Technical Options for Diluted Mine Methane Mitigation and Utilisation

摘要

Current research and development on mine methane mitigation and utilisation focuses on methane emitted from underground coal mines,in particularventilation air methane (VAM).This is because (1) it represents most of the methane emitted from coal mines;and (2) it is most difficult to capture and use,asthe air volume is large and the methane resource is dilute and variable in both concentration and flow rate.It is estimated in China that over 70% of the drainagegas has a methane concentration of less than 30%,and this should be targeted for the mitigation and utilisation as well. VAM mitigation/utilisation requires either treatment in its dilute state,or concentration up to levels that can be used in conventional gas fuelled engines.This paper reviews most of the existing and developing VAM technologies,and discusses potential technical issues for their applications at mine sites.Then,based on fundamental thermodynamic laws the paper analyses methods for the concentration and oxidisation of methane in mine ventilation air to gain insightinto the effect of methane concentration.They are simplified as far as possible to allow conclusions to be drawn as to the limits of what is possible withventilation air methane.The analytic results are summarised to provide a guide on thermodynamic limitations for each technical process.