Additional literature concerned with co-firing FB with coal may be found in papers by Anna — malai et al. (2007a, 2007b), Sweeten et al. (2003), Frazzitta et al. (1999), Arumugam et al. (2005), Annamalai et al. (2003) and Annamalai et al. (2003b). However, most co-firing experi­mental results with FB seem to indicate that NOX emissions did not increase and sometimes even decreased. Therefore, it is hypothesized that FB may also be used in reburning facilities to both partially supplement coal and to reduce NOX emissions.

3.11.1 NO emissions with longer reactor

The comparison of the NO measurements normalized to 3% O2 in the exhaust with that of Frazzitta et al. (1999) is given in Figure 3.36. The measurements are depicted for the co-firing of 80:20 coal:FB blend with a 97% burnt fraction. Under both study conditions, a similar fuel N conversion efficiency of ~ 16% was observed. However, a lower NO value was measured as compared to the previous study, which might be attributed to the longer residence time available in the modified reactor. The residence time in the prior study was ~0.5 s at hot conditions as compared to ~1sin the modified longer reactor. The higher duration available in the longer reactor aids the reduction of NO to further lower values. The increased residence times with modified reactor attributes 17% reduction in the normalized NO emission.