Abstract
The ventilation air–methane (VAM) released from underground mines is often transported into regenerative thermal oxidizer (RTO) devices and burnt into heat energy. This study numerically investigates the scenarios where explosion occurs inside the RTO and the flame and pressure waves propagate back quickly towards the VAM discharge duct. Possibilities of secondary explosion in the discharge duct, hence in the downstream underground mines, are examined. The results critically showed that when the methane concentration accumulated in the RTO reached 7.5% or above, the flame generated from the explosion jumped to the evasé of the discharge section (over a distance of 29.4 m) and could induce explosions in underground mines.
Highlights
Evasé and Capture Duct forIn ventilation air–methane (VAM) abatement systems, methane is released from underground mines and subsequently transported into regenerative thermal oxidizer (RTO) devices where exothermic reactions take place [1]
The results suggest that with 5% methane in the RTO and a distance of 29.4 m between the capture duct and the evasé, the flame cannot jump the gap to induce the secondary explosion in the evasé
The above results critically confirm that with a distance of 29.4 m in between the capture duct and evasé, once explosion occurs inside the capture duct with a methane concentration of ≥7.5%, the flame propagates into the evasé and induces the secondary explosion
Summary
In ventilation air–methane (VAM) abatement systems, methane is released from underground mines and subsequently transported into regenerative thermal oxidizer (RTO) devices where exothermic reactions take place [1]. From a technical point of view, direct coupling seems more practical and provides better control of the entire VAM abatement system It provides an easy path for the flame and pressure waves to propagate from the RTO to the mine evasé, and vice versa. Specification of the flame speed is involved in some approaches (e.g., progress variable (c) based modeling [7,8]), which have to employ empirical factors in the source term, limiting their applicability and prediction accuracy. The main objective is to understand the possibilities for the flame and pressure waves to propagate from the capture duct to the exit of the evasé and subsequently induce secondary explosions in underground mines
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