In this fifth installment of a 14-part series of monthly articles, The Combustion Institute recognizes the 2017 Distinguished Papers selected from among the scientific papers presented during the 36th International Symposium on Combustion. Congratulations to Myrrha E. Andersen, Nabanita Modak, Christopher K. Winterrowd, Chun Wai Lee, William L. Roberts, Jost O.L. Wendt, and William P. Linak for winning the DPA in the Formation and Control of Pollutants and Greenhouse Gases colloquium.

The authoritative paper, Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion, explores environmental issues (unintended or beneficial) associated with developing air pollution control technologies. Coal combustion in an oxygen-carbon dioxide environment is notably different than combustion in oxygen-nitrogen (air). While previous research efforts have focused on issues involving suppressed ignition, flame stability, and heat transfer, far fewer studies have looked at the environmental impacts.

The scientific team’s research has expanded current understanding of organic and black carbon emissions from pulverized coal combustion, added to informed current emission inventories, and explored differences in organic and black carbon behavior between conventional air-coal, and developing oxy-coal combustion technologies. The team has successfully determined that carbonaceous emissions including both soot and organic hazardous air pollutants can be minimized in oxy-coal combustion.

The outcomes of the paper have an immediate impact on the understanding of submicron particulate emissions. Measurements performed during previous studies suggested black carbon comprised a significant fraction of submicron aerosol. The scientific team discovered an inverse relationship with particle diameter; black and organic carbon dominated the submicron aerosol. That finding suggests that, contrary to previous understanding, inorganic ash components often comprised a relatively small fraction of the submicron particles. Comparison of relative amounts of submicron black and organic carbon over four experimental conditions (air-coal and three oxy-coal) allowed the team to identify separate mechanisms of organic and black carbon formation consistent with oxy-coal combustion’s effect on ignition delay, and therefore, propose methods to minimize both organic and black carbon.

In the long-term, the scientific team believes the extra degree of freedom offered by oxy-coal combustion to independently control the relative amount and placement of oxygen within the flame will provide a significant benefit to increase combustion efficiencies. The research will also help to minimize both hazardous organic air pollutants and black carbon. The beneficiaries of the research include the U.S. Environmental Protection Agency (EPA) program offices that contend with the environmental consequences of developing energy technologies. Other beneficiaries include boiler manufacturers and energy utilities that will develop a new generation of efficient and environmentally sustainable combustion systems.

The scientific team’s work was conducted primarily at the EPA Office of Research and Development’s combustion research laboratories. For oxy-fuel research, EPA/ORD operates the 10 W entrained flow reactor used for these experiments and a 50 kW furnace with integrated compression and purification unit (CPU), designed to study pollutant formation, behavior, and partitioning in both the oxy-coal combustor and the subsequent CO2 treatment processes. Research for the paper was initiated in 2011 and completed in 2015.

About 1,300 papers were submitted to the 36th Symposium in 14 combustion science colloquia. Those papers were categorized by teams of colloquium coordinators and co-chairs, and then distributed to approximately 1,000 scientific reviewers. One paper in each discipline was awarded the recognition of Distinguished Paper.

The 14 Distinguished Papers undergo committee review for consideration to receive the Silver Combustion Medal that will be awarded during the 37th Symposium in Dublin, Ireland. A paper selected for this honor exemplifies quality, achievement, and significance to advance a field of combustion science. Distinguished papers are selected biennially from among the scientific papers presented during the International Symposium on Combustion and accepted for publication in the Proceedings of The Combustion Institute.