(487d) Ash Formation and Deposition During Oxy-Coal Combustion

Oxyfuel combustion is an attractive option for coal-based power generation with CO2 capture. However, there are a number of engineering challenges that must be addressed before this technology can be successfully deployed. Ash deposition is one that has significant impacts on power plant design and operation but has not been well investigated under oxy-coal combustion conditions. This paper is designed to explore ash formation and deposition during oxy-coal combustion with once-through CO2. All experiments were conducted in a down-fired oxy-fuel combustor with a designed capacity of 100 kW. To investigate the effects of oxy-firing, air-coal combustion experiments were also carried out for comparison purposes. Combustion conditions under consideration included: (a) air; (b) 27%O2/73%CO2; (c) 32%O2/68%CO2. The excess oxygen in the flue gas for all combustion cases was fixed at 3%. Ash particle size distributions (PSDs) were obtained through a Berner Low Pressure Impactor (BLPI). BLPI size-segregated ash, bulk ash and deposit samples were collected and subjected to chemical analyses. The physico-chemical properties of the ash and deposit samples were characterized. Such information was used to identify major constituents that contributed to ash deposition, which were also correlated to ash properties. Differences in ash and deposit properties between air- and oxy-firing were discussed. Features of ash formation and deposition during oxy-coal combustion were generalized.