Optimisation of a Thermal Flow Reversal Reactor for Ventilation Air Methane Mitigation

Ventilation air methane (VAM) generally accounts for 50-85% of the total fugitive emissions from an underground coal mine depending on mine site conditions. VAM presents a challenge to mitigation or use as an energy source because VAM represents the largest proportion of methane emissions from coal mines, its air volume flow rate is large and the methane resource is dilute and variable in concentration, and it contains dust, and is almost 100% moisture saturated.  Thermal flow reversal reactors (TFRRs) have achieved commercial scale with a number of demonstration units in the world. However, existing TFRRs are usually equipped with a packed bed structure, which generally exhibits two operational problems:

• dust clogging inside the bed resulting in frequent unit shut down and higher maintenance costs.
• high pressure drop through the bed resulting in high power consumption in unit operation.

This project aimed to optimise the VAMMIT thermal oxidiser to achieve less pressure drop and higher methane oxidation efficiency, while also investigating the safety associated with VAMMIT unit operation. This project also investigated the feasibility of a catalytic VAM mitigator to operate at much lower temperatures (~450-700 oC) to completely avoid stone dust decomposition and enable operation at lower methane concentrations. The project focussed on:

• Optimisation of the honeycomb bed structure of VAMMIT;
• Optimisation of operating parameters of VAMMIT;
• Feasibility study of a new catalytic version VAMMIT;
• Investigation of safety management associated with VAMMIT.

This project has been successfully completed with all the research tasks accomplished. The improvements of novel pilot-scale VAMMIT prototype unit has been studied by optimising its bed structure and operating parameters. Also, new safety measures are investigated to couple with the prototype VAMMIT unit for better safety management. A catalytic version VAMMIT unit has been designed and evaluated under various conditions based on a commercial Pt-based honeycomb monolith catalyst.