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Show BOO 700 600 ON ~ 500 en @ ~ 400 '0 e- o. a. 300 )( 0 Z 200 100 o 0 0 6. "il 0 f- + f-f-f-o -10- EI Cere/on I Middleburg Ap",1 . 1S, Tertiary air : antl-clockwlse swirl Ap =1 .0S, Tertiary air : anti-clockwlss swirl EI Cere/on I EI Cerejon Ap.,1 .1S, Tertiary air : clockwise swirl 8 Ap:1 .0S, Tertiary air : clockwise swirl B Cerejon I Natural GBS 6. Ap.,1 .1S, Tertiary air : clockwise swirl "il Aps l .0S, Tertiary air : clockwise swirl 9 I 10 20 Rebum fuel fraction (%) 0 6. ~ + t 30 Figure 9 Effect of rebum fuel fraction on NOx These results confirm the previous findings in that NOx can be reduced when the reburn fuel is high in volatile matter and reactivity. Burnout The burnout values presented in the following figure was obtained using the expression: [ 1- original ash % in coal ] ( ) _ residual ash% in solid * Burnout Tx -[1 - on.g.m a1 as hO10 Ii' ll coa1 ] 100 100 Gottelborn as primary fuel: Natural Gas or Gottelborn as reburn fuel Figure 10 shows that burnout values with the baseline burner (gbbase) were in the range 98.8 - 99.9%. Reburning with natural gas (gbng) or Gottelborn coal (gbgb) shows that for the majority of cases burnout is > 99 %. There was no significant difference in burnout when reburning with natural gas or coal. However, it is observed that NOx emissions are lower when reburning with na tural gas and that the common factor with burnout levels in the range 98.5 % <Tx< 99 % was when the tertiary air was introduced within the burner itself, i.e. at position 1 or 2. |