All the experiments are conducted in a 0.45 m I.D. pilot scale vortexing fluidized bed combustor. In this work, rice husk, soybean, and high sulfur subbituminous coal are used as feeds and silica sand is employed as the bed material. The effects of various operating conditions, such as bed temperature, excess air ratio, fuel property, and method of temperature control on NO and N{sub}2O emissions have been investigated. The experimental results reveal that NO emissions increase with excess air ratio and are almost independent of bed temperatures (650°C-760°C). In addition, the amount of NO and N{sub}2O increases while water is injected into the combustor. The high-volatile fuel appears to form significant amount of NO and N{sub}2O above the bed surface, however, NO emission detected at the outlet of the combustor decreases with volatile content. Compared with the primary air, bed temperature is the dominant factor for the trade off of NO and N{sub}2O. Generally speaking, most of NO is formed above the bed surface; achieves a maximum value at the position below the inlet of secondary air, and reduced considerably within the freeboard. The amount of N{sub}2O emitted from the combustion of biomass is minimal.
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