Experimental study on the precipitation and oxidation characteristics of alkane gas in coal spontaneous combustion oxidation process

In this paper,an experimental study on the spontaneous combustion of the coal samples in Seam #3 at No 302 mechanized mining face in Xing’an coal mine was conducted.In the situation that the supply air concentration is at 20.9%,10% and 7% respectively,the concentration evolutions of alkane gases,such as C2H6 and C3H8,are studied with coal temperature.It is found that the concentrations of alkane gases such as C2H6 and C3H8 at an oxygen concentration of 20.9% increase rapidly when the coal temperature reaches 180oC,then decrease at a coal temperature of 400oC.When the oxygen concentration is at 10%,the concentrations of alkane gas increase quickly at a coal temperature of 280oC,reaching a peak at a temperature of 400oC.When the oxygen concentration is at 7%,the concentrations of alkane gas increase suddenly at a coal temperature of 250oC,and then it declines at a temperature of 400oC.Moreover,the concentration evolution of C3H8 and C2H6 is a decreasing function of coal temperature in the alkyl chain ratio at an oxygen concentration of 20.9%,while it is an increasing function at oxygen concentrations of 10% and 7%.