OCR Text |
Show conducted with a conventional Type R nozzle; ten advanced Type R nozzle configurations were also evaluated. The baseline nozzle (Figure 4) was comprised of the tangential fuel inlet, coal stream deflector vanes, and a spirally rifled nozzle with a convergent tip. A furnace side view of the baseline Type R coal nozzle is shown in Photo 5. ~' ~/:' SPIRALLY· RIFLED TIP SPIRALLY·RIFLED NOZZLE TANGENTIAL FUEL PRIMARY AIR INLET .. 'DEFLECTOR VANES Figure 4: "Baseline" Type R Coal Nozzle Schematic Photo 5: Furnace Side View of the "Baseline" Type R Coal Nozzle Combustion test data from the "BaseJine" RO-II configuration is shown in Figure 5 which depicts NOx (ppm corrected to 3% O2) as a function of flue gas O2 concentration. As is characteristic of a diffusion flame burner, NOx increases with increasing excess air level. The primary point of the figure is that at a nominal excess air level of 20% (approx. 3.5% O2) , measured NOx was approximately 650ppm (approx. 0.9 Ib/MBtu). Under all excess air conditions, NOx exceeded the target value of 0.5 Ib/MBtu. The most optimum coal nozzle arrangement of the ten tested is shown in Figure 6. As shown in the schematic, the optimum RO-II coal nozzle retains the tangential fuel/primary air inlet, deflector vane assembly, and spirally rifled nozzle of the Type R design. The optimum RO-II arrangement includes the addition of a venturi diffuser assembly, which is a channeled flow control device, and a convergent nozzle tip with axial rifling vs. spiral rifling as in the baseline case . Photo 6 is a "furnace Side" view of the optimum nozzle arrangement. 4 ~r-------------------------------------~ S 700 ~ 600 2 500 Q. Q. il I 200 +-----,--~~-----,-~ I 61 Figure 5: "Baseline" Nozzle Assembly, NOx vs. O2 TANGENTIAL FUEL'PRIMAAY AIR INLET + n ~ L - I VENTURI DIFFUSER ADJUSTMENT RODS ...J.--,~======~~ . r--S-W-FF-'NG--80-X-FO-~--=r-=---~--~~,,~ . AXIAL NOZZLE ADJUSTMENT SPIRIALLY.RIFLED DEFLECTOR VANES NOZZLE ~~ NOZZLE TIP WITH I:J..j A><~""UNG Figure 6: Venturi Diffuser Nozzle Assembly, Test EqUipment Schematic Photo 6: "Furnace Side" View of the Optimum Nozzle Arrangement for the RO-II Burner |