TY - JOUR
TI - Influence of over fire air system on NOx emissions: An experimental case study
AU - Hodžić Nihad
AU - Kazagić Anes
AU - Metović Sadjit
JN - Thermal Science
PY - 2019
VL - 23
IS - 3
SP - 2037
EP - 2045
PT - Article
AB - In this work, various combinations of the NO emission influencing factors and their x combined effects in air staging combustion on level of furnace, using over fire air, were investigated in an experimental lab-scale furnace. At this, process temperature were varied in the range from 950°C to 1450°C, excess air ratio in primary zone in the range λ = 0.9 - 1.2, while distance of over fire air nozzles from the burner outlet varied until a 1 given distance of 2/5 of total length of furnace. Basic fuel is brown coal from Middle Bosnia coal basin, mixed in two coal blends and one coal-woody biomass blend, to combine an effect of fuel characteristics variation on NO emission. Results shows that x an average reduction of NO emission over tested temperature range, when using over x fire air against conventional air supply with over fire air switched off, is 26.5%. At this, much more NO emission reduction for two coal blends were occurred at higher x temperatures – at 1350°C and above, where an average NO emission reduction is x 32.5%. Furthermore, it was found that the NO emission decreased with an increase in x distance of over fire air nozzles from the outlet level of burner until a distance of 1/3 of total furnace length; with further increase of the distance, NOx emission is stabilised and no further effect to NOx emission reduction was observed, while CO emission and unburnt increased.