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

Abstract

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.