102 / 2023-06-15 15:29:46

Numerical analysis of the influence of the longwall gateroad convergence and the manner of its liquidation on the methane distribution

Methane,Longwall Face Ventilation,Goaf Gas Managment,CFD modelling,Case Analysis

During longwall coal mining, a situation may arise in which the liquidation of the longwall gateroad behind the coalface is abandoned. In practice, the liquidation of longwall gateroad is abandoned when arch supports are severely deformed and damaged as a result of excessive loading associated with increased stress conditions or when, according to the assessment of the mining supervisor, there is a safety risk to the crew employed in the liquidation. In the case of longwall mining under methane hazard conditions, the inability to decommission the longwall gateroad behind the coalface is an additional factor increasing the amount of methane released into the working of a longwall. In Polish coal mines, the majority of exploited longwall panels are ventilated by the "U" method; the rest are ventilated by the "Y" method, sometimes by the small "Y', "H," and "Z" methods. The air flow in the working of a longwall may be disturbed due to the natural convergence (deformation) of the longwall gateroad and lead to a change in its original cross-section. Reducing the cross-section of a longwall gateroad causes local resistances in the air flow and changes in aerodynamic potentials, which lead to emergency states of the ventilation process in the longwall panel.

In the article, on the basis of experience and the results of in-situ tests in the longwall panel ventilated by the method of ventilation on "U" and "Y", a numerical analysis using CFD methods has been carried out, and conclusions have been drawn on the formation of methane hazards. It was decided to signal the important role of the method of liquidation and the geometric parameters of the gateroads left in the goaf on the distribution of methane in the region of the outlet. Simulations were performed in SolidWorks Flow Simulation, which uses CFD methods (Computational Fluid Dynamics).