Study on the dynamic evolution law of spontaneous coal combustion in high-temperature regions

In regard to coal spontaneous combustion (CSC) in the goaf, it is difficult to determine the high temperature regions due to its hidden fire source, while effective prevention and control of CSC in the goaf have become increasingly difficult. COMSOL Multiphysics was adopted to conduct theoretical calculations and numerical simulation analysis of the dynamic evolution of high temperature regions in CSC process. The results indicated that the general trend of the high-temperature regions in the experimental furnace involved movement from the middle and upper parts to the lower air inlet. The high-temperature regions in the goaf was mainly concentrated on the air inlet side. Both the advancing speed and air supply rate at the working face impacted the dynamic evolution of the high-temperature regions. With the increase of the advancing speed, the heat and mass transferred process in the goaf became more and more intense, so that the caving coal and rock entered the suffocation zones after a short period of oxidation and temperature rise. Moreover, the temperature difference between the suffocation zones and the deep goaf was small, so there was some uncertainty in the high-temperature area. With the increase of air supply, the heating rate of high-temperature point increased, and the material migration speeds in the goaf also increased, which made the high-temperature regions move towards the deep part of the goaf, which was more unfavorable to the prevention and control of CSC.

Automated summary

This study conducted theoretical calculations and numerical simulations using COMSOL Multiphysics to analyze the dynamic evolution of high temperature regions in coal spontaneous combustion (CSC). The results showed that the movement of high temperature regions in the experimental furnace was from the middle and upper parts to the lower air inlet. The high temperature regions in the goaf were mainly concentrated on the air inlet side. The advancing speed and air supply rate at the working face influenced the dynamic evolution of the high temperature regions.