CFD modelling of nitrogen injection in a longwall gob area

This paper describes computational fluid dynamics (CFD) simulations conducted to investigate the effectiveness of N₂ injection in an active panel and a sealed longwall gob area to prevent and suppress spontaneous heating of coal using various injection locations and flow rates. In the active panel simulations, a single longwall panel with a bleederless ventilation system was simulated. The spontaneous heating of crushed coal from pillars was simulated and N₂ was injected from different locations on the headgate side and through boreholes from the surface. The N₂ injection rate at each location was varied between 0.18 m³/s and 0.94 m³/s (380 and 2000 cfm). In the sealed longwall simulations, seal leakage rate was varied to determine its effect on N₂ injection effectiveness. The results of this study should aid mine ventilation engineers in developing more effective N₂ injection strategies to prevent and control spontaneous heating of coal in underground coal mines.