10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Understanding Early Stage Processes during Pulverized Coal Combustion in a Two-stage Flat Flame Burner
DISHANT KHATRI, Adewale Adeosun, Akshay Gopan, Zhiwei Wang, Richard Axelbaum, Washington University in St. Louis
Abstract Number: 1756 Working Group: Combustion-Generated Aerosols: the Desirable and Undesirable
Abstract In pulverized coal burners, coal particles transition from a short period of locally reducing environment, caused due to the fast release of volatiles from a dense region of coal particles, to an oxidizing environment. This “reducing-to-oxidizing” transition can influence combustion processes such as ignition, particulate formation, and char burnout. Traditionally, fundamental studies on coal combustion have been conducted in systems which neither capture the “reducing-to-oxidizing” transition nor the high a heating rate of practical combustors. In this work, the formation and evolution of sub-micron particles are investigated in a novel two-stage flat flame burner that simulates the “reducing-to-oxidizing” transition and with heating rates on the order of 105 K/s. The particle size distribution (PSD) of the sub-micron particles, and their composition are measured using SMPS and SEM-EDX, respectively. Measurements are carried out under both an oxidizing environment (20% oxygen) and a “reducing-to-oxidizing” environment at two different nominal gas temperatures (1300 K and 1800 K), and three residence times (15, 30 and 60 ms). To differentiate between soot and mineral matter, the SMPS is operated in a tandem fashion, with a high-temperature furnace between the two SMPS measurement locations. The furnace is supplied with a sufficient amount of oxygen to burn off soot in the sampled aerosol stream. The results, including the difference between the oxidizing and reducing-to-oxidizing environments, will be discussed.