Defeat The Dragon: Coal Fires Between Self Ignition And Fire Fighting

Spontaneous coal fires in near surface coal seams are a worldwide recognized problem. They are destroying coal as a resource and emit climate relevant gases like CO2 both in considerable amounts. While the extinction of such fires is a most desirable goal, the estimation of the actual input of greenhouse gases into the atmosphere is of great interest especially in the context of the Kyoto protocol as such values are needed as baseline for the Clean Development Mechanism policies. Under the framework of the Sino-German Coalfire research project we develop numerical models of such coal fires. The aim of our calculations is first to understand the governing physical and chemical processes that are relevant for the whole combustion process. Based on such gained insights we study the coal fire spreading along the seams for typical situations. From these scenario calculations we can deduce informations needed to support the CDM baseline estimation and to assess the progress of fire extinguishing efforts like water injection and surface covering to dissipate the heat and suffocate the fire. We present case studies using the finite-element-code ROCKFLOW applied to realistic geometries based on field observations in the Shenhua Group Coal Mining Area Wuda (Inner Mongolia, PR China).