| OCR Text |
Show Fuel velocity Fuel velocities were varied from 225 to 750 fps. There appeared to be a small improvement in N O x emissions as velocity increased. Velocities below 300 fps often resulted in poor flame appearance and furnace pressure pulsation, and occasionally in higher C O emissions from the furnace. Fig. 7 shows a typical comparison of N O x emissions for varying fuel velocity. 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 H R a m air/LNI NOx emissions; 3 injectors, injector angle = 5, t - 4 Jx£* *^ • i velocity = 226 fps • velocity = 750 fps 1900 2000 2100 2200 Terrperature, F 2300 2400 Figure 7 Number of injectors Work to date regarding optimum number of fuel injectors is inconclusive. Some configurations performed as well or better with one injector than with three. Others appeared to be slightly better with three injectors. Results of our laboratory testing of LNI with the HiRam burner conclusively demonstrate that N Ox emissions can be dramatically reduced by application of LNI method to burners fired with natural gas and ambient air. Fig. 8 shows a comparison of N O x emissions for an LNI burner compared with a conventional low N O x burner firing into the same furnace. The N O x emissions at 2000 F were 0.017 lb/MMBtu for the LNI burner, compared with 0.06 lb/MMBtu for the same burner fired in conventional mode. 9 |
