS:

• Coal spontaneous combustion
• carbon monoxide
• gray correlation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Duo Zhang, Jun Deng and Hu Wen conceived the work and designed the experiments. Xiaoxin Cen, Weifeng Wang and Yang Xiao collated the experimental data. Duo Zhang wrote the manuscript with contributions from all authors.

Additional information

Funding

The project was supported by the National Natural Science Foundation of China 51904234,51974240 (grant numbers 51904234 and 51974240). We thank NES, Edanz Group China (https://www.nesediting.cn/) for editing the English text of a draft of this manuscript.