Influence of Oxygen Volume Fraction on Thermal Effect of Spontaneous Coal Combustion
In order to investigate the effect of O2 volume fraction in goaf on the exothermic reaction of spontaneous coal combustion,coal samples at different O2 volume fractions were tested by STA-449-F3 simultaneous thermal analyser.DSC(Differential Scanning Calorimetry)and DDSC(Derivative Differential Scanning Calorimetry)curves under different O2 volume fractions were used to observe the change of heat flow curves and analyze the characteristic temperature of coal samples.The exothermic amount under different O2 volume fractions was measured to assess the influence of O2 volume fraction on the exothermic thermal effect of coal.The experimental results showed that the characteristic temperatures of coal samples gradually decreased with the decrease of O2 volume fractions,and the characteristic temperature t1 changed little,the t2 point(thermal current φ=0 mW/mg)shifted locally along the positive direction of X axis with the decrease of O2 volume fraction,t3 point(φ=φmax)showed a lag phenomenon with the decrease of O2 volume fraction.Through further analysis and verification,it was concluded that the exothermic reactions during spontaneous combustion of coal under different O2 volume fraction conditions were significantly different,and and the low O2 volume fraction had an obvious inhibitory effect on the exothermic reactions of spontaneous combustion of coal.The importance of O2 volume fraction for the exothermic reaction of coal spontaneous combustion was revealed,and a new experimental basis for further understanding the spontaneous combustion mechanism of coal in the goaf was provided.
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