Predicting N sub 2 O emissions from circulating fluidized-bed coal combustion

A parametric pilot-scale investigation of three low- and two high-rank coals has shown that temperature and coal type are the dominant parameters influencing nitrous oxide (N{sub 2}0) emissions. Excess air, limestone feed rate, and air split have a minor impact on N{sub 2}0 emissions. A model to predict N{sub 2}0 emissions has been developed and will be refined with further experimentation. Typically, N{sub 2}0 measured emissions from atmospheric FBCs can range from 40 to 200 ppM, depending on the coal properties and operational and design parameters. In contrast, pulverized coal-fired boilers emit very low levels (0-10 ppM) of N{sub 2}0. The purpose of this paper to report the effect of key operating parameters, the relative importance of coal type, and the potentially significant coal properties for producing N{sub 2}0 emissions in a circulating fluidized-bed combustor (CFBC). The generation of N{sub 2}0 emissions is quantified in an empirical model based on the experimental data.