OCR Text |
Show residue containing almost 0,o*% organic nitrogen, and gave a result of 255 ppm * of NOx at 1.6% excess oxygen, (8% excess air). Extrapolating from the curve of results, this would give less than 200 ppm * at 0.5% excess oxygen, (2i% excess air). At a 7 % lower heat release, a similar steam generator fitted with a conventional forced draft burner using a special oil gun having a long, narrow, low intensity type flame which should be good for suppressing NOx, gave approximately 450 ppm * of NOx at 0 to 2 percent excess oxygen, (0 to 10 percent excess air). It is interesting to note that using the method of approximating NOx described above at 15% of excess air without constants, gives 45 ppm NOx (fixation) plus 550 ppm NOx (fuel) making a total expected 595 ppm. Thus the toroidal combustor produced 43 percent of expected NOx and the conventional long flame burner was 76 percent of expected NOx, a 33 percent improvement in favor of the toroidal combustor. FIELD RESULTS NOISE The graph shown in figure 6 illustrates the results of noise level tests performed on a toroidal combustor firing at 70 MM BTU/hr. using heavy oil fuel. In order to minimize the effect of background noise from fans, motors, steam traps and furnace resonances, the readings were taken at three distances away from the outer air casing. The IS085 curve shown is a standard for sound level exposure of operators during the course of an eight hour day. Above this level damage to unprotected human hearing may result. CONCLUSIONS \^^->' The high velocity combustor described has demonstrated the practical feasibility of reducing NOx formation in a burner that is very acceptable processwise. (*AII ppm NOx corrected to 3% oxygen, 16j% excess air in flue gases for mass flow comparisons. ) 13/13 |