The University of Newcastle, Australia

This significant $27million five-year project aims to determine the critical science and engineering issues that underpin safe operation of Ventilation Air Methane (VAM) capture ducts, part of Large-Scale VAM abatement systems proposed by the Australian coal industry to address fugitive emissions.

Methane is a potent greenhouse gas that is around 25 times more effective as a global warming agent than carbon dioxide.

Fugitive methane emissions from underground coal mining account for 28.3million tonnes, or around 5% of Australia’s CO2 equivalent greenhouse gas emissions.

These emissions arise from a range of sources that must be mitigated where possible to reduce environmental impacts.

Coal mine methane (CMM) is captured from working mines by various means such as pre and post drainage, and within the mine’s ventilation stream where it is known as Ventilation Air Methane (VAM).

A critical area of concern for the operation of VAM abatement plants on a coal mine sites is the explosion hazard, and how to effectively counteract a potential explosion event should it  happen.

The principle vision of this project is to facilitate the uptake of existing, emerging and next generation VAM abatement technologies by establishing a validated set of safety design guidelines.

Scientists and engineers have tested and quantified a range of potential gas and gas-particulate hazards while trialling technologies to prevent or mitigate explosions. Data from the project will inform and enable safer engineering and policy solutions for the coal mining industry in Australia and beyond.

The Project is led and conducted by the University of Newcastle in partnership with South 32, Glencore and the Australian Coal Association Low Emissions Technologies Ltd (ACALET).

A series of project outcomes, including the demonstration of a Large-Scale VAM capture duct complete with safety control measures and supporting design and testing information, will provide greater understanding of the underlying science and engineering issues that are necessary for the development of industry guidelines.

This project will provide substantial industry-wide benefit through the removal of technical barriers currently preventing full-scale commercial deployment of VAM abatement technologies.

The scope of the project is focused on addressing safety issues and control measures associated with the VAM capture duct given the crucial role of this component in the safe introduction of any VAM abatement technology platform into a coal mine.

The principle vision of this project is to facilitate the uptake of existing, emerging and next generation VAM abatement technologies by establishing a validated set of safety design guidelines.

The Project is led and conducted by the University of Newcastle in partnership with South 32, Glencore and the Australian Coal Association Low Emissions Technologies Ltd (ACALET). The Project is structured under a flagship model to maximise collaboration among researchers, government and industry.

Project Leader

Prof. Behdad Moghtaderi

Project Manager

Dr Jafar Zanganeh

Chief Investigators

Prof. Behdad Moghtaderi

Dr Jafar Zanganeh

Project Sponsors

Commonwealth (50%) & ACALET (50%)

Number of Project Phases

4

  

Total Project Budget

$26,951,400 comprising $24,998,696 cash and $1,952,704 in-kind

Project Duration

4 years plus 9 months extension

Project Start Date

19 July 2013

Project End Date

March 2018

A critical area of concern for the operation of VAM abatement plant on a coal mine site is the explosion hazard and how to effectively counteract a potential explosion event should this mishap eventuate.

Upset conditions within the mine such as outburst or strata failure could lead to a sudden spike in methane levels within the VAM above the lower explosive limit or LEL of 5%.

The VAM abatement units are a likely ignition source if preventable controls do not divert or dilute the flammable mixture before it enters one or more of the abatement units.

An explosion with a resultant flame and pressure wave may be directed back towards the mine and claims lives and property damage.

Deflagration and Detonation

Deflagration and detonation are two types of explosions reported widely in extractive industries.

A deflagration is the most common type of fire and explosion characterised by a combustion front moving at a sub-sonic flame speed, a separate pressure wave of up to 10 Bar influenced by a heat transfer propagation mechanism.

A transition from deflagration-to-detonation or DDT can occur when the combustion zone couples with the shock wave to form a more violent detonation type explosion. A detonation is the most violent form of explosion with greatest potential for severe damage with pressures in the range of 20 to 80 Bar.

The flame can increase to supersonic speeds under a compression propagation mechanism by the influence of confinement and/or obstructions interaction.

Countermeasures

Countermeasures are defined as “an action taken to counteract a danger or threat”.

Such extrinsic or add-on safety measures typically are applied as separate layers of protection and are seen as a last line of defence should earlier actions directed to defeat the accident sequence (e.g. inherent safety, dilution etc.) fail to achieve the required level of tolerable risk.

Choosing an optimum countermeasure system involving one or more categories is recognised as being a complex and difficult task, particularly for a highly variable hybrid gas/dust mixture such as VAM.

Also one must consider the potential for a deflagration low intensity type of explosion to transition to a more intense detonation type explosion under suitable conditions.