Insights

Mercury and other trace metals in the gas from an oxy-combustion demonstration plant

Organisation: Australian National Low Emissions Coal Research & Development (ANLEC R&D), Macquarie University

            

 

To highlight the research and achievements of Australian researchers, the Global CCS Institute together with ANLEC R&D will hold a series of webinars throughout 2017. Each webinar will highlight a specific ANLEC R&D research project and the relevant report found on the Institute’s website. This is the seventh webinar of the series and presented the results of a test program on the retrofitted Callide A power plant in Central Queensland.

The behaviour of trace metals and the related characteristics of the formation of fine particles may have important implications for process options, gas cleaning, environmental risk and resultant cost in oxy-fuel combustion.  Environmental and operational risk will be determined by a range of inter-related factors including:

  • The concentrations of trace metals in the gas produced from the overall process;

  • Capture efficiencies of the trace species in the various air pollution control devices used in the process; including gas and particulate control devices, and specialised systems for the removal of specific species such as mercury;

  • Gas quality required to avoid operational issues such as corrosion, and to enable sequestration in a variety of storage media without creating unacceptable environmental risks; the required quality for CO2 transport will be defined by (future and awaited) regulation but may be at the standards currently required of food or beverage grade CO2; and

  • Speciation of some trace elements 

Macquarie University was engaged by the Australian National Low Emissions Coal Research and Development Ltd (ANLEC R&D) to investigate the behaviour of trace elements during oxy-firing and CO2 capture and processing in a test program on the retrofitted Callide A power plant, with capability for both oxy and air-firing. Gaseous and particulate sampling was undertaken in the process exhaust gas stream after fabric filtration at the stack and at various stages of the COcompression and purification process. These measurements have provided detailed information on trace components of oxy-fired combustion gases and comparative measurements under air fired conditions.  The field trials were supported by laboratory work where combustion took place in a drop tube furnace and modelling of mercury partitioning using the iPOG model.
 
The results obtained suggest that oxy-firing does not pose significantly higher environmental or operational risks than conventional air-firing.  The levels of trace metals in the “purified” COgas stream should not pose operational issues within the COProcessing Unit (CPU).

This webinar was presented by Peter Nelson, Professor of Environmental Studies, and Anthony Morrison, Senior Research Fellow, from the Department of Environmental Sciences, Macquarie University.

Here is a recording of the webinar and a browsable version of the slides used in the presentation: