Experimental investigations on the thermal destabilization and performance enhancement of ventilation air methane in a reversed flow oxidation reactor

Proper mitigation and utilization of coal mine ventilation air methane (VAM) are important to alleviate resource shortage and environmental issues. This work presents a pilot-scale experimental analysis of heat storage and oxidation performance in a VAM-fuelled reversal flow reactor, aiming at elucidating the thermal destabilization behaviour and providing feasible ways to maintain the system stability. Experimental results show that the system could become unstable under variable conditions. When the methane concentration is varied from 0.74 % to 0.70 %, the temperature is gradually becoming steady after operating the system for 5160 s. However, this balance will be broken, and the combustor is extinguished if the methane concentration is decreased from 0.68 % to 0.64 %. A critical average temperature of 780 C-degrees in the combustion chamber is identified, below which the system starts to become unstable. Further analysis reveals the importance of heat-releasing proportion from the regenerator to the fresh gases in determining the system performance with the methane concentration varied. A sufficiently low proportion implies that the fresh gases cannot be properly preheated when entering the combustion chamber. Finally, increasing ventilation gas flow rate and reducing switching time are shown to be effective in promoting the oxidation process due to the enhanced heat storage.