OCR Text |
Show mixing of the air introduced through the OF A pons minimizes this concern and any potential CO emission problems. Variation of unburned combustibles with reburn zone parameters such as coal fineness, fuel split, and FGR were determined by numerous measurements. Fly ash samples were withdrawn isokinetically from the stack and analyzed for combustibles. In addition, total mass loadings of the fly ash were measured in order to determine the combustion efficiencies for baseline and reburning conditions. Figure 4 shows the carbon content of the fly ash for baseline and reburning conditions. Unburned combus- 1.1 • BASEUNE CONDmON 1 - (NO REBURNING) REBURNlHG CONDmON- • STANDARD GRIND (63% THROUGH 200 MESH) iczi i 0.9 - • MEDIUM GRIND (711'% THROUGH 200 MESH) • ANE GRIND (110'% THROUGH 200 MESH) C III ;:) c O.B E. i" Q. e:. 0.7 o· ~ • 0 0.6 - ~ c '~" III 0.5 - c~ c ~. 0.4 0.3 0.2 0.8 0.9 tibles for the SBS baseline conditions are low (less than 1 %). Operating under the reburning mode increases the fly ash carbon content to approximately 4 to 10% (depending on the reburn coal input and coal fineness). At the reb urn zone stoichiometry of 0.9 (full-scale design point) for utilizing the fine grind coal, unburned combustibles content of the fly ash was approximately 5%. The combustion efficiencies were calculated from percent ash in the convection pass, carbon content of the fly ash, and coal analysis. The overall change of combustion efficiencies between the baseline condition and reburning with fine grind coal was only 0.05%. INDIANA LAMAR COAL; 3% STACK 0,; 6-MlWON BTUlHR 11 12 REBURN ZONE STOICHIOMETRY Rgurl 3. Pllot·Sea/. NO. Em/sslolu 1.15 10 9 B t 7 ~ '~" 6 0 u z 0 5 GI II: C U ~ 4 c ~ ..J ~ 3 2 • 8ASEUNE CONDmON (NO REBURNING) REBURNING CCHOmON-REBURN ZONE STOICHIOMETRY 0.15 • STANDARD GRIND (63% THROUGH 200 MESH) • MEDIUM ORIND (78% THROUGH 200 MESH) • ANE GRIND (110'% THROUGH 200 MESH) 0..8 0.85 INDIANA LAMAR COAl; 3% STACK 0 ,; I-MILUON BTUlHR o ~----~----~------r-----~-----r----~-----.----~ o 10 20 30 PERC£NT RESURNING Figure 4. Pllot-Sc,,. Combustible L".,., 4 |