Experimental and in-situ estimation on hydrogen and methane emission from spontaneous gasification in coal fire

Abstract

In order to quantitatively understand the wasteful and combustible gas resources which are released from underground coal fires caused by spontaneous combustion, the emission characteristics of hydrogen and methane in the thermochemical process of coal oxidation are investigated by both laboratory tests and on-site measurements. Employing an adiabatic oxidation test, the releasing rules of index gases in limited space were estimated with programmed temperature rising up to 200 °C. Experimental results demonstrate that the releasing concentrations of methane and hydrogen preform an exponential trend with oxidation temperature, while the release rates are significantly influenced by the metamorphic degrees and oxygen supplement conditions. Field survey was also operated to trace the gaseous products in a typical coal fire area in Xinjiang Region, China via gas monitoring at surface emission vents and fractures. Measurement data illustrate a good consistency between the index gases and the stage of coal spontaneous combustion, and the exhaust hydric gases are estimated at more than 1000 tons per year. The presented method and results could provide a useful reference to gaseous products estimation for coal spontaneous combustion.