1409 over 25% methane • CataVAMTM: A catalytic flow reversal reactor with a high-performance catalytic regenerative bed designed for self-sustaining destruction of as low as 0.1% methane, optimised for the 0.2-0.4% methane range typical of Australian VAM conditions CSIRO has also been developing emerging technologies for methane emissions abatement involving photocatalytic oxidation and novel catalyst materials for thermal catalytic oxidation. Photocatalytic oxidation is targeting ultra-low level and diffuse methane emissions, which is promising for abating open cut fugitive emissions or offset by destructing atmospheric methane with solar energy. Developing novel catalysts with high activity and durability and low cost is to accelerate wide implementation of catalytic VAM mitigation. 2. HIGH TECHNOLOGY READINESS LEVELS VAM ABATEMENT TECHNOLOGIES VAMCAT Lean-burn gas turbines are being developed worldwide. CSIRO designed a 1% methane catalytic combustion gas turbine system based on methane catalytic combustion experimental data and the design criteria for a turbine system. A 1% methane turbine can use a greater proportion of ventilation air compared with a 1.5% or 2% methane gas turbine unit. Thermodynamic analysis indicates that lean-burn turbines can be operated at lower methane concentrations to 0.8%, depending on heat recovery effectiveness. A 25 kWe prototype VAMCAT unit was designed, constructed and tested at CSIRO laboratories in 2009, followed by trials conducted at coal mines in China and Australia. Field trials at Appin Coal mine were carried out to test the 25kWe VAMCAT prototype unit for the first time under real VAM conditions in Australia (Figure 1). In November 2017, a series of planned site trials of the VAMCAT unit were undertaken by using actual VAM at full speed. CNG was used to replace drainage gas that had stopped being produced in April 2016. Results from these site trials demonstrates that the unit is capable of stable operation with 0.8% methane, generating approximately 8-21 kWe of electricity (Figure 2). Figure 1. VAMCAT unit installed at Appin Coal mine in Australia: (a) site infrastructure - safe ducting system and (b) VAMCAT unit. VAMMIT Thermal flow reversal reactor (TFRR) is the most mature technology for VAM abatement through thermal oxidation of methane at high temperatures above 850 oC. The TFRR technology employs the flowreversal principle to transfer combustion heat to a solid medium, and then back to incoming ventilation air to raise its temperature to the ignition temperature of methane oxidation. CSIRO’s VAM mitigator (VAMMIT) uses a similar operational principle and configurations to the existing TFRRs but it includes a novel bed structure. As shown in Figure 3(a), the VAMMIT unit is mainly composed of (1(1) a novel regenerative bed made of honeycomb ceramic blocks and an innovatively designed flow diverting section that is connected with a start-up burner for easy start-up and a bursting disc for safety management, (2) two VA flow direction switch cylinders that periodically switch the flow direction of VA, and (3) a start-up burner, where liquified petroleum gas (LPG) is burnt to produce hot flue gas to preheat the regenerative bed. The
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