Coal Quality Testing of Six Coals in a Pilot Scale Combustion Facility Upgraded to Simulate Modern Power Station Capabilities

The Australian export thermal seaborne coal market has grown significantly over the last 25 years and apart from the growth of the market, there have been a number of significant developments in the industry over the last couple of decades.  Technology utilised by end users of Australian coals has advanced significantly during this timeframe and producers need access to a test facility that can simulate these to maintain competiveness.  The ALS-ACIRL pilot scale combustion test facility is one of the few independent facilities available in the world for testing thermal coals.  Since its construction and commissioning in 1985, is has been used extensively to evaluate coal quality, investigate beneficiation and blending options, and conduct numerous research programmes aimed at improving the understanding of aspects of thermal coal combustion.  The primary objective of the research project was to upgrade ALS-ACIRL's pilot scale combustion facility to simulate modern power plant technology.  The upgrade proposed a modification of the burner from the conventional burner to a low-NOx burner.

CFD modelling was performed by the University of Newcastle to assess potential design modifications and recommend a design.  The design was validated with a series of combustion tests to investigate NOx reduction potential and impact on burnout efficiency.  The validation tests confirmed NOx reductions in the order of 30 percent could be made with only a small impact on burnout efficiency.

Modifications were made to the combustion furnace to allow tertiary air flow through eight nozzles located around the burner.  Two nozzles diameters were investigated.  Several validation tests with two test coals showed NOx emissions could be reduced by approximately 30 percent but with a detrimental effect on burnout efficiency.  Utilising the larger diameter nozzle which produced a lower tertiary air velocity, the deterioration in burnout efficiency was acceptable whereas the small diameter nozzle produced unacceptably low burnout efficiencies.

ALS-ACIRL's combustion test facility was successfully upgraded to simulate a first generation low-NOx combustion burner which is capable of reducing NOx emissions by up to 30 percent.  The upgraded facility is capable of differentiating coal quality performance between different coals.