Experimental research on the emission of higher molecular weight gases during coal oxidation

Abstract In addition to the common gaseous products such as CO, CO2, CH4, C2H6 and C3H8, a large number of gaseous products with relatively high molecular weight could also be generated during coal spontaneous combustion. To investigate the evolution of higher molecular weight (HMW) gases during coal oxidation, a qualitative and quantitative analytical method was established based on gas chromatograph-mass spectrometer (GC–MS), by using which the evolution of HMW gases during the oxidation of coal samples were studied for the first time. The results show that the amount of HMW gases generated from three experimental coal samples significantly differed. Among the three coal samples, the bituminous coal (QD coal) with 22 different kinds of gaseous products detected had the highest gas production, including propane, propene, acetone, acetaldehyde, propionaldehyde and 17 kinds of C4-C6 hydrocarbons. And all the gases released from QD coal except acetone increased regularly with the oxidation temperature. The critical temperatures of HMW gases almost cover the entire process of QD coal oxidation at low temperature, which greatly supplements the blank forecast interval that exists when using conventional indicator gases to forecast coal spontaneous combustion. The research results provide a theoretical basis of using HMW gases as indicator gases to improve the prediction accuracy of coal spontaneous combustion.