OCR Text |
Show - 6 - level. The following ranges of flue gas emissions measured are shown in the table below: Gottelborn/ Danish coal/ Med Mac/ Straw Straw Straw NOx (ppm) 150-1000 150- 900 150-950 S02 (ppm) 200-850 200-2000 200-575 HCl (mg/m3 275-40 275-40 300-20 Burnout (%) 96-99.9 96-99.9 95-99.4 For all three coals similar NOx trends were observed, as shown in Figure 6. The main parameters affecting the NOx and S02 emissions are co-firing ratio, coal type and burner staging. For the high intensity un-staged flames, an increase in Hel emission from 30 up to approximately 200 mg/mo3, for 00/0 straw to 40% straw respectively, was observed for all three coals. This is due to the relatively high chlorine content in the straw (0.280/0). The effect of flame type and co-firing ratio on the HCl emissions is less clear, especially for the medium volatile coal. In general burnout decreases when co-firing is practised. In the cofiring range of 10-20 % straw input, burnout is lower, 97-990/0, when com pa red to 100% coal firing, see Figure 7. In general burnout is slightly lower for the medium volatile bituminous coal. This indica tes a trend of preferential burning of the higher volatile fuel [3] . I-Io'\"v'ever, t\,VO competitive effects are to be considered when analysing the burnout of a straw /coal flame i.e. the relatively |