Novel Cost-effective Ventilation Air Methane Mitigator

The overall project goal was to develop a novel self-sustaining mine ventilation air methane (VAM) mitigator in a scalable format, and demonstrate it at an Australian mine as a step towards commercial uptake. The specific objectives were to design and construct a 0.5 Nm3/s VAM mitigator (VAMMIT) unit, a type of thermal flow reversal reactor, and then test its performance under various conditions such as different VAM concentrations and flow rates.

This project developed a newly structured regenerative bed made of honeycomb ceramic blocks. The novel bed structure significantly reduces the pressure drop and avoids dust deposition inside the beds. The AMMIT prototype unit was designed to process 0.5 Nm3/s ventilation air of 0.3 -1.0 vol.% methane. The regenerative bed was designed with specified ceramic blocks. To preheat the regenerative bed during the start-up process, a special start-up burner was also designed. Overall assembly of the unit was completed in October 2012.

The VAMMIT prototype unit was successfully commissioned with some modifications such as fixing the ventilation air bypassing the regenerative bed, an assembling error caused by the contractor. A series of planned tests with simulated ventilation air of 0.5-0.7 Nm3/s with 0.3-1.25 vol.% methane were carried out. These experimental results demonstrated the VAM mitigation performance and advantages of the proposed novel honeycomb bed structure over the existing packed bed.

In addition to the original project scope, numerical modelling was developed using ANSYS Fluent software to simulate the VAMMIT process and to predict its performance. The model was validated by experimental data obtained from the VAMMIT prototype unit. Then scale-up numerical modelling with the validated governing equations and boundary parameters was used to predict the performance of a full scale VAMMIT unit processing 17Nm3/s of ventilation air. Based on the numerical simulation results of the full scale unit, it was found that the full scale unit should operate in a self-sustaining mode with 0.3% methane in air.

Based on the research outcomes the following R & D would be needed to develop a full scale VAMMIT unit:

· Site trials of a small pilot scale prototype unit;

· Ceramic material improvement including corrosion and thermal shock resistance depending on the site trial outcomes;

· Optimisation of honeycomb bed structure for better efficiency and maintenance;

· Scale-up and commercialisation.