Experimental study of coal spontaneous combustion high-temperature region spreading characteristics

Abstract

To solve the difficult problem of determining the change law of key point temperature and gas during the motion of high temperature area inside the coal mine seam, this study used the simulation platform of coal spontaneous combustion (CSC) development to investigate the temperature, gas concentration, functional group migration, and change rule of key points with layers in the holistic process of high-temperature region (HTR) spreading of Wen-Zhuang coalmine in Shanxi province, China. The analysis involved the dynamic change rule among temperature, oxygen consumption rate, CO, and C2H4. Finally, with the gray correlation method, the changes of the dominant functional groups released by CO and C2H4 were explored, which revealed the transport rule between the functional groups and the regional spreading in the HTR spreading process. The results show that the temperature of coal body and the rate of oxygen consumption gradually decreased with the deepening of coal layers. Among them, as the coal seam burns, the coal body will appear to “collapse”, along with the phenomenon of “re-ignition”; at the combustion point temperature of each coal layer, the activity of the oxygen-containing functional group was the largest, the activity of hydroxyl group was the smallest, and the activity of aliphatic and aromatic hydrocarbons was similar. Among them, the hydroxyl group, aromatic hydrocarbon, and oxygen-containing functional group had the same trend changing with the deepening of the layers, exhibiting a trend of first decreasing after increasing and later decreasing, and positively correlated with the ignition temperature of each layer. The trend of aliphatic hydrocarbon was opposite to the trend of other functional groups and negatively correlated with the ignition temperature of each layer. The research results of this paper can be used for disaster prevention in the HTR of mine fires, and parameters, such as indicator gases, functional groups and temperature, can be used to determine and deter the migration trend of mine fires, providing a theoretical basis for the prevention and control of high-temperature diffusion of coal spontaneous combustion.