ACARP ACARP ACARP ACARP
Mine Site Greenhouse Gas Mitigation

The Oxidation of Methane in Mine Ventilation Air Using Porous Burner Technology

Mine Site Greenhouse Gas Mitigation » Mine Site Greenhouse Gas Mitigation

Published: October 09Project Number: C14079

Get ReportAuthor: Andrew Harris | University of Sydney

One of the key challenges facing the Australian coal industry is to improve the sustainability of its operations and products. Previous research has demonstrated that significant gains can be made by mitigating the methane contained in mine ventilation air (MVA). Converting this methane into carbon dioxide will lead to an immediate reduction of 87% in global warming potential from coal mines in Australia, defined as the difference between emitting methane and carbon dioxide to atmosphere.

 

MVA emissions are characterised by very low methane concentrations (typically less than 1%) and high flow rates, with significant fluctuations in both. These attributes constitute the major barriers to the oxidation of the methane in MVA. Consequently, a cost effective mitigation technique has yet to be proven.

 

Porous burners are a possible lean-burn mitigation technology with the potential to overcome these challenges. They operate on the principle that the presence of a porous solid in the combustion chamber of the burner serves as a means of recirculating heat from the hot combustion products back to the incoming methane/air mixture; this preheating of the incoming mixture enables the burner to operate in 'ultralean' mode on gases with a methane concentration below the lean flammability limit for a free flame (5 vol% methane in air).

 

The project had two objectives: The first was to investigate the applicability of porous burners for the combustion of the methane component of MVA. This involved determining the lowest combustion limit able to be achieved, as well as operating and control methodologies for mine site implementation. The second was to investigate the underlying scientific principles of lean methane combustion, including the influence of firing rate and heat recovery. This research is relevant to all MVA mitigation technologies that use combustion, including the Megtec VocsidizerTM and CSIRO VamcatTM systems.

 

To meet both objectives, a novel porous burner with a design flowrate of 129 kg/hr and duty of 40 kW was constructed. The burner comprised a 90 cm high, 26 cm diameter cylindrical combustion chamber filled with a porous bed of 60% alumina, ½" ceramic saddles, combined with an arrangement of heat exchanger tubes for preheating the incoming methane/air mixture. In designing the burner a computational fluid dynamics model of gas flow into the combustion chamber was developed in order to verify the suitability of the design as regards providing an even flow distribution. The model was used to evaluate two alternative designs-one in which the methane and air feeds were separate, and the other in which they were premixed-the burner was ultimately constructed in the premixed configuration.

 

A series of experiments was undertaken in which burner operating conditions were systematically varied and the temperature profile in the porous bed measured to determine if, and where in the bed, the flame stabilized. The exhaust gas was monitored for carbon monoxide and unburned hydrocarbons to confirm that combustion was complete. In respect of the first project objective, results illustrating transient combustion at a feed methane concentration of 0.5% are presented, along with a novel control strategy for continuous operation of a porous burner system at an operating mine site that does not require a flow reversal system. In respect of the second objective, results illustrating the burner's full operating range, behaviour and performance are presented.

 

Stable (i.e. with a stable flame front) ultra-lean combustion was demonstrated at methane concentrations of > 3 vol% methane at firing rates between 50 and 300 kW/m2, with transient combustion (i.e. a moving flame front) observed for more dilute mixtures (0.5 vol%). The combustion process was very stable to perturbations in the methane concentration and flow rate, typically taking several hours to react to any changes. When operating in the transient combustion regime, the depth of the bed allowed for ~ 45 minutes of combustion before a spike of higher concentration gas was required to return to flame front to the bottom of the bed. This process could be repeated indefinitely.

 

The collective results from the project suggest that porous burners are a suitable technology for MVA methane mitigation; they are simple and low cost with similar performance limits to existing MVA combustion technologies.

 

Further research is recommended into the use of stable, high temperature combustion catalysts supported on novel porous materials that will improve operating performance (i.e. lower the methane concentration limit and reduce the bed pressure drop) and consequently decrease operating costs. The completion of an engineering study is also recommended; such a study should incorporate an assessment of the commercialisation potential of the technology, including capital and operating costs, mine vent integration and options for remote operation.

Underground

Health and safety, productivity and environment initiatives.

Underground

Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C19024Establishing Ecologically Sustainable Mine Water Release Criteria In Seasonally Flowing Streams

Extreme rainfall conditions in the Fitzroy Catchment over an approxi...

C25030Coal Mine Open Pit Final Void Closure And Relinquishment - Addressing Uncertainty In Coal Mine Environmental Planning

This report addresses uncertainties faced by coal mine operators whe...

C27046Estimation Of True Deformation Vector From Slope Radar Monitoring

Slope deformation radar monitors are now widely used in open cut coa...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27004Improving Coal Flotation With Oscillatory Air Supply

This report provides detailed information on coal flotation with os...

C25018Improving Solids Recovery And Moisture Reduction In Ultrafine Coal Dewatering

This report provides detailed information on fine coal dewatering in...

C27028Lab Froth Flotation Testing Guide With Coal Quality

Correct outcomes from laboratory froth flotation testing in coal bor...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C26039Nanoporosity In Cokes: Their Origin, Control And Influence On CO2 Reactivity

This project using the outcomes of previous project C24060, examine...

C28063A Comprehensive Technical Review Of High-Efficiency Low-Emission (HELE) Pulverised Coal Combustion Technologies For Power Generation

Research and development has been undertaken worldwide to realise co...

C28064Carbon Structure Transformation During Coking Of Australian Coking Coals: Better Understanding The Coke Formation

Carbon structures of coke that are formed during the plastic layer a...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

C26004CFD Modelling Of Reverse Thermal Oxidisers For VAM Abatement - CFD Modelling Of Fixed-Bed RTO Devices

The project is part of a larger multi‐phase program of study a...

C27058Technological Assessment Of A Recycle Reactor For VAM Abatement

Underground coal mining emits high volumes of methane, diluted in ve...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community

NERDDC

National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook

NERDDC