Numerical investigations of methane flow characteristics on a longwall face Part II: Parametric studies

To further understand methane flow characteristics on a longwall face, this study focuses on the investigation of methane flow behaviour under six different operating and mining conditions, namely, the impact of ventilation in terms of both flow rate and the ventilation scheme, coal seam gas content, adjacent gas bearing strata, drum sprays and the maingate (MG) curtain. Modelling results obtained from the parametric studies were compared with the corresponding base model results, through which the impact of single parameter on the methane distribution characteristics along the longwall face was investigated. Modelling results indicate that: 1) flow rate has major impact on the methane concentration around the shearer and at the inner tailgate (TG) corner while the impact is minor at the upper TG corner; 2) methane emission from adjacent gas bearing strata significantly affects the methane distribution at the immediate goaf and at the upper TG corner of the face; 3) the use of a TG cut through behind the face is very effective in diluting the methane accumulated at the upper TG corner; 4) methane levels in the vicinity of drums and downstream is reduced greatly with the operation of drum sprays