Coal combustion is responsible for roughly one-third of the CO2 emissions in the United States. Capturing CO2 from conventional coal-fired power plants could be very costly because of the low concentration of CO2 in the flue gas. One approach to increase the CO2 concentration is to remove the nitrogen from the oxidizer, so-called Oxy-combustion. In this scenario, cooled flue gas is recycled back to the combustor to control temperature. Our previous studies in a lab-scale drop tube furnace reported the effects of this type of combustion on submicrometer particle formation. When the N2 in air was replaced with CO2, submicrometer particle formation and growth via nucleation and condensation was delayed due to the higher heat capacity of CO2 compared to N2, which deterred volatilization of coal and char(1). In the present work, the effects of the oxy-coal combustion on the formation and fate of multi-pollutants, including submicrometer particles, gaseous mercury and toxic elements, are investigated in a 25 kW coal-fired combustor. The aerosol characteristics, including the size distribution, morphology and composition of submicrometer particles are examined using the Scanning Mobility Particle Sizer (SMPS), Scanning Electron Microscopy (SEM), and X-ray fluorescence spectroscopy (XRF). Gaseous mercury is measured using the method developed by Hedrick et al.(2). Partitioning and forms of trace elements is determined using leaching analysis procedure developed by Finkelman et al(3). The results are compared with those obtained under air-coal combustion. The aerosol characteristics of submicrometer particle are also compared with those obtained from the lab-scale drop tube system1.

References: 1. Suriyawong, A.; Gamble, M.; Lee, M..H.; Axelbaum, R.L.; Biswas, P., Energy & Fuels, 2006, 20(6), 2357-2363. 2. Hedrick, E.; Lee, T.G.; Biswas, P.; Zhuang, Y., Environ. Sci. Technol., 2001, 35(18), 3764-3773. 3. Finkelman, R.B.; Palmer, C.A.; Krasnow, M.R.; Aruscavage, P.J.; Seller, G.A.; Dulong, F.T., Energy & Fuels, 1990, 4, 755.

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