A TRIAL TO SEPARATE FORMATION AND REDUCTION PROCESS DURING NO EMISSION IN FLUIDIZED BED COAL COMBUSTION
A new approach to evaluate NO formation and reduction processes separately in fluidized bed coal combustion has been investigated. Sixteen different coals were burned in a lab-scale bubbling fluidized bed combustor with three different char loadings by changing the inlet oxygen concentration to 20 ％, 15 ％ and 10 ％. When O2 consumption rate in the bed becomes zero, N conversion ratio to NO (XNO) indicates a special value without contribution of NO reduction by char particles in the bed. We call it “ultimate NO conversion ratio (XNO *). This imaginary NO conversion ratio, XNO *, expresses an NO conversion of a coal particle which burns singly in a fluidized bed combustor. Since there are no other char particles in the bed, XNO * should express a coal’s original NO emission. XNO * can be determined by an extrapolation of a line, which is determined by a least-squares method, showing the relationship between XNO and O2 consumption rates for each tested coal. By this technique, the contribution of char particles to NO reduction and the original NO emission of the tested coals can be separated from each other. XNO * depended on the N content and O/N molar ratio. Effect of the bed temperature on the sensitivity of XNO on char loading, which expresses the effect of NO reduction by char particles, was very different among the different coals. On the other hand, the contribution of char particles on N2O emission was affected little and experiments showed that a burning char particle cannot reduce N2O. This result suggests that the reduction by the char particles involves the competitive reaction of NO and N2O, and the effect of the N2O reduction by burning char particles was less than NO reduction. Consequently, experiments showed that the effect of NO reduction by char particles was very important in the fluidized bed combustion when final NOx emission is evaluated deeply.
NO coal fluidized bed combustion ultimate NO emission char
T.Murakami Y.Suzuki A.K.Durrani
Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technolo University of the Punjab, Pakistan
国际会议
第20届国际流化床燃烧会议(20th International Conference on Fluidized Bed Combustion)
西安
英文
1005-1010
2009-05-18（万方平台首次上网日期，不代表论文的发表时间）