Factors Affecting NO Reduction during O_2/CO_2 Combustion

摘要

O_2/CO_2 combustion is a promising technology to facilitate carbon capture in pulverized coal-fired power plants. The reduction of recycled NO, influence of CO_2 concentration on the conversion ratio of fuel N to NO, interaction between recycled NO and fuel N, and other factors were experimentally investigated, and correlations were quantitatively obtained. The conversion ratio from fuel N to NO increased with an increasing CO_2 concentration in the absence of coal but decreased in the presence of coal The reduction ratio of NO in the recycled gas depended upon the oxygen/ fuel stoichiometric ratio, X, and increased with the NO concentration in the recycled gas when X = 0.7 and 1.0 but decreased when X = 1.2. The conversion ratio from fuel N to NO decreased with an increasing NO concentration in the recycled gas, because of the interaction between fuel N and recycled NO. The global conversion ratio from fuel N to exhausted NO in O_2/CO_2 combustion was derived from the experimental results and analysis of the system. The relative importance of different factors in the low conversion ratio from fuel N to exhausted NO in O_2/CO_2 combustion has been quantified and found to depend upon X. Under all conditions investigated, the reduction of recycled NO was the major factor (over 70%) contributing to the low NO emission in O_2/CO_2 combustion.