1411 Figure 3: CSIRO VAMMIT: (a) diagram of the honeycomb regenerative bed and VAMMIT unit, and (b) the pilot VAMMIT prototype unit built at CSIRO laboratories. A VAMMIT prototype unit was built and tested at CSIRO laboratories (Figure 3b) and then fully installed at Appin mine in Australia in April 2017. A series of planned hot trials were successfully completed with actual VAM by December 2017. For example, as shown in Figure 4, during the continuous site trials, the actual VAM concentration varied between 0.51% and 0.86%, less than 0.02% methane was present in the exhaust flue gas from the VAMMIT unit. Major results of the VAMMIT site trials are: • The VAMMIT unit operation was self-sustainable with a range of VAM concentrations between 0.3 and 1.0 vol. %. The minimum methane concentration required for self-sustaining operation of the VAMMIT unit was found to be 0.3 vol %. • Regardless of the inlet VAM concentration variation, the methane concentration in the flue gas was stable, less than 0.02%. • The centre bed temperature was measured above 1,005 oC and was stable over the test period. • The pressure drop across the regenerative bed was in the range of 0.8-1.0 kPa under all test conditions. During the site trials without a dust filter, the pressure drop did not increase with the time, indicating that the dust had a negligible effect on VAMMIT’s performance. • Due to the variation of inlet VAM concentration, the methane oxidation efficiency varied as well but in average was higher than 96%.
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