OCR Text |
Show (4) The Effect of Using Staged Air and Adding Cooling water Fig.9 and Fig.10 show the NO and NOx concentration profiles respectively by adding cooling water and staged air at different total excess air 13% and 20%. Results show that the lowest nitrogen oxides emissions were at ~ -1= 0.65-0.7 which agrees with Takagi's data [8] and Chen's data [4]. Adding cooling water to reduce local flame temperature at l/D=5, nitrogen oxides would reduced about 10-16%. And, as reducing local flame temperature at l/D=8, nitrogen oxides would reduced about 3-4%. So, when adding cooling water with staged air at l/D=5 could get lower nitrogen oxides formation at about 20-22 ppm. Conclusions In this study, the conclusions are: 1. At the stoichiometric ratio, the formation of NO and NO x reach maximum values. And,NO and NO x emissions will increase with increasing radial air flow rate. 2. At lower equivalent ratio, lowest CO emission by ad justing radial as rate could be found when the axial air flow is fixed. 3. Adding cooling water without staged air at l/D=8 (120 cm from burner) could lower nitrogen oxides emission. 4. Adding cooling water with staged air at l/D=5 (75 cm from burner) could lower nitrogen oxides emission. 5. At ~ -1=0.65-0.7, the lowest nitrogen oxides emission could be found. |