OCR Text |
Show SUMMARY The results reveal the sensitivity of burner perfonnance to the preparation of the fuel-air mixture. In the present case, the processes of mixing significantly and dramatically affect the fonnation and emission of NOx as well as the combustion efficiency. The challenge is to understand why this behavior occurs and, once the understanding is in place, to identify criteria in the design that minimizes the formation of NOx concomitant with a maintenance or, ideally, an increase in combustion efficiency. This, in fact, is the goal of the present program. With regards to the relationship between combustion efficiency and NOx emission, the current data set is encouraging. A composite of the results is presented in Figure 8. Note that there is one condition (30% excess air, radial injector, low swirl) where the NOx is markedly reduced (25 ppm) without a sacrifice in overall combustion efficiency (99.9%). This condition, as well as others yet to be uncovered with similar and potentially enhanced perfonnance, will provide valuable insights relative to (1) the fuel-air mixing characteristics that give rise to desired NO perfonnance without undue sacrifice of efficiency, and (2) practical burner design strategies. Further parametric study, modelling, and in-situ measurements are underway to reveal and understand these conditions. 60.00 50.00 E 40.00 ~ d 30.00 Z 20.00 10.00 0.00 10% 100/0 200/. 200/. 3001. 400/0 Excess Air - ..0.. _-Axial Swlrt - ...........- 90" Swirt 6 Rad. . SwIr1 Figure 8: 100,000 Btu/hr-Composite Results 11 1.00 0.90 0.80 0.70 0.60 "'C 0.50 'i (f) 0.40 0.30 0.20 0.10 _ ......... 0.00 40% |