Analysis of Methane Concentration Distribution at U-Ventilated Longwall Outlet – Case Study

Abstract

The methane hazard concerns a growing number of longwalls in the Polish coal mining industry each year. Mitigating this hazard, both of work safety and economic reasons requires the application of preventive measures adequate to its level. Commonly threat level is estimated based on registered methane concentrations, which fluctuate and highly depends on the place of measurement. The article presents studies on the average and maximum methane concentrations at the longwall outlet, including analyses of the interdependence of methane concentration in methanometry sensors installation locations.

Influence of the Auxiliary Air-Duct Outlet and the Brattice Location on the Methane Hazard—Numerical Simulations

“…Despite the lack of research on the impact of the auxiliary devices' location in the tailgate on the methane concentration distribution, the obtained results are consistent with suspected distribution. The general distribution coincides with the previously conducted in situ tests performed in a similar working equipped with a brattice and air-duct [37]. The greatest accumulation of methane occurs in the zones where methane sensors are usually located, i.e., under the ceiling in the mixing zone and on the tailgate wall opposite to the longwall outlet.…”

“…The primary solver settings are summarized in Table 2. Based on the measurements and previous experience [35][36][37], the boundary conditions of the model were established. The inflow to the model is indicated in the following planes: Due to the short section of the modeled longwall, as a result of the tests performed, it was decided to omit the parameter of methane inflow from the face of the exposed seam.…”

“…In the tailgate: opposite to the longwall outlet (sensor C on the CC plane). The plane located in the tailgate behind the ventilation partition (DD ) was omitted at this stage because the high heterogeneity of the methane-air mixture [37] in this location, which may result in high errors.…”