large area goaf; coal spontaneous combustion; buoyancy effect; multi-field coupling; numerical simulation

Abstract

In order to effectively prevent and control coal spontaneous combustion disasters in Tangjiahui Mine, thermogravimetric experiments were used to analyze the thermal reaction kinetics characteristics of coal samples at different heating rates and different oxygen volume fractions. The results showed that at the same oxygen volume fraction, the apparent activation energies of coal at heating rates of 2 ℃/min, 5 ℃/min, 10 ℃/min were 150.27 kJ/mol, 131.97 kJ/mol, 106.86 kJ/mol, respectively; in addition, at the same heating rate, the apparent activation energies of coals with oxygen volume fraction of 6%, 9%, 12%, 15%, 18%, 21% are 106.86, 120.61, 127.31, 131.58, 135.26 and 136.82 kJ/mol, respectively. The apparent activation energies decrease with the increase of heating rate and oxygen volume fraction, and the change law is basically in line with the increase of logarithmic function. The calculation results of activation energy kinetics reveal that the degree of coal-oxygen composite reaction is different under different heating rates and different oxygen volume fractions.

Keywords

• spontaneous combustion of coal
• characteristic temperature
• thermodynamics
• temperature rising rate
• oxygen volume fraction
• activation energy